The effects of supervision on three different exercises modalities (supervised vs. home vs. supervised+home) in older adults: Randomized controlled trial protocol.

BACKGROUND: Multicomponent physical exercise programs are a viable strategy for treating physical decline resulting from the aging process in older populations and can be applied in supervised and home-based modalities. However, the magnitude of the intervention effects in terms of physical function development may vary according to the modalities application due to different supervision degrees.
OBJECTIVE: This study aims to compare the effects of supervision in a multicomponent exercise program in different application modalities (supervised vs. home vs. supervised+home) in neuromuscular adaptations, muscle strength, gait, physical function, and quality of life, analyzing the differences between intensity, volume, and density of home and supervised sessions in community older adults.
METHODS: This protocol is a randomized controlled clinical trial with a sample of 66 older adults divided into three groups: supervised exercise (SUP = 22), home-based exercise (HB = 22), and supervised plus home-based exercise (SUP+HB = 22). The multicomponent exercise program will last 12 weeks, three times per week, for 60 min per session and include warm-up, balance, muscle-strengthening, gait, and flexibility exercises. The study's primary outcomes will be neuromuscular function, composed of the assessment of muscle isokinetic strength, muscle architecture, and neuromuscular electrical activation. The secondary outcome will be physical function, usual and maximum gait speed with and without dual-task, and quality of life. All outcomes will be assessed at baseline and post-intervention (week 12).
CONCLUSION: This study will be the first clinical trial to examine the effects of different supervision levels on home-based exercises compared to supervised protocols. The results of this study will be essentials for planning coherent and viable home-based programs for older adults. TRIAL REGISTRATION: Brazilian Registry of Clinical Trials. Number RBR- 7MZ2KR. https://apps.who.int/trialsearch/Trial2.aspx?TrialID=RBR-7mz2kr.

Introduction

Physical exercise is recommended to prevent or reduce the effects of aging in older people and has been applied in the supervised and home-individual form [1-4]. In general, supervised programs are more effective than home-based programs for improving muscle strength, balance, physical function, and quality of life [3,5]. However, home-based programs are a good option for older adults with limited mobility or who need assistance to go to the training center and have little time for exercise due to family or work responsibilities.

In order to reduce the differences between home-based and supervised programs, recent studies have proposed adding a supervised-group session to home-based programs [6,7]. The addition of supervised-group sessions aims to provide greater exercise supervision, improving the control over frequency, intensity, and progression of exercises, which has been pointed out as one of the main limitations of home-based programs [8]. Nevertheless, control the effect of different supervision levels may directly affect the improvements in older adults’ muscle strength and physical function. However, this hypothesis remains unclear due to the lack of information regarding the impact of different supervision levels in home-based programs.

The indirect supervision of home-based programs may result in limitations in the quality of exercise execution, resulting in exercises with a lower range of motion, less vigorous intensities, and longer rest interval between sets, impairing the exercise effects when compared to supervised training [8]. Thus, the strength gains with resistance exercise are generally associated with a combination of neural and morphological factors, such as increases in muscle mass, reductions in fat infiltration [9], improved firing rate, and decreased antagonist muscle co-activation (Mian., 2006) [10,11], which may not be so effective when performed at home.

To the best of our knowledge, this is the first study that aimed to analyze the neuromuscular mechanisms responsible for improvements in muscle strength and physical function in older adults with the addition of supervised sessions in home-based programs compared to totally unsupervised (home) and supervised training. Thus, we hypothesize that the addition of supervised sessions in home-based programs will lead to greater improvements in neuromuscular mechanisms due to the higher control over the training variables when compared to home-based programs. Besides, we believe that the addition of supervised sessions in home-based programs will provide similar neuromuscular benefits compared to fully supervised training interventions.

Therefore, understanding the influence of different exercise supervision levels on neuromuscular mechanisms and how it may change muscle strength and physical function seems essential for planning coherent exercise programs for older adults, expanding training strategies for that population. Thus, this study had two objectives: Compare the effects of a multicomponent exercise program in different application modalities (supervised vs. home vs. supervised+home) in neuromuscular adaptations, muscle strength, gait, physical function, and quality of life of older adults; and analyze the session intensity, volume, and density of different training modalities (supervised vs. home vs. supervised+home) s in community older adults.

Materials and methods

Trial design

It is a protocol for a randomized controlled clinical trial, investigator-blinded, with three parallel groups. Participants are individually randomized to one of the three groups in a 1:1:1 allocation ratio. The Research Ethics Committee approved the project at the Federal University of Paraná, Brazil (UFPR) (CAAE:20181219.4.0000.0102). The study protocol was developed based on the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines [12]. The study follows the CONSORT guidelines [13], and all the items from the World Health Organization Trial Registration Data Set were registered in the publicly accessible Brazilian Registry of Clinical Trials (RBR-7MZ2KR). Any change made to the protocol will be reported to the Research Ethics Committee and modified in the Brazilian Registry of Clinical Trials.

The enrolled participants’ assessments will be carried out at baseline prior to randomization, and after three months, as described below (Fig 1).

Fig 1

Schematic representation of participant recruitment and allocation.

Study setting

The study will be carried out in the city of Curitiba, Paraná, Brazil. In Paraná, the older population increased by 15.92% in the last five years, totaling 1.717.889 people [14]. In 2017, Curitiba registered 268.700 people aged over 60 years old. According to population projection assumptions, the number of older adults in Curitiba is expected to rise to 432.500 in 2030 and 544.500 in 2040.

Eligibility criteria

The inclusion criteria will be: men and women aged > 60 years; be able to perform basic daily activities; not engaged in structured physical exercise program (previous six months); without cognitive impairment determined through the Mini-Mental State Examination [15].

Exclusion criteria include physical or motor limitations that make it impossible to perform functional tests; recent history of stroke or heart failure; uncontrolled acute or chronic metabolic disorders; severe osteoporosis; two or more fractures in the last year; medical contraindications for participation in an exercise program.

The participants will not be allowed to participate in another physical protocol concurrently with the present study.

Recruitment, randomization, and treatment allocation

The study will be carried out in Curitiba, Paraná, Brazil. Volunteers will be recruited by dissemination through digital media (local digital newspaper and Facebook) and health units.

After checking the inclusion and exclusion criteria and analyzing the screening/anamnesis, the volunteers will sign a Free and Informed Consent Form. The participants will then be randomized by blocks into one of the three groups of equal size by a researcher who is not involved in the study. The randomization will be made at the randomization.com website. A second researcher not involved in the study will receive an envelope with the participants’ allocation, contacting them to inform them about their specific training group. The researchers who carry out the evaluations and interventions will be blinded to the distribution of the groups.

Intervention groups

Volunteers will participate in a multicomponent exercise program combining supervised and home-based exercise for 12 weeks, three times per week, 60 min per session. Participants will be divided into (1) supervised exercise (SUP), who will attend supervised group sessions at the training center; (2) home-based exercise (HB), who will participate in individual sessions at home; (3) supervised plus home-based exercise (SUP+HB), who will attend to one session per week at the training center and two sessions per week at home. Physical educators or physiotherapists will guide the supervised sessions at the training center.

The volunteers who will attend home sessions (HB and SUP+HB) will have an initial visit to their home to receive recommendations about how to perform the exercises safely. A guide with illustrations and instructions to reinforce proper exercise execution will be provided to each participant with space for recording the sessions performed and possible occurrences. On this occasion, they will receive ankle cuff weights (1, 2 and, 4 kg) to the strength training and a square stepping for walking exercises. To control program adherence, participants will record the days they complete the program, and they will also receive messages with incentives to perform the exercises at home.

