Single-step and cumulative knee loading during high cadence running

Higher running cadence contributes to lower knee loading per step but increases the number of loading cycles, with implications for load accumulation. It is also unknown if knee load reductions from higher cadence persist throughout a run. We evaluated the influence of high cadence running on single-step and cumulative knee loading in distance runners. Thirty-one participants (16 males, 15 females, Age = 21.74 ± 2.86 years, 1.73 ± 0.05 m, 65.4 ± 5.1 kg, Self-selected running Speed = 3.27 ± 0.27 m/s) completed habitual and high (+10%) cadence runs in a counterbalanced order for 30-minutes on an instrumented treadmill. A musculoskeletal model estimated patellofemoral and tibiofemoral joint (PFJ and TFJ) loading and muscles forces. A 2 (condition) by 5 (time) repeated measures ANOVA revealed main effects of condition and time. High vs. habitual cadence running had lower peak patellofemoral joint force (PFJF) (p < 0.001) and peak tibiofemoral joint force (TFJF) (p < 0.001). Peak PFJF was higher at 30 than 10 (p = 0.045), 15 (p = 0.007), and 20 (p = 0.002) minutes of running, but no difference in TFJF (p = 0.202). Peak quadriceps (p < 0.001), hamstring (p = 0.048), and gastrocnemius (p < 0.001) forces were lower during high cadence running. Across conditions, peak quadriceps force was higher at 30 versus 10 (p = 0.035), 15 (p = 0.008), and 20 (p = 0.002) minutes, and peak gastrocnemius force was lower at 30 versus 10 (p = 0.004), and 15 (p = 0.004) minutes. Paired t-tests revealed lower cumulative loading in high vs. habitual cadence running in the PFJ (p = 0.012) and TFJ (p = 0.004). Lower single-step knee loading in high vs. habitual cadence running was maintained despite extra loading cycles. Altered muscle forces may be sources of lower knee loading.