The doctors have also urged people recovering from Covid-19 to slowly return to physical activity. Although the direct causal association of sudden cardiac death and Covid-19 remain unproven, cardiologist Prof Rakesh Yadav and others have said in the Indian Heart Journal – a peer-reviewed publication of the Cardiology Society of India – that sudden cardiac death (SCD) has emerged as one of the disturbing concerns with Covid-19 infection.

Recently Pune-based 42-year-old Aditya Kelkar, who had run several half and full marathons, passed away long after recovering from Covid-19. The sudden death of 49-year-old well-known fitness expert Kaizzad Capadia due to Covid-19 has also added to the sense of shock among the community of runners and gym-goers.

Nikhil Shah, the coordinator of the group Pune Running that has been in existence for 12 years, said they were shocked to learn about Kelkar’s death. “He had recovered from Covid-19 and started his exercise regimen, climbing hills and cycling. He was among our key runners and then he had this massive heart attack,” Shah said.

Dr Abhijit Lodha, a consulting physician with Ruby Hall Clinic, said that Covid-19 varies widely in the way it affects people. Covid is known to increase blood clotting and hence before undertaking any vigorous exercise, it is prudent to consult a doctor, he said. Shah pointed out that the diet also plays an important role. “Several have the notion that if they are into swimming and cycling, they can eat whatever they want,” he said.

“People are taking up heavy workouts without proper guidance,” said Dr Rituparna Shinde, a cardiologist with Poona hospital. “There is a thin line between exercise and exertion. It is a must to exercise but due care should be taken not to cross certain limits which can trigger the release of certain hormones leading to arrhythmia and causing sudden cardiac death,” the doctor said.

It is also pertinent for those setting out to exercise in their 40s and after 40s to undergo a cardiac evaluation as prevention can be done by controlled and graded monitored exercise,” Dr Shinde said.

Experts also said that participating in these endurance events has become a style statement. Sports physiotherapist Dr Anand Gangwal said that people should remember to exercise more for their personal benefit and less for posting on social media. “There should be an understanding of one’s own body and when to stop exercising,” Dr Gangwal said.

Dr Prashant Mishra, senior cardiologist with Deenanath Mangeshkar hospital, said that before embarking on marathons or high-intensity exercises, people must get evaluated.

Dr Aditya Kelkar, city-based eye surgeon who has organised National Institute of Ophthalmology (NIO) Vision Marathons for the last seven years, said that it was crucial to understand that exercising is also a recreational activity to keep fit.

“Besides post-Covid phase – for three months at least after recovery – underlying undiagnosed asymptomatic hypertrophic cardiomyopathy, arrhythmic tendency, supplements and most importantly a dehydrated state after vigorous exercise are responsible factors (for deaths). It is important to get a proper cardiac evaluation before signing up for a gym programme irrespective of age while an ECG, echo and stress test should be sufficient to screen out high-risk ones,” said Dr Omkar Thopte, a 38-year-old cardiologist who has completed 600 km BRM, an endurance cycling event.

Several cardiologists have also said that gyms should be equipped with automated external defibrillators and staff should be trained in cardiopulmonary resuscitation (CPR) to deal with emergency situations.