Does fasting affect sporting performance?

The announcement that the 2012 London Olympics will take place during Ramadan, the holy month when Muslims fast, has caused a stir among the Islamic sporting community.

“Common concerns among coaches and athletes [are] training and fasting,” said Dr. Ahmad Munir Che Muhamad, senior lecturer, Exercise Science Unit, Sports Centre, Universiti Malaya.

and] a reduction in capacity to perform submaximal exercise for extended periods of time.

“There are also concerns in terms of reduction in cognitive function and motor control ie, relating to sports skills … [and] a decline in sports performance.”

However, despite the general negative perception of fasting during Ramadan on an athlete’s performance, there is little scientific evidence to support this belief, Ahmad told the audience at the 2nd Asian Hydration and Sports Nutrition Seminar 2010 held in Kuala Lumpur.

Studies thus far showed that Ramadan intermittent fasting altered metabolic responses ie, daytime oral temperature, subjective alertness and mood decreased. [Ann Nutr Metab 2000;44(3):101-7]

Other effects of fasting include an increase in subjective and objective daytime sleepiness and increased sleep latency (ie, the transition from waking to sleeping) at night. [J Sleep Res 2003;12(2):95-101, J Sleep Res 2001;10(4):319-27]

A study by Reilly and Waterhouse also found that the rhythm and performance of an athlete was very much related to circadian rhythm and body temperature, and that at the peak of body temperature (about 6 o’clock in the evening), people were more willing to engage in physical activity. [Physiol Behav 2007;90(2-3):219-28]

But there is conflicting data regarding sporting performance and fasting, despite studies such as that by Zerguini et al, which showed that fasting reduced sporting performance (ie, a soccer player’s endurance capacity as well as sprint and dribbling speed and agility). Other studies, however, discovered otherwise (ie, sporting performance was not affected. [Br J Sports Med 2007;41(6):398-400, J Sports Sci 2008;26 Suppl 3:S15-27, J Sports Sci 2008; 26 Suppl 3:S71-9]

Ahmad concluded that whilst overall exercise intensity of the training session is similar between fasting and non-fasting groups, on average, people who fast feel more hungry, thirsty and tired during Ramadan. They are also less prepared to train and marginally less able to concentrate.

As fasting athletes may also be affected by alterations in circadian rhythm, disturbance in the sleep-wake cycle, reduction in energy reserves, timing of testing and their fitness levels, they and their coaches have to take note of these in order to maintain, if not optimize, performance levels.

Source: mims.com