The exercise program will consist of functional exercises of muscle strength, balance, flexibility, and gait, based on the recommendations of Singh et al. [16] and American College of Sports Medicine [17] (ACSM). Each session will be divided into 05 minutes of dynamic and articular warm-up, 10 minutes of dynamic and static balance exercises, 25 minutes of muscle-strengthening exercises, 10 minutes for gait exercises, and 10 minutes of flexibility exercises.

The exercise program will consist of four phases: phase 1 (1 to 3 weeks), phase 2 (4 to 6 weeks), phase 3 (7 to 9 weeks) and, phase 4 (10 to 12 weeks). Each phase will differ in the load and difficulty level of exercises, as shown in Table 1. The session intensity will be measured by the rate of perceived exertion (RPE) according to Borg Scale (6–20). In all groups analyzed, an explanation regarding the scale will be provided as well as a familiarization with the protocol before the start of interventions. Those measurements will be analyzed in different moments of the session, aiming to characterize the intensity perceived. In all training sessions, the volunteers will be encouraged to perform the exercises respecting the 1:3 ratio for strength exercises[18].

Table 1

Multicomponent exercise program planning.

Modality	Balance Training	Resistance Training	Gait Training	Flexibility Training
Volume	1–2 sets of 4–5 different exercises emphasizing static and dynamic postures for 30 seconds	Phase 1: 3 sets of 12 repetition, 1-min interval between setsPhase 2: 3 sets of 10 repetition, 30-s interval between setsPhase 3: 3 sets of 8 repetition, 1-min interval between setsPhase 4: 3 sets of 8 repetition, 30-s interval between sets.	1 set5 repetition6 gait exercises	Sustain stretching exercises for20 sec to each major muscle groups
Intensity	Progressive difficulty with increases in complexityPhase 1: reduction of foot support base.Phase 2: unstable surface.Phase 3: reduction of visual information.Phase 4: objects manipulation.	Phase 1: 13–15 on the Borg Scale.Phase 2 to 4: 15–17 on the Borg Scale.	Phase 1 to 4: 12–13 on the Borg Scale (40–60%of heart rate reserve)	Phase 1 to 4:Progressive neuromuscularfacilitation technique, which involves stretching as far as possible, then relaxing the involved muscles, then attempting to stretch further, and finally holding the maximal stretch position for at least 20 seconds.
Exercises
	Static exercises: single-leg, semi-tandem, and tandem position, single-leg stand with knee elevation.Dynamic exercises: perform forward, backward, and lateral walking in plantarflexion, dorsiflexion, and tandem position. Transfers of chairs, move over objects, and step-ups.	Phase 1 and 2:Sit-to-stand a chair; Standing knee; Pelvic lift; Wall sitting isometric; Sitting ankle plantar flexion; Standing ankle plantar flexion; Barbell curl; Bend-over dumbbell row; Halter front raise; Lying hip extension; Lying hip flexion; Sit-up; Walking lunges; Standing knee flexion; Standing hip extension; Hip adductor Exercise; Hip abductor ExercisesPhase 3 and 4:Wall sitting isometric; Barbell curl; Bend-over dumbbell row; Sit-up; Walking lunges; Standing knee flexion; Squat; Seated Knee Extension; Pelvic lift; Standing hip flexion; Standing calf raise; Bent over row; Dumbbell curls; Dumbbell Side Lateral Raise; Hip extension; Stiff legged deadlift; Step-Ups; Abductor Exercises; Adductor Exercise.	Walk at the usual and maximum speed, and exercises involving square stepping. The square-stepping Exercise was based on the study conducted by Shigematsu colleagues (2008).	Exercises involving major muscle groups, including hip and knee flexion and extension, and abduction and adduction. Besides the addition of upper limb stretching movements.

The training protocol will be modified if the participant undergoes severe pain or discomfort when carrying out the training program. Besides, the protocol will be interrupted if the participant is committed to any illness that may prevent exercise execution.

Aiming to enhance the validity of the presented data, several methods will be used to assess exercise protocol adherence, including engagement in the supervised exercise sessions, filling a calendar in the home sessions, and weekly calls to remember the importance of performing the exercise.

Measurements

The evaluation sessions will be conducted in the biomechanics laboratory in CECOM at UFPR, where trained evaluators will administer the tests. The evaluators responsible for applying the exercise program will not participate in evaluating the sample, aiming to guarantee a simple blind study. The steps and timeline of the assessments can be observed in Fig 2.

Fig 2

Representation of the timeline and assessments of the study.

All participants visited the laboratory on two nonconsecutive days with a minimum of 48 hours of resting to perform baseline evaluations. In the first visit, participants will be requested to answer a clinical anamnesis, followed by an anthropometric assessment. All protocols applied for primary and second outcomes will be described below.

Primary outcomes

Muscle isokinetic strength

The evaluation of muscle isokinetic strength will be performed using the Biodex Multi-joint System dynamometer (Biodex Medical Systems. Inc. Shirley. NY. USA). The protocol includes two sets of three repetitions of the knee, hip, dorsiflexion, and plantarflexion concentric flexion/extension movements at 60°/s and 180°/s of dominant limb, with a two-minute interval between sets [19]. Participants will be positioned following the Biodex factory specifications, which are described by Symons et al. [20].

Each test will be performed twice at the same evaluation session, with different verbal commands of the evaluator: in the first test, a submaximal set will be used for familiarization, followed by a second test, which will be held with maximum strength for the record. Data will be acquired at 1000 Hz, and all muscle strength tests will be analyzed using the Biodex System 3 Advantage software, version 3.2. The variables analyzed will be peak torque/body weight, total work, and average power.

Neuromuscular function

The neuromuscular function will be evaluated using an isokinetic dynamometer Biodex along with surface electromyography (EMGs). Aiming to determine the voluntary activation level (VAL), the twitch interpolation technique will be used [21]. The present study protocol will stimulate the posterior tibial nerve, activating the sural triceps muscles (soleus and gastrocnemius) [22].

For the acquisition of EMG signals, an electromyograph (Trigno Wireless, Delsys, USA) will be used, with an electric stimulator (Neuro IOM-Neurosoft®) with bipolar surface electrodes AMBU Neuroline 715. The muscle analyzed will be the lateral gastrocnemius (LG) and medial gastrocnemius (MG) of the dominant limb, and the electrode placement process will follow the Surface EMG for the Non-Invasive Assessment of Muscles (SENIAM) recommendations [23,24]. Electrodes will be placed on the LG, MG, and tibialis anterior [23].

The reference electrode will be placed in a central position at the same leg of the stimulation, and an electrode for electrical stimulation will be placed over the patellar tendon. For the stimulation of the posterior tibial nerve, the cathode will be placed in the popliteal fossa.

After the electrodes are placed, the participant will be positioned on the isokinetic dynamometer to evaluate the ankle, as described by Symons et al. (2004). Data collection will be carried out during maximum voluntary isometric contraction (MVIC), which will consist of three maximal contractions of five seconds each.

