Impact of Load Variation on Lower Limb Joint Torque during Overhead Squats

Area of Science:

• Biomechanics
• Kinesiology
• Sports Science

Background:

• Overhead squats (OHSs) are complex movements requiring significant mobility and stability.
• Understanding how varying loads affect OHS kinematics and kinetics is crucial for performance and injury prevention.
• The interplay between trunk positioning, hip/knee joint torques, and shoulder flexibility in OHS is not fully elucidated.

Purpose of the Study:

• To analyze kinematic and kinetic changes during OHS with increasing loads.
• To investigate the relationship between OHS movement mechanics and shoulder joint flexibility.

Main Methods:

• Fourteen male college students performed OHS with no load, 20% body mass (BM), and 40% BM.
• Motion capture and ground reaction force data were collected during the squats.
• Correlation analyses were performed between trunk angles, joint torques, and shoulder flexibility measures.

Main Results:

• Relative peak hip torque increased significantly with 20% and 40% BM loads compared to no load.
• Relative peak knee torque did not show a significant increase with added load.
• A negative correlation was found between relative peak hip torque and lower trunk angle at the center of mass's lowest point.
• Shoulder flexibility was positively correlated with the lower trunk angle at the center of mass's lowest point.

Conclusions:

• In OHS, increased load primarily elevates hip torque, not knee torque, especially at lower relative loads.
• The lower trunk's forward lean during OHS is influenced by hip torque and enhanced by shoulder joint flexibility.
• These findings offer insights into optimizing OHS technique and assessing movement limitations.