Parental and peer support and modelling in relation to domain-specific physical activity participation in boys and girls from Germany.

BACKGROUND: Physical activity (PA) as a precondition of child development is related with social environmental correlates. However, domain-specific PA and gender issues have been neglected in studies on social support and modelling and PA in school-aged children. The aim of this study was to assess the relationships of parental and peer modelling and social support with domain-specific PA participation in a large sample of school-aged children, taking gender into account.
METHODS: 3,505 school children aged 6 to 17 years old participated in the German nationwide 'MoMo' cohort-study. By using the MoMo-PAQ the participants and their parents provided self-report data on perceived social support and social modelling and domain-specific PA participation. Relationships of social environmental variables and the physical outcomes were analysed by logistic regression analyses.
RESULTS: At secondary school level, girls were less likely than boys to participate in physical activity in and outside of sports clubs, extra-curricular physical activity and in outdoor play (p < 0.05), but at primary school level this pattern only applied to club sport (p < 0.01). Girls also received less social support than boys (p < 0.01). Physical activity participation in all domains was associated with any of the social support and modelling variables and differences between physical activity domains and between boys and girls occurred. Most consistently physical activity in sports clubs was related with the social environmental correlates in boys (primary school: R2 = 0.60; secondary school: R2 = 0.45) and girls (primary school: R2 = 0.53; secondary school: R2 = 0.47).
CONCLUSIONS: In future, reciprocal relationships of social environmental variables and PA should be considered in longitudinal studies to obtain insights into the direction of the associations. Furthermore, interventions encompassing the social environment and focussed particularly on the promotion of domain-specific PA in girls in secondary school-age are warranted.

Introduction

Physical activity and sports are essential protective factors for many non-communicable diseases like diabetes mellitus, and dementia and strongly related to cardio-metabolic biomarkers, physical fitness, bone health, quality of life, and psychological distress [1, 2]. Furthermore, regular physical activity can increase life-expectancy [3] and physical activity is a precondition for the motoric, cognitive, emotional and social development of children [4]. However, in Germany, only 17.4% of boys and 13.1% of girls comply with the physical activity guidelines of the World Health Organization [5], which recommend a minimum of 60 minutes of at least moderate physical activity per day [6].

There is a gap in levels of physical activity and physical activity participation between male and female children starting early in life and continuing through adulthood until old age [7-10]. In Germany, gender differences in physical activity participation favouring males can be observed already from the age of four onwards [5] and are also pronounced in later stages of life [11]. Gender-related social constructive theories such as “doing gender” or the socialisation theory [12] partly ascribe gender differences between boys and girls to social and cultural norms and socialisation processes. Although traditional and conventional ways of seeing boys and girls and even stereotypical gender roles are more flexible in the field of physical activity and sports, there are still predominant role concepts [13, 14]. Many sports and leisure-time physical activities do not comply with traditional images of femininity [15]. Thus, girls are less likely to engage in physical activity and sports activities–especially in seemingly typical masculine activities like playing soccer [16]–as this is not compatible with their learned female behavioural role [15].

Additionally, the social environment probably reacts differently to girls and boys: first, as many physical activities and sports are viewed as traditionally masculine (e.g., boxing or soccer) or feminine (e.g., synchronised swimming), parents, peers or caregivers are more likely to nudge children to choose activities that comply with their gender roles based on these stereotypes [17]. Second, the encouragement of significant reference persons to engage in sports and physical activity participation might be greater in boys than in girls, because physical activities in principle are rather assigned to masculine behaviour [18, 19]. Third, based on Social Learning Theory [20], children`s behaviour and behavioural choices are also affected by social models, and it has been indicated that children are more likely to imitate behaviours of same-sex models [21]. The same-sex imitation hypothesis assumes that imitation of social models occurs as a function of credibility and relevance of the social model, so that children tendentially prefer imitation of the same-sex parent [21]. Thus, girls possibly have fewer same-sex models for physical activity because women and especially their mothers are less active than the fathers as available male role models for boys [22, 23].

Overall, parental and peer modelling and social support are considered to enable or to foster physical activity participation in children and youth. Parental modelling of activity is positively related to children’s participation in physical activity like outdoor play, sports or walking for transport [24-27]. For example, the provision of instrumental support like driving a child to places where they can play sports or buy equipment are necessary assistances to engage in some sporting activities. Concerning support from parents, evidence on positive relationships of tangible and intangible social support on youth’s physical activity were obtained from many studies as summarised in review articles [28, 29]. In a study of fifth grade students from Germany, Schoeppe et al. [30] confirmed the same-sex imitation hypotheses by finding relationships between girls’ leisure-time physical activity and maternal sport participation and between boys’ activity and paternal sport participation. Similar results were found by Lijuan et al. [31] in Chinese children, by Kirby et al. [32] in Scottish adolescents, and by Cheng et al. [33] in Brazilian adolescents. Another study from Germany reported positive relationships of social support and social modelling from parents and moderate-to-vigorous physical activity (MVPA) in elementary school children and also emphasised gender differences in MVPA, but did not analyse parental influences on MVPA separately for both genders [27]. Schmiade and Mutz [34] also ascertained that social support and parental modelling predicted children’s participation in organised sports courses in preschool children from Germany, but did not focus on differences between boys and girls. Focussing on gender differences in the provision of social support, Hoefer et al. [35] found parents being more likely to transport boys to physical activity locations than girls. However, in a recent study of 11-year old children from Shanghai [36] no gender differences in terms of logistic support and explicit modelling for physical activity of parents were observed.

Some studies also indicated the role of social support and social modelling from peers predicting physical activity in children and adolescents. The presence of peers and the presence of peers being physically active were associated with an increase in physical activity in a wide range of children and adolescents from the age of 3–5 to 15 years old [37-40]. In a study of adolescents from central England boys also perceived more peer support than girls [41].

In relation to the course from childhood to adolescence, it has been assumed that the significance of parental modelling and support declines in favour of an increase of the significance of peer modelling and support [42]. However, this has only been confirmed by few studies that simultaneously examined parental and peer influences on physical activity in relation to age groups [32, 38, 43].

In summary, until now a large body of scientific literature on the relationships of social support and social modelling with physical activity in children and adolescents is available. However, previous research has sparsely focussed on gender differences concerning this relationship. Little is known about gender differences in the provision of social support from parents and peers. Furthermore, previous studies analysing the effects of social support have mainly concentrated on overall or leisure time physical activity [29, 43], or on active transportation [44], but did not take a large variety of different domains of physical activity like physical activity in sports clubs, extra-curricular physical activity, and outdoor play into account [45]. Nevertheless, in a study on social influences on adolescent health-related physical activity in structured and unstructured settings Spink and colleagues [46] showed that in structured settings peer compliance predicts membership in high active groups, and in unstructured settings peer conformity is additionally relevant for participation in high active groups. Thus, we hypothesize that for specific domains different types and providers of social support and social modelling are relevant.

Taking the previous mentioned research gaps into account, the aim of this study is to examine gender differences in parental and peer support and modelling for physical activity participation, and the relationship of parent and peer social support and modelling with domain-specific physical activity participation in a large sample of children and adolescents from Germany.

Material and methods

Study design

The MoMo Study is a nationwide study on physical fitness and physical activity in German children and adolescents, and part of the German Health Interview and Examination Survey for Children and Adolescents, KiGGS [47, 48]. To ensure a diverse sample of German children and adolescents, a nationwide, stratified, multi-stage sample with three evaluation levels was drawn [49]. First, a systematic sample of 167 primary sampling units was selected from an inventory of German communities stratified according to the BIK classification system that measures the level of urbanisation and the geographic distribution [48]. The probability of any community being picked was proportional to the number of inhabitants younger than 18 in that community. Second, an age-stratified sample of 28,400 randomly selected children and adolescents was drawn from the official registers of local residents. 17,641 participated in the KiGGS Baseline study (62.1%) between 2003 and 2006. At the second measurement point (KiGGS Wave 1 study) a total of 12,368 children and adolescents participated [50]. 6,076 out of those 12,368 participants were randomly assigned to MoMo Wave 1. The final number of participants aged 4–17 years in MoMo Wave 1 was 3,994. After exclusion of children who do not attend primary or secondary schools (mainly aged 4 and 5), a total of 1,388 primary and 2,117 secondary school children remained, building the final sample of this cross-sectional study.

