Longitudinal assessment of cardiorespiratory fitness and body mass of young healthy adults during COVID-19 pandemic.

Physical activity was reduced during the COVID-19 pandemic, especially when lockdowns were mandated; however, little is known about the impact of these lifestyle changes on objective measures of cardiorespiratory fitness. To address this knowledge gap, we evaluated the cardiorespiratory fitness of 14 young healthy adults (4 women, age: 27 ± 6 yr) just before the pandemic and after ∼1 yr of public health measures being in place. During fitness assessments, participants performed submaximal pseudorandom cycling exercise to assess cardiorespiratory kinetics, and a 25 W·min-1 ramp-incremental cycling test to determine peak oxygen uptake (V̇o2). Cluster analysis identified two subgroups of participants: those who had reduced peak V̇o2 at the 1-yr follow-up (-0.50 ± 0.17 L·min-1) and those whose peak V̇o2 was maintained (0.00 ± 0.10 L·min-1). Participants with reduced peak V̇o2 also exhibited slower heart rate kinetics (interaction: P = 0.01), reduced peak O2 pulse (interaction: P < 0.001), and lower peak work rate (interaction: P < 0.001) after 1 yr of the pandemic, whereas these variables were unchanged in the group of participants who maintained peak V̇o2. Regardless of changes in peak V̇o2, both subgroups of participants gained body mass (main effect: P = 0.002), which was negatively correlated with participants' level of self-reported physical activity level at the follow-up assessment (mass: ρ = -0.59, P = 0.03) These findings suggest that some young healthy individuals lost cardiorespiratory fitness during the pandemic, whereas others gained weight, but both changes could potentially increase the risk of adverse health outcomes and disease later in life if left unaddressed.NEW & NOTEWORTHY Some young healthy adults experienced cardiovascular deconditioning during the COVID-19 pandemic, with measurable reductions in cardiorespiratory fitness, whereas others experienced no change in fitness but gained body mass, which was related to self-reported physical activity during the pandemic.

INTRODUCTION

Public health measures and government-imposed lockdowns aimed at preventing the spread of the SARS-CoV-2 virus have unintended consequences that negatively impact people’s lives. Worldwide during the pandemic, many people lived less active lifestyles (1–4), ate poorly (1), and were psychologically stressed due to feeling isolated or inactive (5, 6). Recent reports suggest that university students performed ∼20% less moderate-to-vigorous physical activity and have increased their sedentary time by up to 3 h per day during the pandemic (7). The impact of reduced physical activity is then compounded by consuming less nutritious foods and increased consumption of alcohol (7). These changes in lifestyle and physical activity may manifest as reductions in cardiorespiratory fitness (CRF) or weight gain, which are both independent predictors of health, as lower CRF is associated with a higher risk of cardiovascular disease, various cancers, and all-cause mortality (8), whereas weight gain from young to middle-age is associated with increased risk of all-cause mortality and chronic disease (9, 10). Indeed, multiple studies have reported weight gain during pandemic-related lockdowns (11–13). Accordingly, it is of the utmost importance to understand how restrictions during the pandemic affected CRF and body mass of healthy individuals, which will help inform decisions about future measures to combat public health crises.

Most data collected during the pandemic have been via online questionnaires about daily activities and lifestyle, which may be plagued by recall bias if compared with prepandemic levels reported retrospectively (14). From these self-reported data, it is possible to infer changes in CRF based on reduced activity levels, but objective laboratory-based measures are lacking. Fortunately, we conducted fitness assessments of young healthy adults for a study immediately before the pandemic (15), and we were able to rerecruit participants for a follow-up fitness assessment ∼1 yr after pandemic restrictions had been in place to quantify how CRF changed. It was hypothesized that participants’ CRF would be reduced during the pandemic.

METHODS

Participants

Fourteen young healthy adults (4 women, age: 27 ± 6 yr, height: 1.73 ± 0.06 m, mass: 72.7 ± 11.1 kg) volunteered to participate in this study. Participants had no known cardiovascular, respiratory, or metabolic conditions, and none was taking any medications that would influence the cardiovascular response to exercise. All participants were instructed to arrive at the laboratory for testing at least 2 h postprandial, abstain from alcohol consumption and vigorous exercise in the 24 h preceding each test, and to avoid caffeine consumption on the day of the tests. No participants had been vaccinated for COVID-19 at the time of the fitness assessment during the pandemic, as vaccines were not widely available to young healthy adults in Canada before data collection was complete. The study protocol was approved by the Office of Research Ethics at the University of Waterloo (ORE No. 42980) and conforms to the Declaration of Helsinki, except for registration in a trial database. All participants gave verbal and written consent before enrolment in the study.

