Three-dimensional kinematic comparison of treadmill and overground running.

The treadmill is an attractive device for the investigation of human locomotion, yet the extent to which lower limb kinematics differ from overground running remains a controversial topic. This study aimed to provide an extensive three-dimensional kinematic comparison of the lower extremities during overground and treadmill running. Twelve participants ran at 4.0 m/s (+/- 5%) in both treadmill and overground conditions. Angular kinematic parameters of the lower extremities during the stance phase were collected at 250 Hz using an eight-camera motion analysis system. Hip, knee, and ankle joint kinematics were quantified in the sagittal, coronal, and transverse planes, and contrasted using paired t-tests. Of the analysed parameters hip flexion at footstrike and ankle excursion to peak angle were found to be significantly reduced during treadmill running by 12 degrees (p = 0.001) and 6.6 degrees (p = 0.010), respectively. Treadmill running was found to be associated with significantly greater peak ankle eversion (by 6.3 degrees, p = 0.006). It was concluded that the mechanics of treadmill running cannot be generalized to overground running.