A Comparison Between Male and Female Strength to Body Mass Ratios and Varus/Valgus Knee Angles During Jump Landings

The reason for the presence of valgus knee angles during jumping in certain individuals is unclear. It appears to be more prevalent in females but has been observed in male subjects as well. Valgus knee position has been attributed to an increase in knee injury. The purpose of this investigation was to compare valgus/varus knee angles during various jumps and lower body strength levels between males and females relative to body mass. Seventeen recreationally active females (age: 21.94±2.59 years; height: 167.32±5.20 cm; mass: 64.42±8.39 kg; % body fat: 26.89±6.26; squat 1RM: 66.18±19.47 kg; S:BM: 1.03±0.28) and thirteen recreationally active males (age: 21.69±1.65 years; height: 176.85±7.26 cm; mass: 72.39±9.23 kg; % body fat: 13.15±5.18; squat 1RM: 115.77±30.40 kg; S:BM: 1.59±0.31) performed a one repetition maximum in the squat (1RM) and three of each of the following jumps: counter-movement jump (CMJ), 30 cm drop jump (DJ30), 45 cm drop jump (DJ45) and 60 cm drop jump (DJ60). Knee angles were analyzed through videography, concentric forces were collected from a force plate, and body composition was analyzed by dual energy X-ray absorptiometry to allow for squat to body mass ratio (S:BM) and squat to fat-free mass (S:FFM) to be calculated. Significant differences (p = 0.05) were found between male and female 1RM, male and female S:BM, and male and female S:FFM. Significant differences were found between male and female varus/valgus knee positions during maximum flexion (MF) of the right leg in the CMJ, DJ30, DJ45 and DJ60. Significant differences were found between male and female varus/valgus knee positions during maximum flexion of the left leg in the CMJ, DJ30, DJ45 and DJ60. Peak concentric force data was only found to be significant between males and females at CMJ, but not at DJ30, DJ45, or DJ60. Correlations between varus/valgus knee angles and S:BM for all for jumps displayed moderate, nonsignificant relationships (CMJ, r = 0.445; DJ30 r = 0.448; DJ45 r = 0.449; DJ60 r = 0.439). In conclusion, males and females have significantly different lower body strength levels and varus/valgus knee position when landing from jumps. The discrepancy in strength level could be an important factor in knee position when landing.