The effect of surface on knee landing mechanics and muscle activity during a single-leg landing task in recreationally active females

Objective

Investigate the effect of surface on frontal plane knee angle, knee moment and muscle activity.

Design

Randomised cross over.

Setting

University Laboratory.

Methods

Twenty females performed single-leg hop-landings onto sand, grass and firm surfaces. Kinematic, kinetic and muscle activity data were obtained. Compatibility curves were used to visualise parameter estimates alongside P- values, and S-value transforms.

Results

Knee angle for firm-sand (mean difference $\overline{\left(d\right)}$ = −2.2°; 95% compatibility interval (CI): −4.6 to 0.28, p = 0.083, s = 3.6) and firm-grass ($\bar{d}$ = −1.9; 95% CI: −4.3 to 0.5, p = 0.125, S = 3) yielded <4 bits of reputational information against the null hypothesis (H). 5 bits (p = 0.025) of information against H were observed for knee moment between firm-sand ($\bar{d}$ = 0.17 N m/kg-1. m-1; 95% CI: 0.02 to 0.31) with similar effects for firm-grass ($\bar{d}$ = 0.14 N m/kg-1. m-1; 95% CI: −0.02 to 0.29, p = 0.055, S = 4). Muscle activity across surfaces ranged from almost no (S = 1) reputational evidence against H (Quadriceps and Hamstrings) to 10–13 ‘bits’ against H for lateral gastrocnemius (lower on sand).

Conclusions

Our study provides valuable information for practitioners of the observed effect sizes for lower-limb landing mechanics across surfaces in asymptomatic females.