How to Hit Peak Fitness After 40

Not long ago, 40 was considered over the hill in sports. But we are increasingly seeing athletes, like the skier Lindsey Vonn, 40, and the climber Chris Sharma, 43, staging midlife comebacks. Peak performance is still within reach for the rest of us, too. Just look at Ken Rideout, a father of four from Nashville who became serious about distance running in his mid-40s and then one of the world’s fastest marathoners his age by his early 50s.

You can absolutely be fitter at 40 or 50 than you were at 30 — it will just take effort, said Dr. Elizabeth Matzkin, an orthopedic surgeon at Mass General Brigham Sports Medicine in Boston. “And you have to approach training differently,” she added.

Many people make the mistake of continuing the same workouts of their 20s into their 40s and beyond, said Dr. Miho Tanaka, who also works at Mass General Brigham, directing the Women’s Sports Medicine program. But in order to build resilience in aging joints, most people need to completely change the way they exercise as they get older.

“Your body will adapt, it just takes longer,” she said, especially if you’ve taken a prolonged break from exercise. And strength and cardio are just one part of your overall fitness equation. You might have been able to get away without warm ups, cool downs, mobility work and proper sleep and nutrition in your 20s. But they become nonnegotiables as we age, she said.

Why it’s harder to train as you age.

Your muscle mass starts declining in your 30s. Gaining it requires ever more work as you get older, far more so for the body’s fast-twitch muscle fibers, which are responsible for explosive movements like sprinting, than for slow-twitch endurance muscles. This is why we see more marathoners peaking in their 40s and fewer sprinters, Dr. Tanaka said.

Also, the tendons and ligaments that support your joints get weaker and more rigid, thanks to the same drop in collagen that causes your skin to wrinkle, she added.