Lower-extremity biomechanics during forward and lateral stepping activities in older adults

Abstract

Objective. To characterize the lower-extremity biomechanics associated with stepping activities in older adults. Design. Repeated-measures comparison of kinematics and kinetics associated with forward step-up and lateral step-up activities. Background. Biomechanical analysis may be used to assess the effectiveness of various ‘in-home activities’ in targeting appropriate muscle groups and preserving functional strength and power in elders. Methods. Data were analyzed from 21 participants (mean 74.7 yr (standard deviation, 4.4 yr)) who performed the forward and lateral step-up activities while instrumented for biomechanical analysis. Motion analysis equipment, inverse dynamics equations, and repeated measures anovas were used to contrast the maximum joint angles, peak net joint moments, angular impulse, work, and power associated with the activities. Results. The lateral step-up resulted in greater maximum knee flexion ( P<0.001) and ankle dorsiflexion angles ( P<0.01). Peak joint moments were similar between exercises. The forward step-up generated greater peak hip power ( P<0.05) and total work ( P<0.001); whereas, the lateral step-up generated greater impulse ( P<0.05), work ( P<0.01), and power ( P<0.05) at the knee and ankle. Conclusions. In older adults, the forward step-up places greater demand on the hip extensors, while lateral step-up places greater demand on the knee extensors and ankle plantar flexors. Relevance. Clinicians may use data from biomechanical analyses of in-home exercises to more effectively target specific lower-extremity muscle groups when prescribing exercise activities for older adults. The forward step-up is recommended for maintaining or improving hip extensor performance; whereas, the lateral step-up is recommended when targeting the knee extensors and ankle plantar flexors.