Running gait biomechanics associated with hamstring and quadriceps strength profiles.

Objective: To evaluate the relationships between quadriceps and hamstring strength profiles and running gait kinetics in healthy adult athletes.

Design: Cross-sectional.

Setting: Hospital-affiliated injury prevention clinic.

Participants: 554 healthy adult runners (355 F, 199 M).

Main outcome measures: Mass-normalized quadriceps and hamstring strength were obtained using hand-held dynamometry. Cadence, stride length, %stance, and body weight (BW) normalized peak vertical ground reaction force (vGRF) were obtained using an instrumented treadmill. Linear regression analyses were used to assess the relationships between mass-normalized hamstring and quadriceps strength and running biomechanics. Logistic regression analyses were used to assess relationships between hamstring:quadriceps (H:Q) symmetry profiles (≥0.5, <0.5) and running biomechanics.

Results: Quadriceps strength was directly associated with cadence (p < 0.001) and stride lengths (p = 0.01), and inversely associated with %stance phase (p < 0.001) and vGRF (p < 0.001). Hamstring strength was directly associated with higher cadence (p = 0.003) and height-normalized stride length (p < 0.001), yet inversely associated with %stance phase (p < 0.001) and BW-normalized peak vGRF (p < 0.001). More symmetric H:Q profiles were associated with longer height-normalized stride lengths (p = 0.03).

Conclusions: Quadriceps and hamstring strength profiles were weakly inversely associated with vGRF and percentage of the gait cycle in stance phase among healthy adult runners.