Data collection

MoMo Wave 1 data was collected between 2009 and 2012. In the MoMo Study data on physical activity was collected at central locations at the aforementioned 167 stratified sample points in Germany which were close to the participants’ homes. In order to avoid systematic bias in the study results by regional or seasonal trends, the sequence of sample points visited for data collection was laid down beforehand in a random route planning. After being approached by an information letter and providing written informed consent, the children and adolescents were examined in the presence of a qualified interviewer on site [47]. Children and adolescents answered a questionnaire on their physical activity behaviors and on social environmental aspects (up to the age of 11 they did so with the help of their parents). The survey was conducted in German language.

Participation in both surveys was voluntary and anonymous and participants were informed about data security regulations prior to the investigation. Data on socio-demographics (socioeconomic status, migration background) was obtained in the KiGGS Wave 1 survey by means of telephone-based interviews. Both parents of children and adolescents up to age 17 as well as their children (from age 11) were interviewed. The survey was administered by a German-language interviewer.

Measures

Physical activity participation

The MoMo Physical Activity Questionnaire (MoMo-PAQ) was used to assess self-reported habitual physical activity in different domains (physical activity in sports clubs, leisure-time physical activity outside of sports clubs, physical education, extracurricular physical activity, outdoor play, active commuting to school) in children and adolescents [51]. The MoMo-PAQ consists of 28 items and measures different domains of physical activity in a normal week, without a defined reference period. Data obtained with the MoMo-PAQ are moderately reliable (test-retest reliability: ICC = 0.68) [52]. The original verion of the MoMo-PAQ is available elsewhere [51, 53].

Participants were asked if they regularly participate in physical activity in sports clubs. They could list up to four different physical activities in sports clubs they regularly engage in. A dichotomous variable “physical activity in sports clubs” was built according to 1–“regular participation in physical activities in sport clubs” or 0–“no physical activities in sport clubs”.

Additionally, participants were asked to if they regularly participate in physical activities outside of sports clubs (e.g., playing soccer with friends, jogging, or Inline skating). They could state up to four unorganised, leisure-time physical activities taking part outside of sports clubs. A dichotomous variable “physical activity outside of sports clubs” was built according to 1–“regular participation in physical activities outside of sports clubs” or 0–“no physical activities outside of sports clubs”.

Extra-curricular physical activity participation was assessed by a question about whether the participants attend in extra-curricular physical activities. Extra-curricular physical activities are common in German schools. For example they include soccer, dancing, or ball sport courses for which interested school children can apply voluntarily. These courses usually take part every week and the attendees take part on a regular basis. For data analysis a dichotomous variable “extra-curricular physical activity” was built according to 1–“regular participation in extra-curricular physical activities” or 0–“no extra-curricular physical activities”.

Unorganised outdoor play was assessed by an 8-scaled item about days per week in which the child or adolescent plays outside (“How often do you normally play outside during a week (for example: playing tag, skipping rope or going to the swimming pool)?”). A dichotomous variable “outdoor play” was built according to 1–“four or more days per week with outdoor play” or 0–“no to three days per week with outdoor play”.

Commuting to school was assessed by a question about how the children and adolescents commute to school most of the time [7]. A dichotomous variable “active commuting to school” was built according to 1–“by foot or by bike, pedal-scooter or other active commuting modes” or 0–“by motor vehicle, train, bus or other inactive commuting”.

Parental and peer modelling

Paternal and maternal modelling were measured by two single items (e.g., “Does your father regularly do sports?”) which had a dichotomous answer format of 1–„yes”and 0–„no“. Peer modelling was also measured by a single item („How many of your friends regularly do sports?“) with a four-point rating scale ranging from 1–“none” to 4–“most of my friends”.

Parental and peer support

Parental support scales followed the theoretical basis from Uchino [54] who postulated four functions of social support encompassing emotional, instrumental/tangible, informational, and companionship support for being related to physical activity. Each scale included the mean score (possible range: 1–4) of two items which were based on a four-point rating scale (e.g., for emotional support: “How important is sport in your family?” 1– “not at all” to 4– “very important”). Peer support included the mean score (possible range: 1–4) of a scale containing three items which were also based on a four-point rating scale (e.g., “How often do your friends ask you if you want to play outside or do sport with them (e.g., playing soccer. Riding a bicycle. Inline skating)?” 1– “never” to 4– “always”). The scales on social support had good or moderate test-retest reliability over a period of one week (test-retest reliability: ICC = 0.83; ICC = 0.67) [53]. The social support scales and further information on their validity and reliability are presented elsewhere [53].

Confounding factors (sociodemographic correlates)

A migration background was assumed if the participant themselves had immigrated to Germany, if at least one parent was not born in Germany, or if both parents immigrated to Germany or had no German nationality [55]. Individual-level socioeconomic status (SES) was derived separately for both parents and included items on educational and professional status and the total household income [56]. The higher of the two parental scores was used for analysis. Participants with separated parents were assigned the socioeconomic status of the parent they lived with. All three aspects income, educational and professional status were scored on a scale from 1 to 7 and a sum score was created (range: 3–21) and categorized into low (3–8), medium (9–14) and high (15–21) socioeconomic status [57]. The type of residential area was defined according to the number of residents living in the participant’s hometown differentiated in rural area (<5,000 residents), small town (5,000–19,999 residents), medium-sized town (20,000–99,999 residents) and city (>99,999 residents). Additionally, the “region in Germany” (former East and West Germany) was captured.

Statistical analysis

All analyses were conducted with SPSS Version 25. Socio-demographic characteristics were analysed using descriptive statistics (mean and standard deviation for continuous variables and frequency in percentage for categorical variables). Chi2-tests and t-tests were used to determine gender differences in social support, social modelling and PA outcome variables.

In order to analyse the different effects of parental and peer modelling and support on variables of domain-specific physical activity participation, multiple separate logistic regressions with the different dichotomous physical activity variables as dependent variables, the modelling and support variables as correlates and age, socioeconomic status, region in Germany, residential area, and migration background as confounders were run. From these logistic regressions, odds ratios (OR) which express the influence of the different modelling and support scales on the fact whether a participant is active or not were obtained. Higher levels express a higher chance to be active in the specific domain with higher amounts of social support or positive modelling.

Results

Sample description

Data from 3,505 (1,788 girls, 1,717 boys) children and adolescents was eligible for the analysis in the current study. The age of the children and adolescents participating in the study ranged from 6 to 17 years, with a mean of 11.97 (SD = 3.26) years. Further information on socio-demographic characteristics of the study sample is presented in Table 1.

Table 1

Description of the study sample [n (%)].

	Overall (N = 3505)	Girls (n = 1788)	Boys (n = 1717)
School-type
primary school children	1388 (39.6)	699 (39.1)	689 (41.1)
secondary school children	2117 (60.4)	1089 (60.9)	1028 (59.9)
Socioeconomic status
low	255 (7.7)	124 (7.3)	131 (8.2)
medium	2159 (65.4)	1120 (66.2)	1039 (64.7)
high	885 (26.8)	448 (26.5)	437 (27.2)
Migration background
yes	216 (6.2)	103 (5.8)	113 (6.6)
no	3289 (93.8)	1685 (94.2)	1604 (93.4)
Residential area
rural area	839 (23.9)	413 (23.1)	426 (24.8)
small town	1122 (32.0)	585 (32.7)	537 (31.3)
medium-sized town	979 (27.9)	490 (27.4)	489 (28.5)
city	565 (16.1)	300 (16.8)	265 (15.4)
Region in Germany
former east	1141 (32.6)	587 (32.8)	554 (32.3)
former west	2364 (67.4)	1201 (67.2)	1163 (67.7)

Note. N = total sample size; n = group sample size

Social support and social modelling in relation to gender

Gender differences in social support and social modelling are presented in Table 2. In all categories the mean value of social support was higher in primary school children than in secondary school children. In relation to gender, boys received more peer support than girls in primary as well as secondary school children. Furthermore, boys in primary school had higher levels of parental companionship support and in secondary school higher levels of parental emotional and informational support than girls. Additionally, peer modelling was higher in boys than in girls in both school levels. No gender differences were found in parental modelling. A higher percentage of maternal modelling was found than paternal modelling.

Table 2

Social support, social modelling and physical activity in different domains by gender and grade level.

