Physiological Responses to Shuttle Repeated-Sprint Running

This study investigated the influence of 180 changes of direction during a repeated-sprint running test on performance, cardiorespiratory variables, muscle deoxygenation and post-exercise blood lactate ([La](b)) levels. Thirteen team-sport athletes (22 +/- 3 yr) performed 6 repeated maximal sprints with (RSS, 6 x [2 x 12.5 m]) or without (RS, 6 x 25 m) changes of direction. Best and mean running time, percentage speed decrement (%Dec), pulmonary oxygen uptake (VO(2)), vastus lateralis deoxygenation (Hb(diff)) and [La] b were calculated for each condition. Best and mean times for both protocols were largely correlated (r = 0.63 and r = 0.78, respectively), and were `almost certainly ' higher for RSS compared with RS (e. g., 5.30 +/- 0.17 vs. 4.09 +/- 0.17 s for mean time, with the qualitative analysis revealing a 100 % chance of RSS time being greater than RS). In contrast, % Dec was ` possibly ' lower for RSS (2.6 +/- 1.2 vs. 3.2 +/- 1.3 %, with a 79 % chance of a real diff erence). Compared with RS,.V O 2 (40.4 +/- 4.2 vs. 38.9 +/- 3.8 mL. min -1. kg -1, with a 90 % chance of a real diff erence) and [La] b (10.0 +/- 1.7 vs. 9.3 +/- 2.4 mmol. L -1, with a 70 % chance of a real diff erence) were ` possibly ' higher. Conversely, there were no diff erences in Hb diff (11.5 +/- 3.2 vs. 10.9 +/- 3.0 mu M, with the comparison rated as ` unclear '). To conclude, the present results suggest that the ability to repeat sprints can be considered as a general quality. They also suggest that repeated shuttle sprints might be an eff ective training practice for eliciting a greater systemic physiological load, but perhaps not a greater loading of the vastus lateralis.