Effects of specific core re-warm-ups on core function, leg perfusion and second-half team sport-specific sprint performance: a randomized crossover study

This study examined the effects of a specific core exercise program, as a re-warm-up regime during the half-time period, on inspiratory (IM) and core (CM) muscle functions, leg perfusion and the team sport-specific sprint performance in the initial stage of the second half of a simulated exercise task. Nine team-sports players performed a simulated team-sport intermittent exercise protocol (IEP) in two phases, on a non-motorized treadmill, interspersed by a 15-min half-time break. During the half-time period subsequent to the 25-min Phase-1 IEP, the players either rested passively or performed 4-min CM exercise concomitant with inspiratory loaded breathing following 11-min passive recovery. The changes in IM and CM functions, leg perfusion and repeatedsprint ability mediated by the two recovery modes were compared. Following Phase-1 IEP, there was a significant decline in IM and CM functions respectively, revealed by the decreases in maximal inspiratory pressure (PImax:-8.1%) and performance of a sport-specific endurance plank test (SEPT:-29.7%, p < 0.05). With the 15-min passive recovery, the decline in IM and CM functions from pre-exercise levels were not restored satisfactorily (PImax:-6.4%, SEPT:-19.0%, p < 0.05). Moreover, repeatedsprint ability during the Phase-2 IEP tended to decrease (peak velocity:-2.3%, mean velocity:-2.1%) from the levels recorded in Phase-1. In contrast, following the re-warm-up exercises during half-time, the restoration of IM and CM function was accelerated (PImax:-0.9%, SEPT:-3.3%, p <0 .05). This was associated with enhanced repeated-sprint ability (peak velocity: +3.0%, mean velocity: +2.0%, p < 0.05) in Phase-2 IEP. Nevertheless, the changes in the anterior thigh muscle perfusion assessed by nearinfrared spectroscopy following the re-warm-up exercises was not different from that of passive recovery (p > 0.05). The findings suggest that a brief inspiratory-loaded CM exercise regime appears to be an effective re-warm-up strategy that optimizes second-half repeated-sprint performance and core function of players in team sports.