When hard workouts turn harmful: Understanding overtraining syndrome

Pushing workouts too far without rest can lead to overtraining syndrome, a condition that hurts performance, mental health and long-term fitness, experts warn

Most type-A gym rats can recall a time when they went too far. Maybe it was an excessive weight-room session, or a few too many miles on a long run, resulting in knee or lower back pain, joint stiffness or muscle soreness.  Do that once and you’ll feel it for a few days. Do that often and you could be facing a far more serious problem. 

Anyone who’s ever worked out hard knows how it feels to overreach, overdo, overtrain. But if you stay in that “over” zone too long, it can lead to a medical condition called overtraining syndrome, or OTS. 

 

“All training is designed to challenge our bodies to adapt and improve,” says David S Gazzaniga, an orthopedic surgeon and the division chief of sports medicine at Hoag Orthopedic Institute in Southern California. But stressing the body without sufficient rest and recovery can flip your progress on its ear. 

Instead of gains, your overall strength and performance start sliding into the negatives, “impacting both your mental and physical health,” he says. It goes beyond your calves barking at you when you try to walk down the stairs the next morning. 

There are countless proven benefits to being dedicated and pushing yourself with your workouts. But OTS doesn’t develop from just one intense workout. It comes from repetition, and it’s cumulative. 

It can disrupt the body’s normal functions, causing hormone imbalances, a suppressed immune system, muscle-tissue breakdown or even kidney damage. OTS can also leave you more susceptible to stress fractures, chronic tendonitis and other overuse injuries, all of which can leave you benched for months. 

Other symptoms can include headaches, disorientation, irregular bowel movements and, in women, inconsistent menstrual cycles, says Colin Robertson, a UK-based exercise and nutrition scientist who has worked with members of Team GB across four Summer Olympics. 

“Going to the gym and smashing yourself for 45 minutes six days a week with no rest, you’re no longer facilitating an adaptation. You’re just applying too much negative stress on your system,” says Robertson. “It’s debilitating.”

 

Gathering hard stats on how many people experience OTS is challenging, says Jason Lake, an orthopedic surgeon at OrthoArizona in Gilbert, Arizona. “There aren’t enough robust, large-scale studies to cite a precise prevalence rate.” 

But doctors say they’re seeing more instances of it, and many cases go unreported or can be mistaken for other conditions.

“We do see consistent patterns showing that endurance athletes and individuals training at high volumes or intensities are at greater risk for [OTS],” says Jillian Kleiner, a licensed physical therapist at Hinge Health in Denver. 

Not your usual bounce-back 

For Hannah M. Le, 27, the road to OTS started with networking. She exercised twice a day in October 2024 to maximize the value of her gym membership and find ways to promote her business selling hair scrunchies. Le figured the best place to meet people in her target market — women who want a scrunchie that can handle tough workouts — was at the gym.

“I had just moved to NYC and had less than a year to make my company profitable and be able to sustain myself. I was in peak survival mode,” she wrote via email. 

Within three months, the plan was backfiring. Le found herself sacrificing sleep to hit the gym, eliminating days off and cutting her recovery time down to zero. Tracking her health metrics over six months, she found that her heart-rate variability, or the time between heartbeats, kept fluctuating. It was the first sign something was wrong. Soon after that, she was diagnosed with OTS. 

“The worst part was the soreness,” she wrote. “So many intense knots [in my body] that even massage therapists wouldn’t be able to manage.” 

It often starts with fatigue, Kleiner says. You might feel burned out, not bouncing back from workouts as usual and dreading the ones ahead. “Other signs to look out for with OTS include persistent muscle soreness, decreased strength or speed, poor sleep, mood changes, anxiety, depression, increased inflammation and recurring illness or a weakened immune system,” she says. 

Post-workout soreness typically peaks 24 to 72 hours after exercise and should resolve in about a week. “If it’s lasting longer than that, even at rest, it could be a red flag for overtraining,” Kleiner says. 

Rest for the weary 

Recovery is essential to a successful exercise regimen, whether you’re trying to get back in shape or maintain your current level of fitness. “It’s in that rest phase where you make your gains,” Lake says. “And sleep is the single most efficient recovery strategy.” 

But rest isn’t only about getting seven to eight hours of sleep. Nor does it equal total inactivity, Kleiner says: “Gentle movement like yoga, stretching or walking can help improve blood flow and mobility without overloading your system.”

It’s also smart to use this kind of active recovery to mentally recharge before returning to more structured or rigorous training, she says. 

The first step toward avoiding and recuperating from OTS starts in your brain, Kleiner says, with shifting to a more balanced approach to fitness. 

“The goal is to find your movement sweet spot. The place where you’re doing the right amount of movement for your body,” she says. “The exercise or activity is challenging but doable.” 

Next, diversify your routine, Gazzaniga says. Yes, you may have been running the same distance or hitting those laps at the pool every other evening for the past decade. But mixing things up will only help improve your overall wellness. 

Le found this balance by dropping back to one workout a day instead of two. “I also started focusing on doing strength-training exercises that allow me to do the other activities that I truly enjoy, like skiing, golf and hiking.” 

Cross-training is the secret to preventing OTS and overuse injuries, Gazzaniga says. Exercise that involves isometric strengthening, like yoga or tai chi, can be particularly helpful, especially for older people. 

If your fitness goal is longevity, the key is recognizing when you’re doing too much — and knowing that rest is the right way forward.