Equating Unilateral and Bilateral Half-Squat Loads: Neuromuscular and Kinetic Analysis.

Area of Science:

• Sports Science
• Biomechanics
• Exercise Physiology

Background:

• Unilateral and bilateral exercises elicit different neuromuscular and biomechanical responses.
• Equating loads between unilateral (1-leg) and bilateral (2-leg) exercises is crucial for training and rehabilitation.
• Predictive equations can standardize exercise prescription across different modalities.

Purpose of the Study:

• To develop predictive equations for unilateral half-squat loads equivalent to bilateral half-squat loads.
• To match neuromuscular activation, velocity, and force outputs between exercise types.
• To provide tools for practitioners to estimate equivalent loads for training and rehabilitation.

Main Methods:

• Twelve male soccer players performed incremental 1-leg and 2-leg half-squats on a Smith-machine.
• Surface electromyography (EMG) of vastus lateralis and medialis was recorded.
• Barbell velocity and force outputs were measured across loads.
• Linear regression analyses were used to derive predictive equations.

Main Results:

• Three predictive equations were developed for 1-leg loads based on 2-leg loads:
• Muscle activation: 1-leg load = 50% of 2-leg load - 2 kg (r=0.923-0.997, p<0.05).
• Barbell velocity: 1-leg load = 71% of 2-leg load - 17.6 kg (r=-0.916 to 0.994, p<0.05).
• Force output: 1-leg load = 41% of 2-leg load - 28 kg (r=0.937-0.998, p<0.05).

Conclusions:

• Initial predictive equations enable practitioners to equate unilateral and bilateral half-squat exercises.
• These equations facilitate accurate load prescription and performance comparisons in training and rehabilitation.
• Further validation on diverse populations and sports is necessary.