By: Terry Donaldson

In this article I want to talk about the effects of dehydration on a fighter’s performance. This is a well documented and supported effect in many physiological and medical textbooks. Long bouts of intense practice and hot environments can cause a loss of as much as 3 litres and hour, of which 90% is due to sweating. This also means a significant loss of electrolytes which are essential for optimal physiological functioning. This deficiency of water molecules in relation to other dissolved solutes within the blood is called dehydration. A decrease of 30% in performance can be associated with as little at 2% dehydration within the body and by the time your brain elicits a thirst response you have lost even greater than 2%. So how is performance affected? Here are some key physiological functions that become compromised:

i) Reduced blood and plasma volume, this results in a decrease in the amount of blood pumped out by the heart, consequently the heart has to work harder in an attempt to maintain an adequate blood (oxygen) supply to the working muscles

ii) Decrease testosterone levels

iii) Increase blood lactate accumulation

iv) impaired ability to sweat; resulting is an increased risk of overheating

v) Reduced muscle blood flow, waste removal, and heat dissipation

Each of these are essential to the fighter in order to maintain their power, strength and endurance during a fight or practice.

Another common practice that relates to this topic is weight cutting. This is an extremely stressful practice on the body. I personally do not agree with it but it is a practice that is likely here to stay in the MMA world. This procedure involves cutting water intake even while exercising, cutting food intake, using saunas, and special sauna suits which accelerate body water loss. This procedure is used by fighters looking to drop weight in order to qualify for a given weight class. Extreme amounts of fluid can be lost with such practices and profound decreases in performance is the inescapable consequence especially with extreme cutting. In many cases the time between the weigh-in and first contest is usually insufficient for fluid and electrolyte balance to be fully re-established in muscles, or for the rehydration and replenishment of muscle and liver glycogen. There is simply not enough time for normal physiological nutritional and hormonal levels to reach the homeostatic properties needed for optimal performance. The recovery process can take anywhere from 4-48hours depending on the amount of weight lost and most weigh ins are followed by the event before the fighter can recover. Suffice to say, cutting can have an undesirable effect on performance, but if it must be done ensure that you rehydrate yourself as much as possible before the fight. Ensure adequate electrolytes and glucose are introduced back into the body using high quality organic fruit juices, water, and or pedialyte. You can also add a pinch or 2 of sea salt into your water to ensure electrolyte replenishment.


– On non training days drink half your body weight (lbs) in ounces. Eg. 200lbs individual requires 100ounces or approx 3litres of water a day. (1L=32ounces).

– On heavy training days expect to double this intake, especially when training in warmer climates or higher elevations.
Water is more readily absorbed when it is room temperature. Cold water aggravates the stomach and intestine lining, and is not readily absorbable until your body warms it.

-Add a pinch of sea salt to your water to ensure adequate electrolyte replacement

– Don’t waste your money on expensive, sugary, processed substitutes such as Gatorade or powerade type sports drinks.

– If/When cutting use high quality organic juices to replace glucose levels, as well as water with sea salt. Pedialyte also works well in these cases of recovery.

-Robergs, R.A. and Roberts, S.O. (1997). Exercise Physiology: Exercise, Performance, and Clinical Applications. Mosby (London).
-Booth, A. Mazur, A.C. and Dabbs, J.M. (1993). “Endogenous testosterone and competition: the effect of fasting.” Steroids. 58 (8), pp.348-350.
-Wilmore, J.H. and Costill, D.L. (1994). Physiology of Sport and Exercise. Human Kinetics (Champaign IL).
-Armstrong, L.E. (1992). “Making weight in hot environments.” National Strength and Conditioning Journal. 14 (5), pp.29-30.
-Clarkson, P. Manmore, M. Oppliger, B. Steen, S. and Walberg-Rankin, J. (1998), “Methods and strategies for weight loss in athletes: A round table.” Gatorade Sports Science Institute. 8 (1), pp.1-9.