The VAL will be analyzed through two supramaximal doublets (two electrical stimulation with 200 μs pulse width, 10 ms interstimulus interval, and 1000 mA maximum output) applied percutaneously femoral nerve during the MVIC. The optimal stimulation intensity will be determined from the M wave and strength measurements before each test session. The stimulation intensity will increase by five mA until there is no further increase in the peak force contraction. Therefore, an addition of 30% of the highest value will be added to assure a supramaximal stimulation.

The first stimulation will be delivered during an MVIC, which will be nominated as the superimposed twitch. Followed the first stimulation, a second stimulus will be given 3 s after the MVIC, being nominated as the potentiated twitch. Both the STw and the PTw amplitudes allowed the VAL quantification, as proposed by Merton (1954). The variables analyzed will be the peak torque, contraction time, torque development rate analyzed through the formula (RTD = PT/CT), half-relaxation time, and VAL.

Muscle architecture

The muscle architecture (fascicle length, pennation angle, and muscle thickness) of MG muscle of dominant limb will be assessed using an ultrasound (Konica Minolta Medical Imaging Inc Newark-Pompton Turnpike, Wayne, NJ, USA) in B mode with linear arrangement transducer (4 cm height x 2 cm length, 10 MHz), with the depth adjusted to 4 cm for the MG.

The image of MG will be performed with the participant resting in the prone position, with the feet hanging from the edge, and an ankle joint angle at 15° dorsiflexion will be fixed. The ultrasound transducer will be positioned at 30% of the portion between the fibula’s lateral malleolus and the lateral condyle of the tibia [25]. The transducer will be oriented in the axial plane, aligned perpendicularly to the muscle, and moved from the center to the lateral position along with templates demarcated on the skin.

It is important to highlight that the gastrocnemius muscle is essential to maintain independence, gait speed and reduce falls risk. However, the aging process causes a muscle architecture alteration, reducing the cross-sectional area, pennation angle, and fascicle length. These age-related alterations resulting in a reduction of strength and muscle power, gait speed and functionality [26].

Secondary outcomes

Gait

The gait will be analyzed through the instrumented walking monitor ProtoKinetics Zeno Walkway (ProtoKinetics LLC, Havertown, Pennsylvania). The evaluation protocol will consist of four patterns: walking at the usual speed, maximum speed, the usual speed with a dual-task, and maximum speed with a dual-task for a distance of 10 meters. Dual-task gait will be assessed using an arithmetic cognitive task (countdown from 50) [27].

The parameters will be analyzed: gait speed (m/s), cadence (steps/min), stride time (secs), stride length (m), stride width (m), single and double support time (secs), and swing time (secs). Besides, the walk ratio (WR) will be obtained by dividing step length by cadence [28], and the locomotor rehabilitation index (LRI) is calculated as the percentage ratio between self-selected speed and optimum speed (algebraically LRI = 100 × self-selected speed/optimum walking speed) cc.

Physical function

The physical function will be assessed using the Short Physical Performance Battery Test [29] and the Senior Fitness Test [30], aiming to verify muscle strength, agility, and dynamic and static balance. The Short Physical Performance Battery Test is composed of tandem, semi-tandem, side-by-side stands balance test, 4-meters walking speed test, and 5-times sit-to-chairs stand test. The Senior Fitness Test is composed of 5 times sit to chair stand test, arm curl test (number within 30 seconds), chair sit and reach test (distance between fingers and toe), back scratch test (distance between the two third fingers), Timed-up-and-go (time to rise, walk 3 m and return to the chair) and 6-minute walk test (distance walked in 6 minutes).

Quality of life

Quality of life will be assessed using the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) [31]. The SF-36 comprises 36 questions that cover eight health domains: physical limitation because of health problems, social limitation because of physical or emotional problem, usual role activities limitation because of physical health or emotional problems, body pain, general mental health, vitality, and general health perceptions.

Physical activity level and exercise intensity control

The physical activity level and the control of the exercise intensity will be evaluated using an accelerometer (Actigraph brand, model GT3X). To analyze the physical activity level, participants will be instructed to use the device for seven consecutive days, all day long, withdrawing only to sleep and to perform water activities, including bathing [32]. The accelerometer will be attached to the ankle of the dominant leg, just above the malleolus. It will be considered valid data the use of the accelerometer for at least four days, where at least one day has to be recorded during the weekend. The day will be considered valid when at least 10 hours are recorded. The data will be collected at a frequency of 60 Hz. The process of downloading and analyzing data will be carried out by the Actilife software using the Freedson equation [32].

The exercise intensity will be controlled by the use of accelerometers during the exercise sessions. The analyzed variable will be the average calories spent per day and session, sedentary time, light, moderate, vigorous, and very vigorous activities.

Sample size

The sample size calculation was made using the G*Power software (version 3.1) [33]. A priori analysis was performed with the following input parameters: effect size (0.25) [7], type I error (0.05), type II error (0.95), number of groups (3), number of measurements (3), and a correlation between group (0.5). Also, the loss rate of 20% was considered. Thus, our analysis revealed a sample size of 66 subjects, divided into three groups of 22 participants.

Adverse outcomes

Aiming to prevent the sample from performing exercises wrongly, and in order to avoid falls and fractures, the exercise will be monitored by physical education professionals as well as physiotherapists. Nevertheless, the participants will be monitored by the Rating of perceived Exertion to ensure the recommended intensity level, avoiding the deleterious effect of high-intensity exercise in older populations. In the case of muscle injury, physical training will be suspended.

Statistical methods

For data analysis, the results will be reported using descriptive statistics and mean and standard deviation. All data will be analyzed by intention-to-treat, with baseline scores substituted for missing follow-up data. The Shapiro-Wilk test will be applied to verify the normality of the data and the Levene test for the sample’s homogeneity. For parametric data, a comparison between groups and periods (pre and post-training) will be analyzed by an ANOVA of mixed-models with Bonferroni’s post-hoc test. When differences between groups were observed at the baseline, a covariance analysis (ANCOVA) will be applied. In addition, a Pearson’s correlation coefficient (r) was calculated to verify the magnitude of the possible observed effects, considering r = .10 as a small effect, r = .30 as a medium effect, and r = .50 as a large effect [34]. P-values less than 0.05 will be considered statistically significant. The tests will be performed using the IBM SPSS Statistics software version 25.

Discussion

The present study’s objective is to compare the effects of different supervision levels in a multicomponent exercise program using three different application modalities in muscle strength, gait, physical function, and quality of life, verifying if different training modalities result in different neuromuscular adaptations. Finally, analyze if the addition of supervised sessions in home-based intervention promotes different impacts on the exercise intensity, volume, and density in community older adults.

We hypothesize that adding a supervised session in a home-based program will improve the neuromuscular function (muscle isokinetic strength, quality, and muscle composition), obtaining similar effects to a SUP exercise program, resulting in better effectiveness compared to a strictly HB intervention. It is already known that some factors as quality of exercise execution, range of motion, intensity, the interval between sets, and exercise progression may promote advantages in supervised training sessions compared to home-based interventions. Thus, we believe that the addition of a supervised session in the home-based group will provide direct feedback regarding the intensity, volume, and density of the physical exercise, promoting similar effects in the SUP+HB will be similar to SUP.

Our hypothesis is based on other studies that compared home-based programs with some degree of supervision. In a study conducted by Boshuizen et al. (2005), it was verified that maximal isometric knee strength and the walking speed significantly increase in the group with higher supervision (two group sessions supervised and one unsupervised home session per week) compared to the medium supervision group (one supervised group session and two unsupervised home sessions per week) [35]. Lacroix et al. (2016) found similar results regarding training-related improvements for the Romberg Test, stride velocity, Timed Up and Go Test, and Chair Stand Test in favor of the higher supervised group (two group sessions supervised and one unsupervised home session per week) compared to home-based program (three unsupervised home session per week). Therefore, it is possible to suggest that the addition of supervised sessions can enhance the effects of home-based exercises in older adults.