Exercise Testing

In the months before the pandemic as part of another study (15), participants visited the laboratory on multiple occasions to perform a maximum effort exercise test and pseudorandom exercise of different intensities. On the first visit, participants performed a ramp-incremental exercise test to exhaustion (4-min baseline at 25 W followed by a 25 W·min−1 ramp) to estimate each participant’s ventilatory threshold and peak oxygen uptake (V̇o2). Strong verbal encouragement was provided to the participants during the ramp exercise test. In one of the subsequent visits, the participants performed a pseudorandom binary sequence (PRBS) exercise test, where the work rate alternated between 25 W and 90% of the ventilatory threshold (see Fig. 6 in Amelard et al. (15) for details on the precise timing of changes in work rate during the PRBS exercise protocol). The mean work rate at 90% of ventilatory threshold was 108 ± 10 W. The pseudorandom test consisted of 3.5 min of warm-up, followed by two complete repetitions of a 7.5-min PRBS. Pseudorandom exercise is a unique protocol designed to evaluate cardiorespiratory response dynamics (16–18). All exercise tests were performed in an environmentally controlled laboratory on an electronically braked cycle ergometer (Lode Excalibur Sport, Lode B.V., Groningen, The Netherlands). Participants were asked to maintain cycling cadence at 60 rpm for all exercise tests. Pulmonary gas exchange was measured breath-by-breath using a portable metabolic system (MetaMax 3B-R2, CORTEX Biophysik, Leipzig, Germany), which was calibrated before each testing session according to the manufacturer’s guidelines. Heart rate during 5 min of seated rest before exercise, as well as during exercise was recorded (Polar H7, Polar Electro Oy, Kempele, Finland).

Approximately 1 yr following the implementation of public health measures, participants were rerecruited to participate in the present study. Briefly, public health measures in Waterloo region included an initial lockdown that lasted for ∼2 mo, followed by stages of reopening of various economic sectors. Outdoor recreation facilities with adequate physical distancing were not allowed to be used until the middle of June 2020. Activities with prolonged exposure to another person were not allowed until after the middle of July 2020. During this time, many recreational facilities remained closed, or were open for a very limited number of people to use at a given time, depending on the local restrictions and public health unit guidelines. In the fall of 2020, harsher restrictions on sports and recreation facilities were reintroduced provincially, eventually culminating with another full lockdown in December of 2020 and a stay-at-home order extended into mid-February. Once the province-wide stay-at-home order was lifted, local restrictions remained in place in Waterloo region, such that gyms and recreational facilities remained closed until beginning of data collection during the pandemic, which coincided with the onset of the third wave of SARS-CoV-2 infections in Ontario, Canada (end of February and March of 2021). Follow-up fitness assessments occurred 1.30 ± 0.29 yr after the initial fitness assessment at a similar time of day. In the follow-up visit, participants’ seated resting heart rate was reevaluated during a 5-min period. Next, participants performed the same PRBS exercise protocol as their test from before the pandemic (i.e., work rate alternating between 25 W and 90% prepandemic ventilatory threshold), and then had a 10-min period of seated rest. After the 10-min rest, the participants completed 4-min baseline cycling at 25 W followed by the 25 W·min−1 ramp-incremental exercise test to exhaustion. PRBS and maximal effort tests were combined into one laboratory visit to minimize risk of exposure to SARS-CoV-2.

Physical Activity Questionnaires

When participants visited the laboratory during the pandemic for their follow-up fitness assessment, they were also asked to complete the Global Physical Activity Questionnaire (19) to evaluate physical activity levels during the pandemic. Participants were instructed to complete the questionnaire as a representation of their “typical week” leading up to the fitness assessment, which reflected the restriction period when participants could not access indoor sports and recreation facilities, or gyms. The Global Physical Activity Questionnaire was used because it interrogates different ways that people are physically active (work, active transportation, and recreation), and could provide insight into how participants felt the pandemic affected their daily routines, especially with a shift to working from home and the closure of many recreational sports facilities and gyms.

Data Analysis

Seated rest.

Resting heart rate was calculated as the mean heart rate over the 5-min period of seated rest.

Ramp exercise.

