VO2 slow component: physiological and functional significance.

This paper offers a brief synopsis of the five preceding papers which constitute the proceedings of the symposium "Mechanistic basis of the slow component of VO2 kinetics during heavy exercise." The key features have been taken from each paper and a coherent position regarding the site and potential underlying mechanisms for the "excess" VO2 is presented. The hypothesis is developed that some aspect of fiber type recruitment patterns might be responsible for this phenomenon. Elucidation of the precise determinants of VO2 during heavy exercise is fundamental to our understanding of muscle energetics. Furthermore, certain patient populations, whose exercise tolerance is limited by impaired cardiovascular and/or respiratory capacity, may benefit from interventions designed to constrain the magnitude of the VO2 slow component.