Thus, a systematic review [8] notices that the possible causes for SUP programs’ superiority over HB interventions rely on improved control over the intensity, volume, and density of physical exercises made during the SUP program. Hence, it was verified through a meta-analysis that the SUP programs’ superiority could be reduced or dismissed when small portions of supervision to HB programs were added. It suggests that the supervision made through calls, home visits, as well as attendance to training centers, would be an effective strategy to improve the exercise program’s effectiveness.

However, to the best of our knowledge, the impact of improved supervision levels at HB interventions was not compared regarding the amount nor the type of supervision received during the exercise program in neuromuscular adaptations, isokinetic muscle strength, gait, physical function, and quality of life. Therefore, this is the first study that aims to verify if the addition of supervised sessions in a home-based program modifies the intensity, volume, and density of the exercise compared to SUP and HB intervention programs. Limitation of the study includes the spontaneous physical activity, such as the locomotion to the training site or daily activities (walk/transport), which will be monitored by accelerometry but will not be controlled in order to minimize or optimize the amount of time spent in these activities, since that type of activity must be performed in supervised group to go to the training site.

Conclusion

This study aims to compare the impact of supervision on HB exercises to SUP protocols using a gold-standard method to verify the neuromuscular parameters, such as electromyography, to analyze the muscle activation as well as the reaction time, elucidating the mechanisms underlying the muscle mass and strength development. The gold-standard method will provide a more consistent and accurate result, allowing a better understanding of those specific mechanisms. Knowing the effective contribution of neuromuscular mechanisms in muscle strength and physical function development with different exercise programs is essential for planning plausible and viable programs for older adults, expanding therapeutic strategies to older adults who have difficulty attending the training site.

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3 Nov 2020

PONE-D-20-25040

The effects of supervision on three different exercises modalities (center vs. home vs.  center+home) in older adults: Randomized controlled trial protocol

PLOS ONE

Dear Dr. Costa,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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The level of supervision in a multicomponent exercise program will be tested in older people. The study's question is timely and interesting to the audience of Plos One. While the reviewers and me found positive view on your paper, some major concerns were raised, particularly on reviewers 1 and 4. Please, reply all points carefully.

introduction

I think you can developing further your rationale for justifying the multicomponent program

lines 87-89 - Even interesting showing the basic rationale for neuromuscular adaptations, consider focusing on specific adaptations in elderly. For example, previous studies have shown that muscle weakness in aging leads to joint instability resulting in higher co-contraction levels and metabolic cost of walking (https://doi.org/10.1111/j.1748-1716.2006.01522.x and https://doi.org/10.1186/s40798-019-0228-6), possibly the multicomponent strategy can enhance primary outcomes of functionality as self-selected walking speed through neuromuscular and aerobic combined adaptations.

Another general suggestion is including two crucial markers of evaluation in gait analysis. the walking ratio (https://doi.org/10.1016/j.gaitpost.2018.08.030) and the locomotor rehabilitation index (10.4103/2468-5658.184750).

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Reviewer #1: General comments

This is an interesting randomized controlled trial protocol, with the objective of 'compare the effects of a multicomponent exercise program in different application modalities (center vs. home vs. center + home) in neuromuscular adaptations, muscle strength, gait, physical function, and quality of life 'and' analyze the differences between intensity, volume, and density of home and face-to-face sessions in community older adults'. It is an important starting point for evaluating different exercise programs for older adults.

The study is quite relevant and the findings will be of interest to professionals and scientists working with older populations. The manuscript is well and clearly written, the evaluation methods are adequate to answer the research question, requiring some adjustments.

Specific comments

Introduction:

- Updated referential, but some articles are with pre-frail elderly women, be careful with these studies.

- Consider inserting the stated hypothesis of the study (or primary outcomes).

- In general, the introduction is very well written, but I miss a specific focus on the research question, that is, addressing the subject of the two objectives of the work.

Methods:

- Consider registration with the International Clinical Trial Registry.

- I don't feel comfortable agreeing with the inclusion criterion (page 6 – 129) "not engaged in regular physical activity or exercise programs (previous six months)", I suggest analyzing this criterion.

- It is interesting to find other forms of dissemination for more people to be served (university page, health units, community center).

- Consider a screening / anamnesis of the patients together with the verification of the criteria, precious information appears at these moments.

- Figure 1 comments:

Many doubts arise regarding the use of the Borg Scale for the intensity of the exercises, especially for the group that will do the exercises at home.

Do the exercises seem to be focused only on the lower limbs? it is necessary to have a balance between lower and upper limbs, after all we also need them for the activities of daily living. Gait training also deserves more attention, proposing exercises at maximum walking speeds is interesting.

- Page 9 – 180: “…exercise. The participants will not be allowed to participate in another physical protocol concurrently with the present study.”

This stretch can be in the inclusion / exclusion criteria.

Measurements:

- The topic 'Measurements' can be accompanied by a figure explaining the steps and timeline of the assessment.

- 'Primary outcomes' are very well defined and explained, but 'Secondary outcomes' need to be explored (gait, Physical function and quality of life).

- Page 13 - 294 – “…and fractures, the exercise will be monitored individually by physical education professionals as well as physiotherapists.”

Reviewing this statement, 'individually' does not seem to be viable in this training model.

- Statistical methods - ANOVA will be used, I suggest using Generalized Estimation Equations (GHG), which is from the ANOVA family but more robust.

Discussion and Conclusion:

Page 20 - 313 to page 22 - 345:

- The hypothesis must be presented in the introduction and discussed here.

- The discussion is based only on one study (a systematic review) it is necessary to include others.

- It is important to emphasize the use of the gold-standard method, but it is necessary to include a paragraph that reflects on the benefits that the tested intervention will provide to the community and how it can be disseminated in the scientific community.

Reviewer #2: The proposed study will be a three-arm, randomized controlled clinical trial with 22 subjects in each arm to determine the effects of exercise supervision on three different exercise modalities. Outcomes and QOL will be assessed pre and post-intervention and compared between the three arms.

Minor revisions:

1- Line 285: Indicate the statistical testing method which achieves 95% power.

2- Line 309: Consider replacing the following sentence, “The coefficient of p <0.05 will be adopted to determine the significance.” with “P-values less than 0.05 will be considered statistically significant.”

3- Line 308: The magnitude of the coefficients appear to be more important than testing the null hypothesis that p=0. For this reason, possibly the p-values do not need to be reported.

Reviewer #3: The methodological and evaluation procedures are clearly written and are repeatable, however some points deserve attention:

- In the description of the proposed exercises it is not clear in sufficient detail to allow the work to be replicable especially at this stage. It is suggested to prepare a table with the phases (for weeks) as mentioned in the text, highlighting the phases of each session (warm-up, main part, calm down, etc ...) names of the exercises and the progression of volume and intensity.

- To assess muscle strength in the isokinetic dynamometer, it is recommended to evaluate the two lower limbs, so that it is possible to check the possible differences between the two segments in the pre and post intervention period and still make correlations if these values can interfere with balance static and dynamic subjects.