Baseline V̇o2, heart rate, O2 pulse, and respiratory exchange ratio (RER) were calculated as the mean values over the last minute of cycling at 25 W. Peak heart rate was defined as the highest heart rate at the end of the test. Peak V̇o2, O2 pulse, and RER were defined as the highest values computed from 20-s moving averages. V̇o2 at ventilatory threshold was also estimated by visual inspection using standard ventilatory and gas exchange indices (and their ratios) as previously described (20). The work rate at 90% prepandemic ventilatory threshold used in the PRBS exercise was estimated as the work rate associated with the given V̇o2 after left-shifting the V̇o2 response by the mean response time, which was determined using segmented regression (21).

PRBS exercise.

Breath-by-breath V̇o2 data were edited on an individual basis to remove aberrant data, as previously described (16). V̇o2 and heart rate data were linearly interpolated to 1 Hz. For each test, the first 3.5 min of V̇o2 and heart rate data were excluded a priori as a warm-up, and then the two full PRBS repetitions were ensemble averaged to produce a single 7.5-min response. V̇o2 and heart rate kinetics were evaluated using the maximum of the cross-correlation function between the V̇o2 or heart rate response and the work rate profile (MATLAB R2020b, The MathWorks Inc., Natick, MA), where a higher maximum cross-correlation reflects faster kinetics.

Statistical Analysis

Statistical analysis was conducted using R (v 4.0.3). K-means cluster analysis [library: Ckmeans.1d.dp (22)] was performed on peak V̇o2, and two groups of participants were identified: those who had reductions in peak V̇o2 (n = 4) and those who did not (n = 10). Subsequently, linear mixed models with time (pre vs. during pandemic) and group (reduced vs. maintained CRF) as fixed effects, and participant as a random effect were used to evaluate how physiological variables were affected during the pandemic [library: lmerTest (23)]. In the case of significant effects, pairwise comparisons of the estimated marginal means with Holm correction for multiple comparisons were used for post hoc analysis [library: emmeans (24)]. Mann–Whitney U test was used to compare self-reported physical activity in MET min·wk−1 during the pandemic between the two groups of participants identified by the K-means cluster analysis. Spearman correlation was used to investigate the association between self-reported MET min·wk−1 of physical activity during the pandemic and the change body mass, the change in body mass index, or the change in peak V̇o2. Pearson correlation was used to evaluate the relationship between heart rate kinetics and V̇o2 kinetics before and during the pandemic. Statistical significance for these comparisons was set at P ≤ 0.05. Data are presented as means ± standard deviations.

RESULTS

A summary of baseline, pseudorandom, and peak exercise responses comparing before versus during the pandemic is presented in Table 1. K-means cluster analysis on the change in peak V̇o2 identified two subgroups, indicating not all individuals responded similarly during the pandemic. In one subgroup, CRF was reduced during the pandemic (−0.50 ± 0.17 L·min−1; n = 4), whereas it was maintained in the other group (0.00 ± 0.10 L·min−1; n = 10; Fig. 1). The subgroup of participants who experienced large reductions in peak V̇o2 had higher prepandemic peak V̇o2 compared with the group that maintained their CRF (P = 0.04). Likewise, peak O2 pulse and peak work rate were also lower during the pandemic in the reduced CRF group, but maintained in the other group. Peak O2 pulse (P = 0.04) and peak work rate (P = 0.08) before the pandemic also tended to be higher in the participants who experienced reductions in CRF compared with those who maintained CRF.

Table 1.

Summary of baseline, pseudorandom, and peak exercise responses from before and during the pandemic

