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Testosterone and Overtraining

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In order to strip body fat and gain muscle you need to train hard. You start to see results and you enjoy going so you continue to up the intensity. We know that when we weight train our testosterone levels get a boost – but is more exercise necessarily better?

If you train hard too regularly it can have a serious affect on your performance, a term referred to as ‘overtraining’. It can affect the body in a number of different ways. In this article we’ll take a look at the effects of this condition on your T levels.

You will learn:

  • What is overtraining?
  • Does it affect testosterone levels?

What is overtraining?

Whenever we exercise we gradually create an environment of ‘stress overload’ – we break down muscle tissue and stress the heart and lungs in order to force a response. If we then provide the body with rest, it recovers and grows back bigger and stronger. This is a process called ‘adaptation’.

If you don’t give your body enough rest you create an imbalance between overload and adaptation and consequently you don’t allow the body to regenerate. When this occurs you begin to feel tired, and if you still continue to exercise without rest you become exhausted.

Otherwise referred to as ‘staleness’, ‘athlete chronic fatigue’ and ‘unexplained under-performance syndrome’, overtraining (OT) can be defined as…

the accumulation of training and/or non-training stress resulting in long-term decrement in performance capacity with or without related physiological and psychological signs and symptoms in which restoration of performance capacity may take several weeks or months [1]

The symptoms of OT can be diverse and specific both to the individual and also the type of training they undertake. These include:

  • Reduced performance – loss of strength and fitness
  • Feelings of physical fatigue, tiredness and exhaustion
  • Loss of muscle and body weight
  • Reduced immune system – more likely to suffer from common cold
  • Alterations to hormones

One such hormone that may be altered by overtraining is that of testosterone. But how does excessive exercise affect it? Read on to find out…


Key Point: Overtraining is the imbalance between exercise and rest, and can cause symptoms such reduced performance, fatigue, loss of muscle and exhaustion.

Does overtraining affect testosterone?

The symptoms of OT can be largely placed into four main categories – psychological, physiological, biochemical and immunological [2]. One element of the ‘biochemical’ category of symptoms – testosterone, has often been used to diagnose OT in elite athletes.

Depending on the intensity or duration of exercise, hormones can either be anabolic – help you to build muscle, or catabolic – break down muscle. For that reason, excessive exercise may negatively impact T levels. Here’s what the studies say:

#Study 1: A study in the British Medical Journal [3] analysed testosterone levels in rugby players to see if they could determine the relationship between hormones, state of fitness and exhaustion.

The authors of the study reported that T levels correlated well with feelings of tiredness, and about 25% of players classed as excessively fatigued had T levels up to 30% lower than normal. One player had almost a 50% drop in T.

The study concluded that testosterone concentrations were influenced by tiredness, and is therefore a valid marker of OT

#Study 2: Similarly, a study of 5 swimmers in the International Journal of Sports Medicine [4] found that T levels were lower after 2 weeks of hard training, and related to decreases in performance following intensive training.

This effect has also been found in rowers too. Vervoorn et al [5] found that during a 1988 Olympic training camp, the testosterone levels of the rowers were far lower during periods of heavy training than during recovery. 

Additionally, cortisol levels – a stress hormone that has been found to decrease muscle mass and have negative effects on T was elevated.

#Study 3: An interesting study by Schelling et al [6] investigated the effects of playing positions, playing time, and phase of the season on both testosterone and cortisol levels in basketball players.

The researchers were able to work out that T levels were lower in those that played the most and also during months with most games. They also reported that cortisol levels were higher in those that played specifically between 13 and 25 minutes per game, and that the players’ ‘testosterone-cortisol ratio’ – basically a measure to show catabolic or stressed hormonal status, was higher during periods of excessive tiredness.

The authors concluded that monitoring T and cortisol is recommended to prevent excessive stress.

#Study 4: Lastly, Häkkinen and colleagues [7] wanted to find out how intensive weight lifting affected hormones, in particular the T:cortisol ratio. To do this, the researchers asked 8 elite weightlifting volunteers to train twice per day over a 1-week training period.

The strength of the group decreased, demonstrating that they were overtrained. Testosterone was found to be significantly low in the afternoon sessions, and the T:cortisol ratio was also negatively impacted as well.

This showed that even a short, intensive training phase can reduce T levels if insufficient rest is given.


Key Point: Research shows that overtraining can decrease testosterone, increase cortisol and negatively impact your testosterone-to-cortisol ratio.

Summary – T levels and overtraining

Overtraining is defined as exercise-related stress that has a long-term effect on performance capacity. It can take weeks or months to recover from, and is ultimately an imbalance between exercise and recovery.

The symptoms of OT can be diverse and specific both to the individual but usually include These include a reduction in performance – loss of strength and fitness, feelings of fatigue and tiredness, loss of body weight and changes to hormones.

Research shows that in times of excessive training and exercise, overtraining can decrease your testosterone levels that can contribute to a loss of muscle. Additionally, a hormone called cortisol can increase – as the body’s stress hormone this can also contribute to decreased muscle but also fat gain.

Research suggests that overtraining can affect hormones in the following ways:

a) Lowers testosterone

b) Increases cortisol

c) Decreases the testosterone-to-cortisol ratio

It is important to keep testosterone levels high, rest periods in-between training sessions are well managed. If you are a competitive athlete and you don’t rest, it could mean that you’re performance is effected, and for those that train for muscle gain it could mean that you lose muscle quickly.

Make sure you plan rest days and weeks in advance and stick to them.


  1. Halson SL, Jeukendrup AE. Does overtraining exist?: An analysis of overreaching & overtraining research. Sports Med 2004; 34(14): 967-98
  2. Hug M, Mullis PE, Vogt M, et al. Training modalities: overreaching and overtraining in athletes, including a study of the role of hormones. Best Prac Res Clin Endoc Metab 2003; 17(2): 191-209
  3. Maso, F et al. Salivary testosterone and cortisol in rugby players: correlation with psychological overtraining items. Br J Sports Med. 2004; 38: 260-263
  4. Flynn MG, Pizza FX, Boone Jr JB, et al. Indices of training stress during competitive running and swimming seasons. Int J Sports Med 1994; 15 (1): 21-6
  5. Vervoorn C, Quist AM, Vermulst LJ, et al. The behaviour of the plasma free testosterone/cortisol ratio during a season of elite rowing training. Int J Sports Med 1991; 12 (3): 257-63
  6. Schelling, X et al. Using testosterone and cortisol as biomarker for training individualization in elite basketball: a 4-year follow-up study. J Strength Cond Res. 2015; 29(2): 368-78
  7. Häkkinen, K et al. Daily Hormonal and Neuromuscular Responses to Intensive Strength Training in 1 Week. Int J Sports Med, 1988; 09(6): 422-428