Two Weeks of Repeated-Sprint Training in Soccer: To Turn or Not to Turn?

Purpose: To compare the effects of 2 repeated-sprint training programs on fitness in soccer. Methods: Fifteen semiprofessional soccer players (age: 24 +/- 4 y; body mass: 77 8 kg) completed 6 repeated-sprint training sessions over a 2-week period. Players were assigned to a straight-line (STR) (n = 8; 3-4 sets of 7 x 30 m) or change of direction (CoD) (n = 7; 3-4 sets of 7 x 20-m) repeated-sprint training group. Performance measures included 5-, 10-, and 20-m sprints, countermovement jump, Illinois agility, and Yo-Yo Intermittent Recovery Test level 1 (YYIRTL1) performance. Internal (heart rate) and external (global positioning system-derived measures) training loads were monitored throughout. Data were analyzed using magnitude-based inferences. Results: Internal and external loads were higher in the STR group than in the CoD group with large differences in maximum velocity (28.7%; +/- 90% confidence limits, 3.3%), moderate differences in mean heart rates (7.0%; +/- 1.4%) and PlayerLoad (17.6%; +/- 8.6%), and small differences in peak heart rates (3.0%; +/- 1.6%). Large improvements in 5-m (STR: 9.6%; +/- 7.0% and CoD: 9.4%; +/- 3.3%), 10-m (STR: 6.6%; +/- 4.6% and CoD: 6.7%; +/- 2.2%), and 20-m (STR: 3.6; +/- 4.0% and CoD: 4.0; +/- 1.7%) sprints were observed. Large and moderate improvements in YYIRTL1 performance were observed in the STR (24.0%; +/- 9.3%) and CoD (31.0%; +/- 7.5%), respectively. Between-groups differences in outcome measures were unclear. Conclusions: Two weeks of repeated-sprint training stimulates improvements in acceleration, speed, and high-intensity running performance in soccer players. Despite STR inducing higher internal and external training loads, training adaptations were unclear between training modes, indicating a need for further research.