Effects of Workloads and Cadences on Frontal Plane Knee Biomechanics in Cycling

Although effects of workload and cadence on sagittal plane knee biomechanics in cycling have been widely studied, few studies have examined their impact on the frontal plane. Purpose: The purpose of this study was to investigate the effects of different workloads and cadences on knee sagittal and frontal plane biomechanics. Methods: Eighteen healthy participants (age, 55.7 +/- 11.0 yr) volunteered for this study. A motion analysis system and a custom instrumented pedal were used to collect five cycles of three-dimensional kinematics (240 Hz) and pedal reaction force (PRF, 1200 Hz) during 2 min of cycling in each of eight testing conditions, including five workload conditions of 0.5, 1, 1.5, 2, and 2.5 kg at 60 rpm, and three cadence conditions of 70, 80, and 90 rpm with 1-kg workload. Two one-way repeated measures analyses of variance were used to examine the influence of cadence and workload on selected variables (P < 0.05). Results: Increased workloads with constant rpm caused an increased peak knee abduction moment from 5.82 to 14.36 NIm and peak knee extension moment from 11.61 to 37.16 N.m. Increased workloads also significantly increased peak medial and vertical PRF. Increased cadences at the constant workload had no effects on peak knee abduction moment but caused increased peak anterior and vertical PRF and peak knee flexion moment. Conclusions: The findings of this study indicate that increasing workload at constant cadence significantly increased peak knee abduction moment. Further study may be needed to demonstrate the efficacy of appropriate levels of workload and cadence in knee osteoarthritis and other populations with knee problems.