Impacts Of Step-rate And Gait Speed Changes On Knee Moments Across Age

PURPOSE: Investigate the effects of increasing step rate on knee flexion and adduction moments across different walking speeds in individuals aged 18-75. METHODS: Thirty-seven participants (Age = 42.95 ± 19.32, 26 Females) were recruited and classified into three age groups: Young (18-39), Middle (40-59), Old (60-75). All participants underwent gait analysis involving motion capture on an instrumented treadmill. Walking trials were conducted at three distinct speeds: preferred, 10% below preferred, and 10% above preferred. At each speed, participants walked at three step rate conditions: preferred step rate, 5% above preferred, and 10% above preferred. Inverse dynamics were calculated for each trial and normalized to bodyweight, peak knee flexion and adduction moments were identified as the peak values during the stance phase, and knee flexion and adduction moment impulses were defined as the positive area under each waveform. Separate repeated measures analyses of variance (RMANOVAs) were used to assess the influence of age group, walking speed, and step rate on both peak and impulse measures for knee flexion moment and knee adduction moment. RESULTS: There was no effect on peak knee flexion moment or knee flexion moment impulse by step rate or gait speed, but age group had a significant effect on both (p < 0.001). In both cases, the old age group had lower values compared to the young and middle age groups. Similarly, the only significant effect on peak knee adduction moment was group (p < 0.001), and the old age group had lower values compared to the young and middle age groups. With knee adduction moment impulse there were significant effects for both age group (p < 0.001) and step rate (p = 0.02). In this case, knee adduction moment impulse was lower in both the middle and older age groups compared to the young age group, and decreased with increases in step rate across all speeds and age groups. CONCLUSION: Increasing step rate had no effect on knee flexion moments and peak knee adduction moment, though increases in step rate decreased knee adduction moment impulse. Significant group differences were found across all variables, suggesting the knee moments vary significantly across age.