- It is not clear why the gastrocnemius muscles were chosen to assess muscle architecture.

- Why not evaluate the muscular architecture of the chosen muscles in the two lower limbs? it is likely that changes will occur after interventions that may in any way interfere with results such as strength and balance.

- The authors did not describe where all the data underlying the findings will be available when the study is completed.

- Report how the possible intervening variables of the study will be treated (uncontrolled) and how they can be minimized.

Reviewer #4: Dr. Sabrine Nayara Costa and co-authors present a registered protocol proposal entitled:The effects of supervision on three different exercises modalities (center vs. home vs. center+home) in older adults: Randomized controlled trial protocol. The study proposal addresses the interesting, albeit already very discussed topic of the effectiveness of home physical activity programs carried out without specialized supervision. The manuscript presents some grammatical inaccuracies about the conjugation of some verbs and the formation of some sentences. It should be corrected. Overall it appears interesting but requires significant changes.

First of all, I would not use the unclear term "center" to mean the supervised activity (commonly just referred as supervised). The abstract appears poor and not very specific in the backgroung part. Figure 1 is not complete and could be simplified or even removed and explained in the text.The “study setting” chapter presents unnecessary information. Hypertension or diabetes, very common pathologies in the over 60s, are not mentioned among the exclusion criteria.

In the introduction, the purpose of the research is not clear, in particular in the reasons for these measures and why these parameters should change following a different training mode (Muscle architecture, neuromuscular function ...). Better define the experimental question.

Line 153 sessions, not session

Line 170 does not seem correct to require maximum speed for all exercises, explain better.

The method of customizing the workload is real unclear. BORG scale? Explain in particular regarding resistance training. Was spontaneous physical activity not included in the workouts monitored all time long? For example, walking to go to the gym.

"Muscle strenght" should be defined as "Muscle isokinetic Strenght"

Line 319, Sentence not clear, better define the rationale for this hypothesis as already said several times

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Reviewer #1: Yes: Valeria Feijo Martins

Reviewer #2: No

Reviewer #3: No

Reviewer #4: No

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14 Dec 2020

Dear Doctor Peyré-Tartaruga,

We would like to thank you for the opportunity to review and correct the previously submitted manuscript ID PONE-D-20-25040 - "The effects of supervision on three different exercises modalities (center vs. home vs. center+home) in older adults: Randomized controlled trial protocol". We appreciate the reviewers' comments and thank them for their thoughtful suggestions for improving our manuscript. We attended all the reviewer requests and included them in the document. Our point-by-point responses are detailed below.

ACADEMIC REVIEWER COMMENTS TO THE AUTHOR:

COMMENT 1:

Introduction

I think you can developing further your rationale for justifying the multicomponent program

lines 87-89 - Even interesting showing the basic rationale for neuromuscular adaptations, consider focusing on specific adaptations in elderly. For example, previous studies have shown that muscle weakness in aging leads to joint instability resulting in higher co-contraction levels and metabolic cost of walking (https://doi.org/10.1111/j.1748-1716.2006.01522.x and https://doi.org/10.1186/s40798-019-0228-6), possibly the multicomponent strategy can enhance primary outcomes of functionality as self-selected walking speed through neuromuscular and aerobic combined adaptations.

Author Reply:

First of all, we would like to thank you for the suggestion. We have adjusted the introduction according to your comments in order to provide a better understanding of the manuscript objectives and rationality. We choose to use only one of the two recommended references for the introduction, considering the study objectives.

COMMENT 2:

Another general suggestion is including two crucial markers of evaluation in gait analysis. the walking ratio (https://doi.org/10.1016/j.gaitpost.2018.08.030) and the locomotor rehabilitation index (10.4103/2468-5658.184750).

Author Reply:

Thank you for the suggestions. Those analyses will contribute to a better understanding of the walking speed in older adults. Those analyses were added to the manuscript:

Page 9, Line: 286 – 288:

“Besides, the walk ratio (WR) will be obtained by dividing step length by cadence 27, and the locomotor rehabilitation index (LRI) is calculated as the percentage ratio between self-selected speed and optimum speed (algebraically LRI = 100 × self-selected speed/optimum walking speed).”

=============================

REVIEWER #1:

General comments

This is an interesting randomized controlled trial protocol, with the objective of 'compare the effects of a multicomponent exercise program in different application modalities (center vs. home vs. center + home) in neuromuscular adaptations, muscle strength, gait, physical function, and quality of life 'and' analyze the differences between intensity, volume, and density of home and face-to-face sessions in community older adults'. It is an important starting point for evaluating different exercise programs for older adults.

The study is quite relevant and the findings will be of interest to professionals and scientists working with older populations. The manuscript is well and clearly written, the evaluation methods are adequate to answer the research question, requiring some adjustments.

Author reply:

We want to thank you for all the comments. They were really interesting and will improve the manuscript quality. The answers to those comments will be presented in a point-by-point below.

COMMENT 1:

Introduction:

- Updated referential, but some articles are with pre-frail elderly women, be careful with these studies.

Author Reply:

Thank you for your observation regarding the references. However, we choose to keep those references since only two of them used pre-frail older adults. The first one (Garcia et al., 2020) was cited to demonstrate that home-based exercise is a viable strategy to prevent aging's deleterious effect. With that in mind, we also used studies with sarcopenic and dwelling community older adults. The other study used with pre-frail older adults was used to present strategies to improve control over home-based exercise. That study was cited along with a study with older adults with increased risk of falls.

Considering that home-based exercise has been used as a tool for older adults with limited mobility or enhanced risk of adverse effects, it was necessary to use studies with specific older populations (sarcopenic, pre-frail, and fallers) to develop new researches in the field.

COMMENT 2:

- Consider inserting the stated hypothesis of the study (or primary outcomes).

- In general, the introduction is very well written, but I miss a specific focus on the research question, that is, addressing the subject of the two objectives of the work.

Author Reply:

Thank you for your suggestion. We observed that the introduction had some flaws regarding the hypothesis and research question, and therefore, we aimed to re-write the last paragraphs of the introduction.

The modifications can be observed on page 4-5, line 90-104:

“The indirect supervision of home-based programs may result in limitations in the quality of exercise execution, resulting in exercises with a lower range of motion, less vigorous intensities, and longer rest interval between sets, impairing the exercise effects when compared to supervised training8. Thus, the strength gains with resistance exercise are generally associated with a combination of neural and morphological factors, such as increases in muscle mass, reductions in fat infiltration9, improved firing rate, and decreased antagonist muscle co-activation (Mian., 2006) 10,11, which may not be so effective when performed at home.

To the best of our knowledge, this is the first study that aimed to analyze the neuromuscular mechanisms responsible for improvements in muscle strength and physical function in older adults with the addition of supervised sessions in home-based programs compared to totally unsupervised (home) and supervised training. Thus, we hypothesize that the addition of supervised sessions in home-based programs will lead to greater improvements in neuromuscular mechanisms due to the higher control over the training variables when compared to home-based programs. Besides, we believe that the addition of supervised sessions in home-based programs will provide similar neuromuscular benefits compared to fully supervised training interventions.”

COMMENT 3:

Methods:

- Consider registration with the International Clinical Trial Registry.

Author Reply:

Our study was registered and approved in the Brazilian Registry of Clinical Trials, associated with the International Clinical Trials Registry Platform: https://www.who.int/ictrp/network/rebec/en/

COMMENT 4:

- I don't feel comfortable agreeing with the inclusion criterion (page 6 – 129) "not engaged in regular physical activity or exercise programs (previous six months)", I suggest analyzing this criterion.

