Influence of Different Loads on Force-Time Characteristics during Back Squats

Area of Science:

• Biomechanics
• Exercise Physiology
• Sports Science

Background:

• The deceleration sub-phase in back squats (BSQ) can limit muscle stimulation across the full range of motion.
• Previous research on BSQ deceleration has been limited to a single load condition.

Purpose of the Study:

• To determine if a deceleration sub-phase occurs during BSQ with varying loads.
• To analyze the impact of different loads on the duration and negative impulse of the BSQ deceleration sub-phase.

Main Methods:

• Sixteen resistance-trained men performed BSQ at loads ranging from 0% to 85% of their one-repetition maximum (1RM).
• Measurements were taken using a force plate to calculate deceleration sub-phase duration and negative impulse.
• Data analysis involved comparing these metrics across the different load conditions.

Main Results:

• A deceleration sub-phase was observed across all tested loads (0%-85% 1RM).
• Relative deceleration sub-phase duration decreased significantly as load increased from 12% to 85% 1RM.
• Negative impulse during deceleration increased significantly from 0% to 42% 1RM.

Conclusions:

• The deceleration sub-phase is a consistent component of the back squat, irrespective of external load.
• With low to moderate loads, a significant portion of the deceleration occurs within the concentric phase.
• High loads result in a shorter deceleration sub-phase but a greater negative impulse.