How joint torques affect hamstring injury risk in sprinting swing-stance transition

Area of Science:

• Biomechanics
• Sports Medicine
• Human Movement Analysis

Background:

• Hamstring strain injuries are common in athletes.
• The exact mechanisms leading to these injuries remain unclear.
• Understanding muscle loading during high-speed activities is crucial.

Purpose of the Study:

• To investigate hamstring muscle mechanics during maximum-effort sprinting.
• To identify critical loading conditions contributing to hamstring strain injuries.

Main Methods:

• Collected 3D kinematics and ground reaction force data from elite sprinters.
• Measured maximal isometric hip and knee torques.
• Analyzed sprinting gait cycle using intersegmental dynamics.

Main Results:

• Passive torques at knee and hip joints lengthened hamstrings during initial stance and late swing.
• Active hamstring muscle torques counteracted these passive effects.
• Knee joint muscle torque exceeded maximal isometric knee flexion torque by 1.4 times.

Conclusions:

• Hamstring muscles are subjected to high strain during initial stance and late swing phases of sprinting.
• The interplay between passive and active muscle torques increases susceptibility to injury.
• These findings highlight specific phases in sprinting where hamstring strain risk is elevated.