Sports Med 2008; 38 (1): 37-51

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 1. The Physiological Response to the Yo-Yo Intermittent Recovery (IR) Tests . . . . . . . . . . . . . . . . . . . . . . . . 38 2. Reproducibility of the Yo-Yo IR Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 3. Performance of Different Groups of Athletes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 4. Performance in the Yo-Yo IR Test in Relation to Performance during Competition . . . . . . . . . . . . . . . . 44 5. Seasonal Changes in Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 6. Relationship Between the Yo-Yo IR Tests and Maximal Oxygen Uptake . . . . . . . . . . . . . . . . . . . . . . . . . 47 7. Non-Exhaustive Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 The two Yo-Yo intermittent recovery (IR) tests evaluate an individual’s ability Abstract to repeatedly perform intense exercise. The Yo-Yo IR level 1 (Yo-Yo IR1) test focuses on the capacity to carry out intermittent exercise leading to a maximal activation of the aerobic system, whereas Yo-Yo IR level 2 (Yo-Yo IR2) determines an individual’s ability to recover from repeated exercise with a high contribution from the anaerobic system. Evaluations of elite athletes in various sports involving intermittent exercise showed that the higher the level of competition the better an athlete performs in the Yo-Yo IR tests. Performance in the YoYo IR tests for young athletes increases with rising age. The Yo-Yo IR tests have shown to be a more sensitive measure of changes in performance than maximum oxygen uptake. The Yo-Yo IR tests provide a simple and valid way to obtain important information of an individual’s capacity to perform repeated intense exercise and to examine changes in performance. The activity profile and physical demands of turns, tackles, high-speed runs and sprints.[1,2,5,7,8] many sports involving intermittent exercise, such as Physiological determinations, such as heart-rate rebasketball and soccer, have been studied extensively cordings as well as metabolic measurements of over the last decade.[1-10] It is well established that muscle and blood samples collected during competisuch sports have high physical demands due to tion, have furthermore shown that in many of these multiple brief intense activities, such as jumps, sports the aerobic loading is high throughout the