Comparison Between Unilateral and Bilateral Plyometric Training on Single and Double Leg Jumping Performance

Abstract

The phenomenon of bilateral deficit in jumping implies that greater muscle power can be developed when performing maximal single leg jumps, compared with two-leg jumps. Thus, it may be hypothesized that training with single leg plyometric exercises would be more effective compared to an equivalent volume of double leg plyometric training. PURPOSE: To compare the effects of unilateral and bilateral plyometric training on single and double leg jumping performance. METHODS: Fifteen moderately trained subjects (age: 19.6±2.1 yrs, height: 172±9 cm, body mass: 65.6±10.6 kg) were randomly assigned to either a unilateral (U, n=7) or a bilateral group (B, n=8). Both groups performed maximal effort plyometric leg exercises two times per week for 6 weeks (6 exercises per session, 3 sets of 10 repetitions per exercise), as well as 3 sets of knee extensions and flexions at 70%-90% of their 1 repetition maximum. The U group performed all plyometric and knee flexion/extension exercises with both legs, while the B group performed half the repetitions with each leg, so that the total exercise volume was the same. Jumping performance was assessed by double and single leg countermovement jumps (CMJ) and drop jumps (DJ) from 30 cm, measured using an optical measurement system (Optojump). Reactive strength index (RSI) was calculated from DJ data (jump height and ground contact time). Results were analyzed using a 2 x 2 ANOVA with repeated measures in one factor and Tukey’s post-hoc test. RESULTS: CMJ with both legs significantly improved equally in the U and B groups by 12.1±7.2% and 11.0±5.5% (p<0.001), respectively. However, single-leg CMJ, quantified as the sum of dominant and non-dominant single leg CMJ, only improved in the U group (19.0±7.1%, p<0.001) and was unchanged in the B group (3.4±8.4%, p=0.80). Similarly, RSI for single leg only improved in the U group (from 0.95±0.21 to 1.17±0.25 m·s-1, p=0.002), but not in the B group. CONCLUSIONS: Plyometric training with single leg exercises was more effective in increasing both single and double-leg jumping performance, compared to bilateral training.