Effect of Loading Configuration on Kinematics and Kinetics for Deadlift and Squat Exercises: Case Study in Modeling Exercise Countermeasure Device for Astronauts

This study compares squat and deadlift exercises performed with two different loading configurations: 1) on a novel single-cable resistance exercise countermeasure device (ECD) for spaceflight and 2) with free weights. The results compare joint kinematics and kinetics between different loading configurations for each exercise, and also between the two exercises for each loading configuration. Single-cable versions of the squat (using a harness) and deadlift (using a T-bar) performed on the Hybrid Ultimate Lifting Kit (HULK) ECD have significantly different sagittal plane joint angle kinematics (both peak angle and range of motion) as well as joint kinetics (both peak joint moment and joint impulse) vs. their free weight equivalents at the same load. Differences also exist in hip abduction and rotation. Overall, the single-cable configurations tend to reduce peak joint angles, ranges of motion, peak joint moment and joint impulse vs. free weights. A notable exception is the lumbar joint, which is more heavily loaded for single-cable squats vs. free weight squats. This may have implications for both training benefit and possible risk of injury. Deadlift and squat exercises work the lower body musculature in different ways, with the deadlift emphasizing hip and lumbar extension and the squat emphasizing knee extension. Based on these findings, we would advocate the use of both movements in the exercise prescriptions of astronaut crews on deep-space missions.