# Effects of Stationary Bikes and Elliptical Machines on Knee Joint Kinematics during Exercise

## TL;DR

This study compares how stationary bikes and elliptical machines affect knee movement and joint load during exercise.

## Contribution

The study reveals novel insights into how different exercise equipment affects knee joint torque and peak forces during pedaling.

## Key findings

- Elliptical machines induce higher knee joint torque compared to stationary bikes.
- Peak torque occurs at different joint angles depending on the equipment used.
- Higher pedaling speed correlates with increased peak knee joint torque on both machines.

## Abstract

Background and Objectives: This study examined the influence of stationary bikes and elliptical machines on knee movement and joint load during exercise. Materials and Methods: Twelve healthy male participants engaged in pedaling exercises on stationary bikes and elliptical machines at speeds of 50 and 70 revolutions per minute (rpm). Knee movement and joint load were assessed using a motion analysis system. Results: The results indicated that elliptical machines induced higher knee joint torque compared to stationary bikes. Notably, peak torque occurred at different joint angles, with stationary bikes reaching an earlier peak at 70°–110° and elliptical machines showing a later peak at 135°–180°. Increased pedaling speed correlated with higher peak knee joint torque on both machines. With the elliptical machine, a higher pedaling frequency correlated with increased peak forces on the knee and ankle joints, as well as vertically. Interestingly, both types of equipment were associated with enhanced peak knee joint torques during high-speed pedaling. Conversely, constant pedaling on elliptical machines limited the ankle angle and could induce inward rotation. Conclusions: This study focused on knee joint torque variations during pedaling on indoor stationary bicycles and elliptical machines. Elliptical machines showed higher peak values of forces and torque, particularly during the propulsive and recovery phases, indicating potential challenges to the knee joint. Notably, peak pedal angles occurred earlier on indoor stationary bicycles, emphasizing the impact of equipment choice on joint kinetics.