ABSTRACT
This chapter describes the four 'domains' of exercise intensity in terms of changes in acid-base status and respiratory gas exchange dynamics. Four domains of exercise intensity have been identified based on the characteristic responses of blood acid-base status and pulmonary gas exchange. These are moderate exercise, heavy exercise, severe exercise, and extreme exercise. The exercise intensity at the Tlac/Tvent is a powerful predictor of endurance exercise performance. The chapter reviews the methods that have been used to delineate the transition from moderate to heavy intensity exercise, in particular the lactate and gas exchange thresholds. It also reviews the methods that have been used to delineate the transition from heavy to severe intensity exercise, in particular the maximal lactate steady-state and critical power. The chapter highlights the importance of knowledge of the exercise domains in predicting the physiological response to exercise, and in prescribing and regulating exercise intensity within endurance training programmes.