		Primary school-children					Secondary school-children
		Descriptive statistics			Bivariate analyses		Descriptive statistics			Bivariate analyses
		overall	boys	girls	t or chi2	p-value	overall	boys	girls	t or chi2	p-value
Peer support	Mean ± SD	2.78 (0.55)	2.82 (0.56)	2.74 (0.53)	2.55	0.011*	2.59 (0.61)	2.70 (0.59)	2.48 (0.60)	8.44	<0.001***
Parental emotional support	Mean ± SD	3.07 (0.55)	3.10 (0.56)	3.05 (0.55)	1.63	0.104	2.95 (0.65)	3.00 (0.63)	2.98 (0.66)	3.84	<0.001***
Parental informational support	Mean ± SD	3.10 (0.53)	3.12 (0.54)	3.07 (0.52)	1.60	0.109	2.82 (0.64)	2.86 (0.64)	2.79 (0.64)	2.68	0.007**
Parental instrumental support	Mean ± SD	3.11 (0.76)	3.12 (0.77)	3.09 (0.75)	0.78	0.434	2.86 (0.79)	2.89 (0.79)	2.83 (0.79)	1.66	0.098
Parental companionship support	Mean ± SD	2.53 (0.56)	2.58 (0.58)	2.48 (0.54)	3.37	<0.001***	2.06 (0.68)	2.09 (0.70)	2.03 (0.66)	1.86	0.064
Peer modelling	Mean ± SD	3.07 (0.78)	3.12 (0.78)	3.03 (0.78)	2.04	0.042*	3.16 (0.79)	3.32 (0.73)	3.02 (0.82)	8.81	<0.001***
Paternal modelling	% yes	47.2	46.8	47.7	0.09	0.762	47.9	48.1	47.8	0.02	0.886
Maternal modelling	% yes	52.9	51.7	54.2	0.87	0.350	53.5	51.7	55.2	2.68	0.102
Physical activity in sports clubs	% participating	66.8	70.7	62.9	9.61	0.002**	65.3	71.9	59.0	38.41	<0.001***
Extra-curricular physical activity	% participating	26.1	27.6	24.7	1.51	0.219	16.6	18.4	14.8	4.54	0.033*
Physical activity outside of sports clubs	% participating	44.5	44.3	44.7	0.02	0.884	49.7	52.6	46.9	6.62	0.010*
Outdoor play	% with ±4 day/week	95.9	95.6	96.3	0.36	0.548	68.0	73.2	63.0	25.14	<0.001***
Active commuting to school	% active commuters	56.8	55.5	58.0	0.89	0.347	45.0	44.4	45.6	0.28	0.599

Note.

*p < .05

**p < .01

***p < .001.

Gender differences were also found in physical activity participation in sports clubs in both primary and secondary school children, with girls being less often physically active in sports clubs than boys. Furthermore, in secondary school children, girls were less likely to be physically active outside of sports clubs, in extra-curricular physical activity, and in outdoor play, but not in active commuting to school.

Logistic regression analyses on the relationships of the social environment on physical activity

The results of the logistic regression analyses are presented separately in one table for each domain (Tables 3 to 7). With one exception in the models of active commuting to school, all significant relationships found in our analyses were positive relationships (the more/higher the support or modelling, the higher the chance to be physically active).

Table 3

Relationships of social support and modelling and physical activity participation in sports clubs.

	Primary school children						Secondary school children
	boys			girls			boys			girls
		95% CI			95% CI			95% CI			95% CI
	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound
Peer support	1.55**	1.12	2.15	1.35	0.98	1.87	2.97***	2.28	3.86	1.83***	1.46	2.29
Parental emotional support	6.16***	4.15	9.15	3.79***	2.67	5.38	5.63***	4.23	7.52	3.86***	3.02	4.92
Parental informational support	6.22***	4.18	9.24	4.80***	3.30	6.99	4.69***	3.59	6.12	3.51***	2.77	4.44
Parental instrumental support	10.67***	7.22	15.75	8.36***	5.90	11.85	6.11***	4.71	7.92	5.92***	4.63	7.57
Parental companionship support	3.13***	2.20	4.46	1.64**	1.19	2.28	2.88***	2.26	3.67	2.40***	1.92	3.02
Peer modelling	2.27***	1.76	2.93	2.28***	1.78	2.91	2.80***	2.27	3.45	2.72***	2.26	3.26
Paternal modelling	1.89**	1.30	2.76	1.92***	1.35	2.73	2.34***	1.74	3.16	1.57**	1.20	2.04
Maternal modelling	1.59*	1.10	2.29	1.65**	1.17	2.33	1.85***	1.38	2.47	1.51*	1.16	1.96
R2(all predictors)	0.60			0.53			0.45			0.47

Note. All models were adjusted for age, socioeconomic status, region in Germany, residential area, and migration background

*p < .05

**p < .01

***p < .001.

Table 7

Relationships of social support and modelling and active commuting to school.

	Primary school children						Secondary school children
	boys			girls			boys			girls
		95% CI			95% CI			95% CI			95% CI
	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound
Peer support	1.41*	1.05	1.90	1.37*	1.00	1.88	1.06	0.85	1.32	1.02	0.83	1.27
Parental emotional support	1.11	0.83	1.48	1.12	0.83	1.51	0.96	0.78	1.18	1.18	0.97	1.44
Parental informational support	1.20	0.95	1.70	0.93	0.69	1.28	0.92	0.75	1.13	1.15	0.94	1.40
Parental instrumental support	0.72**	0.58	0.90	0.81	0.65	1.02	0.69***	0.58	0.81	0.94	0.80	1.11
Parental companionship support	1.05	0.79	1.40	0.80	0.59	1.09	0.89	0.74	1.08	1.11	0.91	1.35
Peer modelling	1.15	0.93	1.43	1.21	0.98	1.51	0.85	0.71	1.01	0.97	0.83	1.14
Paternal modelling	1.40*	1.01	1.95	1.68**	1.20	2.35	0.96	0.74	1.24	1.20	0.93	1.55
Maternal modelling	1.52*	1.10	2.10	1.70**	1.22	2.37	1.14	0.88	1.48	0.83	0.65	1.08
R2(all predictors)	0.11			0.13			0.11			0.11

Note. All models were adjusted for age, socioeconomic status, region in Germany, residential area, and migration background

*p < .05

**p < .01

***p < .001.

Regarding physical activity participation in sports clubs, all social support and social modelling indicators were significantly related with the outcome in both age groups in boys and in girls attending secondary schools (Table 3). In girls from primary schools, only peer support was not related to physical activity in sports clubs. The explained variance was highest in the regression model for physical activity in sports clubs in comparison to the other physical activity domains in all age and gender groups (0.45 to 0.60).

Extra-curricular physical activity participation was associated with parental support in boys and girls from primary schools and with peer support, peer modelling, and parental support in children from secondary schools (Table 4). Additionally, paternal modelling was related to extra-curricular physical activity in girls from secondary schools.

Table 4

Relationships of social support and modelling and participation in extra-curricular physical activity.

	Primary school children						Secondary school children
	boys			girls			boys			girls
		95% CI			95% CI			95% CI			95% CI
	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound
Peer support	1.23	0.88	1.72	1.02	0.72	1.46	2.35***	1.71	3.24	1.74**	1.27	2.38
Parental emotional support	1.85***	1.31	2.62	1.46*	1.03	2.07	1.49**	1.13	1.97	1.67**	1.25	2.24
Parental informational support	1.70**	1.19	2.42	1.64*	1.12	2.39	1.32*	1.01	1.73	1.37*	1.03	1.83
Parental instrumental support	1.75***	1.35	2.27	1.33*	1.03	1.72	1.36**	1.10	1.69	1.66***	1.30	2.12
Parental companionship support	1.22	0.88	1.70	1.43*	1.01	2.04	1.25	0.98	1.60	1.45**	1.11	1.92
Peer modelling	1.21	0.95	1.56	1.00	0.77	1.28	1.50**	1.18	1.92	1.47**	1.17	1.86
Paternal modelling	1.18	0.81	1.73	1.11	0.76	1.62	1.34	0.95	1.89	1.66**	1.15	2.38
Maternal modelling	1.25	0.85	1.83	1.10	0.75	1.62	1.03	0.73	1.45	0.87	0.68	1.39
R2(all predictors)	0.14			0.09			0.12			0.11

Note. All models were adjusted for age, socioeconomic status, region in Germany, residential area, and migration background

*p < .05

**p < .01

***p < .001.

Explained variances in the models of physical activity outside of sports clubs were low (0.04 to 0.08) (Table 5). In these models, peer support was only related to extra-curricular physical activity participation in secondary school children and peer modelling with extra-curricular physical activity of boys also from secondary schools. Parental emotional support was related to physical activity participation in boys in both age groups and parental companionship support with physical activity participation in girls and boys from primary schools and girls from secondary schools. Furthermore, paternal and maternal modelling were associated with physical activity participation in secondary school girls and maternal modelling also with boys from primary schools.