	Maintained CRF, n = 10‡		Reduced CRF, n = 4		Time	Group	Interaction
	PRE	During	PRE	During	P value	P value	P value
Mass, kg	68.0 ± 8.7	69.6 ± 8.3	84.6 ± 6.2	89.0 ± 6.3	0.002	0.002	0.10
Body mass index, kg·m−2	23.1 ± 2.8	23.7 ± 2.4	27.3 ± 2.2	28.8 ± 2.4	0.003	0.009	0.11
Resting heart rate, beats·min−1	69 ± 10	71 ± 8	72 ± 2	81 ± 9*	0.002	0.20	0.05
Pseudorandom responses
Mean heart rate, beats·min−1	115 ± 11	121 ± 12	105 ± 6	115 ± 11	0.01	0.17	0.47
Heart rate kinetics, CCFmax	0.70 ± 0.04	0.68 ± 0.04	0.69 ± 0.04	0.62 ± 0.04*†	<0.001	0.07	0.01
V̇o2 kinetics, CCFmax	0.67 ± 0.03	0.65 ± 0.04	0.66 ± 0.06	0.65 ± 0.04	0.25	0.95	0.40
Baseline responses
Heart rate at 25 W, beats·min−1	94 ± 14	106 ± 13	87 ± 4	100 ± 6	<0.001	0.35	0.83
V̇o2 at 25 W, L·min−1	0.68 ± 0.04	0.74 ± 0.05*	0.83 ± 0.05†	0.81 ± 0.05†	0.29	<0.001	0.05
O2 pulse at 25 W, mL·beat−1	7.4 ± 1.0	7.1 ± 1.0	9.6 ± 0.8	8.2 ± 1.0	0.01	0.007	0.07
RER at 25 W	0.81 ± 0.04	0.82 ± 0.04	0.81 ± 0.02	0.81 ± 0.02	0.72	0.95	0.82
Peak responses
Peak heart rate, beats·min−1	183 ± 11	186 ± 9	187 ± 11	192 ± 14	0.06	0.42	0.60
Peak V̇o2, L·min−1	2.86 ± 0.46	2.86 ± 0.44	3.59 ± 0.37†	3.09 ± 0.36*	<0.001	0.08	<0.001
Peak O2 pulse, mL·beat−1	15.8 ± 2.5	15.7 ± 2.4	19.5 ± 1.3†	16.5 ± 1.4*	<0.001	0.10	<0.001
Peak RER	1.17 ± 0.05	1.16 ± 0.06	1.15 ± 0.03	1.16 ± 0.07	0.97	0.80	0.46
Peak work rate, W	258 ± 31	256 ± 33	302 ± 17	269 ± 23*	<0.001	0.12	<0.001

Means ± SD; CCFmax, maximum of the cross-correlation function; CRF, cardiorespiratory fitness; RER, respiratory exchange ratio; V̇o2, oxygen uptake. ‡, n = 9 for maintained CRF group for mean resting heart rate. *Different (P < 0.05) from PRE within a given group. †Different (P < 0.05) from maintained CRF group at a given time point. Significant main and interaction effect P values are shown in bold.

Figure 1.

Comparison of peak oxygen uptake (V̇o2) before (PRE) and during the pandemic for the reduced and maintained cardiorespiratory fitness (CRF) groups. Dashed and solid lines in boxes represent the mean and median, respectively, with the lower and upper boundaries of each box representing the first and third quartiles. Each color represents a unique participant. *Different (P < 0.05) from PRE within a given group. †Different (P < 0.05) from maintained CRF within a given time point.

Resting heart rate (interaction: P = 0.05) was elevated in the reduced CRF group (P = 0.02), but not in the maintained CRF group (P = 0.29), at the follow-up assessment. Conversely, main effects of time on mean heart rate while cycling at 25 W (P < 0.001) and during the PRBS exercise (P = 0.01), suggest that both groups experienced elevated submaximal exercise heart rates after 1 yr of the pandemic. Peak heart rate during the ramp exercise test tended to be elevated in both groups at the follow-up assessment (main effect of time: P = 0.06). However, heart rate kinetics (interaction: P = 0.01; Fig. 2) were slowed during the pandemic in the group that experienced reduced CRF (P = 0.002), but not in the maintained CRF group (P = 0.13). Group mean V̇o2 kinetics measured after 1 yr of the pandemic were not statistically different from the prepandemic values in either group (P > 0.05). Despite no statistical change in V̇o2 kinetics, V̇o2 and heart rate kinetics were still associated at both prepandemic (r = 0.74, P = 0.003) and during pandemic time points (r = 0.56, P = 0.04).

Figure 2.

Group mean (maintained CRF: n = 10 participants; reduced CRF: n = 4) heart rate (A) and oxygen uptake (V̇o2; C) time-series responses to pseudorandom exercise (gray) before (red) and during (black) the pandemic. Comparison of heart rate (B) and V̇o2 (D) kinetics before and during the pandemic. A higher maximum cross-correlation function (CCFmax) indicates faster kinetics. Dashed and solid lines in boxes represent the mean and median, respectively, with the lower and upper boundaries of each box representing the first and third quartiles. Each color represents a unique participant. *Different (P < 0.05) from PRE within a given group. †Different (P < 0.05) from maintained CRF within a given time point. CRF, cardiorespiratory fitness.

