Optimization of applied loads for assessing load-velocity relationship during back squat

Area of Science:

• Sports Science
• Biomechanics
• Strength and Conditioning

Background:

• The load-velocity (L-V) relationship is crucial for understanding force production during resistance exercises.
• Accurate L-V profiling requires appropriate load selection to ensure validity.
• Traditional methods may use higher loads than necessary, potentially limiting practical application.

Purpose of the Study:

• To identify the lightest loads that validate the L-V relationship in back squats.
• To compare the modified multiple-point and in-field two-point methods for L-V assessment.
• To determine optimal load combinations for reliable L-V profiling.

Main Methods:

• Twenty college athletes performed back squats with incremental loads (20-90% 1RM).
• Mean velocity (MV) was measured during multi-point (modified) and two-point (in-field) tests.
• Individual L-V relationships were modeled using collected MV data.

Main Results:

• The modified multiple-point method demonstrated concurrent validity up to 70% and 80% of 1RM.
• The in-field two-point method was valid only under 20% & 90% 1RM conditions (r ≥ 0.810).
• Mean velocity at heavy loads was higher with the in-field two-point method compared to the standard method.

Conclusions:

• For modified multiple-point squat L-V assessment, loads from 20% to 70% 1RM are recommended (MV ~1.0 m/s to 0.6 m/s).
• The in-field two-point method requires the lightest and heaviest loads (20% & 90% 1RM) for validity (MV ~1.0 m/s to 0.4 m/s).
• These findings optimize load selection for accurate L-V relationship assessment in back squats.