Joint-Level Analysis of the Barbell Back Squat During Chain and Elastic Variable Resistance Use

Area of Science:

• Biomechanics
• Sports Science
• Strength and Conditioning

Background:

• Variable resistance (VR) training, using chains (CVR) or elastic bands (EVR), is increasingly used in strength training.
• Understanding the biomechanical differences between CVR, EVR, and free-weight (FW) resistance is crucial for optimizing training protocols.

Purpose of the Study:

• To compare the kinetic and kinematic variables of the barbell back squat using CVR, EVR, and FW resistance.
• To identify potential differences in joint loading and force production across these resistance types.

Main Methods:

• Fifteen men performed barbell back squats under three resistance conditions: CVR, EVR, and FW.
• Kinetic (ground reaction force, rate of force development) and kinematic (joint range of motion, angular velocity, moments, power) data were collected.
• 1-repetition maximum (1RM) testing and familiarization sessions were conducted prior to testing.

Main Results:

• Peak ground reaction force was higher with FW than with VR. Concentric rate of force development was greater with CVR than FW.
• Lower limb angular velocities were generally faster with both VR conditions compared to FW.
• FW produced greater hip and lumbar spine moments than VR. CVR produced greater hip, lumbopelvis, and lumbar spine moments than EVR.

Conclusions:

• CVR may be superior to EVR for enhancing power development.
• EVR may be a safer option for individuals with lumbar spine concerns due to reduced spinal loading.
• Both VR methods offer distinct biomechanical advantages that can be leveraged for specific training goals.