Author Reply:

We understand your concerns, and we choose to remove the regular physical activities from the inclusion and exclusion criteria. However, considering that the analyzed parameters (muscle strength, neuromuscular function, muscle architecture, gait, physical function, and quality of life) are influenced by structured physical activities, we choose to keep that parameter. Therefore, considering that this variable could be a confounder factor, the inclusion of physically active participants engaged in structured training programs could lead to misinterpretations.

Page 6, line 139:

“not engaged in structured physical exercise program (previous six months)”

COMMENT 5:

- It is interesting to find other forms of dissemination for more people to be served (university page, health units, community center).

Author Reply:

Thank you for the suggestion. The dissemination through digital media (local digital newspaper and Facebook) includes the University page and community center. However, we added the dissemination in health units.

Page 7, line 149-150:

“The study will be carried out in Curitiba, Paraná, Brazil. Volunteers will be recruited by dissemination through digital media (local digital newspaper and Facebook) and health units.”

COMMENT 6:

- Consider a screening / anamnesis of the patients together with the verification of the criteria, precious information appears at these moments.

Author Reply:

Thank you for your suggestion; this information was added to the manuscript.

Page 7, line 151:

“After checking the inclusion and exclusion criteria and analyzing the screening/anamnesis, the volunteers will sign a Free and Informed Consent Form.”

COMMENT 7:

- Figure 1 comments:

Many doubts arise regarding the use of the Borg Scale for the intensity of the exercises, especially for the group that will do the exercises at home.

Author Reply:

Thank you for your observation. However, Figure 1 is the schematic representation of participants' recruitment and allocation. Nevertheless, according to your comment regarding the Borg Scale, we believe that you are referring to Table 1. The session intensity will be measured by the rate of perceived exertion (RPE) according to Borg Scale (6-20). Those measurements will be analyzed in different moments of the session, aiming to characterize the intensity perceived. In all groups analyzed, an explanation regarding the scale will be provided as well as a familiarization with the protocol before the start of interventions. Concerning home-based intervention, the subjects will be instructed regarding the RPE protocol whenever necessary. That information was added in the manuscript on Page 8, Line 182-187.

“The session intensity will be measured by the rate of perceived exertion (RPE) according to Borg Scale (6-20). In all groups analyzed, an explanation regarding the scale will be provided as well as a familiarization with the protocol before the start of interventions. Those measurements will be analyzed in different moments of the session, aiming to characterize the intensity perceived.”

COMMENT 8:

Do the exercises seem to be focused only on the lower limbs? it is necessary to have a balance between lower and upper limbs, after all we also need them for the activities of daily living. Gait training also deserves more attention, proposing exercises at maximum walking speeds is interesting.

Author Reply:

Thank you for your comment. Regarding the strength training, the exercise protocol will provide exercise for both, upper and lower body. The full description of the exercises can be observed in the updated Table 1, in exercises:

Page 8:

Phase 1 and 2: Sit-to-stand a chair; Standing knee; Pelvic lift; Wall sitting isometric; Sitting ankle plantar flexion; Standing ankle plantar flexion; Barbell curl; Bend-over dumbbell row; Halter front raise; Lying hip extension; Lying hip flexion; Sit-up; Walking lunges; Standing knee flexion; Standing hip extension; Hip adductor Exercise; Hip abductor Exercises

Phase 3 and 4: Wall sitting isometric; Barbell curl; Bend-over dumbbell row; Sit-up; Walking lunges; Standing knee flexion; Squat; Seated Knee Extension; Pelvic lift; Standing hip flexion; Standing calf raise; Bent over row; Dumbbell curls; Dumbbell Side Lateral Raise; Hip extension; Stiff legged deadlift; Step-Ups; Abductor Exercises; Adductor Exercise.

Regarding gait exercises, the subjects will perform several exercises using different speeds and with different stimulus. The information about gait exercises are provided on page 8, Table 1, exercise section:

“Gait: Walk at the usual and maximum speed, and exercises involving square stepping. The square-stepping Exercise was based on the study conducted by Shigematsu colleagues (2008).”

COMMENT 9:

- Page 9 – 180: “…exercise. The participants will not be allowed to participate in another physical protocol concurrently with the present study.”

This stretch can be in the inclusion / exclusion criteria.

Author Reply:

Thank you for your suggestion. The phrase was reallocated to the Eligibility criteria section Page Line.

Page 7, line 145-146:

“The participants will not be allowed to participate in another physical protocol concurrently with the present study.”

COMMENT 10:

Measurements:

- The topic 'Measurements' can be accompanied by a figure explaining the steps and timeline of the assessment.

Author Reply:

Thank you for the suggestion, and the figure was added in the Page 10, Line 207.

COMMENT 11:

- 'Primary outcomes' are very well defined and explained, but 'Secondary outcomes' need to be explored (gait, Physical function and quality of life).

Author Reply:

Thank you for your observation. Due to a limited number of words, we choose to precisely describe the primary outcomes, considering that several different methods and protocols can be used to test the purposed outcomes. The battery test and the questionary of the secondary outcomes (Short Physical Performance Battery Test, Senior Fitness Test, and SF-36) are standard and widely described in the literature. However, considering your observation, we added the description of the secondary outcomes at Page 14, Line 293-305.

“Physical function:

The Short Physical Performance Battery Test is composed of tandem, semi-tandem, and side-by-side stands balance test, 4-meters walking speed test, and 5-times sit to chair stand test. The Senior Fitness Test is composed of 5 times sit to chair stand test, arm curl test (number within 30 seconds), chair sit and reach test (distance between fingers and toe), back scratch test (distance between the two third fingers), Timed-up-and-go (time to rise, walk 3 m and return to the chair) and 6-minute walk test (distance walked in 6 minutes).

Quality of life:

The SF-36 comprises 36 questions that cover eight health domains: physical limitation because of health problems, social limitation because of physical or emotional problem, usual role activities limitation because of physical health or emotional problems, body pain, general mental health, vitality, and general health perceptions.”

COMMENT 12:

- Page 13 - 294 – “…and fractures, the exercise will be monitored individually by physical education professionals as well as physiotherapists.”

Reviewing this statement, 'individually' does not seem to be viable in this training model.

Author Reply:

The word individually used in the mentioned phrase referred to the contact with the older adult through phone-calls or home-based visits, not necessarily to control supervised group sessions. However, we understand that the word "individually" could lead to misunderstandings, suggesting an individual control of the exercise session; therefore, we aimed to remove the word "individually" from the text, which did not affect the phrase context.

Page 15, line 330-331:

“…the exercise will be monitored by physical education professionals as well as physiotherapists.”

COMMENT 13:

- Statistical methods - ANOVA will be used, I suggest using Generalized Estimation Equations (GHG), which is from the ANOVA family but more robust.

Author Reply:

Thank you for your suggestion. We choose to use this analysis because the study objective is usually analyzed by an ANOVA mixed models, allowing the evaluation of the effects of different exercise programs across interventions (within groups) as well as to compare the effect between groups. Although we are not changing it in the present manuscript, we will consider this analysis method (GHG) during the data analysis after the protocol application.

COMMENT 14:

Discussion and Conclusion:

Page 20 - 313 to page 22 - 345:

- The hypothesis must be presented in the introduction and discussed here.

