Is overtraining affecting your performance?

Have you ever wondered if you're training too much? Dr Dan looks at how to spot overtraining and what it could be doing to your performance.

We’ve all heard the phrase that you can have too much of a good thing, but is that true when it comes to your fitness routine? Well, yes. By training too much, you could be doing yourself harm.

In this blog, we investigate overtraining syndrome, how to spot it, and what to do about it.

What is overtraining?

The idea of training is to push your body to make adaptations, which, in turn, increase your performance. Training often involves putting your body under stress to rebuild stronger than before. If you get this right, you are training optimally — and you’ll notice yourself getting better and better.

The key to optimal training is to maximise your exercise energy expenditure within the top limit of what your physiological reserve can handle. Yes, you will be tired for a few hours or the rest of the day, but you should feel decent and strong the next day (leg day aches notwithstanding). But what happens when you get the balance wrong?

Over-reaching is an accumulation of training load that outweighs the body’s ability to recover, which leads to a decline in performance.

You’ve maybe done a bit too much, but after a short period of rest and recovery — a couple of days off, you will return to normal, or you may even notice positive gains (termed super-compensation).

Over-reaching is not necessarily a bad thing. But, it can be difficult to distinguish over-reaching from the early stages of overtraining syndrome.

Overtraining Syndrome (OTS) is a condition brought about by excessive training without the necessary recovery.

Overtraining syndrome is characterised by:

  • Persistent fatigue
  • Poor performance
  • Lack of improvements
  • Change in mood
  • Hormone disruption
  • A propensity for infections

Overtraining can sometimes take months of rest to recover fully from, which no athlete wants to deal with.

The training spectrum

You can think of training as a spectrum:

Undertraining ➔ optimal training ➔ over-reaching ➔ overtraining

The prevalence of overtraining syndrome varies from sport to sport. The most common sports for overtraining include endurance sports, such as:

  • Swimming
  • Triathlon
  • Cycling
  • Rowing
  • Distance running (to a lesser extent)

Symptoms of OTS

Parasympathetic changes (more common in aerobic sports) Sympathetic changes (more common in anaerobic sports) Other
Fatigue Insomnia Anorexia
Depression Irritability Weight loss
Bradycardia (slow heart rate) Agitation Lack of concentration
Loss of motivation Tachycardia (fast heart rate) Heavy, sore, stiff muscles
  Hypertension (high blood pressure) Anxiety
  Restlessness Waking feeling unrefreshed

How to spot if you’re overtraining

Everyone is unique, and every sport has different demands on the body. That means there’s no one size fits all criteria, but there are some common threads.

The first thing is awareness. Make time for objective and subjective feedback from you and your trainer. If you’re taking your training seriously, you’ll be keeping a record of performance (reps, load, times, etc.). These should be improving over time. In the new athlete, these improvements will be fast and noticeable, but over time it plateaus as you have essentially hit your peak. At this stage, it’s marginal gains.

If you trend things out on a graph, you don’t want to see a drop in performance. We’re not talking about the odd day here or there (that’s normal). If you’re seeing a steady decline, despite best efforts, over a few weeks - it is an alarm bell.

At the same time, you should be checking in with yourself and talking with your trainer/coach/team. You need to lose the ego and be open and honest about how you’re feeling. If something’s not right, then you need to flag it up early rather than pushing through it (easier said than done for an athlete!).

Blood tests are a valuable tool. It’s beyond the scope of this article to talk about the ways we use blood tests for Olympic-level athletes. Instead, let’s look at what’s realistic for the amateur athlete.

What blood tests can tell you about your training

The Ultimate Performance Test has been specifically designed for athletes, and it’s full of biomarkers to monitor.

A rough schedule to include blood tests within your training routine would be:

  • Start with a baseline test - before a new training programme or competition.
  • Take a peak test - mid-way through a competition or training cycle.
  • Complete with a recovery test - one-two weeks after a training cycle.

Sometimes we can tell a lot from unique one-off markers, but often when it comes to sports performance, we gain the most information from looking at the trends over time.

At Medichecks, you can see your trend results clearly on your tracker graph. Here’s what your results might tell us.


