Electrolyte supplementation during severe energy restriction increases exercise capacity in the heat

This study was done by Lewis James, Stephen Mears, and Susan Shirreffs to examine the effects of electrolyte supplementation during severe energy restriction on exercise capacity in the heat.

The participants were nine healthy males with a mean age of 25 years old. All of the participants were physically active. They participated in this study voluntarily through their University. None of the subjects were trained in cycling prior to the study.

The experiment consisted of five different trials every other week for 5 months. The first trial was preliminary, the second trial was for familiarization, and the last three were the experimental trials. The study was completed in England during the summer. During the trials, the participants rode a stationary cycle at 60% V02max to failure in 95 degree heat. The preliminary trial was completed in order to find the participants V02max. The familiarization trial was completed to get the participants used to the cycling protocol as well as the urine and blood collection that was used to collect the data during the trial.

To introduce energy restriction, they were assigned three different diets depending on which experimental trial they were in at the time. The control group ate on average 2654 calories every 24hrs (based on their calculated resting energy expenditure) while the other two experimental groups ate on average 883 calories every 24hrs. One experimental group and the control group consumed electrolytes in the form of sodium chloride and potassium chloride pills. The other group took a placebo pill in the form of maltodextrin.

The experimental group that did not receive the electrolytes lost the most body mass, had the lowest plasma volume, had the lowest exercise capacity, and had the highest heart rate. The experimental group that consumed the electrolyte pills had similar numbers to the control group, though they lost slightly more body mass. This study suggests that electrolyte supplementation during caloric restriction will mitigate the negative effects of heat on the body.

James, Lewis J., Stephen A. Mears, and Susan M. Shirreffs. “Electrolyte Supplementation During Severe Energy Restriction Increases Exercise Capacity In The Heat”. European Journal of Applied Physiology 115.12 (2015): 2621-2629. Web. 23 Mar. 2016.