Unilateral Training for Strength: From Fixing Imbalances to Boosting Athletic Performance

The bilateral deficit (BD) refers to the phenomenon where the force produced bilaterally is less than the sum of each limb's unilateral maximum. For example, both legs together produce less force than the sum of each leg independently. BD is most pronounced in beginners, older adults, and certain athletes. Unilateral training reduces the BD and improves per-limb output.

An RCT by Munn et al. (2004) comparing unilateral and bilateral arm curls found equivalent 1RM strength gains. For hypertrophy, meta-analytic data suggest little difference between conditions when volume and intensity are matched (Gentil et al., 2017). However, unilateral exercises place greater stabilization demand on the core, effectively training trunk muscles simultaneously.

Equivalent

strength gains vs bilateral

+ Core demand

added benefit of unilateral training

Most athletic movements — running, kicking, throwing — are unilateral in nature. The single-limb strength and neuromuscular coordination built through unilateral training transfers more directly to these movements. Research specifically shows benefits for sprint speed, change-of-direction ability, and single-leg jump performance.

A hybrid approach combining bilateral and unilateral exercises is most practical. Perform primary lifts (squat, deadlift, bench) bilaterally, and supplement with Bulgarian split squats, single-leg RDLs, and single-arm dumbbell presses. Adding just 1–2 unilateral exercises per session is enough to address imbalances over time.