After several weeks of releasing hormones in response to stresses (training), the body will dampen the response to these hormones, which results in releasing fewer hormones.

We might see:

  • High and then low cortisol
  • Low prolactin
  • Low female sex hormones
  • Low male sex hormones

Sex hormones may manifest in loss of normal menstrual function in women and reduced libido in men. For men, a hybrid marker to look at is the testosterone:cortisol ratio.

Immune system

During exercise, you breathe deeper, and your gut permeability increases, both of which can expose you to more bugs.

Excessive training can cause an increase in your stress hormones, which can dampen your immune system. So, we might see this reflected in your white cell count. If your immune system is dampened, you become more vulnerable to infections, in particular respiratory tract infections.

Muscle damage and repair

Creatinine kinase is produced when your muscles break down from heavy exercise (and you often feel your muscles ache after hard workouts). If muscles aren’t repairing quickly, then they’ll also struggle to hold your body’s energy stores in the form of glycogen, so you’ll get more tired more quickly.

Aerobic breakdown

Endurance athletes can lose blood (and therefore iron from the haemoglobin) more easily than other athletes. This is because their muscles break down red cells as they rub together, the gut does a similar thing and foot stamping crushes them as well. Top-level athletes ideally want to have haemoglobin towards the high end of the normal range, and for every 1g/Kg lost, your VO2 Max will decrease a little bit.

Nutrient depletion

Nutrients are fuel, and you’ll use them up through exercise. Keep these optimised, and you can check your levels through blood results. Your iron and vitamin D levels can affect performance if levels drop.

I think I have OTS — now what?

If you think you might be experiencing overtraining syndrome, be sure to let us know in your health questionnaire. Tell us about your current training regimen and why you think you may be experiencing overtraining syndrome. The more information you can give us, the more our doctors can help you, and with OTS in mind, they’ll interpret your results differently.

Quick note: Other syndromes you may have heard of are relative energy deficiency in sport (RED-S) and the female athlete triad. These are part of the same family as OTS. Unfortunately, women are more vulnerable to overtraining issues than men, due to issues with oestrogen and loss of blood through menstruation.

We’ll be writing blogs on these in due course.

What can I do about OTS?

We often say prevention is better than cure, but for an athlete at risk from OTS, this has never been truer. For people who do go on to get OTS, the only cure is rest. And by rest, it means proper rest for weeks, sometimes even months. No competition and serious deconditioning. You can think of it as a serious injury. No athlete wants this.

So instead, the key is to prevent it. The easiest way to do this is by monitoring yourself as outlined above — diaries, check-ins, and blood tests. If you notice something’s not right, then STOP. Take a few days, and then restart. That’s the way to do it.

You can also look to optimise other aspects of your life:

  • Make sure you have good nutrition. Home-cooked, whole foods, nutrient-rich for your sport.
  • Get a calorie tracker. Make sure you’re taking in everything you need.
  • Sleep well. Read our blog on the effects of poor sleep.
  • Plan rest days. Ensure your training and competition schedule incorporates plenty of rest days.
  • Reduce stress. Try to minimise stresses in other aspects of your life.
  • Keep up your fluids. Stay well hydrated and ensure you’re getting fresh air.


  1. Jeffrey B. Kreher, MD,*† and Jennifer B. Schwartz, MD. Overtraining Syndrome: A Practical Guide. Sports Health. 128-138, 2012, Vol. 4, 2.
  2. MACKINNON, LAUREL T. Overtraining effects on immunity and performance in athletes. Immunology and Cell Biology. 502-509, 2000, Vol. 78.
  3. Gleeson, Michael. BIOCHEMICAL AND IMMUNOLOGICAL MARKERS OF OVER-TRAINING. Journal of Sports Science and Medicine. 31-41, 2002, Vol. 1.
  4. Stellingwerff, T., Heikura, I.A., Meeusen, R. et al. Overtraining Syndrome (OTS) and Relative Energy Deficiency in Sport (RED-S): Shared Pathways, Symptoms and Complexities. Sports Med 51, 2251–2280 (2021).

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