During the pandemic, the amount of physical activity self-reported by those who had reduced CRF (580 ± 421 MET min·wk−1) was not statistically different from those who maintained CRF (1372 ± 1125 MET min·wk−1; P = 0.29), although there was large variability between what participants reported. Participants’ mass (main effect of time: P = 0.002; main effect of group: P = 0.002) and body mass index (main effect of time: P = 0.003; main effect of group: P = 0.009) increased during the follow-up period regardless of the change in CRF, but both mass and body mass index were higher at all assessment time points in the group who experienced losses in CRF. The change in body mass (ρ = −0.59, P = 0.03; Fig. 3) and the change in body mass index (ρ = −0.57, P = 0.03) were both negatively associated with the self-reported physical activity at the 1-yr follow-up; however, the change in peak V̇o2 was not associated with self-reported physical activity at the 1-yr follow-up (ρ = 0.15; P = 0.59).

Figure 3.

Relationship between the change in participants’ body mass and self-reported physical activity during the pandemic. Red and black circles signify participants in the reduced and maintained cardiorespiratory fitness groups, respectively.

DISCUSSION

The purpose of this study was to objectively quantify how ∼1 yr of public health restrictions affected CRF of young healthy adults. In partial support of our hypothesis, we observed substantial reductions in peak V̇o2 in a subset of our participants, indicating reduced CRF during the pandemic; however, other participants were able to maintain peak V̇o2 at the follow-up assessment, but had significant weight gain. Other indicators of cardiovascular function, such as peak work rate, peak O2 pulse, and submaximal exercise heart rate kinetics, were diminished in the participants who experienced reductions in CRF but were stable in the group who maintained CRF during the pandemic. Accordingly, living through the COVID-19 pandemic has affected humans differently, with some experiencing reductions in CRF, whereas others gained weight, but regardless of losing fitness or gaining weight, both of these changes can potentially have detrimental consequences later in life if left unaddressed.

Reduced CRF observed in a subset of participants demonstrates how detrimental inactivity and lifestyle modification during the pandemic can be for cardiovascular health, even in young healthy individuals. In the subset of participants with reduced CRF, peak V̇o2 was reduced by ∼14% (range: 10%–19%), which is similar in magnitude to reductions in peak V̇o2 observed following 1–2 mo of strict bed rest (25). Comparable reductions in peak V̇o2 have also been reported following three decades of aging in the Dallas Bed Rest Study 30-yr follow-up (26). Interestingly, participants who experienced large reductions in CRF during the pandemic had significantly higher prepandemic peak V̇o2 and peak O2 pulse, as well as a tendency for higher peak work rates than those who maintained CRF, which suggests that those with higher prepandemic peak V̇o2 in our sample were more affected. This is similar to findings during bed rest, as baseline peak V̇o2 values have been reported to be inversely related to the change in absolute peak V̇o2 following bed rest (25). Large reductions in peak O2 pulse underlie the changes in peak V̇o2 in the reduced CRF group, suggesting that cardiac deconditioning occurred leading to reduced peak stroke volume. Deconditioning in these individuals with reduced peak V̇o2 is also supported by elevated resting heart rate during the pandemic follow-up, and slower heart rate kinetics, which were not observed in participants who maintained CRF. However, both reduced and maintained CRF groups exhibited increased mean heart rate at 25 W and during PRBS exercise, with the mechanism underlying the elevated submaximal exercise heart rates in the maintained CRF group remaining unknown. Nevertheless, if physical activity habits and aerobic fitness do not improve following the pandemic, it will put these individuals who experienced large reductions in CRF at higher risk for developing adverse health outcomes and chronic disease later in life (8). In this group of participants with reduced CRF, the potential for increased risk of adverse health outcomes is then compounded by simultaneous weight gain of on average 4.4 kg over the course of ∼1 yr.

Increased body mass at the 1-yr follow-up assessment was also found in participants who maintained CRF. Main effects of group and time were observed, indicating that participants who experienced reductions in CRF were larger than those who maintained CRF, but that participants in both groups gained weight during the pandemic. Weight gain in young adulthood is particularly problematic, as it is associated with increased risk of developing chronic disease later in life and reduced odds of healthy aging (10). Previous reports have identified multiple and complex reasons for why people gained weight during pandemic lockdowns, including reduced sleep, increased snacking, stress coping, and reduced physical activity (11–13). Notably, one study continued to track changes in weight 5 mo following the easing of pandemic restrictions, and determined that most people either maintained the higher body weight or continued to gain weight in the months postlockdown, suggesting that the health effects of increased mass during the pandemic are likely to persist (12). In the present study, we were unable to account for many of these complex lifestyle and diet interactions and their effects on our participants’ body mass; however, we did assess self-reported physical activity via a questionnaire at the follow-up assessment. Moderate inverse correlations were observed between self-reported physical activity at the time of the 1-yr follow-up assessment and the change in body mass or the change in body mass index, which also support that low levels of physical activity contribute to weight gain during the pandemic. Increased body mass in combination with either maintained or reduced peak V̇o2 may have a functional impact when performing activities of daily living, which are typically weight-bearing. Greater energy expenditure, and therefore a greater fraction of peak V̇o2, will be needed to move a heavier body against gravity, leaving a lesser fraction available to perform external tasks.