Table 5

Relationships of social support and modelling and participation in physical activity outside of sports clubs.

	Primary school children						Secondary school children
	boys			girls			boys			girls
		95% CI			95% CI			95% CI			95% CI
	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound
Peer support	1.28	0.95	1.73	1.24	0.91	1.68	1.85***	1.47	2.33	1.74***	1.40	2.16
Parental emotional support	1.41*	1.04	1.90	1.24	0.92	1.66	1.24**	1.01	1.52	1.06	0.87	1.28
Parental informational support	1.35	1.00	1.83	1.22	0.90	1.65	1.12	0.91	1.37	1.05	0.86	1.27
Parental instrumental support	1.05	0.84	1.30	1.03	0.83	1.28	1.08	0.92	1.27	1.08	0.92	1.27
Parental companionship support	1.84***	1.36	2.48	1.59**	1.17	2.16	1.11	0.92	1.34	1.26*	1.03	1.53
Peer modelling	1.13	0.91	1.41	1.18	0.95	1.46	1.44***	1.20	1.72	1.02	0.87	1.19
Paternal modelling	1.08	0.77	1.50	0.96	0.69	1.33	1.14	0.88	1.48	1.37*	1.07	1.77
Maternal modelling	1.56**	1.12	2.17	1.35	0.97	1.88	1.27	0.98	1.64	1.40**	1.09	1.80
R2(all predictors)	0.07			0.04			0.08			0.07

Note. All models were adjusted for age, socioeconomic status, region in Germany, residential area, and migration background

*p < .05

**p < .01

***p < .001.

Concerning outdoor play peer support was significantly related to the outcome in all age and gender groups and additionally, all parental support constructs and peer modelling were also significant correlates in boys and girls from secondary schools (Table 6).

Table 6

Relationships of social support and modelling and regular outdoor play.

	Primary school children						Secondary school children
	boys			girls			boys			girls
		95% CI			95% CI			95% CI			95% CI
	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound	OR1	Lower bound	Upper bound
Peer support	4.27***	1.88	9.72	5.25***	2.17	12.73	3.65***	2.47	4.86	3.81***	2.88	5.03
Parental emotional support	1.98	0.80	4.92	1.22	0.51	2.94	1.63***	1.28	2.07	1.39**	1.11	1.74
Parental informational support	2.02	0.87	4.67	1.83	0.77	4.35	1.78***	1.41	2.25	1.42**	1.13	1.78
Parental instrumental support	1.35	0.72	2.52	1.78	0.91	3.45	1.46***	1.21	1.76	1.22*	1.01	1.47
Parental companionship support	1.89	0.79	4.52	2.16	0.78	6.00	1.75***	1.38	2.22	1.49**	1.28	1.88
Peer modelling	1.77	0.92	3.43	1.07	0.55	2.07	1.65***	1.34	2.04	1.23*	1.03	1.49
Paternal modelling	1.36	0.51	3.66	2.44	0.75	7.94	1.29	0.95	1.76	1.13	0.84	1.52
Maternal modelling	1.21	0.45	3.27	1.25	0.44	3.55	1.18	0.87	1.61	1.01	0.75	1.36
R2(all predictors)	0.27			0.25			0.31			0.42

Note. All models were adjusted for age, socioeconomic status, region in Germany, residential area, and migration background

*p < .05

**p < .01

***p < .001.

Concerning active commuting to school, in the present study paternal and maternal modelling and peer support were significantly associated with the outcome in primary school children (in boys and girls) (Table 7). Additionally, parental instrumental support was negatively related to active commuting to school in boys from primary as well as from secondary schools, indicating that the boys were less likely to actively commute to school if their parents provided more instrumental support for physical activity.

Discussion

The present study revealed gender differences in parental and peer support and modelling for physical activity participation. Additionally, we found associations of social support and social modelling on physical activity participation in a variety of different physical activity domains in a large sample of children and adolescents from Germany. By considering gender differences and by taking physical activity in different domains into account, this study provides differentiated information on the relationship of social behaviour on physical activity in youth. Overall, the results of this study revealed that gender and physical activity domains matter with respect to social behavioural relationships with physical activity in children and adolescents.

In the present study girls were less likely to be physically active than boys in almost all domains of physical activity. These finding was expected, given the fact that previous studies also presented gender differences in overall physical activity and MVPA that became more apparent in the transition from childhood to adolescence [5, 8, 58]. Previous reviews [59, 60] revealed that there is an annual decline in physical activity during adolescence (age 10–19 years) and that the decline has increased during the early stage of adolescence in girls. Contrary, in boys the decline in physical occurs during the later stages. The authors assumed that these findings might be an effect of sexual maturation, which usually happens earlier in girls compared to boys. However, social influences are also conceivable as a reason for gender differences and for declines in physical activity in the transition from childhood to adolescence [61]. Hence, future health promotion programs should especially focus on the early stage of adolescence in girls (up to the age of 13) and the older adolescent boys (from 13 years of age on). They should particularly prevent declines in physical activity during adolescence and aim to prevent the emergence of physical activity inequalities in adolescent boys and girls.

One reason for gender inequalities in physical activity in different domains could be the differences in social support perceived from peers and parents. The present study showed in accordance with other studies of children in grades five to eight from the US [35, 62], that girls received less social support from parents and from their peers than boys. Furthermore, in the present study the differences in levels of social support in boys and girls seem to be greater in secondary school children than in primary school children. However, there are no differences in instrumental support, indicating that parents do not differentiate between sons and daughters when providing instrumental support, for example, by driving their child to sports facilities or by buying them sports equipment. Nevertheless, some previous studies did not suggest that girls receive less parental support for physical activity than boys [31, 63, 64]. Another possibility is, that higher levels of physical activity in boys which have been found in many studies [5, 8, 9], require higher levels of social support, which could lead to a higher readiness of parents or peers to provide support [62]. Therefore, it is possible that boys receive more parental support for physical activity than girls because they claim for more support to conduct their activities.

Contrary to previous studies showing that mothers have a higher risk of inactivity than fathers [23, 65, 66] and that women are less active than men [67], we found no significant differences in modelling in mothers and fathers. However, our indicators on parental modelling were based on the children’s and adolescents’ reports. As a result these are indicators of perceived modelling and do not display the objective/real behaviour of the parents. Thus, the findings of the present study could be a result of the higher presence of mothers in the households taking care of their children and having their physical activity recognised by their children. Even if fathers were more active than mothers, this might not have been recognised by their children when they were asked about regular physical activity of their fathers and mothers. Imitation of social models is a function of awareness of social modelling behaviour and only occurs if the model has been recognised and was significant for the child [20].

However, same-sex hypothesis could not be confirmed in the present study. Imitation of same-sex models was not observed in most domains. This could be due to changing role models of mothers and fathers in Germany. Hence, family policies are changing in Germany and more families break out of traditional roles and today mothers are more often employed and fathers are more often taking care of their children and the household [68]. Consequently, role behaviour in regard to physical activities, sports and play could change and probably other mechanisms of social learning than same-sex imitation could occur. Further studies on social support and modelling in relation to physical activity should take into consideration who takes care of the child and to what extent.

With respect to peer modelling and support, boys reported having more physically active friends and perceived more peer support than girls, in line with expectations given the facts that more boys are regularly physically active than girls, and that youth tend to surround themselves with same-sex peers [69]. Additionally, in accordance with increasing differences in physical activity levels between boys and girls from childhood to adolescence, gender differences in peer modelling were more prevalent in secondary school children than in primary school children. As peer modelling and support were associated with a number of domain-specific physical activity measures, interventions targeting peer groups could be effective in promoting physical activity [70, 71].