- The discussion is based only on one study (a systematic review) it is necessary to include others.

- It is important to emphasize the use of the gold-standard method, but it is necessary to include a paragraph that reflects on the benefits that the tested intervention will provide to the community and how it can be disseminated in the scientific community.

Author Reply:

Thank you for your suggestions. We have reviewed the Discussion and Conclusion in order to improve it according to your request. The modifications can be observed in Page 16-18.

REVIEWER #2:

The proposed study will be a three-arm, randomized controlled clinical trial with 22 subjects in each arm to determine the effects of exercise supervision on three different exercise modalities. Outcomes and QOL will be assessed pre and post-intervention and compared between the three arms.

COMMENT 1:

Minor revisions:

1- Line 285: Indicate the statistical testing method which achieves 95% power.

Author Reply:

We indicated that the power achieved is 95% in the following sentence:

Page 15, line 322-326:

“A priori analysis was performed with the following input parameters: effect size (0.25) 7, type I error (0.05), type II error (0.95), number of groups (3), number of measurements (3), and a correlation between group (0.5).”

Thus, the Alpha (type I error) used was 0.05, and Beta (type II error) used was 0.95, providing the desired power level (95%).

COMMENT 2:

2- Line 309: Consider replacing the following sentence, “The coefficient of p <0.05 will be adopted to determine the significance.” with “P-values less than 0.05 will be considered statistically significant.”

Author Reply:

Thank you for your suggestion. The phrase was adjusted according to your request.

Page 16, line 344-345:

“P-values less than 0.05 will be considered statistically significant.”

COMMENT 3:

3- Line 308: The magnitude of the coefficients appear to be more important than testing the null hypothesis that p=0. For this reason, possibly the p-values do not need to be reported.

Author Reply:

Thank you for your suggestion. We agree that the magnitude of the coefficient is more appropriate to define the impact of the training method in older adults since small changes can be observed in the magnitude of the effect. Therefore, we will use your suggestion during the data analysis, and we removed the idea of P's coefficient as reported above.

Reviewer #3:

The methodological and evaluation procedures are clearly written and are repeatable, however some points deserve attention:

COMMENT 1:

- In the description of the proposed exercises it is not clear in sufficient detail to allow the work to be replicable especially at this stage. It is suggested to prepare a table with the phases (for weeks) as mentioned in the text, highlighting the phases of each session (warm-up, main part, calm down, etc ...) names of the exercises and the progression of volume and intensity.

Author Reply:

Thank you for your suggestion. We changed the Table 1 in order to provide a better view of the exercise program. The modifications can be observed in page 9, line 191.

COMMENT 2:

- To assess muscle strength in the isokinetic dynamometer, it is recommended to evaluate the two lower limbs, so that it is possible to check the possible differences between the two segments in the pre and post intervention period and still make correlations if these values can interfere with balance static and dynamic subjects.

Author Reply:

We understand the importance of evaluating both lower limbs in an isokinetic dynamometer, and we already used that method in our research group in other studies. However, in the present study, we had some reasons to choose the analysis in only one limb; the first one is related to the study objective, which does not include the evaluation of the difference between limbs and dynamic/static balance after the training intervention. Besides, the post-intervention evaluation of the same limb will provide the answers related to the neuromuscular system and the training method.; the second is related to Biodex complex setups that include the calibration of some equipment (EMG and Neuro IOM-Neurosoft®) for neuromuscular evaluations. The third reason is related to the time spent during the evaluations. The protocol described in the present study last at least 4 hours (divided into two days) to be completed, so the addition of another limb would promote a significant increase in the time spent during the analysis. In previous studies conducted in our lab, we lost several individuals during our analysis process due to the long time spent during the initial assessments.

COMMENT 3:

- It is not clear why the gastrocnemius muscles were chosen to assess muscle architecture.

Author Reply:

Thank you for the suggestion. The information was added to the manuscript.

Page 13, line 296-299:

It is important to highlight that the gastrocnemius muscle is essential to maintain independence, gait speed and reduce falls risk. However, the aging process causes a muscle architecture alteration, reducing the cross-sectional area, pennation angle, and fascicle length. These age-related alterations resulting in a reduction of strength and muscle power, gait speed and functionality 26.

COMMENT 4:

- Why not evaluate the muscular architecture of the chosen muscles in the two lower limbs? it is likely that changes will occur after interventions that may in any way interfere with results such as strength and balance.

Author Reply:

We understand the importance of evaluating both lower limbs. However, in the present study, we had two reasons to choose the analysis in only one limb; the first one is related to the study objective, which does not include evaluating the difference between limbs; the second is associated with the time spent during the evaluations. The protocol described in the present study last at least 4 hours (divided into two days) to be completed, so the addition of another limb (in both, isokinetic dynamometer and muscle architecture) would promote a significant increase in the time spent during the analysis.

Nevertheless, the biggest part of studies that aimed to analyze the effect of training interventions in muscle architecture only analyzed the dominant limb. Thus, since it was more viable considering the problems mentioned above, only the dominant limb will be analyzed.

COMMENT 5:

- The authors did not describe where all the data underlying the findings will be available when the study is completed.

Author Reply:

Thank you for pointing that out. That information was added in Page 13, Line 114-115:

“Data Availability: All relevant data are within the paper and its Supporting Information files.”

COMMENT 6:

- Report how the possible intervening variables of the study will be treated (uncontrolled) and how they can be minimized.

Author Reply:

Thank you for your suggestion. The spontaneous physical activity, such as the locomotion to the training site or daily activities (walk/transport), will be monitored by accelerometry but will not be controlled in order to minimize or optimize the amount of time spent in these activities, since that type of activity must be performed in supervised group to go to the training site. That information will be added at the end of the discussion as a limitation to the present study Line 18, Page 387-391:

“Limitation of the study includes the spontaneous physical activity, such as the locomotion to the training site or daily activities (walk/transport), which will be monitored by accelerometry but will not be controlled in order to minimize or optimize the amount of time spent in these activities, since that type of activity must be performed in supervised group to go to the training site.”

REVIEWER #4:

Dr. Sabrine Nayara Costa and co-authors present a registered protocol proposal entitled:The effects of supervision on three different exercises modalities (center vs. home vs. center+home) in older adults: Randomized controlled trial protocol. The study proposal addresses the interesting, albeit already very discussed topic of the effectiveness of home physical activity programs carried out without specialized supervision. The manuscript presents some grammatical inaccuracies about the conjugation of some verbs and the formation of some sentences. It should be corrected. Overall it appears interesting but requires significant changes.

First of all, I would not use the unclear term "center" to mean the supervised activity (commonly just referred as supervised).

The abstract appears poor and not very specific in the backgroung part.

Figure 1 is not complete and could be simplified or even removed and explained in the text.

The “study setting” chapter presents unnecessary information. Hypertension or diabetes, very common pathologies in the over 60s, are not mentioned among the exclusion criteria.

In the introduction, the purpose of the research is not clear, in particular in the reasons for these measures and why these parameters should change following a different training mode (Muscle architecture, neuromuscular function ...). Better define the experimental question.

Author Reply:

Thank you for your suggestions. Your suggestions were quite interesting and will improve the quality of the manuscript. We will answer all the questions and appointments made in your revision in a point-by-point that can be observed below.

COMMENT 1:

The manuscript presents some grammatical inaccuracies about the conjugation of some verbs and the formation of some sentences. It should be corrected.

