Influence of variable resistance loading on subsequent free weight maximal back squat performance

Area of Science:

• Sports Science
• Exercise Physiology
• Biomechanics

Background:

• Optimizing warm-up protocols is crucial for maximizing athletic performance.
• Variable resistance (VR) exercise offers a unique training stimulus compared to traditional free-weight resistance (FWR).

Purpose of the Study:

• To investigate the potentiating effects of VR exercise during warm-up on subsequent maximal squat performance.
• To analyze changes in biomechanics and muscle activation following VR preconditioning.

Main Methods:

• 16 recreationally active men performed squat protocols under control (FWR) and experimental (VR) conditions.
• One-repetition maximum (1RM) squat, 3D knee kinematics, and electromyogram (EMG) signals were recorded.
• VR involved 35% of the load generated from band tension during warm-up sets.

Main Results:

• 81% of subjects increased their 1RM squat after VR warm-up (mean increase 7.7%), while no increase was observed after FWR.
• Reduced peak and mean eccentric and concentric knee angular velocities were noted after VR.
• No significant differences in knee flexion angle or EMG amplitudes were found between conditions.

Conclusions:

• VR preconditioning effectively potentiates the neuromuscular system to enhance maximal lifting performance.
• Athletes can incorporate VR into warm-up routines to improve squat performance.
• VR enhances performance without significant changes in muscle activation or joint kinematics.