Biomechanical investigation on incline jogging

Introduction

Jogging is a natural extension of walking, and with the interest of the general population in exercise for health, countless people get into jogging as a recreation pursuit. Injuries in jogging are often and primarily overuse injuries due to repetitive, increased loading in the lower extremities for a long period and over long distances. For convenience reasons, more and more people jog on a treadmill at a gym or at home. One popular mode on a treadmill for targeting the cardio-respiratory system is the incline. However, adjusting the mode could also affect the movement, loading and muscle firing patterns of the lower extremities. Few studies performed a comprehensive analysis to include three-dimensional (3D) kinematic, kinetic and electromyography (EMG) measurements of jogging. Furthermore, there is no systematic study to investigate the biomechanical effects of different incline grades on jogging. The goal of this study was to determine the 3D joint kinematics, kinetics and EMG of lower extremity during treadmill jogging at different incline grades.

Methods

The major equipments used were 1) Motion analysis system, 2) Treadmill with force plate system 3) EMG system. We collected the above-mentioned data at five slopes (25%, 20%, 15%, 10%, 5%) with the speed at 3 m/s.

Results

Cadence and ground reaction force increased with the increased slope. The ground reaction force was about two times of the body weight during jogging at 15% slope. The contact period of the foot during incline jogging was shortened but the loading rate of the lower extremity was increased. Most of lower extremity muscles activity increased with the increased incline.

Conclusions

Systematic investigation of the effects of different jogging speeds and inclines on the treadmill can help to identify the possible causes of injuries and provide clinicians with suggestions for appropriate and safe prescription of treadmill jogging. By comprehensively studying their effect on muscle firing patterns, it may be possible to provide a rehabilitation clinician or coach guidelines for selective training of a specific muscle group.