More and more details appear on masks that are safe and therapeutic and as effective as a vaccine. Data also indicate that masks can also be worn during exercise. It does not change the amount of oxygen in the blood, so it can be worn when running or driving.

However, the guidelines for preventive measures in gyms and yoga institutes of the Ministry of Health stated that while masks are compulsory within the premises, they are not required during exercise.

Just a viewfinder should be used as far as possible during yoga practice or exercise in gymnasiums. The use of masks (in particular N-95 masks) during exercise can cause trouble breathing.

Several physicians, coaches, and athletes agreed that wearing masks during exercise could impede airflow, particularly oxygen flow. They indicated that masks could increase the absorption of carbon dioxide and increase the heart rate, raising the risk of failure.

Reference
Should you wear masks during exercise? ICMR chief says yes, doctors, coaches disagree. https://theprint.in/health/should-you-wear-masks-during-exercise-icmr-chief-says-yes-doctors-coaches-disagree/539632/