Effects of a Passive Assistive Hamstring Device on Overground Running Kinematics and Hamstring Activation.

Author

• Quinn Castner, Clemson UniversityFollow

Date of Award

5-2026

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Bioengineering

Committee Chair/Advisor

Dr. Reed Gurchiek

Committee Member

Dr. John Desjardins

Committee Member

Dr. Divya Srinivasan

Abstract

Hamstring strain injuries are among the most common and recurring injuries in sports, occurring most often during the terminal swing phase of gait. Despite progress in rehabilitation, the incidence of injury has only increased, suggesting a need for a novel intervention. We designed a passive, assistive, wearable device with two specific criteria in mind: to offload the hamstrings during running, and do so without hindering normal kinematic patterns. The device consists of an adjustable elastic band anchored proximally at the waist and distally just above the ankle joint center. It stretches and shortens with the hamstrings, providing passive hip extension and knee flexion torques. This thesis aims to evaluate the efficacy of our device with respect to the two design criteria. The first study examined the effects of the device on the thigh and shank kinematics and sprint performance during overground running using inertial measurement units (IMUs). Participants completed two 40-yard sprints with and without the device. Results from wearing the device indicated a small decrease in top speed (1.05%) and an increase in sprint time (1.14%). Kinematic comparisons revealed low mean absolute differences between conditions (2.49% ± 1.17 for the shank and 3.47% ± 1.21 for the thigh) and low differences in standard deviation (1.61% ± 1.43 and 2.41% ± 1.60, respectively). This suggests the device has a small effect on overground running kinematics that is likely clinically irrelevant. The second study quantified muscle activity of the semitendinosus and biceps femoris using surface electromyography (EMG). Participants completed one trial with and without the device on a treadmill at jogging and sprinting speeds (3.5 m/s and 5.0 m/s). Results demonstrated a speed- and muscle-specific response. There was a significant reduction in semitendinosus activation during jogging (2%), indicating effective offloading during less demanding activities. However, biceps femoris activation significantly increased during sprinting (7.6%). This suggests our device may be inducing a flexion perturbation, requiring increased biceps femoris activation to maintain knee extension, regulate shank deceleration, and ensure joint stability prior to ground contact. These findings indicate that the device changes natural running kinematics by negligible amounts, while non-uniformly affecting hamstring muscle activity. This partially supports its potential as a rehabilitation tool. However, the increased activation observed at higher speeds suggests a more complex interaction between the wearer and device, which calls for further insight.

Recommended Citation

Castner, Quinn, "Effects of a Passive Assistive Hamstring Device on Overground Running Kinematics and Hamstring Activation." (2026). All Theses. 4726.
https://open.clemson.edu/all_theses/4726