Examining Unilateral and Bilateral Exercises through the Load-velocity Relationship

Area of Science:

• Biomechanics and Exercise Physiology
• Sports Science Research

Background:

• The load-velocity (L-V) relationship is crucial for understanding force production in resistance training.
• Previous research has primarily focused on bilateral movements, leaving the unilateral L-V relationship less explored.

Purpose of the Study:

• To investigate the load-velocity (L-V) relationship during unilateral bench-press (BP) and leg-press (LP) exercises.
• To compare the unilateral L-V relationship with bilateral variants.
• To identify potential differences between preferred and non-preferred limbs in the L-V relationship.

Main Methods:

• Nineteen healthy men performed incremental tests for unilateral and bilateral BP and LP.
• Load-velocity data were collected across two sessions with a 48-hour rest period.
• Statistical analysis compared L-V relationships between unilateral and bilateral conditions and between limbs.

Main Results:

• A strong L-V relationship was observed for unilateral BP (R²=0.97) and LP (R²=0.96).
• Higher movement velocities were achieved in unilateral exercises compared to bilateral, particularly at 30-70% 1RM for BP and 30-45% 1RM for LP.
• No significant differences were found in the L-V relationship between preferred and non-preferred sides.

Conclusions:

• Unilateral resistance exercises exhibit a robust load-velocity relationship, similar to bilateral movements.
• Unilateral performance allows for greater movement velocity, especially with lighter to moderate loads.
• Interlimb asymmetries in strength do not appear to affect the consistency of the L-V relationship within unilateral exercises.