Concerning the relationship of social support and social modelling with domain-specific physical activity, physical activity in sports clubs was most consistently related with the social environmental variables. Another study with adolescent girls, also found that parental and peer support were associated with sports club membership [72]. In Germany a high proportion of children and adolescents (42.2%– 71.6% depending on age and gender group) are members of sports clubs and are regularly playing sports in a club [73]. Thus, sports clubs play a central role in offering organised and instructed physical activity opportunities, and parents and peers are important instigators for boys and girls of all school-age groups. Lower levels of physical activity participation in sports clubs in girls, especially in older girls from secondary schools, could be traced to the lower levels in some kinds of social support they receive in comparison to boys.

With respect to physical activity outside of sports clubs such as free inline skating during leisure-time, jogging, or skating on halfpipe facilities that are not organised, the relevance of parents as providers of social support seem to give way to peers when transitioning from primary to secondary school. This is in line with previous studies, indicating a shift from the relevance of parents towards a growing significance of peers when children grow older [42, 62]. However, parental companionship and modelling of physical activity are still relevant factors in relation to physical activity outside of sports clubs in secondary school girls, indicating that parents might be important facilitators for leisure-time physical activity in adolescent girls. This is also true with regard to outdoor play which was also correlated with all parental support constructs in secondary school children. Morrissey and colleagues [74] who examined family support and non-school physical activity levels in adolescents also found relationships of family support with out of school physical activity. Thus, the importance of parents as promoters of physical activity seems to maintain in adolescence with respect to unorganised physical activities.

Furthermore, in regard to outdoor play and extra-curricular physical activity, the relevance of the social environment grows from primary to secondary school, but no differences in boys and girls were observed. In primary school children outdoor play was fostered by peers. Since parents tend to offer more independent outdoor play to their child if he or she is accompanied by a friend [75], peer support could be a facilitator of outdoor play for younger children regardless of gender. Equally in secondary school children, peers remain important supporters of outdoor play and all types of parental support were relevant factors.

As found in another study [44], peer support and parental modelling fostered walking or biking to school in boys, and girls from secondary school. Unexpectedly, parental instrumental support negatively predicted active commuting to school in boys which were the only negative associations between social environmental constructs and domain-specific physical activities in our study. However, one of the two items of the instrumental support variable included the question on how often parents drive their child to sports facilities. Obviously, parents who are willing to drive their child to sports facilities are also more likely to drive their child to school instead of recommending active modes of transport to school. Nevertheless, there is no explanation why this relationship was only found in boys.

Strengths and limitations

The strength of the current study is the examination of the relationships of social modelling and social support on physical activities in a variety of different domains in a nationwide large sample of children and adolescents. The study showed that these relationships were different regarding different physical activity domains and the mechanisms of social influences on children’s and adolescents’ physical activity seem to differ between physical activities in different domains. Thus, this study contributes to a better understanding on social influences on physical activity by taking domain-specific physical activity into account instead of focusing on overall physical activity or on MVPA. Furthermore, the large sample size and the inclusion of children and adolescents with a wide age range enabled an analysis of differences between primary and secondary school children. Additionally, due to the fact that the data was drawn from a nationwide study conducted in 167 communities in Germany the results of this study have a high degree of representativeness.

Nevertheless, some limitations of the study have to be mentioned. First, the data of this study is cross-sectional and does not allow for the analysis of causal relationships. Therefore, we do not know the direction of the relationships found, and it is also possible that the physical activity behaviour of the children and adolescents influenced the social environment instead of the other way around. Second, all data was captured from self or proxy reports and is prone to bias. For example, as in younger children parental reports were used to capture social support and social modelling, it is possible that parents misjudged the data. In addition, it is possible that the children did not perceive the same level of support and modelling as gauged by their parents. Third, only unspecified social support and modelling from parents and peers has been considered, and no domain-specific support and modelling data have been captured (e.g. parental informational support for active commuting to school or peer support for physical activity in sports clubs). However, Giles-Corti and colleagues [76] recommended measures to be behaviour- and context-specific. Furthermore, it could be relevant to take the family model and the main caregiver into account. Thus, further research should differentiate between social support from main caregivers and other relatives and should consider if the child lives in a single-parent family, in a traditional family, or in alternative family units.

Conclusion

In conclusion, the present study provided comprehensive data from Germany on social support and social modelling of peers and parents and domain-specific physical activity of school children by taking gender into account. The results emphasised that these relationships vary by gender, age and physical activity domain and clearly indicate the need for the consideration of these aspects in future research. As stated by Giles-Corti et al. [76], research on environmental correlates of physical activity should be based on behaviour-specific measures that are used to predict context-specific behaviours. To go along with this recommendation, future research should focus on domain-specific physical activity behaviours and further use domain-specific social support and social modelling variables. As differences in social support between structured and unstructured physical activity settings have been observed by our study and by Spink and colleagues [46], these aspects should be observed in future research. Moreover, the reciprocal relationships of social environmental variables and physical activity should be considered, and longitudinal studies are necessary to get insights into the direction of the associations and the underlying mechanisms.

In interventions to promote physical activity in children and adolescents relevant providers of support and modelling should be targeted [77]. Showing that peer modelling and support were related to a number of domain-specific physical activity measures, interventions including peer groups could be promising in the promotion of physical activity [70, 71]. For the participation in organized sport activities in sport clubs, parents and peers are important providers of support and modelling in all age groups and for both genders and, thus, should be targeted in intervention programs. With regards to gender, interventions encompassing the social environment are required to break through gender norms and gendered cultures that neglect girls’ physical activity needs and provide insufficient support for physical activity to girls–especially in the secondary school age. Same-sex hypotheses postulating social learning by focussing on same-sex models has not been confirmed in the present study.

5 Sep 2019

[EXSCINDED]

PONE-D-19-17332

Parental and peer support and modelling in relation to domain-specific physical activity in boys and girls from Germany

PLOS ONE

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Reviewer #1: Introduction

Really nice integration of theory in the background. Overall nice review of literature.

Page 3, line 43 - adiposity is not a disease, it is a risk factor

Page 4, line 66 - change "probably" to "likely" or another word

Page 4, line 67 - change "typically" to "typical"

Page 5, line 95 - change "form" to "from"

Page 5, line 96 - spell out MVPA first time

Page 6, lines 119-120 - what is meant by different domains and domain-specific? This is explained in the methods, but should be introduced in this section as well

Material and Methods

Page 7, line 147 - remove comma after children

Page 8, line 170-171 - say this in the intro as examples of domains (same as comment above)

Page 8-9 - for PA in sports clubs, PA outside sports clubs, and extra-curricular PA, why were these variables dichotomized rather than used as continuous? The cutoff of 0 vs 1 or more minutes seems very arbitrary. Is this how these variables have been used in the past? I would suggest using these variables as continuous and linear rather than logistic regression for these three outcomes.

Page 14 - "...girls had a lower prevalence in physical activity..." - prevalence is not the right word here

Page 15 - Table 2 - Revise title - "Social support, social modeling, and domain-specific physical activity by gender and grade level"

Page 15 - Table 2 - Peer support, parental support, and peer modeling - doesn't make sense to me to show these as means/SD, I think you should show percents in each category as these are categorical variables. PA in sports clubs, PA outside sports clubs, and extra-curricular PA should be shown as mean number of minutes rather than "% yes". For outdoor play, if it is going to be shown as dichotomous, specify that this is the percent who said 4+ days/week.

Tables 3-5 - should be multivariate linear regression

Discussion, Strengths/limitations, conclusion

First paragraph, first sentence - split into more than one, it is long right now

Second paragraph, first sentence - revise, it is unclear

Page 28, last sentence - should it say shift rather than swift?

Page 30, last sentence - Corti, not Gorti

Add more implications for intervention work in the discussion and/or conclusion, or even a separate section

Reviewer #2: General Comment: This is an interesting study conducted with a large number of adolescents from Germany. However some aspects can still be improved in the manuscript and there are some doubts that can be better clarified throughout the text.

Comment: In the results section in the abstract, enter more information with the continuous values of the main results.

Comment: The introduction is too long, some paragraphs could be reduced to make reading more dynamic.

Comment: In the introduction, it needs to be made clear where this study is progressing compared to articles on this topic previously published in the literature.

Comment: Please insert in the methods the sample size calculation used for this study.