V̇o2 kinetics was statistically unchanged over time despite observing slower heart rate kinetics in the reduced CRF group. This is similar to the findings of Koschate et al. (27) during 60 days of head-down tilt bed rest, as they also found slowed heart rate kinetics around a higher mean heart rate, but not V̇o2 kinetics during moderate-intensity PRBS exercise. During both prepandemic and pandemic assessments of the present study, heart rate and V̇o2 kinetics were significantly associated, although a higher correlation coefficient was observed at the prepandemic time point. It is also important to note that three of four participants who experienced reductions in CRF had lower maximum cross-correlation values for V̇o2 at the 1-yr follow-up assessment. Therefore, we may be underpowered to detect differences in V̇o2 kinetics given the small subgroup of participants with reduced CRF and the inherent noise associated with breath-by-breath V̇o2 signals (28), so interpretation of the influence of the cardiovascular system on V̇o2 kinetics in this study must be done with caution.

Limitations

Menstrual cycle was not controlled for in our female participants when evaluating their cardiovascular responses to submaximal pseudorandom and maximal exercise before versus after ∼1 yr of the pandemic. However, menstrual cycle phase is not expected to greatly influence our study outcomes (29, 30).

In the present study, supramaximal verification of peak V̇o2 was not conducted to ensure that values were truly maximal (31). However, in the reduced CRF group, the combination of elevated resting heart rate, reduced peak O2 pulse, and slower heart rate kinetics all provide strong evidence that cardiovascular deconditioning occurred in these individuals during the pandemic. Furthermore, peak heart rates were similar, if not slightly higher during the pandemic for many participants, as well as participants were highly motivated and familiar with maximum effort exercise testing. Importantly, all participants in the reduced CRF group had elevated peak heart rates during the pandemic compared with prepandemic (mean increase: 5 beats·min−1), which is similar to the change in peak heart rate that is often observed concomitantly on cessation of endurance training (32) or with reduced CRF following prolonged bed rest (33) and might be related to the impact of exercise training on the intrinsic heart rate (34).

Our study was limited to a relatively small sample size because there was a limited number of individuals who had their fitness assessed just before the pandemic. We also acknowledge that there were factors beyond our control, such as participants’ diet and how the pandemic affected each participant’s lifestyle, mental health, and daily activities differently. Accordingly, the magnitudes of change in CRF and body mass observed in our cohort may not be reflective of all young healthy individuals during the pandemic. However, our data do provide important insight into the potential impact of living through a pandemic on objective, laboratory-based indicators of cardiovascular health.

Conclusion

Our laboratory-based, objective results suggest that some individuals experienced substantial reductions in CRF and gained body mass during the pandemic, whereas others maintained CRF, but still gained body mass. Regardless of whether participants lost CRF or only gained weight, both changes may put young adults who are currently healthy at higher risk for adverse health outcomes later in life if left unaddressed. Accordingly, it is paramount that people find alternative places and ways to exercise safely to maintain CRF and manage their body mass during times of public health crisis.

GRANTS

This work was supported by the Natural Sciences and Engineering Research Council of Canada grant held by R. L. Hughson (No. RGPIN-6473), and Canadian Institutes for Health Research Banting and Best Canada Graduate Scholarship (201911FBD-434513-72081) held by E. T. Hedge.

DISCLOSURES

R. L. Hughson is the Schlegel Research Chair in Vascular Aging and Brain Health. None of the other authors has any conflicts of interest, financial or otherwise, to disclose.

AUTHOR CONTRIBUTIONS

E.T.H. and R.L.H. conceived and designed research; E.T.H. performed experiments; E.T.H. and R.L.H. analyzed data; E.T.H. and R.L.H. interpreted results of experiments; E.T.H. prepared figures; E.T.H. drafted manuscript; E.T.H. and R.L.H. edited and revised manuscript; E.T.H. and R.L.H. approved final version of manuscript.