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Experts recommend caution when returning to your fitness routine after Covid, RSV, or influenza

Experts recommend caution when returning to your fitness routine after Covid, RSV, or influenza

It’s a new year (2024) and you’re finally taking your resolution to exercise regularly serious. However, you get knocked down by Covid-19. Or maybe you’re a dedicated fitness enthusiast and want to resume your normal routine, but you get a bout with respiratory syncytial virus or influenza.


Regardless of the situation, the primary concern is how to restart your fitness routine safely once fully recover. While a simple head cold or a brief stomach flu may not be cause for much concern, Covid-19, RSV, and influenza are more serious illnesses that require careful consideration when resuming exercise. 


Dr. R.J. Turner, a primary care and sports medicine physician with UTHealth Houston explained that resuming exercise requires caution because these three ailments are viral infections known to cause systemic inflammation throughout the body. According to him, “What that inflammation can do is irritate your heart and lungs, which ultimately can affect your breathing and the way your heart beats. It takes time for your body to completely recover from a viral infection.”


It may take even longer than usual to return to the gym if you’re an older adult or have underlying health issues like diabetes or high blood pressure. Extra caution is required if you have preexisting heart or lung conditions.


Another crucial factor to consider is the duration of your illness and subsequent inactivity. Marisella Villano, a certified personal trainer and owner of Marvil Fit in Hampton Bays, New York, explained that muscle strength starts to decline after five to seven days of inactivity. 


In fact, muscle atrophy can begin within eight hours following surgery.2 Furthermore, a study published in The International Journal of Biochemistry & Cell Biology3 in 2013 found that being bedridden for less than two weeks can lead to a 5% to 10% reduction in muscle mass in your quadriceps.



Planning your return

Regardless of the viral infection you had, it’s advisable to wait at least five to seven days after recovery before returning to the gym. Additionally, you should be able to engage in your daily activities without experiencing excessive fatigue.


“Your body, heart, and lungs need to recover. You don’t want to push it too early and then have complications,” emphasized Turner.


If your Covid infection was accompanied by heart- or lung-related symptoms such as chest pain or difficulty breathing, the American College of Cardiology (ACC)4 recommends consulting your physician before resuming exercise. Furthermore, if the Covid infection resulted in myocarditis, an inflammation of the heart, the ACC guidelines advise refraining from exercise for three to six months.


Slow and easy does it, once you’re cleared to resume your workouts. Turner advised beginning with light exercise by keeping your heart rate below 70% of your maximum. To calculate your maximum heart rate, subtract your age from 220, then calculate 70% of that value. For example, a 40-year-old would have a maximum heart rate of 180 beats per minute (220 minus 40). 70% of 180 is 126. So, a 40-year-old’s heart rate should initially remain below 126 beats per minute. Using a heart-rate monitor or fitness watch can help track your heart rate.


Villano recommended starting with easy-pace walking for the first 10 days after recovery before gradually progressing to moderate exercise. She advised you to avoid resuming the full-intensity exercise that you were doing prior to your illness. Instead, reduce your loads by at least 10% to 15%.


At her fitness studio, Villano observed that some of her clients attempted to immediately resume their workouts after recovering from Covid, despite her warning against it. The outcomes were consistent: These eager individuals experienced fatigue earlier than before, with their heart rates rising at lower workloads post-illness. Some even reported feeling lightheaded.


“I have to talk them off the ledge and tell them their gains are cumulative,” she said. Reducing your workload doesn’t equate to losing all the gains you’ve made.


Pay attention to your body

Pay close attention to your body’s signals as you gradually resume your regular fitness routine. While experiencing some fatigue is normal during this transition, it’s essential to be mindful of any signs of abnormal heart activity, such as racing or irregular heartbeats, or if you experience chest pain. In such cases, stop immediately and see your physician.


According to Turner, you should be concerned about heart attacks and developing heart arrhythmias. You should also try to be well-hydrated and consume nutritious foods, both during illness and when resuming physical activity. This is because your body requires sufficient energy to fight infections and fuel your workouts.


When frustrated or discouraged about how long it’s taking to fully recover, it’s important to remember this: Individuals who engage in regular physical activity are less likely to fall ill,5 and if they do contract an infection, it typically manifests less severely than in sedentary individuals.


“At the end of the day, the healthier we are, the better outcomes we have if we do get sick,” Turner concluded.



  1. McManus M R. (2023). Take caution resuming your fitness routine after Covid, RSV or influenza, experts say. CNN Health. Retrieved March 20, 2024, from 
  2. Stone K R. (2020) How to Prevent Muscle Atrophy. The Stone Clinic. Retrieved March 20, 2024, from 
  3. Bodine SC. Disuse-induced muscle wasting. Int J Biochem Cell Biol. 2013 Oct;45(10):2200-8. doi: 10.1016/j.biocel.2013.06.011. Epub 2013 Jun 22. PMID: 23800384; PMCID: PMC3856924.
  4. 2022 ACC Expert Consensus Decision Pathway on Cardiovascular Sequelae of COVID-19 in Adults: Myocarditis and Other Myocardial Involvement, Post-Acute Sequelae of SARS-CoV-2 Infection, and Return to Play: A Report of the American College of Cardiology Solution Set Oversight Committee. J Am Coll Cardiol 2022;Mar 16:[Epub ahead of print]. 
  5. Martin SA, Pence BD, Woods JA. Exercise and respiratory tract viral infections. Exerc Sport Sci Rev. 2009 Oct;37(4):157-64. doi: 10.1097/JES.0b013e3181b7b57b. PMID: 19955864; PMCID: PMC2803113.
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