Dehydration likely reduces the benefits of resistance exercise

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Over the years, I have become increasingly interested in the value of resistance exercise in maintaining or increasing muscle mass and strength, as well as its impact on general health and wellbeing. Individuals engaging in resistance exercise are often concerned that they fuel themselves adequately afterwards. A usual goal here is to supply the muscle with the protein/amino acids required to repair and regenerate muscle.

I was interested to read a study recently which suggests that the effects of resistance exercise might be affected by our state of hydration [1]. In this study, young men performed resistance exercise in three states of hydration: normal hydration, 2.5 per cent dehydration, and 5.0 per dehydration. A number of physiological markers were assessed prior to and after exercise.

Two of the most notable findings of this study were that in a dehydrated state, the men experienced:

1. higher levels of ‘stress’ hormones cortisol and noradrenaline

2. lower levels of testosterone

This is relevant because, generally speaking, stress hormones such as cortisol are ‘catabolic’ – which means they facilitate the breakdown of body tissue including muscle. On the other hand, testosterone is ‘anabolic’ – meaning it stimulates muscle generation.

All-in-all, what these results show is that performing resistance exercise in a dehydrated state may lead to fewer gains in terms of muscle development. Another problem with dehydration is that it will generally lead to individuals being able to do less work in a given session too, further limiting the benefits to be had from the exercise.

Prior to resistance exercise (or any exercise) it generally helps to be properly hydrated. As a general rule, I advise drinking enough water to ensure urine remains pale in colour throughout the course of the day.


1. Judelson DA, et al. Effect of hydration state on resistance exercise-induced endocrine markers of anabolism, catabolism, and metabolism. J Appl Physiol. 2008;105:816-824

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