Effects of instrument-assisted soft tissue mobilization technique on strength, knee joint passive stiffness, and pain threshold in hamstring shortness.

BACKGROUND: Hamstring shortness is the most common musculoskeletal condition in sports athletes, which often contributes to hamstring strain injury. To effectively mitigate the hamstring shortness, contemporary HR, SCS, and IASTM soft tissue techniques have been used. The best practical evidence about the therapeutic effects and the biomechanical mechanisms underpinning these manual techniques remain unknown.

OBJECTIVE: The purpose of this study was to compare the effects of HR, SCS, and IASTM techniques on improving hamstring and quadriceps muscle strength, related ratio, knee joint passive stiffness, and pain threshold.

METHODS: Forty-five participants (21 males and 24 females) with hamstring shortness participated in this study. The participants were randomly assigned to each of the three soft tissue mobilization technique groups. A Biodex System Isokinetic Dynamometer was used to measure muscle strength and knee joint passive stiffness during knee extension and flexion. Pressure algometry was used to measure hamstring pain threshold. One-way ANOVA were used to determine the statistical significance of the hamstring and quadriceps strength, related ratios, knee joint passive stiffness, and pain threshold in each technique. The significance level was set at α= 0.05.

RESULTS: The IASTM group showed greater improvement in the peak quadriceps strength (p= 0.000), the peak quadriceps and hamstring (Q:H) strength ratio (p= 0.004), passive knee stiffness (p= 0.000), and pain threshold (p= 0.017) than the HR or SCS groups.

CONCLUSION: The present comparative study provided first clinical evidence that IASTM technique is a best soft tissue mobilization technique to improve the strength, associated strength ratio, knee joint passive stiffness, and pain threshold among individuals with hamstring shortness.