Is cardio enough to live longer? Harvard trained doctor gives reality check on what matters after 40

For years, cardio has been hailed as the cornerstone of fitness. But according to Dr. Darshan Shah, a Harvard-trained physician and longevity specialist, relying solely on running, cycling, or other cardio workouts may not be enough to maintain health as we age. Speaking on The Doctor’s Kitchen Podcast with Dr. Rupy Aujla, Shah gave a reality check: after 40, strength training should take center stage.

“You really have to add strength training into your routine after the age of 40,” Shah said in the interview, a clip of which was later shared on Instagram. “Most of my patients, especially women, are very focused on cardio. I’m not saying cardio is bad, but you’ve got to cut it in half and make the other half strength training.”

The science of aging muscles
Shah explained that the human body naturally loses muscle and bone density with age, a process that accelerates after 40. Women, in particular, can lose between 3% and 8% of muscle mass per decade after 30, and even more following menopause. Without proactive strength training, this decline can leave people weaker, less mobile, and more vulnerable to chronic illness.

“We’re genetically programmed to break down muscle at a much faster rate after 40,” Shah noted. “If you’re not using it, you’re losing it. That’s why so many people end up frail in later years.”


More than just muscles
The benefits of resistance training extend beyond strength and mobility. Research shows it supports cardiovascular health by lowering blood pressure and improving cholesterol and blood sugar regulation. It has also been linked to better sleep quality, which often deteriorates with age, and improved mood and weight management.

Physiotherapist Emma Mitchell, speaking separately about misconceptions around women and strength training, said fears of becoming “too bulky” are misplaced. “For many women, it’s actually difficult to build large amounts of muscle. What most achieve through regular strength workouts is a toned, more defined look, along with significant health benefits,” she explained.

A holistic approach to longevity
Shah, who has performed more than 20,000 surgeries and later expanded into wellness and preventive medicine, believes fitness is one of several pillars of a long and healthy life. On the podcast, he outlined four core areas: lifestyle medicine, functional medicine, preventive medicine, and longevity-focused treatments such as supplements and advanced therapies.

“As we get older, looking after our muscles isn’t just about looking good,” Shah told The Doctor’s Kitchen Podcast. “It’s about staying strong, mobile, and independent for as long as possible.”

Cardio is still valuable, especially for heart and lung health. But according to Shah, anyone serious about healthy aging needs to balance it with regular strength training—ideally two to three sessions a week. His message is clear: after 40, the road to longevity runs not just on the treadmill, but also through the weight rack.