“Extra-curricular physical activity was assessed by a question about whether the participants attend in extra-curricular physical activities with frequency, type of activity and duration. A dichotomous variable “extra-curricular physical activity” was built according to 1–“one or more minutes extra-curricular physical activities” or 0–“no extra-curricular physical activities”.

Comment: What types of extracurricular physical activities would be considered? Please explain this further in the methods section.

Comment: A question in the methods section, did only the teens answer the questionnaires or did the teens' parents also answer some questions about social support for their children's physical activity? If so, this needs to be better addressed in the methods section.

“Participants with separated parents were assigned the socioeconomic status of the parent they lived with. All three as pects income, educational and professional status were scored on a scale from 1 to 7 and a sum score was created (range: 3–21) and categorized into low (3–8), medium (9–14) and high (15–21) socioeconomic status [57].”

Comment: This is an important aspect in the present study, please, would like the authors to present the analysis considering children of parents living together and in the other analysis children of separated parents. My question is whether children of parents living together could be more physically active when bought from children of separated parents?

Comment: In the results section, would the authors have social support information regarding parental gender? If so, it would be pertinent to analyze this relationship stratified: example: fathers x daughters; fathers x son; mothers x son; mothers x daughters.

“These findings were expected, given the fact that previous studies also presented gender differences in overall physical activity or moderate to vigorous physical activity that became more apparent in the transition from childhood to adolescence [6,9,58,59].”

Comment: Why would this happen? The authors need to advance in this aspect in the discussion.

“Another possibility is, that higher levels of physical activity in boys which have been found in many studies [5,6,9], require higher levels of social support, which could lead to a higher readiness of parents or peers to provide support [60]. Therefore, it is possible that boys receive more parental support for physical activity than girls because they claim for more support to conduct their activities”.

Comment: Would not the practice of previous physical activity of parents in their own childhood and adolescence be a factor to be considered in this relationship? Would the more physically active father throughout his life have a greater chance of his son being more physically active? So would the relationship between mothers and daughters? There is information in this sense in the literature that could be inserted as an important aspect in the discussion.

Comment: What are the practical applications of this study?

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11 Sep 2019

Response to review: Ms. No. PONE-D-19-17332

PLOS ONE

Dear Colleagues,

Please find enclosed our revision of the following research article:

“Parental and peer support and modelling in relation to domain-specific physical activity participation in boys and girls from Germany”

We would like to thank the reviewers for their comments. We believe that the quality of our manuscript has improved by implementing the suggestions and comments received. We hope we have addressed all the reviewers’ concerns and comments to your satisfaction.

Please find our response to the comments below. The reviewers’ comments are shown in regular font, and our responses are shown below each comment in italic:

Reviewer #1:

Introduction:

1. Really nice integration of theory in the background. Overall nice review of literature.

Thank you.

2. Page 3, line 43 - adiposity is not a disease, it is a risk factor

We deleted adiposity from the list of diseases.

3. Page 4, line 66 - change "probably" to "likely" or another word

Done.

4. Page 4, line 67 - change "typically" to "typical"

Done.

5. Page 5, line 95 - change "form" to "from"

Done.

6. Page 5, line 96 - spell out MVPA first time

Done.

7. Page 6, lines 119-120 - what is meant by different domains and domain-specific? This is explained in the methods, but should be introduced in this section as well

We added some more information and examples.

Material and Methods

8. Page 7, line 147 - remove comma after children

Done.

9. Page 8, line 170-171 - say this in the intro as examples of domains (same as comment above)

See above.

10. Page 8-9 - for PA in sports clubs, PA outside sports clubs, and extra-curricular PA, why were these variables dichotomized rather than used as continuous? The cutoff of 0 vs 1 or more minutes seems very arbitrary. Is this how these variables have been used in the past? I would suggest using these variables as continuous and linear rather than logistic regression for these three outcomes.

We agree with you and think, it could be also interesting to investigate the relationship of social environmental factors with the amount (level) of physical activity. However, it is also possible to consider physical activity participation as a dichotomous variable (1) and we decided to focus on whether or not the children and adolescents participated in physical activity in different domains due to various reasons: we focused on a large number of different domains of physical activity of which some are commonly measured in a dichotomous way (active vs. non-active; participation vs. non-participation). For example, in active transportation research it is very common to investigate whether a person is actively commuting or not (2-4) and research on correlates/determinants of active transportation focuses on the question which factors determine whether a person is an active or passive commuter. Regarding extra-curricular physical activity there is a similar situation (5-7). However, previous research on overall sports or physical activity participation also used dichotomised PA items (8-11). In addition, on a theoretical basis this is based on the assumption that there are different correlates/determinants of sports/physical activity participation (active vs. non-active) and of the amount of daily/weekly exercise/physical activity. Our paper focusses on participation and we revised the manuscript to make this even more conspicuous throughout the manuscript.

11. Page 14 - "...girls had a lower prevalence in physical activity..." - prevalence is not the right word here

We revised this sentence.

12. Page 15 - Table 2 - Revise title - "Social support, social modeling, and domain-specific physical activity by gender and grade level"

Done.

13. Page 15 - Table 2 - Peer support, parental support, and peer modeling - doesn't make sense to me to show these as means/SD, I think you should show percents in each category as these are categorical variables.

Our social support scales are based on more than one item (2 or 3) and thus, contain calculated mean values. That is why we presented the mean/SD in our tables as also done in other studies before (12-14).

14. PA in sports clubs, PA outside sports clubs, and extra-curricular PA should be shown as mean number of minutes rather than "% yes". For outdoor play, if it is going to be shown as dichotomous, specify that this is the percent who said 4+ days/week.

We revised the column with the information on the units given in the table. See also our answer to your comment no. 10.

15. Tables 3-5 - should be multivariate linear regression

See our answer to your comment no. 10.

Discussion, Strengths/limitations, conclusion

16. First paragraph, first sentence - split into more than one, it is long right now

Done.

17. Second paragraph, first sentence - revise, it is unclear

We revised the sentence.

18. Page 28, last sentence - should it say shift rather than swift?

We corrected this typo.

19. Page 30, last sentence - Corti, not Gorti

We corrected this typo.

20. Add more implications for intervention work in the discussion and/or conclusion, or even a separate section

We added some implications for interventions in the discussion and conclusion.

Reviewer #2:

General Comment:

21. This is an interesting study conducted with a large number of adolescents from Germany.

Thank you.

22. However some aspects can still be improved in the manuscript and there are some doubts that can be better clarified throughout the text.

Thank for your comments. We hope that, in the revised manuscript, we have addressed all your concerns and comments to your satisfaction.

Further comments:

23. In the results section in the abstract, enter more information with the continuous values of the main results.

We added some more information on the estimates of our analyses in the abstract.

24. The introduction is too long, some paragraphs could be reduced to make reading more dynamic.

We revised and shortened the introduction. However, by having the first comment from the first reviewer in mind we retained our review of the literature.

25. In the introduction, it needs to be made clear where this study is progressing compared to articles on this topic previously published in the literature.

We revised the penultimate and last paragraph of the introduction to embed our study into the state of research.

26. Please insert in the methods the sample size calculation used for this study.

The MoMo Wave 1 Study is part of the longitudinal German Health Interview and Examination Survey for Children and Adolescents, KiGGS. The survey aims to investigate and monitor health and health behaviour in children and adolescents from Germany and encompasses over 17,000 and 12,000 children and adolescents in the baseline and wave 1 data collection, respectively. In the MoMo Study as a module study of KiGGS a large proportion of the KiGGS participants could participate (in wave 1: nearly 4,000). For our research question we analysed the data from the MoMo participants that was available. Thus, no specific sample size calculation has been conducted for the research question at hand.

27. “Extra-curricular physical activity was assessed by a question about whether the participants attend in extra-curricular physical activities with frequency, type of activity and duration. A dichotomous variable “extra-curricular physical activity” was built according to 1–“one or more minutes extra-curricular physical activities” or 0–“no extra-curricular physical activities”. What types of extracurricular physical activities would be considered? Please explain this further in the methods section.

We added some more information.

28. A question in the methods section, did only the teens answer the questionnaires or did the teens' parents also answer some questions about social support for their children's physical activity? If so, this needs to be better addressed in the methods section.

