We all know that dehydration impairs endurance performance, but what about team sport performance?

The Introduction

Dehydration during endurance events has long been known to reduce performance. Dehydration equivalent to 2% body weight loss during exercise in a hot environment (31-32°C) impairs endurance performance, but when the exercise is performed in a milder environment (20-21°C) a 2% body mass loss appears to have a lesser and inconsequential effect. In cold environments a body mass loss >2% may be tolerable for endurance exercise. However, little research has ever focused on the effect of dehydration on team sport performance.

The Research

netball1710CG006_Sydney_200triathletes drinkingtriathletes drinkingA group of European sport scientists, one of them a former undergraduate student of mine (Dr David Bishop), examined the effect of dehydration on the ability to do intermittent sprint exercise in the heat (35.5 ± 0.6°C, 48.7 ± 3.4% relative humidity). Eight unacclimatized males (age 23.4 ± 6.2 yr, height 1.78 ± 0.04 m, mass 76.8 ± 7.7 kg) undertook three tets, each over two days. On day 1, they did 90 min of exercise/heat-induced dehydration on a cycle ergometer, before following one of three rehydration strategies. On day 2, they completed either a 36-minute cycling intermittent sprint test with a -0.62 ± 0.74% (normally-hydrated), -1.81 ± 0.99% (slightly dehydrated) or -3.88 ± 0.89% (highly dehydrated) body weight deficit. The intermittent sprint test on the bike was designed to mimic one half of a typical team-sport game and involved 36 minutes of repeated-sprint exercise divided into 2-min periods of a 4-second sprint, 100 seconds of active recovery at 35% of aerobic capacity, and 16 seconds of passive rest.  After the 8th and 16th 4-second sprint, a repeated sprint bout was done comprising five 2-second sprints with 18 seconds of active recovery between sprints. These were also designed to mimic an intense period of sprinting, commonly experienced within team games.

The Results

No difference was observed in average total work (kilojoules) or average peak power (watts) between the three hydration conditions. Total work and peak power output in the sprint immediately following an intense repeated sprint bout towards the end of the 36-minute tests were significantly lower in the highly dehydrated condition than both the normally hydrated and slightly dehydrated conditions. The physiological strain index (heart rate and rectal temperatures) was greater in the highly dehydrated state compared to the normally hydrated state.

The So What?

Greater physiological strain was observed with the greatest degree of dehydration. Sprint performance only slowed in the most dehydrated state near the end of the half-game simulation, following an intense bout of repeating sprinting. The results strongly suggest the need for masters athletes in team sports to be hydrated before they play (avoid the beers the night before and caffeine the morning of play) and to replace fluids consistently during the game. If playing in a tournament requiring a number of games over a few days, ensure you drink after the game to replace your fluids. This can be checked by weighing yourself in minimal underwear before and after the game to see how much weight you’ve lost. One kg (2.2 lb) of weight loss equals 1 litre of fluid lost. The books would say no alcohol or caffeine after the game and drink sports drinks until the urine is clear.

Maxwell, N., Mackenzie, R., Bishop, D. (2009). Influence of hypohydration on intermittent sprint performance in the heat. International Journal of Sports Physiology and Performance, 2009, 4(1): 54-67.