5 Overtraining Myths Explained by Science

Written by Adam Tzur, founder of Sci-Fit. Contributions by Brandon Roberts, PhD, Captain & Research Physiologist. Scientific review by Lee Bell, Senior Lecturer. Published: January 29, 2023.

In this article, we explore the scientific data behind 5 overtraining myths.

Key takeaways

1️⃣ Overtraining exists and has scientific backing.

2️⃣ Symptoms include persistent fatigue and low performance.

3️⃣ Elite athletes may be at risk of overtraining, most regular people are not.

Myth #1: Overtraining Doesn’t Exist

Answer: Overtraining exists, and it is well described in the scientific literature [1] [5] [6] [7] [9]. It is also known as “Overtraining Syndrome” and “Burnout”.

But not everyone thinks it’s real.

You may have heard phrases such as:

  • “More is better”
  • “Push yourself to your limits”
  • “There is no such thing as overtraining, only under recovery”

Even coaches question its existence:

  • “I haven’t seen anyone experience [overtraining]” [2]
  • “Is it overtraining or just work ethic?” [2]

These claims hold some truth. Indeed, it is very hard to become overtrained. It mostly happens to elite athletes. It is rare in strength training and bodybuilding [1] [7].

We asked Brandon Roberts his thoughts on this issue. He does medical research to optimize Warfighters in the US Army:

"While overtraining can occur with any form of exercise, it is less likely to occur with strength training. The risk of other injuries, such as tendonitis or muscle strains, are higher than that of overtraining syndrome."

Brandon Roberts, PhD.
Captain & Research Physiologist, US Army.

Saying overtraining does not exist, is an exaggeration. Many scientific studies describe overtraining syndrome in athletes [1] [4] [5] [6] [7] [9]. Estimates suggest 20% to 60% of athletes may become overtrained at some point in their career [4].

Yet, some researchers have questioned these estimates [12]. We are still learning and trying to find out how prevalent overtraining is.

What Overtraining Is

Overtraining is when you’ve pushed your body too hard for too long [1] [4] [5] [6] [7] [9]. Eventually, it won’t be able to keep up. There are changes in cortisol and heart rate [1]. We call this a catabolic state because your body is breaking down instead of building up.

In practice, you experience a drop in physical performance and fatigue [4] [7] [9] [11].

There are two things that lead to overtraining:

  1. Excessive exercise: for example, intense training every day [7].
  2. Under recovery: not enough food, water, physical rest, mental rest and sleep [7] [9].

You need to do both of these for months, maybe years, until overtraining develops.

In other words, overtraining is all about balance, or the lack of it.

Infographic showing transition from undertraining, to optimal training, to overtraining


Myth #2: Overtraining Only Happens When You Exercise too Much

Answer: Burnout happens when you overtrain and under recover. Under recovery  means eating, sleeping or resting too little. It also includes mental stress.

While it may seem contradictory, overtraining doesn’t have to come exclusively from excessive exercise.

Let’s say you were in a stressful period of your life. Perhaps you would not have time to eat or sleep properly. This would have a major impact on your recovery and exercise capacity.

Instead of a “full glass” of recovery, your glass would only be half full. In which case you have much less energy to expend.

"Excessive exercise is the primary cause of overtraining, as it prevents the body from recovering properly. Even with a high calorie intake, the body may not be able to recover from it. Poor sleep, inadequate nutrition, and other lifestyle habits, can contribute to the risk of overtraining."

Brandon Roberts, PhD.
Captain & Research Physiologist, US Army.

Overreaching versus overtraining

Going from regular training to overtraining is a slow transition. It doesn’t happen overnight.

There are several steps that happen in this transition:

Step 1: Undertraining is when you are training too little to improve performance. Typically it’s caused by a lack of challenge during training. It can also be that recovery between training sessions is too long. Worst case, undertraining leads to a loss of strength or conditioning.

Step 2: Normal training is when you are challenging your own capacity, but also taking enough rest. You recover from your workouts within a day or two.

Step 3: Overreaching happens when you overload your training intensity and/or training volume [1]. You are pushing your limits, and expanding your boundaries.

Athletes typically do this for a period of 7-14 days, as part of a training plan [3]. Then they rest and recover. They do this to boost their performance [3]. Sometimes, athletes overreach unintentionally, by increasing training volume, or doing longer workouts.

Supercompensation is the name of the performance boost that comes after hard training [1] [4] [5] [10]. With overreaching, you aim to maximize the progress coming from supercompensation.

Step 4: Non-functional overreaching can become a reality if you overreach without proper recovery. At this point, you lose performance rather than gain it. You don’t get the benefits of supercompensation [1] [4] [5] [7] [9]. You have to train beyond your capacity for 3-4 weeks before you reach this stage. Some athletes can tolerate training for longer. Training capacity varies a lot between individuals.

