Examination of fatigue development in elite soccer in a hot environment: a multi-experimental approach

The study examines fatigue in elite soccer played in hot
conditions. High-profile soccer players (n 5 20) were studied during match play at 31 1C. Repeated sprint and
jump performances were assessed in rested state and after a
game and activity profile was examined. Additionally, heart
rate (HR), blood lactate, muscle temperature and body mass
changes were determined. Repeated sprint and jump performances were reduced (Po0.05) by 2.6% and 8.2%, respectively, after the game. The fatigue index in the repeated
sprint test was 6.0 0.7% after the game compared with
1.7 1.0% at rest (Po0.05). High-intensity running was
57 4% lower (Po0.05) during the last 15-min interval of
the game compared with the first 15-min period. No
differences were observed in mean HR or blood lactates
between halves. Muscle temperature was 40.5 0.4 1C
after the first half, which was 0.8 0.2 1C higher
(Po0.05) than after the second half. Net fluid loss during
the game was 42% of the body mass. Correlations were
observed between net-fluid loss and repeated sprint test
fatigue index after the game (r 5 0.73, Po0.05) and YoYo intermittent recovery, level 1 test performance and highintensity running during the final 15 min of the game
(r 5 0.51, Po0.05). The study provides direct evidence of
compromised repeated sprint and jump performances induced by soccer match play and pronounced reduction in
high-intensity running toward the end of an elite game
played in a hot environment. This fatigue could be associated training status and hyperthermia/dehydration.