Relationships between modifiable risk factors of hamstring strain injury

Ripley, NJ, Comfort, P, and McMahon, JJ. Relationships between modifiable risk factors of hamstring strain injury. J Strength Cond Res 38(3): 510-516, 2024 - The aims of this study were to determine whether any relationship exists between eccentric hamstring strength and isokinetic strength imbalances and bicep femoris long head (BFLH) architecture. Eighteen physically active men (age 24.7 ± 4.3 years, height 181.9 ± 7.2 cm, mass 84.9 ± 12.9 kg) had resting BFLHmuscle architecture assessed using ultrasound, with images taken at the midmuscle belly. Measures of isokinetic strength of the knee extensors and flexors involved subjects performing 3 maximal effort repetitions of concentric knee extension and eccentric knee flexion at 60°·s-1. Good-excellent relative reliability (intraclass correlation coefficient ≥ 0.86) and low variability (coefficient of variation < 10%) were observed for all variables. Relative BFLHfascicle length (FL) demonstrated significant moderate-to-nearly-perfect associations with isokinetic measures identified as hamstring strain injury risk factors (p < 0.05, r = 0.38-0.92), whereas absolute BFLHFL was not significantly or meaningfully associated with isokinetic measures (p = 0.07-0.961, r = 0.01-0.30). Relative BFLHFL should be considered when assessing resting BFLHmuscle architecture because it is potentially a more appropriate measure of injury risk because of its greater association with strength measures. However, absolute BFLHFL may have a greater usefulness during growth, maturation, and individual proportions.