Force Production Asymmetry in Male and Female Athletes of Differing Strength Levels Bailey CA1, Sato K, Burnett A, Stone MH. Int J Sports Physiol Perform. 2014 PURPOSE – determine the existence of bilateral strength and force production asymmetry and evaluate possible differences based on sex as well as strength level METHODS – Asymmetry was assessed during weight distribution (WtD) testing, unloaded and lightly loaded static (SJ) and countermovement jump (CMJ) testing, and isometric mid-thigh pull (IMTP) strength testing. – 63 athletes (31 male, 32 female) for WtD, SJ and CMJ tests, while 129 athletes (64 male, 65 female) participated in IMTP testing.
– Independent samples t tests were used to determine possible differences in asymmetry magnitude between males and females as well as between strong and weak athletes.
– Cohen’s d effect size estimates were also used to estimate difference magnitudes. SI scores RESULTS
1. Statistically different asymmetry levels with moderate to strong effect sizes were seen between males and females in WtD, 0 kg SJ (peak force; PF), 20 kg SJ (peak power; PP), 0 kg CMJ (PF, PP, net impulse), 20 kg CMJ (PF), but no statistical differences were observed in IMTP variables.
2. Dividing the sample into strong and weak groups produced statistically significant differences with strong effect size estimates in IMTP PF and rate of force development and many effect sizes in jump symmetry variables increased. CONCLUSIONS 1. The results of this investigation indicate that females may be more prone to producing forces asymmetrically than males during WtD and jumping tasks. 2. Weaker athletes displayed more asymmetry than strong 3. This may indicate that absolute strength may play a larger role in influencing asymmetry magnitude than sex.