One of the central questions in the field of health and fitness these days is what type of physical activity is suitable during quarantine due to the COVID-19 pandemic.

Many scientific papers show that a moderate dose of endurance exercise has a beneficial effect on immune responses against viral respiratory infections (1, 2). Endurance exercises, mainly referred to as cardio, can still be done in the home environment with or without equipment quite successfully. Contrary to cardio, it might seem like there are not many solutions for in-home resistance training. However, exercise professionals will undoubtedly know how to put together a strength training program with or without equipment for all levels of practitioners using the principles of strength training and progressive overload as an essential factor. The majority could still benefit from bodyweight strength exercises, because training with low loads (ultimately bodyweight), and a high level of effort (close to failure) seems to have greater importance than total training volume in the accretion of muscle mass, whereas, for high load training (heavyweights), muscle failure does not promote any additional benefits (3). Regular moderate-intensity activities are beneficial, having immune-enhancing effects throughout the reductions of inflammation, increased immune cell turnover, enhanced immune surveillance, and improvement of psychological stress status (4). Also, regular physical activity reduces the risk of chronic metabolic and cardiorespiratory diseases because exercise exerts anti-inflammatory effects (4). Following the moderate-intensity physical activity, an increase in neutrophil and natural killer (NK) cell counts is detected, and salivary IgA (immunoglobulin A) concentrations are enhanced (6, 7). Moderate-intensity physical activity increases stress hormones, which leads to a reduction in excessive inflammation. This leads to a boost in immunity against viral infections via a change in Th1/Th2 cell responses (6). Twenty to thirty percent reduction of upper respiratory tract infections are reported in individuals performing moderate levels of physical activity in their daily life (6). However, prolonged high-intensity physical activity leads to immunosuppression (7,1), so with certainty, we can conclude that duration of high-intensity intervals should be kept at a minimum during self-quarantine as it might lead to cold, fewer or inspiratory tract infection (1).

Homestay is a fundamental safety step that can limit infections from spreading widely. However, prolonged home stays can increase behaviors that lead to inactivity and contribute to anxiety and depression, which in turn can lead to a sedentary lifestyle (poor nutrition and lack of movement) known to result in a range of chronic health conditions. Maintaining regular physical activity and routinely exercising in a safe home environment is an essential strategy for healthy living during the coronavirus crisis (9).

In conclusion, moderate-intensity exercise may be helpful for healthy asymptomatic people and should be recommended. However, due to the high risk of spread, an exercise in private environments (home-based) with proper ventilation and use of personal equipment may be more reasonable (2). A home exercise program using different safe, simple, and easily implementable exercises is suitable to avoid the airborne coronavirus and preserve fitness levels. This program may include aerobic (walking in the house), strengthening, stretching and balance exercises, or a combination of these (9).

References:

1. Shephard, R. J., Verde, T. J., Thomas, S. G., & Shek, P. (1991). Physical activity and the immune system. Canadian Journal of Sport Sciences, 16(3), 169–185.

2. Halabchi F, Ahmadinejad Z, Selk-Ghaffari M. (2020) COVID-19 Epidemic: Exercise or Not to Exercise; That is the Question!, Asian journal of sports medicine, Online ahead of Print; In Press:e102630. doi: 10.5812/asjsm.102630.

3. Lasevicius T, Schoenfeld BJ, Silva-Batista C, Barros TS, Aihara AY, Brendon H, Longo AR, Tricoli V, Peres BA, Teixeira EL. (2019). Muscle Failure Promotes Greater Muscle Hypertrophy in Low-Load but Not in High-Load Resistance Training. J Strength Cond Res.

4. Lombardi, G., Ziemann, E., & Banfi, G. (2019). Physical activity and bone health: what is the role of immune system? A narrative review of the third way. Frontiers in endocrinology, 10.

5. Gleeson, M., Bishop, N.C., Stensel, D.J., Lindley, M.R., Mastana, S.S., & Nimmo, M.A. (2011). The anti-inflammatory effects of exercise: mechanisms and implications for the prevention and treatment of disease. Nature Reviews Immunology, 11, 607-615.

6. Harris, M. D. (2011). Infectious disease in athletes. Current sports medicine reports, 10(2), 84-89.

7. Martin, S. A., Pence, B. D., & Woods, J. A. (2009). Exercise and respiratory tract viral infections. Exercise and sport sciences reviews, 37(4), 157.

8. Ahmadinejad, Z., Alijani, N., Mansori, S., & Ziaee, V. (2014). Common sports-related infections: a review on clinical pictures, management, and time to return to sports. Asian journal of sports medicine, 5(1), 1.

9. Chen, P., Mao, L., Nassis, G. P., Harmer, P., Ainsworth, B. E., & Li, F. (2020). Wuhan coronavirus (2019-nCoV): The need to maintain regular physical activity while taking precautions. Journal of Sport and Health Science, 9(2), 103.