Acute responses to a potentiation warm-up protocol on sprint and change of direction in female football players: a randomized controlled study

Objectives To evaluate the acute effect of exposure to a potentiation warm-up protocol compared to a usual warm-up program. Design Randomized parallel control trial. Setting Synthetic grass in the club's facilities (Portugal). Participants Seventeen female football players (age: 23.9 +/- 3.9 years), were randomly allocated to a control (n = 8) and an experimental group (n = 9). To allocate the players, a table was computer-generated by a research team member with no involvement in the trial. Intervention The control group performed their usual warm-up program, while the experimental group performed a potentiation warm-up protocol with jumps combined with sprints with change of direction. Main outcomes measures The players were tested pre- and post-intervention for a 40-m linear sprint and pre-planned change of direction using the T-test. Statistical analysis An intention-to-treat analysis was performed, with all the participants originally randomized being involved. The normal distribution was verified by the Shapiro-Wilk test. The assumption of sphericity was analyzed. Effect sizes were calculated using partial eta squared. Results No significant pre-post differences in the T-test and in the 40-m sprint were detected for any group. However, in the T-test, large effect sizes in time increments were observed within the experimental (0.27 s; p > 0.05, eta(2)(p) = 0.176) and control groups (0.06 s; p > 0.05, eta(2)(p) = 0.176). Also, in the 40-m sprint, large effect sizes in time increments were observed within the experimental (0.05 s; p > 0.05, eta(2)(p) = 0.251) and control groups (0.09 s; p > 0.05, eta(2)(p) = 0.251). Conclusions The performance-enhancing ability of the potentiation method performed at warm-up was not verified when applied to female football players. Thus, the potentiation methods may not improve sprint and COD ability for this population. However, the lack of statistical significance may have been due to reduced statistical power, as three of four effects suggest acute performance impairment after a supposed potentiation-oriented warm-up. Nevertheless, the presence of a statistical type 2 error cannot be ruled out.