Players of Caja Laboral Baskonia performing a Yo-Yo Intermittent Recovery Test. (Photo: Iñigo Mujika).
Most team sports are characterized by a high intensity, intermittent activity pattern. Team sport players (e.g. football, basketball, rugby, water polo) perform a high number of high intensity and sprint activities of various durations during match play. These bursts of intense activity are interspersed with lower intensity activities also of variable duration.
Insight into the cardiovascular and metabolic demands of these sports provided by simple physiological measurements such as heart rate and blood lactate also indicates that high demands are placed on both aerobic and anaerobic metabolic pathways during match play.
In view of these observations, it is clear that any performance test aiming at the assessment of a player’s physiological capabilities should take into account the intermittent nature of the game and try to mimic the metabolic demands of its intense exercise/recovery activity pattern.
Intermittent performance tests have been developed and validated to assess players’ match-fitness in several team sports. Some of these tests have been used to assess the performance capabilities of players and referees, and to evaluate the effects of various training and nutritional interventions on fitness and performance.
One such test is the Yo-Yo Intermitent Recovery Test (Bangsbo 1994), which has become in the past few years one of the most extensively investigated fitness test from a physiological perspective, but also one of the most widely used test in practical sport settings (Bangsbo 2008).
Description of the Yo-Yo Intermittent Recovery Test
The Yo-Yo Intermittent Recovery Test (YYIRT) was inspired by the multistage fitness test. As in the latter, the subjects undertaking the YYIRT are required to perform 20 m. shuttles, but while the multistage shuttle test is continuous, the YYIRT shuttles are interspersed with a 10-second active recovery period. The YYIRT consists thus of repeated out and back 20 m runs between the starting, turning and finishing line at progressively increasing speed, which is controlled by audio signals from a CD player.
Between each out and back shuttle, the participants have a 10-s period of active recovery, also controlled by audio signals, during which they have to perform a 2 x 5 m. jog. Running speed increases progressively, but the recovery time remains constant throughout the test.
The first time a participant fails to reach the finishing line in time, they receive a warning, and the second time they are withdrawn from the test. The final shuttle number is recorded and converted to total distance covered, which represents the final test result. The YYIRT may be performed at two different levels with different speed increments (Bangsbo 1994, Krustrup et al. 2003).
Level 1
The YYYIRT Level 1 consists initially of 4 running shuttles (0 to 160 m.) at 10-13 km/h and 7 shuttles (160 to 440 m.) at 13.5-14 km/h. Thereafter, running speed continues to increase progressively by 0.5 km/h after every 8 shuttles (i.e. after 760, 1080, 1400, 1720 m, etc.) until a participant fails twice to reach the finish line in time.
The 20 m. distance is marked with a line of cones, and another line of cones is placed 5 m. beyond the finish line, marking the distance to be covered twice (i.e. out and back) during the period of active recovery.
Level 2
The principle of the YYIRT Level 2 is identical to that of Level 1, the main difference being that the initial speed is set at 13 km/h (i.e. participants have 11.0 s. to perform the initial out and back shuttle, in comparison with 14.5 s. in the YYIRT Level 1).
From a metabolic stand point, the main difference between the YYIRT Level 1 and Level 2 is the degree of stimulation of the anaerobic system (Krustrup et al. 2006). At the end of the YYIRT Level 2, the creatine phosphate concentration is lower and the rate of creatine phosphate utilization in the last phase of the test is higher than in the YYIRT Level 1. In addition, the YYIRT Level 2 elicits higher muscle lactate concentration, and the rate of muscle lactate accumulation in the final phase of the test is about five times higher, eliciting also a lower pH at the time of exhaustion. The rate of blood lactate accumulation towards the end of the test and the peak blood lactate concentration are higher in the YYIRT Level 2. In addition, a higher average rate of muscle glycogen utilization is observed during the YYIRT Level 2, suggesting a higher reliance on glycolysis compared with the YYIRT Level 1 (Krustrup et al. 2006).
The above observations suggest that whereas the YYIRT Level 1 is indicative of a player’s ability to perform repeated high-intensity aerobic efforts, the YYIRT Level 2 assesses the capacity to carry out intense intermittent efforts requiring a large anaerobic contribution combined with a significant aerobic component (Krustrup et al. 2006).
Assessment of match fitness in team sports through the Yo-Yo Intermittent Recovery Test (and II)
pouvez vous nous procurer les normes des 2 niveaux
Dans la deuxième partie de l’article, disponible sur mon blog dans quelques jours, il y aura quelques valeurs de référence, ainsi que les références bibliographiques utilisées. Si vous voulez, pous pouvez trouver ces valeurs sur: Bangsbo J. The Yo-Yo Intermittent Recovery Test. A useful tool for evaluation of physical performance in intermittent sports. Sports Med. 2008, 38:37-51.