New Delhi, Oct. 3 -- When Alisha (name changed on request), 48, went to a wellness retreat last year, she was looking to relax and blow off some stress, perhaps come back with a healthy habit or two. She considered herself relatively healthy, and used a smartwatch to track fitness. When the retreat prescribed assessments, she went ahead with them as part of the protocol.

Among the blood tests and other checks was a VO2 max test, where she exercised on a treadmill or cycle while wearing a mask to measure her cardiorespiratory fitness. Her result put her in the "poor" category. "They did explain the test to me and told me why I fell towards the bottom of it. They didn't scare me, but I got worried considering my family's poor heart history...