The science of hydration and refuelling for basketball

How much do basketball players sweat?

Scientists with the Australian Institute of Sport and the Gatorade Sports Science Institute undertook tests on the Australian Men’s Basketball (“Boomers”) squad at a practice session during a team camp.  The squad undertook a training session of more than 2 hours (warm-up, on-court drills, and scrimmages) in an indoor stadium during winter.  The average conditions on court were 12°C and 59% humidity. Players were able to drink from individual bottles during breaks in the practice, or as they rotated between scrimmages. The specific gravity of urine samples (USG) collected immediately after waking up that morning showed that 15 of 17 players were dehydrated from their previous day’s activities.  The following table summarises the estimated losses of fluid and sodium during the session for the 16 players who undertook the full training session (the results of one player who was injured were omitted).

We found a wide variability in sweat losses and fluid intakes between players. While the average fluid deficit over the session was within the general target set for athletes, two players recorded a deficit greater than 2% of their body weight.  In addition, many players carried a fluid deficit from their previous day’s training – therefore, the total level of dehydration by the end of the session may have detracted from their performance at practice.  Monitoring weight changes over the sessions can help players to see how well their hydration practices keep pace with their sweat losses.  It can be hard during a two-day practice to stay well-hydrated – even during winter.

We collected information on the fluid intake strategies of the female and male players from the Australian Institute of Sport basketball teams during several training sessions and matches, during both winter and summer.  Although there was a clear difference in the weather between seasons, the sessions were carried out in an indoor stadium that helped to reduce the differences in playing conditions. The results of our observations are summarised below.

Fluid characteristics during on-court practice – AIS males

Fluid characteristics during games – AIS males

Fluid characteristics during on-court practice – AIS females

Fluid characteristics during games – AIS females

We found that sweat rates and fluid intakes of males were greater than females, reflecting their larger size. Sweat rates during games were higher than in practice, which matches the observation that time spent at high work intensities is greater during competition. Although we recommended that each player find a comfortable fluid intake plan that suits their rates of sweat loss, we noted that a typical fluid intake for junior elite basketball players during active training sessions and games might be ~ 600-1000 ml per hour.  On this basis, the coach or team manager would need to ensure that 20 litres of fluid are available on court for a 2 hour training session or match for a squad of 10-12 players (Broad et al. 1996).

How does hydration and refueling affect basketball?

Several studies involving prolonged intermittent exercise protocols or “stop-start” sports (e.g. tennis, soccer and cricket) show that dehydration and inadequate fuel cause fatigue over the course of the exercise session.  By contrast, when subjects consume fluid and carbohydrate during the session, this fatigue is reduced.  Benefits include better maintenance of activity patterns (greater distances covered at higher speeds in the later parts of a game) and better maintenance of skill and concentration.  The studies summarised below have been conducted on the specific outcomes or issues of basketball.  The duration and intensity of a single game may not be sufficiently challenging to cause nutritional fatigue in all players.  This may need to be judged for each individual.  Tournament play is likely to involve the greatest risk of nutritional fatigue since players may experience difficulty in fully rehydrating and refueling between games.  However, some studies show that players may not fully rehydrate between practice sessions during intensive training periods. Fatigue will occur earlier if fluid balance and fuel stores are not ideal at the start of a new game or practice.

Adolescent male basketball players undertook two simulated “2 on 2” full court basketball games over 40 minutes in which a series of skills and physical tests were repeated.  On one occasion players consumed water to replace their sweat losses.  In the other game, where no fluid was consumed, a fluid deficit of ~2% body weight was accumulated by the end of play.  Dehydration did not alter vertical jump height scores. However, there was a strong trend to reduced performance of a 30 second jump test (19% drop) and the accuracy of field goals (8% drop) in the dehydration trial.  These differences could affect the outcome of a real game. (Hoffman et al. 1995)

Drills and skills simulating a basketball game were undertaken over 4 x 12 min quarters on three occasions by skilled adolescent male players. On one occasion, players started the game with a fluid deficit of 2% body weight, while in other games they consumed water or a sports drink to remain in fluid balance. Shooting percentages were different between trials – 45% in the dehydration trial, 53% on the water trial and 60% with sports drink. Similarly, on-court sprinting performance was reduced by dehydration and enhanced by the addition of the carbohydrate in the sports drink. Changes in the performance of other skills and drills also showed the damaging effects of a fluid deficit and the additional benefits of consuming a sports drink compared with water (Dougherty et al. 2006).

College aged male basketball players undertook exercise in the heat on five separate occasions with various levels of fluid replacement so that they achieved a fluid deficit equal to 0, 1, 2, 3 and 4% of body weight.  Following a short recovery, they undertook a game simulation of basketball skills and drills.  The results showed that as the degree of fluid deficit increased, there was a progressive decrease in the performance of on-court sprints and shooting in comparison to the full hydration trial (Baker et al. 2006).