Effects of Ramadan on physical performance: chronobiological considerations.

This article focuses on changes in Ramadan during the course of the waking day in physical performance, mental performance and gastrointestinal function. Possible explanations of the changes are considered by reference to the roles of the body clock and external factors such as the environment and the individual's lifestyle. The effects of these factors upon training schedules and upon changing the times of training are then discussed in terms of physiology and biochemistry. Delaying the time of training until after sunset has advantages and disadvantages, but it is a regimen that is unlikely to be widely accepted in non-Muslim countries. It is clear that the detailed nature of the problems involved and dealing with them in a manner based upon a firm body of knowledge requires far more experimental investigation.