Eighteen-Month Changes in Physical Activity, Body Weight, Quadriceps Strength, and Gait Biomechanics during the COVID-19 Pandemic

PURPOSE: This study assessed the effects of the COVID-19 pandemic restrictions/lockdowns on physical activity levels, body mass, quadriceps strength, and gait biomechanics over 18 months. METHODS: Ten healthy men were assessed at baseline (~14 wk before first lockdown) and 17.9 ± 0.3 months later (<1 wk after second lockdown). At both times, physical activity levels, body mass, and quadriceps strength were acquired using the International Physical Activity Questionnaire, a force plate, and a dynamometer, respectively. Gait data were also acquired using a motion capture system and force plates during self-paced walking, from which spatiotemporal parameters, knee angles, and external moments were computed. Baseline and follow-up measurements were compared using two-tailed paired t-tests (α = 0.05). RESULTS: At follow-up, participants spent less time doing vigorous physical activity (∆ = −76 ± 157 min·wk(−1), P = 0.048), exhibited a tendency toward increased sedentary time (∆ = +120 ± 162 min·d(−1), P = 0.056), weighed more (∆ = +2.5 ± 2.8 kg, P = 0.021), and showed a trend toward reduced quadriceps strength (∆ = −0.29 ± 0.45 (N·m)·kg(−1), P = 0.071) compared with baseline. At follow-up, participants walked slower (∆ = −0.09 ± 0.07 m·s(−1), P = 0.005), had greater knee flexion angles at heel strike (∆ = +2.2° ± 1.8°, P = 0.004) and during late stance (∆ = +2.2° ± 1.8°, P = 0.004), had reduced knee extension moments (∆ = −0.09 ± 0.09 (N·m)·kg(−1), P = 0.012) and knee internal rotation moments (∆ = −0.02 ± 0.02 (N·m)·kg(−1), P = 0.012) during late stance. CONCLUSIONS: Healthy men exhibited reduced physical activity levels, increased body weight, a tendency toward reduced quadriceps strength, and altered gait biomechanics over the initial 18 months of the COVID-19 pandemic—alterations that could have far-reaching health consequences.