Effects of maturation on combined female muscle strength and ACL structural factors

• Published in: Journal of science and medicine in sport 2016-07, Vol.19 (7), p.553-558
• Main Authors: Davidson, S.P, McLean, S.G
• Format: Article
• Language: English
• Subjects: Adolescent; Age Factors; Analysis of Variance; Anterior Cruciate Ligament - anatomy & histology; Anterior Cruciate Ligament - physiology; Anterior Cruciate Ligament Injuries; Child; Cross-Sectional Studies; Female; Females; Hamstring Muscles - anatomy & histology; Hamstring Muscles - physiology; Humans; Knee; Ligaments; Lower extremity; Muscle strength; Muscle Strength - physiology; Physical Medicine and Rehabilitation; Prevention; Quadriceps Muscle - anatomy & histology; Quadriceps Muscle - physiology; Risk Factors; Sports Medicine; Young Adult
• ISSN: 1440-2440; 1878-1861
• DOI: 10.1016/j.jsams.2015.07.016

Abstract Objectives Relations between lower limb muscle strength and female ACL injury risk are well documented. How these relations combine with key ACL geometries however, is unknown. Identifying how these combined factors are impacted by maturation would benefit current risk screening and prevention efforts. This study compared hamstrings and quadriceps strength and ACL cross sectional area (CSA) indices across three maturation groups. Design Cross-sectional human experimental. Methods MRI scans of the dominant knee were collected in 35 females stratified into early (9.7 ± 0.8 yrs), middle (12.9 ± 1.7 yrs), and late (14.8 ± 0.6 yrs) maturation groups. Hamstring and quadriceps muscle volumes and ACL CSA measures were obtained. Isokinetic strength data were quantified for dominant knee flexors and extensors. Peak hamstring and quadriceps concentric and eccentric strength per unit volume magnitudes (QCSPV, HCSPV, QESPV, HESPV) were determined. Metrics and select ratios were submitted to a one way ANOVA to determine the main effect of maturation. Results Significant decreases occurred in HESPV (N/cm3 ) and ACL CSA (cm2 /kg m), respectively, from early (0.188 ± 0.023 N/cm3 , 0.007 ± 0.002 cm2 /kg m) to middle (0.157 ± 0.029 N/cm3 , 0.005 ± 0.002 cm2 /kg m, p = 0.034, p = 0.029), and middle to late (0.132 ± 0.031 N/cm3 , 0.003 ± 0.001 cm2 /kg m, p = 0.044, p = 0.018) maturation. A significant decrease in HESPV:QCSPV occurred between early (1.795 ± 0.496) and middle (1.362 ± 0.277, p = 0.018) maturation. QCSPV:ACL CSA was significantly greater in late (37.26 ± 13.35) compared to middle (25.81 ± 9.17, p = 0.021) maturation. Conclusions Key ratios between female knee quadriceps and hamstring strength and ACL size parameters, which may directly impact ACL injury risk, are substantially different among three maturation states. The results are potentially hazardous strength mismatches in mid-pubertal females, where a smaller (weaker) ACL may be unable to stabilize quadriceps dominated loading strategies.