Impact of SARS-CoV-2 Infection on Physical Fitness in Air Force Basic Trainees

The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on physical fitness in previously healthy adults is not well understood. In this study, we assess the impact of SARS-CoV-2 infection on the physical fitness test (PT) scores of Air Force basic trainees.

SARS-CoV-2 testing data and trainee fitness test scores for the calendar year 2021 were obtained from U.S. Air Force basic military trainees. Trainees perform a standardized fitness test including push-ups, sit-ups, and a 2.4 kilometer run at the beginning and end of their training. For this study, basic trainees who performed 2 fitness tests in 2021 and also tested positive for SARS-CoV-2 were defined as the infected cohort. These were 1:1 matched by sex to an uninfected control group of basic trainees. Changes in fitness test scores and pass-fail rates were then compared across the infected and control groups.

A total of 23,450 basic trainees performed a PT in calendar year 2021, 975 (4%) of whom tested positive for SARS-CoV-2. A total of 621 (64%) had completed 2 fitness tests during the defined study period and were included in the infected cohort. There were 96 females (15.5%) in each group and 525 males (84.5%) in each group. There was no difference in body mass index between the infected and the control groups (24.0 [Interquartile range (IQR) 21.8 to 36.0] vs. 24.3 [IQR 21.7-36.9], P = .253). The infected group had a higher rate of failing their PT at the end of training when compared to control (15.7% vs. 4.3%, P < .001). When comparing those who passed their first fitness test and went on to fail their second fitness test, this occurred more frequently in the infected group (2.3% vs. 0.81%, P = .037). When comparing trainees who failed their first fitness test and went on to pass their second fitness test, this occurred more frequently in the control group (46.3% vs. 39.6%, P = .016). Among the infected group, there were no differences in second test failure rates when comparing symptomatic to asymptomatic trainees (16.9% vs. 11.8%, P = .143).

SARS-CoV-2 infection was associated with an increased risk of PT failure as well as conversion from a passing to failing test score. There were no differences in second test failure rates in symptomatic compared to asymptomatic trainees. A key confounder to the data was the effect deconditioning had on fitness during isolation.