Step 5: Overtraining. Athletic performance goes down, and you can expect a long period of recovery. It takes a minimum of 4 weeks to recover, but it can take months if not years to fully recover [4] [8] [11] [12].

"Balance is key. There is a risk:reward ratio to consider when increasing volume/intensity. Is the risk of injury or overtraining worth the potential extra 1-2% performance gains? Maybe for some and not for others."

Brandon Roberts, PhD.
Captain & Research Physiologist, US Army.


Myth #3: There is a Definite Sign of Overtraining

Answer: There are many signs of overtraining. Here are some of the most important ones:

  • Persistent fatigue
  • Decreased athletic performance
  • Unstable mood
  • Sleep problems

4 signs of overtraining

These signs can guide you in the right direction. But there are no definite answers [4]. These same symptoms can be observed during periods of intense training.

For example, if you are fatigued, you aren’t necessarily overtrained. It could mean that you are overreaching [4] (details in Myth #2).

The only surefire way to diagnose overtraining is by how long it takes to fully recover [4]. Check out the table under Myth #5 for more information.

What about cortisol and heart rate?

Some studies suggest you can use cortisol and heart rate variability to diagnose overtraining [12].

Researchers have tried measuring the testosterone:cortisol ratio to identify burnout. But it currently isn’t a reliable way to diagnose burnout [1] [4] [7] [12]. The same applies to heart rate measurements [4] [12].


Myth #4: Anyone Can Become Overtrained

Answer: You are unlikely to become overtrained. The ones who are at risk are elite athletes who constantly push their bodies.

Why It Happens in Elite Athletes

Any athlete that is doing very high volume training is at a greater risk for burnout. This depends on the sport. Because of the sheer magnitude of their workouts, elite endurance athletes are at higher risk.

It can also happen to athletes in sports with an endurance component, i.e. Crossfit.

Why It Could Happen in Bodybuilders

There isn’t much scientific evidence that bodybuilders are at risk of burnout. Studies have tried to overtrain strength training athletes, but results are inconclusive [1] [7].

For bodybuilders, one scenario stands out: contest preparation.

Contest prep has the typical hallmarks of overtraining: intense exercise and under recovery. Bodybuilders will often ramp up cardio and drastically reduce calories before a show. This comes in addition to their intense strength training routine.

A bodybuilding contest is hard on the body, and underlines how crucial recovery is after the show.


Myth #5: You Can Quickly Recover From Overtraining

Answer: Recovering from overtraining can take months, in some cases years [11].

"Recovering from overtraining can be a lengthy process, taking anywhere from several weeks to several months. The recovery period varies depending on the individual."

Brandon Roberts, PhD.
Captain & Research Physiologist, US Army.

The table below shows how much time you need to fully recover.

Time to recover Description
Less than a week Normal training
1-2 weeks [5] Overreaching (functional overreaching)
2-4 weeks [5] Non-functional overreaching
4+ weeks [5] [8] [12] Overtraining

If you’re taking a break from normal training, you should be fully recovered within days.

If you’re overreaching (exceeding your capacity), your body should recover and improve within 1-2 weeks [5]. This is known as functional overreaching. Many athletes and lifters use intense periods of training as part of their training plan. If done properly, overreaching boosts training progress and performance gains.

If you’re overreaching far beyond your capacity, then you will fully recover within 2-4 weeks. This is known as non-functional overreaching [4]. If you keep pushing yourself beyond this stage, you may become overtrained [4] [5] [7].

Overtraining only happens when you need at least 4 weeks of rest to recover [8]. But, in many cases, overtraining can take several months to recover from [4] [11]. In the worst cases, years [11].


My own experience: coming close to overtraining

I have personally never experienced overtraining syndrome. And I am glad for that.

Yet, I did come close, one time.

It was during my early 20s, when I trained 1-2 times per day. I would swim, run, and do strength training. I didn’t eat enough to recover from the workouts.

The first thing I noticed was a loss of performance. I couldn’t lift the same weights in the gym. And my lap times would increase. I persisted under the idea that I had to work harder in order to regain my “lost strength”. I was convinced that taking time off would further deteriorate my performance.

At some point, I had to force myself to take time off. I trained very lightly for 3 weeks. After that, I spent some weeks working myself back to my previous performance. Given the recovery time and loss of performance, I would say I was non-functionally overreached.

It was a useful experience. I learned that there is no shame in resting. And the mentality that “more is always better”, can be harmful. Yes, you have to push yourself to reach new heights. But leaving your foot on the gas for too long can have the opposite effect.


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