No, the teens answered the questionnaires without the parents as stated in the methods section (Data collection). Just in young children up to the age of 11 had the help of their parents (but the parents did not answer some questions without the children). For a better understanding, we improved the wording in this paragraph.

29. “Participants with separated parents were assigned the socioeconomic status of the parent they lived with. All three aspects income, educational and professional status were scored on a scale from 1 to 7 and a sum score was created (range: 3–21) and categorized into low (3–8), medium (9–14) and high (15–21) socioeconomic status [57].” This is an important aspect in the present study, please, would like the authors to present the analysis considering children of parents living together and in the other analysis children of separated parents. My question is whether children of parents living together could be more physically active when bought from children of separated parents?

We agree with you that this could be a very interesting and relevant question. However, we do not have in depth data on the family model and the main caregiver. Thus, we included this relevant as an implication in the discussion section.

30. In the results section, would the authors have social support information regarding parental gender? If so, it would be pertinent to analyze this relationship stratified: example: fathers x daughters; fathers x son; mothers x son; mothers x daughters.

Unfortunately, we do not have data on parental support for mothers and fathers separately.

31. “These findings were expected, given the fact that previous studies also presented gender differences in overall physical activity or moderate to vigorous physical activity that became more apparent in the transition from childhood to adolescence [6,9,58,59].” Why would this happen? The authors need to advance in this aspect in the discussion.

We revised this paragraph and gave some deeper insights into this topic.

32. “Another possibility is, that higher levels of physical activity in boys which have been found in many studies [5,6,9], require higher levels of social support, which could lead to a higher readiness of parents or peers to provide support [60]. Therefore, it is possible that boys receive more parental support for physical activity than girls because they claim for more support to conduct their activities”. Would not the practice of previous physical activity of parents in their own childhood and adolescence be a factor to be considered in this relationship? Would the more physically active father throughout his life have a greater chance of his son being more physically active? So would the relationship between mothers and daughters? There is information in this sense in the literature that could be inserted as an important aspect in the discussion.

This is a very relevant and interesting point. We agree with you that fathers are more physically active than mothers (as stated in our manuscript in the following paragraph). However, in our study girls reported similar (in case of paternal modelling rated by secondary school-children) or higher levels of maternal and paternal modelling than boys (see table 2). Boys did not perceive to have more active fathers than girls did and additionally, boys did not perceive to have more active same-sex models than girls.

However, we revised the paragraph to sufficiently deal with this important point.

33. What are the practical applications of this study?

See our answer to comment no. 20 of reviewer #1.

1. Welk GJ. Physical activity assessments for health-related research. Champaign, Ill.: Human Kinetics; 2002.

2. Pabayo R, Gauvin L, Barnett TA. Longitudinal Changes in Active Transportation to School in Canadian Youth Aged 6 Through 16 Years. Pediatrics. 2011;128(2):E404-E13.

3. Titze S, Giles-Corti B, Knuiman MW, Pikora TJ, Timperio A, Bull FC, et al. Associations Between Intrapersonal and Neighborhood Environmental Characteristics and Cycling for Transport and Recreation in Adults: Baseline Results From the RESIDE Study. J Phys Act Health. 2010;7(4):423-31.

4. Bere E, van der Horst K, Oenema A, Prins R, Brug J. Socio-demographic factors as correlates of active commuting to school in Rotterdam, the Netherlands. Prev Med. 2008;47(4):412-6.

5. Ara I, Vicente-Rodriguez G, Perez-Gomez J, Jimenez-Ramirez J, Serrano-Sanchez JA, Dorado C, et al. Influence of extracurricular sport activities on body composition and physical fitness in boys: a 3-year longitudinal study. Int J Obes. 2006;30(7):1062-71.

6. Gracia-Marco L, Tomas C, Vicente-Rodriguez G, Jimenez-Pavon D, Rey-Lopez JP, Ortega FB, et al. Extra-curricular participation in sports and socio-demographic factors in Spanish adolescents: the AVENA study. J Sports Sci. 2010;28(13):1383-9.

7. La Torre G, Masala D, De Vito E, Langiano E, Capelli G, Ricciardi W, et al. Extra-curricular physical activity and socioeconomic status in Italian adolescents. BMC Public Health. 2006;6:9.

8. Mader U, Martin BW, Schutz Y, Marti B. Validity of four short physical activity questionnaires in middle-aged persons. Med Sci Sports Exerc. 2006;38(7):1255-66.

9. Mota J, Almeida M, Santos P, Ribeiro JC. Perceived Neighborhood Environments and physical activity in adolescents. Prev Med. 2005;41(5-6):834-6.

10. Manz K, Mensink GBM, Jordan S, Schienkiewitz A, Krug S, Finger JD. Predictors of physical activity among older adults in Germany: a nationwide cohort study. BMJ Open. 2018;8(5):e021940.

11. Best K, Ball K, Zarnowiecki D, Stanley R, Dollman J. In Search of Consistent Predictors of Children's Physical Activity. Int J Environ Res Public Health. 2017;14(10).

12. Mutz M, Albrecht P. Parents' Social Status and Children's Daily Physical Activity: The Role of Familial Socialization and Support. Journal of Child and Family Studies. 2017;26(11):3026-35.

13. Eime RM, Casey MM, Harvey JT, Sawyer NA, Symons CM, Payne WR. Socioecological factors potentially associated with participation in physical activity and sport: A longitudinal study of adolescent girls. J Sci Med Sport. 2015;18(6):684-90.

14. Trost SG, Sallis JF, Pate RR, Freedson PS, Taylor WC, Dowda M. Evaluating a model of parental influence on youth physical activity. Am J Prev Med. 2003;25(4):277-82.

Submitted filename: SocSupport response to review 11 09 2019.docx

Click here for additional data file.

23 Sep 2019

PONE-D-19-17332R1

Parental and peer support and modelling in relation to domain-specific physical activity participation in boys and girls from Germany

PLOS ONE

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Reviewer #1: 1. I agree and you are correct that it is possible to consider PA participation as a dichotomous variable. My concern was not with the active transportation outcome variable – the way this question was asked in your data would not allow it to be used as continuous, which is why it was not included in my comment. I appreciate your examples for extracurricular and overall PA. Garcia-Marco et al. (2010) use extracurricular PA as dichotomous because this is how the question was asked in their data; La Torre et al. (2006) use a cut-off of 3 hours per week; Mota et al. (2005) assessed PA using an index which split students into four categories (sedentary, low, moderate, vigorous); and Manz et al. (2018) used a cutoff of 1 day per week and gave a reason for this cutoff. None of these examples correspond to the choice you made to use the variable as dichotomous with a cutoff of 1 minute. As stated in my previous comment, the cutoff of 0 vs 1 or more minutes seems very arbitrary. Is 1 minute of PA sufficient to be considered “participation”? If you definitely want to use these three outcomes as dichotomous, I suggest looking at recommendations or your distribution to pick a more appropriate cutoff. For example, in the U.S., there is a recommendation that adolescents participate in 60 minutes of PA every day. Since you have PA split into different types, 60 minutes is probably too high for your cutoff, but it gives you a starting point to think about it. Another starting point is to look at the mean and/or median to create two groups that are roughly the same size. Whatever you decide, the cutoff should be explained in the text and descriptive stats for these three outcomes in Table 2 should be edited accordingly.

2. This was your response to my previous comment about presenting means/SD for Peer support, parental support, and peer modeling: “Our social support scales are based on more than one item (2 or 3) and thus, contain calculated mean values. That is why we presented the mean/SD in our tables as also done in other studies before (12-14).”

You state in the manuscript: “Peer modeling was also measured by a single item (How many of your friends regularly do sports?) with a four-point rating scale ranging from 1-“none” to 4-“most of my friends”.” This is essentially a likert scale. To say that Peer modeling had a mean of 3.07 is meaningless. You should present the proportion in each of the four categories, and this variable should be an indicator variable in your model (i.e. there should be an odds ratio for each category except the reference category).

Peer support scale – Ok, so this is a peer support “score” that could range from 3-12. How is the mean below 3 if that is possible range?

Parental support scales (4 types) – Ok, so each “score” could range from 2-8. This one makes sense.

Reviewer #2: No comments, the authors answered all my questions. The quality of the work improved after the reviews performed by the authors.

