Effect Of Sex And Neuromuscular Training On Lower Limb Stiffness Characteristics And Jump Performance

Stiffness is potentially related to sports injury and athletic performance. Higher stiffness within a certain range may represent lower sports injury risk and better athletic performance. It is not clear whether a sex difference existed in lower limb stiffness changes induced by neuromuscular training. PURPOSE: To investigate the effect of neuromuscular training on lower limb stiffness in both male and female young recreational athletes. METHODS: Eleven recreational athletes (5 females: 24.4 ± 3.4 yr; 6 males: 24.0 ± 3.9 yr) underwent neuromuscular training 3 times a week for continuous 6 weeks, including plyometric training (e.g. squat jump, wall jump et al.) and strength training (e.g. barbell squat, bench press et al.) with progression every two weeks. Pre- and post-intervention measurements included: gastrocnemius lateralis (GL), gastrocnemius medialis (GM), soleus muscle and the Achilles tendon (AT) stiffness on both lower limbs by Myometer; vertical stiffness (Kvert), jump height and reactive strength index (RSI) by force plate during drop vertical jump from a 40 cm step. RESULTS: Two-way repeated measures ANOVA was conducted and found no significant interaction between time and sex in all the variables mentioned above, but significant results on time in left GL stiffness (p=0.021), left GM stiffness (p=0.008), right AT stiffness (p=0.040), Kvert (p=0.019), jump height (p=0.012), and RSI (p=0.008). Paired-T test was further conducted and identified jump height in females increased significantly from pre (0.14 ± 0.04 m) to post (0.18 ± 0.05 m) intervention (p=0.037). After intervention, left GL stiffness had a downward tendency in males (Δ=39.69 ± 68.24 N/m) and females (Δ=70.00 ± 60.46 N/m); left GM stiffness tended to increase in males (Δ=34.17 ± 82.22 N/m) and decrease in females (Δ=29.60 ± 63.53 N/m); right AT stiffness (Δ=52.17 ± 215.48 N/m) and Kvert (Δ=199.33 ± 207.36 N/m) tended to decrease in males; RSI in males (Δ=0.16 ± 0.15 m/s) and females (Δ=0.162 ± 0.146 m/s) tended to increase. CONCLUSIONS: Males and females may achieve similar benefits from neuromuscular training. Neuromuscular training can improve jump performance in females, with a tendency to decrease lower limb stiffness in males and females. Supported by Shanghai University of Sports A1-3G02-19-000209