Acute effect of an intra-set variable resistance of back squats over 30-m sprint times of female sprinters

Introduction: Several pre-conditioning methods have been tested in order to produce Postactivation Potentiation (PAP) in men. However, it is unknown if Intra-Set Variable Resistance generates the same effect in female sprinters. Objective: Thus, the acute effect of an Intra-Set Variable Resistance (I-SVR) protocol of back squats on 30-m sprint times of female sprinters was determined. Material and method: Ten female sprinters were the subjects of this study (age = 20.3 ± 1.9 years, body mass 56.0 ± 6.9 kg, height = 1.64 ± 6.1 m, 30-m sprint = 4609.2 ± 236.4 ms). The pre-conditioning with I-SVR consisted of 4 back squats exercise sets: each set included 22% 1RM X 5 reps (equivalent to 1.0-1.1 m•s ^-1 ), 60% 1RM X 4 reps (equivalent to 0.6-0.7 m•s ^-1 ), and 30-m sprint X 3 with a 2-minute rest. Results: The repeated measures ANOVA did not show significant differences in 30-m sprint after the application of preconditioning protocols with I-SVR (p > 0.05), while [La] provided evidence of a significant increase post-effort (p < 0.0001). However, great individual variations were observed. Conclusions: Considering that the pre-conditioning with I-SVR did not increase the performance in women sprinters, which may be due to insufficient load to elicit a PAP response or that the fatigue induced outweighs the benefit, the coaches considering the use of this pre-conditioning protocol in order to generate PAP must explore its effectiveness individually. Factors such as strength levels, protocol resistance used to generate PAP, and, above all, the recovery interval between pre-conditioning and the following sprint need further research.