Author Reply:

The manuscript underwent a complete grammatical revision to adjust some verbs' conjugation and the formation of some sentences according to the proper English.

COMMENT 2:

First of all, I would not use the unclear term "center" to mean the supervised activity (commonly just referred as supervised).

Author Reply:

Thank you for your observation. The term center was changed to supervised exercise.

COMMENT 3:

The abstract appears poor and not very specific in the backgroung part.

Author Reply:

Thank you for recommending an adjustment in the abstract. The changes are in the abstract to adjust it according to our hypothesis.

COMMENT 4:

Figure 1 is not complete and could be simplified or even removed and explained in the text.

Author Reply:

Figure 1 was added according to SPIRIT 2013 Statement recommendations: Defining Standard Protocol Items for Clinical Trials. More specifically, Figure 1 answer the item “Participant timeline” - Time schedule of enrollment, interventions (including any run-ins and washouts), assessments, and visits for participants. A schematic diagram is highly recommended (Figure). Besides, PLoS One requests a checklist of all SPIRIT items; therefore, we choose to keep Figure 1.

COMMENT 5:

The “study setting” chapter presents unnecessary information.

Author Reply:

The “study setting” was added according to SPIRIT 2013 Statement recommendations: Defining Standard Protocol Items for Clinical Trials. PLoS One requests a checklist of all SPIRIT items; therefore, we choose to keep the study setting.

COMMENT 6:

Hypertension or diabetes, very common pathologies in the over 60s, are not mentioned among the exclusion criteria.

Author Reply:

Thank you for your suggestion. Nevertheless, we consider that this information is informed when we cite “uncontrolled acute or chronic metabolic disorders” in Eligibility Criteria. We only choose to exclude the older adults that present those pathologies without the proper control, considering that 60% of the Brazilian older population have hypertension, and 25% have diabetes.

COMMENT 7:

In the introduction, the purpose of the research is not clear, in particular in the reasons for these measures and why these parameters should change following a different training mode (Muscle architecture, neuromuscular function ...). Better define the experimental question.

Author Reply:

Thank you for your suggestion. We observed that the introduction had some flaws regarding the hypothesis and research question, and therefore, we aimed to re-write the last paragraphs of the introduction. The modifications can be observed on page 4-5, line 90-104:

“The indirect supervision of home-based programs may result in limitations in the quality of exercise execution, resulting in exercises with a lower range of motion, less vigorous intensities, and longer rest interval between sets, impairing the exercise effects when compared to supervised training8. Thus, the strength gains with resistance exercise are generally associated with a combination of neural and morphological factors, such as increases in muscle mass, reductions in fat infiltration9, improved firing rate, and decreased antagonist muscle co-activation (Mian., 2006) 10,11, which may not be so effective when performed at home.

To the best of our knowledge, this is the first study that aimed to analyze the neuromuscular mechanisms responsible for improvements in muscle strength and physical function in older adults with the addition of supervised sessions in home-based programs compared to totally unsupervised (home) and supervised training. Thus, we hypothesize that the addition of supervised sessions in home-based programs will lead to greater improvements in neuromuscular mechanisms due to the higher control over the training variables when compared to home-based programs. Besides, we believe that the addition of supervised sessions in home-based programs will provide similar neuromuscular benefits compared to fully supervised training interventions.”

COMMENT 8:

Line 153 sessions, not session

Author Reply:

Thank you for the correction. The word was correct as recommended.

COMMENT 9:

Line 170 does not seem correct to require maximum speed for all exercises, explain better.

Author Reply:

Thank you for your correction. The idea of “as fast as possible” was removed from the manuscript since the contraction time should respect the 1:3 ratio for strength exercises Page 8, Line 186-187:

“In all training sessions, the volunteers will be encouraged to perform the exercises respecting the 1:3 ratio for strength exercises.”

COMMENT 10:

The method of customizing the workload is real unclear. BORG scale? Explain in particular regarding resistance training. Was spontaneous physical activity not included in the workouts monitored all time long? For example, walking to go to the gym.

Author Reply:

Adjustments in the Figure 1 (page 9, line 191) were made to provide a better understanding of the workload used during at each phase of the intervention.

The session intensity will be measured by the rate of perceived exertion (RPE) according to Borg Scale (6-20). Those measurements will be analyzed in different moments of the session, aiming to characterize the intensity perceived. In all groups analyzed, an explanation regarding the scale will be provided as well as a familiarization with the protocol before the start of interventions. This information was add in page 8, line 182-186.

The spontaneous physical activity, such as the locomotion to the training site or daily activities (walk/transport), will be monitored by accelerometry but will not be controlled in order to minimize or optimize the amount of time spent in these activities, since that type of activity must be performed in supervised group to go to the training site. That information will be added at the end of the discussion as a limitation to the present study Line 18, Page 387-391. Nevertheless, since we will have the accelerometry data, a further analysis regarding the time spent in activities can be performed to verify if the home-based approaches promote different changes in the physical habits.

COMMENT 11:

"Muscle strenght" should be defined as "Muscle isokinetic Strenght"

Author Reply:

Thank you for your suggestion. The term “Muscle Strength” was replaced by “Muscle Isokinetic Strength” when appropriated.

COMMENT 12:

Line 319, Sentence not clear, better define the rationale for this hypothesis as already said several times

Author Reply:

Thank you for your recommendation. The whole discussion was adjusted to provide a better understanding of our hypothesis. Page 16-18.

Submitted filename: Response to Reviewers.docx

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28 Oct 2021

The effects of supervision on three different exercises modalities (supervised vs. home vs.  supervised+home) in older adults: Randomized controlled trial protocol

PONE-D-20-25040R1

Dear Dr. Costa,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does the manuscript provide a valid rationale for the proposed study, with clearly identified and justified research questions?

The research question outlined is expected to address a valid academic problem or topic and contribute to the base of knowledge in the field.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

2. Is the protocol technically sound and planned in a manner that will lead to a meaningful outcome and allow testing the stated hypotheses?

The manuscript should describe the methods in sufficient detail to prevent undisclosed flexibility in the experimental procedure or analysis pipeline, including sufficient outcome-neutral conditions (e.g. necessary controls, absence of floor or ceiling effects) to test the proposed hypotheses and a statistical power analysis where applicable. As there may be aspects of the methodology and analysis which can only be refined once the work is undertaken, authors should outline potential assumptions and explicitly describe what aspects of the proposed analyses, if any, are exploratory.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Is the methodology feasible and described in sufficient detail to allow the work to be replicable?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors described where all data underlying the findings will be made available when the study is complete?

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above and, if applicable, provide comments about issues authors must address before this protocol can be accepted for publication. You may also include additional comments for the author, including concerns about research or publication ethics.

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(Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Dear author,

Thank you for returning my requests. I am satisfied with the manuscript.

Congratulation for the work.

Reviewer #2: All comments have been adequately addressed.

Reviewer #3: The author adjusted all questions related to the doubts and suggestions of the reviewers. The proposed Protocol is adequate and can be replicated in other research. This study is extremely important for the population in question.

**********

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Reviewer #1: Yes: Valeria Feijo Martins

Reviewer #2: No

Reviewer #3: No

5 Nov 2021

PONE-D-20-25040R1

The effects of supervision on three different exercises modalities (supervised vs. home vs.  supervised+home) in older adults: Randomized controlled trial protocol

Dear Dr. Costa:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

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PLOS ONE