It would appear that the rates of improvement might be slowing. Banned substances aside, the past decade has seen advances in our understanding of the factors that influence athletic performance and, ultimately, the setting of new world records. This has undoubtedly contributed to improvements and will continue to shape the progression of world records in years to come. In the 1990s attention shifted to subtler interventions based on a growing understanding of the physiology of exercise and fatigue. So, for some athletes, creatine is a safe, legal, and effective ergogenic aid.
Human beings regulate body temperature by sweating, with the inevitable loss of body water.
Nutritional strategies such as creatine supplementation address the muscle component of the fatigue process. However, fatigue also involves the central nervous system. Levels of 5-HT can be altered by nutritional manipulation of its amino acid precursors. Research remains at an early stage and further studies are required before BCAA supplementation can be recommended to endurance athletes as an ergogenic aid. During exercise, the inspiratory muscles are capable of stealing blood from locomotor muscles, and so impair performance.