(24) GENDER DIFFERENCES IN BARBELL MEAN VELOCITY LOSS DURING SETS TO FAILURE OF BACK SQUAT AND BENCH PRESS

Purpose: To assess the gender differences in absolute barbell mean velocity (MV) and relative velocity loss (LOSS) during sets to failure of back squat and bench press. Methods: Twenty-two trained men (n=12) and women (n=10) volunteered to participate in this study. All participants had their 1-repetition maximum (1RM) estimated from an individualized load-velocity profile during an incremental loading test on the back squat and bench press. Participants then completed 3 sets of back squat and bench press to failure at 75% 1RM with 2-minutes rest between sets. Throughout the sets to failure, MV was measured using an inertial measurement unit (Enode Pro). LOSS was calculated as the relative decline from the first repetition of the set (FIRST) to the last (LAST). MV of FIRST and LAST were analyzed by exercise, gender, and set with a 4-way mixed factorial ANOVA. LOSS and the number of repetitions completed per set (REPS) were analyzed with 3-way mixed factorial ANOVAs (Exercise×Set×Gender). Significant interactions and main effects were assessed with Bonferroni-adjusted post hoc pairwise comparisons. Alpha level was set at p< 0.05 and data are presented as mean±standard deviation. Results: No significant 4-way or 3-way interactions were noted for any of the variables. For MV, a significant set×repetition interaction (p=0.007) was observed. Post hoc tests revealed significant declines in FIRST from set 1 (0.50±0.16m/s) to set 2 (0.47±0.10m/s; p=0.003), but no significant difference from set 2 to set 3 (0.44±0.10m/s; p=0.221); however, LAST experienced no significant change (p=1.000) across sets. Additionally, there was a significant main effect of gender for MV with men (0.41±0.14m/s) producing greater values than women (0.36±0.11 m/s) regardless of repetition, set, or exercise. Furthermore, there was a significant main effect of exercise (p< 0.001) for MV with back squat (0.43±0.12m/s) producing greater values than bench press (0.34±0.13m/s), regardless of repetition, set, or gender. For LOSS, there were no significant effects of gender (p=0.454) or set (p=0.146); however, there was a significant main effect of exercise (p=0.028) with bench press (38.7±14.6%) having a significantly greater LOSS than back squat (32.5±12.2%). For REPS, were significant main effects of exercise (p=0.002) and set (p< 0.001), but not gender (p=0.411). Post hoc tests revealed that more REPS were completed during back squat when compared to bench press. Furthermore, the number of REPS decreased from set 1 to set 2 (p< 0.001) and again from set 2 to set 3 (p=0.036) regardless of exercise or gender. Conclusions: MV is significantly lower in women when compared to men during back squat and bench press; however, men and women appear to complete a similar number of REPS and experience a similar LOSS during sets to failure. Furthermore, MV and the number of REPS completed during back squat sets to failure appear to be greater than during bench press; however, LOSS appears to be significantly greater during bench press when compared to back squat. Lastly, MV for FIRST significantly decreases with fatigue, while LAST and LOSS remain relatively unchanged during repeated sets to failure. Practical Applications: Absolute MV is significantly affected by gender; therefore, using absolute values to prescribe velocity-based training (VBT) may not be appropriate. However, LOSS does not appear to be impacted by gender or fatigue, and thus could be confidently implemented into VBT. Acknowledgements: None