The science of hydration and refuelling for cricket

How much do cricket players sweat?

Scientists with the Australian Cricket team, Gatorade Sports Science Institute and the Australian Institute of Sport undertook tests on the Australian squad during a 2.5 hour training session (warm-up and drills, followed by bowling and batting practice in nets). The weather during the morning training session was hot, averaging 29°C and 50% humidity. Players had access to “drink stations”, with eskies of cold Gatorade and bottled water provided on the cricket ground, and near to the cricket nets. The specific gravity of urine samples (USG) collected immediately after waking up that morning showed that 5 of the 12 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 11 players who undertook the full training session (the results of one player who was injured were omitted).

The average figures suggest that the cricketers generally looked after themselves well. They made use of the available fluids to drink at a rate that replaced ~ 72% of their sweat losses.  On average, the players sweated at a rate of 1200 ml/hour, which is similar to findings from other team sports.  At the individual level, there was a different story due to the large range in results. There was a four-fold difference in the rates of sweat loss between players.  Fluid intakes also varied, although there was a trend for the “bigger sweaters” to drink more fluid during the session. Four players incurred a weight loss of more than 1.5% BW over the session.  One player gained a small amount of weight over the session, by drinking at a rate slightly higher than his sweat losses.  This player had shown a morning urinary sample consistent with dehydration, and had a lower rate of sweat loss during the session.  Replacing a little more than his sweat losses was useful in allowing him to “make up some ground” in removing his fluid deficit.  This is not to be confused with the problem of substantial over-drinking that has been reported among the slower competitors in marathons and ultra-endurance events. In these situations, athletes expose themselves to the risk of hyponatremia (low blood sodium levels) by drinking several litres of fluid in excess of their sweat rates and showing a substantial weight gain over the exercise session.

The only published study of fluid losses during cricket play found that fast bowlers were unable to main good hydration by drinking during the formal breaks in cricket on a hot day. In fact, after two sessions of play (2 x 2 hr), players had lost an average of 4.3% of body weight (BW). Generally, athletes are advised to follow hydration strategies that keep their fluid losses to less than 2% BW (Gore et al. 1993).
How does hydration and refueling affect cricket?

A study of sub-elite cricket players found that a fluid deficit of just under 3% of body weight impaired their ability to undertake a shuttle run in moderate weather conditions. The fluid deficit was also associated with a reduction in the line and length of accuracy of bowling by ~15%, although bowling speed was not affected.  In contrast, bowling skills and endurance were maintained when players drank sufficient fluid over the session to keep the deficit to ~ 1% of body weight. The negative effects of a fluid deficit on performance are generally higher when exercising in hot conditions. (Devlin et al. 2001).