Abstract

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 (????)̄ = -2.2°; 95% compatibility interval (CI): -4.6 to 0.28, p =0.083, s = 3.6) and firm-grass (???? ̄= -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 (???? ̄ = 0.17 N.m/kg-1.m-1; 95% CI: 0.02 to 0.31) with similar effects for firm-grass (???? ̄ = 0.14 45 N.m/kg-1.m-1; 95% CI: -0.02 to 0.29, p =0.055, s = 4). Muscle activity across surfaces ranged 46 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.