Water may not help runners keep their cool
21 May 2007 by Evoluted New Media
Last month 35,674 people ran the London Marathon, many of whom downed as much water as they could at each of the water stations on the route – but did that help them run the gruelling 26 miles 885 yards? Surprisingly, the answer according to one scientist, is no.
Last month 35,674 people ran the London Marathon, many of whom downed as much water as they could at each of the water stations on the route – but did that help them run the gruelling 26 miles 885 yards? Surprisingly, the answer according to one scientist, is no.
According to Dr Chris Byrne of the University of Exeter’s School of Sport and Health Sciences a large fluid intake does not achieve either a better performance, or a cooler body.
Dr Byrne said: “The conventional view among both scientists and the fitness media is that fully replacing sweat losses by fluid intake during exercise will reduce an athlete’s body temperature and improve performance. Our research, which for the first time measured internal body temperature continuously during an actual race, revealed no evidence that fluid intake makes runners cooler or improves performance.”
Dr Byrne and his team monitored a group of male runners taking part in the Singapore Army Half-Marathon, a 21km race that took place in temperatures up to 29?C - the first time that researchers have monitored body temperatures continuously throughout a race. The night before the race, the runners ingested telemetric temperature sensors, which contain temperature-sensitive quartz crystal oscillators that vibrate at a frequency relative to its surrounding temperature and communicate the temperature by radio wave to a recording device worn by the runner.
Over half the runners reached body temperatures exceeding 40?C and all lost an average of 1.5L of sweat per hour. However, Dr Byrne reports that there was no relationship between the amount of fluid each runner consumed, his body temperature and overall performance in the race.
Dr Byrne concludes: “I would encourage people taking part in this season’s big runs to be well hydrated before the race, but not to feel they need to drink water throughout the event. Listen to your body and drink if you feel thirsty, but drinking several litres of water will not help you run any faster.”
The study was published in the journal Medicine & Science in Sports & Exercise.
