The Dangers of Overtraining

  • By Lee Bell BSc (Hons), PGCE, MSc
  • 7 minute read
The Dangers of Overtraining

Overtraining effects around a quarter of all athletes. Destroying gains, fitness and sometimes taking months to recover from. Make sure you know the signs, symptoms and solutions - so you can avoid it.  

So you’re at the gym, smashing the weights. Totally focused. In the zone. Hands chalked, game face on. Shredding your way to new targets.

After all, the ability to take your body to places it has never been before is what separates the best from the rest. Right?

Well, yes and no.

Because when it comes to prolonged, hard, intensive training - more is not always better.

Pushing yourself to the limit to build the perfect physique might seem the right thing to do. But without the proper rest and recovery, your body can buckle under the strain.

In this article we look at the dangers of overtraining. A condition characterized by a loss of strength and speed, low mood, sore muscles and chronic fatigue.   

Key points:

  • It can take weeks, sometimes months to recover from overtraining. During which time you will lose all the fitness you’ve worked hard to build up to that point.
  • As a medical syndrome, overtraining is multifactorial. Risk is increased with not just excessive training but also life stress.
  • Overtraining is very different to tiredness, or simply overreaching during training.
  • There are multiple symptoms to look out for. Including (but exclusively) an unexplained drop in performance, loss of energy, low mood and poor sleep quality.
  • The best way to avoid overtraining is to ‘deload’ regularly and prioritize recovery strategies.

What is overtraining?

Building a strong, lean physique is hard. It takes dedication and effort. And the fitter you are, the harder you need to work to keep improving.

Basic set workouts twice per week isn’t going to deliver the athleticism you want. You need to hit the gym regularly. And hard. Every session will be tough. Because good training must involve a degree of overload. It’s only by intensifying training and getting comfortable with the uncomfortable that you’ll improve. 

But the problem with working so hard is that you put yourself at an increased risk of burnout, fatigue and exhaustion. Especially if you’re smashing it – giving all of your workouts everything you’ve got.

The subject of overtraining is one of the most divisive in the world of fitness. Some believe that it can ruin careers. While others consider it a myth, or an excuse to not push yourself to the cliff-edge of performance.

But what actually is overtraining?

Here’s a definition taken straight from the recent joint consensus between the ECSS and ACSM on the prevention, diagnosis and treatment of the disorder1:

Overtraining is an accumulation of training and/ or non-training stress resulting in long-term decrement in performance in which restoration of performance capacity may take several weeks or months

In simpler terms, overtraining is caused by combining heavy training over a long period of time. With other stressors such as dieting hard, high levels of stress or fighting through illness.

Overtraining is a serious condition, not to be confused with overreaching. If you’re feeling a bit flat on Friday but are back to normal by Monday, that’s not overtraining. If you need to take a week off because of excessive soreness, that’s not overtraining.

What we’re talking about is a condition so brutal that it takes your body weeks, sometimes months to fully recover from. If you’re a competitive athlete, it could sideline you for an entire season.

Overtraining is different to overreaching

Overtraining doesn’t occur overnight. It’s only by training excessively over a sustained period of time that it’ll creep up on you. Think of it like a spectrum, or continuum.

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Let’s say, you push your body for a week and find a new high-volume training plan is showing results. Great! Then, you decide to ditch the recovery time and continue working hard for a couple more weeks. And suddenly find that you’re losing power and feeling weaker.

This is called functional overreaching.

By applying the brakes and adding some recovery time, you’ll be back to full speed in a few days - and see a big improvement when you come out the other side.

Functional overreaching is a technique that many athletes use during pre-competition camps to peak for an event.

Now let’s say that you decide to work through your dip in performance and continue to push yourself in the gym. This prolonged stress will cause a more significant, sustained drop in performance – taking you to a stage known as non-functional overreaching

In other words, it’ll now take you so long to recover that you’ll lose all your fitness gains you worked so hard for.

Non-functional overreaching results in short-term drop in performance capacity with or without related physiological and psychological signs and symptoms in which restoration of performance capacity may take from several days to several weeks

In reality, every person moves along this continuum at a different rate. Some might achieve an overtraining state in a few weeks, for others they can withstand punishing amounts of training for much longer… but it’ll get you eventually if you don’t add in those rest phases.

The diagram above represents the possible stages of training, ranging from acute fatigue to overtraining.

Are you at risk of overtraining?

The reality is that unless you’re working very hard in the gym - or on the track, or on the field – for a sustained period, you won’t ever get anywhere near overtraining.

Even competitive athletes who train for 20-30 hours a week might never suffer from it.

And as we’ve discussed, there’s a huge difference between true overtraining and just feeling a little sore because you threw in a few extra sets the day before.