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26 Sep 2019

Response to review: Ms. No. PONE-D-19-17332R1

PLOS ONE

Dear Colleagues,

Please find enclosed our revision of the following research article:

“Parental and peer support and modelling in relation to domain-specific physical activity participation in boys and girls from Germany”

Again, we would like to thank the reviewers for their comments. We believe that the quality of our manuscript has improved again by implementing the suggestions and comments received. We hope we have addressed all the reviewers’ concerns and comments to your satisfaction.

Please find our response to the comments below. The reviewers’ comments are shown in regular font, and our responses are shown below each comment in italic:

Reviewer #1:

1. I agree and you are correct that it is possible to consider PA participation as a dichotomous variable. My concern was not with the active transportation outcome variable – the way this question was asked in your data would not allow it to be used as continuous, which is why it was not included in my comment. I appreciate your examples for extracurricular and overall PA. Garcia-Marco et al. (2010) use extracurricular PA as dichotomous because this is how the question was asked in their data; La Torre et al. (2006) use a cut-off of 3 hours per week; Mota et al. (2005) assessed PA using an index which split students into four categories (sedentary, low, moderate, vigorous); and Manz et al. (2018) used a cutoff of 1 day per week and gave a reason for this cutoff. None of these examples correspond to the choice you made to use the variable as dichotomous with a cutoff of 1 minute. As stated in my previous comment, the cutoff of 0 vs 1 or more minutes seems very arbitrary. Is 1 minute of PA sufficient to be considered “participation”? If you definitely want to use these three outcomes as dichotomous, I suggest looking at recommendations or your distribution to pick a more appropriate cutoff. For example, in the U.S., there is a recommendation that adolescents participate in 60 minutes of PA every day. Since you have PA split into different types, 60 minutes is probably too high for your cutoff, but it gives you a starting point to think about it. Another starting point is to look at the mean and/or median to create two groups that are roughly the same size. Whatever you decide, the cutoff should be explained in the text and descriptive stats for these three outcomes in Table 2 should be edited accordingly.

We totally agree with you that 1 minute of physical activity in a specific domain does not significantly contribute to physical activity participation or health outcomes of physical activity. The cut-off of 1 or more minutes we decided is a theoretical cut-off used for our intern purposes. The physical activity items target physical activity participation. Participants were assigned to the participation categories if they indicated at least one type of physical activity they regularly conducted in the physical activity domain at hand. However, we totally agree with you that our description of the measures in the methods section was confusing and misleading. Thus, we revised this section for clarification.

Furthermore, we deeply discussed this issue in our author group and thought of possible alternative cut-offs. We were not entirely convinced to set the cut-off at the level of PA recommendations (60min) because we focus on different domains of physical activity and the recommendations postulate a minimum of overall physical activity which can be cumulated over different activities in different domains (as you already recognised). Furthermore, the mean or median is not appropriate in extra-curricular physical activity as the prevalence is too low and this cut-off would not lead to a better distribution across participation and non-participation groups. In relation to physical activity in and outside of sports clubs the cut-off nearly presents the median. From our point of view the mean or median cut-off could be less selective than the cut-off at the >0-point. And as stated above, we wanted to focus on physical activity participation and not on levels of physical activity. We made this distinction and decision, because from a theoretical and empirical perspective there is a difference between different stages of physical activity participation and between predictors of physical activity participation (active vs. non-active) and predictors of levels of physical activity (e.g., Jekauc et al., 2013; Prochaska et al., 1992; Welk, 2002). For example, different socio-demographic predictors have been found for participation in sports clubs and for levels of physical activity in sports clubs, respectively (Jekauc et al., 2013). Thus, it is necessary to decide to focus on physical activity participation or on the level of physical activity and identify the corresponding social environmental predictors.

Due to these arguments that we discussed in our author group we prefer to leave the cut-offs as set.

2. This was your response to my previous comment about presenting means/SD for Peer support, parental support, and peer modeling: “Our social support scales are based on more than one item (2 or 3) and thus, contain calculated mean values. That is why we presented the mean/SD in our tables as also done in other studies before (12-14).”

You state in the manuscript: “Peer modeling was also measured by a single item (How many of your friends regularly do sports?) with a four-point rating scale ranging from 1-“none” to 4-“most of my friends”.” This is essentially a likert scale. To say that Peer modeling had a mean of 3.07 is meaningless. You should present the proportion in each of the four categories, and this variable should be an indicator variable in your model (i.e. there should be an odds ratio for each category except the reference category).

We absolutely understand your point here and this refers to a long consisting discussion. A Likert scale is formal categorical and should be presented by median and modus but there is also some consent in literature, that when the item is symmetrical it can be treated as equidistant and parametric tests can be used. To our knowledge, this is one important reason why symmetrical Likert scales are used that often. A summary of the discussion and some theoretical experiments can be found for example at Lantz (2013). If we argue that these items are not equidistant, we also have to argue that we cannot build sums or means of them like for the other social support scales. Thus, this issue does not only affect the peer modelling item but also the other scales. We agree with you, that this item can just barely be called symmetrical because “none” and “most of my friends” do not sound like logical ends of a spectrum at first glance. However, this wording leads to lesser skewness and kurtosis of the item, because a theoretical pole “every friend” is very hard to affirm by the participants. Thus, the struggle for equidistance and symmetry has its own story in this item. Another reason why we prefer to stick with the metrical assumption is that when we calculate the regressions with this item as categorical, there will be more than one estimate of its influence and we cannot compare the ORs between the constructs peer and parental support without further limitations. This strategy has also been adopted in other studies on social environmental influences on physical activity (Deforche et al., 2010; Shen et al, 2018; Wiium & Safvenbom, 2019).

Due to these points and with the aforementioned arguments at side, we prefer to stuck to our original approach in the current manuscript. However, we see that both options have important advantages and disadvantages (we weight the loss of comparability and consistent threat of all those Likert items high). Thus, we are willing to accept your final decision based on your expertise.

3. Peer support scale – Ok, so this is a peer support “score” that could range from 3-12. How is the mean below 3 if that is possible range?

For social support we computed the mean score of the items included in the scales. For clarification we added this information in the methods section (“Parental and peer support”).

4. Parental support scales (4 types) – Ok, so each “score” could range from 2-8. This one makes sense.

Ok, thanks.

Reviewer #2:

No comments, the authors answered all my questions. The quality of the work improved after the reviews performed by the authors.

Thank you.

Literature:

Deforche, B., Van Dyck, D., Verloigne, M., & De Bourdeaudhuij, I. (2010). Perceived Social and Physical Environmental Correlates of Physical Activity in Older Adolescents and the Moderating Effect of Self-Efficacy. Preventive Medicine, 50, S24-S29. doi:DOI 10.1016/j.ypmed.2009.08.017

Jekauc, D., Reimers, A. K., Wagner, M. O., & Woll, A. (2013). Physical Activity in Sports Clubs of Children and Adolescents in Germany: Results from a Nationwide Representative Survey. Journal of Public Health, 21(6), 505-513. doi:10.1007/s10389-013-0579-2

Lantz, B. (2013). Equidistance of Likert-type scales and validation of inferential methods using experiments and simulations. The Electronic Journal of Business Research Methods, 11(1), 16-28.

Prochaska, J. O., DiClemente, C. C., & Norcross, J. C. (1992). In Search of How People Change. Applications to Addictive Behaviors. American Psychologist, 47(9), 1102-1114. doi:10.1037//0003-066x.47.9.1102

Shen, B., Centeio, E., Garn, A., Martin, J., Kulik, N., Somers, C., & McCaughtry, N. (2018). Parental Social Support, Perceived Competence and Enjoyment in School Physical Activity. Journal of Sport and Health Science, 7(3), 346-352. doi:10.1016/j.jshs.2016.01.003

Welk, G. J. (2002). Physical Activity Assessments for Health-Related Research. Champaign, Ill.: Human Kinetics.

Wiium, N., & Safvenbom, R. (2019). Participation in Organized Sports and Self-Organized Physical Activity: Associations with Developmental Factors. International Journal of Environmental Research and Public Health, 16(4), 16. doi:10.3390/ijerph16040585

2 Oct 2019

Parental and peer support and modelling in relation to domain-specific physical activity participation in boys and girls from Germany

PONE-D-19-17332R2

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4 Oct 2019

PONE-D-19-17332R2

Parental and peer support and modelling in relation to domain-specific physical activity participation in boys and girls from Germany

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