Comparing Knee Joint Load Accumulation During Cycling, Walking, and Running in Individuals With and Without Knee Osteoarthritis.

Cycling is recommended as a conservative treatment for managing knee osteoarthritis (KOA), yet direct comparisons of knee joint loading between cycling and weight-bearing locomotion are limited. This study compared fatigue-weighted cumulative knee joint loading (wCKL) across cycling, walking, and running in individuals with and without KOA. Fifty-six recreational cyclists (19 KOA, 19 age-matched controls, 18 young controls) performed cycling at nine cadence-power combinations (60/80/100 rpm × 157/210/261 W), walking at 1.4 m/s, and running at 3.0 m/s. Three-dimensional kinematics and reaction forces (ground for walking/running, pedal for cycling) were used to compute external knee moments via OpenSim. wCKL was calculated from sagittal-plane and frontal-plane knee moments and scaled to 1 h of activity. Mixed-effects linear models tested task- and group-dependent effects, and dose-equivalence estimates were derived to relate cycling duration to equivalent walking or running exposure. Across planes, cycling produced lower wCKL than running and was not greater than walking. In the sagittal plane, cycling and walking showed comparable wCKL across groups, whereas KOA exhibited reduced sagittal wCKL relative to controls during running. In the frontal plane, KOA demonstrated significantly elevated wCKL during walking and running but not cycling. Dose-equivalence analyses indicated that cycling would need to be performed ~1-2 h to match 1 h of walking and ~3-5 h to match 1 h of running, with larger ratios in the frontal plane for KOA. These findings demonstrate that cycling limits cumulative knee loading compared with running without exceeding walking under the tested conditions.