The purpose of this chapter is to discuss the physi ological adaptations that occur in response to both endurance exercise training and resistance training. A major objective of this chapter is to tie together much of the physiology that has been presented in earlier chapters, because most tissues and organ systems are ei ther directly or indirectly affected by training programs. In the discussion of endurance training, we consider separately those physiological changes that promote an increase in VO, max from those adaptations asso ciated with improvements in prolonged submaximal performance. This is because vo, max is closely linked to the maximal capacity of the cardiovascular system to deliver blood to the working muscles. The ability to sustain long-term, submaximal