How Much Exercise Is Too Much? Experts Explain the Risks

If you’re consistently falling short of your usual race pace or having to remove weight plates from the squat bar, know that this is your body telling you it needs a rest day — or several.

When you exercise, you are causing tiny microscopic tears in the muscle fibers, Harcoff said. After your workout, your body gets to work on repairing those tears. Once repaired, these muscle fibers are even stronger and more resilient than they were before.

This process, however, takes about 24 to 48 hours. So, if you start working those same muscle fibers before they’ve fully repaired from your last workout, you won’t reap the rewards of your labor. If you keep breaking the same muscle fibers down over and over and never allow them to repair, you’re causing them to whittle away, Wickham said. The result? You get weaker. Or worse, you get injured (more on this below).

Your move: Keep a fitness journal where you log all of your reps, sets, weights, and mileage, as well as how difficult your workouts feel. This kind of tracking will help you keep an eye on your overall volume.

To reiterate: If you exercise too much, your body is unable to repair itself between sessions. “If your body cannot recover, you could begin to experience chronic pain in your joints and muscles,” Harcoff said. “In extreme cases, you can even get injured.”

If you have an injury, in addition to meeting with a physical therapist or orthopedic specialist, you’d also benefit from having a personal trainer look at your movement patterns. Sometimes these kinds of injuries are exacerbated by imperfect movement patterns.

(Related: How To Increase Your Running Mileage Without Getting Injured, According to Experts)

You may be quick to blame your grumpiness on your recent interaction with your co-worker or loved one. But if your mood has been sour for a few weeks, your sweat schedule could be the culprit.

“Becoming more irritable, depressed, or starting to lack the motivation to exercise are all indicators of overtraining,” Harcoff said.

Sports medicine specialists have created something called the Brief Assessment of Mood (BAM+), which is a test designed to help coaches keep an eye on athletes' mental wellbeing. This test helps monitor their players for signs of depression and also helps gauge how their bodies are responding to training load, Harcoff said.

Indeed, one 2017 study published in the Journal of Science and Sports Medicine found that an athlete’s BAM+ score, which uses psychological symptoms to determine whether or not an athlete is overtraining, could be used to predict physiological symptoms of overtraining. High creatine kinase levels in the bloodstream are just one indicator, for example.

While you might think that logging hours in the weight room or miles on the trail would help you sleep deeply, going overboard on exercise can actually interfere with your sleep quality and quantity.

When you overtrain, your cortisol (that's the main stress hormone) levels go up. While you need some cortisol to live, chronically high cortisol levels can disrupt your sleep schedule, Wickham said.

“Some people start to become insomniacs and stop being able to fall asleep when they want, and other people can fall asleep but can’t stay asleep.”

It’s common for people experiencing these symptoms to report feeling tired (while also wired) and to develop an increased reliance on caffeine, according to Wickham. But that’s not even the worst of it. He explained: Your body produces the greatest amount of human growth hormone, the main hormone involved in muscle recovery, in your sleep.

“When you stop being able to sleep, you can enter a negative feedback cycle where you’re recovering less and less and less,” he said.

(Related: The Benefits of Drinking Coffee Before or After Working Out, According to Experts)

Implementing sleep hygiene tactics like going to bed at the same time every night and leaving your electronics away from your bed may help. But if overtraining is truly the root of your subpar sleep, the only thing that’s going to help is exercising less, recovering more, and fueling properly.

If you sport a wearable device, consider looking at more than just how many steps you’re logging each day — changes in your resting heart rate will help you figure out if you’re training a sustainable amount for your body.

“When you’re overtraining, your resting heart rate goes up,” said Reda Elmardi, R.D. and C.S.C.S. “Your heart rate beating faster than normal is a sign that your body is working harder than usual,” he said.

Research has demonstrated that if you’ve been training at higher intensities or volumes than normal, your body (including your heart!) is going to go into overdrive, trying to help your body recover from said exercise.

Most people think there are just four vital signs, but there are actually five. “Your menstrual cycle is known as the fifth vital sign, which means it is used as one of the measures of overall well being,” Gersh said.

So, when athletes lose their period, it’s a symptom that there is an underlying issue with their body. Known medically as amenorrhea, the loss of a period suggests that a person is not healthy enough to sustain a pregnancy.

“The reproductive system literally starts to shut down, which results in a person producing less estrogen,” she said.

Far more than just a pregnancy hormone, estrogen is responsible for helping to maintain strong bones. If estrogen levels dip, the risk for bone breaks as well as osteoporosis goes up. Not ideal considering that bones need to be fully intact to compete, regardless of the sport.

“Typically, someone loses their period because they are both over-exercising and under-eating,” Gersh said. Though, it’s worth noting that amenorrhea can also be caused by some types of intrauterine devices, contraceptives, and other medications.

The typical treatment plan for exercise-induced-amenorrhea involves scaling back on training for a week and working with a nutritionist or registered dietitian to ensure you're consuming the fuel you need. Sometimes healthcare providers will prescribe an estrogen supplement to give the body the estrogen it's not currently making naturally, according to Gersh.

Generally, a skipped period is more noticeable than a period that is lighter or comes a few days late. Gersh suggested paying attention to the frequency and volume of flow, too, especially if big races or intense workouts are on the docket.

It’s uncommon for individuals to go from having a normal period one month to no period the next, she added.

“Typically, people have intermediary signs that they’re at risk for amenorrhea, losing their period,” she said. These signs include: irregular cycles, reduced amount of menstrual bleeding, and spotting.

If there are changes in a cycle, she suggested talking to a healthcare provider who can determine proper fueling and recovery plans to reduce risk of period loss, which can jeopardize an athlete’s overall health.

Words by Gabrielle Kassel