That said, overtraining is a real disorder and if you do train hard for long periods across the calendar, it’s a real possibility. And something you should be aware of.

According to research2 here are a few useful stats:

  • Between 7% and 20% of athletes will be affected by overtraining each season.
  • Up to 35% of male and 15% of female athletes will suffer from overtraining at any one time.
  • Up to 65% of athletes will suffer from symptoms of overtraining during their career.
  • Once you’ve been diagnosed with overtraining you have a 90% chance of being diagnosed again.

Overtraining is a real condition and research shows that elite athletes are most at risk due to their chronically high training loads

Signs and symptoms of overtraining

Overtraining reflects what happens when your body tries to fight back against the training schedule you’re putting it through. It involves the breakdown - or ‘maladaptation’ - of several physiological systems.  Often representing the accumulation of multiple factors in addition to your training. These could include personal or lifestyle stress from work, draining relationships or diet lacking the correct nutrition.

Because your body is made up of hundreds of intricate biological systems, it’s unlikely that you’ll experience one specific symptom. Or even two. In fact, the definition of a syndrome suggests a condition characterized by a group of associated symptoms.

Currently, researchers haven’t been able to find a gold standard marker that identifies when an athlete is either at risk of overtraining or has already reached that point. However, there are several symptoms that keep popping up in the research that you should look out for. These include:

  • Elevated morning heart rate and low maximum heart rate.
  • Disturbances in heart rate variability.
  • Bad mood, low energy levels and motivation.
  • Anxiety, restlessness, exhaustion and poor sleep quality.
  • Decline in testosterone and other hormones associated with growth and development.
  • More frequent illnesses, such as sore throats and common colds - due to an ineffective immune system.
  • Increased stress hormones such as cortisol.
  • Potential loss of muscle mass, strength and overall fitness.

There’s no one single symptom of overtraining used for diagnosis, other than a decline in performance. Due to the complexity of your biology, chances are you’ll suffer a range of symptoms

Symptoms can be different in endurance and strength sports

If you track through the research, you’ll find an overwhelming number of studies where overtraining has been measured in endurance sports such as marathon, swimming, triathlon.

There are a few research papers looking at symptoms in team sports, but significantly fewer studies in strength sports such as weightlifting, powerlifting or even bodybuilding.

However, one thing research does illustrate is that symptoms in endurance overtraining can be different to strength sports.3  

For example, while endurance athletes often experience a drop in testosterone during prolonged training, strength athletes who train with heavy loads rarely do. In fact, hormonal measures don’t seem to have any reliability in resistance training studies looking at overtraining.

Strength athletes are more likely to experience the following symptoms when they’re diagnosed with overtraining:

  • Loss of speed and power (followed by a drop in maximal strength)
  • Low mood
  • Possible loss of muscle mass (although this is very understudied)
  • Excessive muscle soreness for extended periods of time

Preventing overtraining

Once you’ve been diagnosed as overtraining, the chances are you’ve be diagnosed again. So prevention is most definitely better than the cure here. Additionally, without high-tech laboratory equipment it can be hard to determine when you’re at a greater risk of overtraining.

So here are a few ways to limit the threat of overtraining:

  • Use training logs and records which are color coded into red, amber and green for intensity. If you start spotting too many ambers or reds in a row, ease off for a few days.
  • Don’t fight through illness or soreness. It’s your body’s way of telling you to apply the brakes, so make sure you do. This process of autoregulation works wonders for progressing performance safely.
  • Change your program every few weeks. Monotony can increase the risk of burnout.
  • If you’re stressed from work, family matters or a lack of sleep - don’t train at your usual intensity. It won’t do you any harm to back off a little.
  • Keep a record of coughs, colds and short-term illnesses. If there’s a sharp increase treat it as a warning sign.
  • Schedule rest and deloading weeks intermittently. See recovery as a training tool rather than just time away from the gym.
  • Listen to your body. If you’re feeling depressed, anxious, or your energy levels are low - ask yourself why.
  • Avoid prolonged calorie restricting, particularly during periods of heavy training load.
  • Ensure higher carbohydrate intake. Low muscle glycogen has been implicated as a cause of overtraining in athletes.


Overtraining is a debilitating condition that effects up to 35% of men and 15% of female athletes. It can take months to recover from and will strip you of all the fitness gains you have worked for.

So when it comes to hard, intensive training - sometimes less is more.

Look out for tell-take signs which can include loss of strength, chronic fatigue, sore muscles, low mood and poor sleep quality. And listen to your body.

Recovery time is not your enemy. Treat it as part of your training schedule. And make sure you fuel your body with the correct nutrition.