by now it should be clear that performance is depen- dent on more than simply having a high vo2 max. In Chap. 23, we saw the role of diet and body com position on performance, and in Chap. 25, we will formally consider "ergogenic" or work-enhancing aids and performance. Sandwiched between these cha ters is a discussion of how the environmental factors of altitude, heat, cold, and pollution can influence performance.