Downloaded from https://journals.lww.com/nsca-jscr by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3vxSPiT876R4auCuxguuEmC7HNnLzeekhplCLeXRiNd+yjC3VPJyO0Q== on 02/20/2019 COMPARISON BETWEEN UNILATERAL AND BILATERAL PLYOMETRIC TRAINING ON SINGLE- AND DOUBLE-LEG JUMPING PERFORMANCE AND STRENGTH GREGORY C. BOGDANIS, 1 ATHANASIOS TSOUKOS, 1 OLGA KALOHERI, 1 GERASIMOS TERZIS, 1 PANAGIOTIS VELIGEKAS, 1 AND LEE E. BROWN 2 1 School of P. E. and Sport Science, National and Kapodistrian University of Athens, Athens, Greece; and 2 Human Performance Laboratory, California State University, Fullerton, California ABSTRACT Bogdanis, GC, Tsoukos, A, Kaloheri, O, Terzis, G, Veligekas, P, and Brown, LE. Comparison between unilateral and bilateral plyometric training on single- and double-leg jumping perfor- mance and strength. J Strength Cond Res 33(3): 633–640, 2019—This study compared the effects of unilateral and bilat- eral plyometric training on single- and double-leg jumping per- formance, maximal strength, and rate of force development (RFD). Fifteen moderately trained subjects were randomly assigned to either a unilateral (U, n = 7) or bilateral group (B, n = 8). Both groups performed maximal effort plyometric leg exercises 2 times per week for 6 weeks. The B group performed all exercises with both legs, whereas the U group performed half the repetitions with each leg, so that total exer- cise volume was the same. Jumping performance was as- sessed by countermovement jumps (CMJs) and drop jumps (DJs), whereas maximal isometric leg press strength and RFD were measured before and after training for each leg separately and both legs together. Countermovement jump improvement with both legs was not significantly different between U (12.1 6 7.2%) and B (11.0 6 5.5%) groups. However, the sum of right- and left-leg CMJ only improved in the U group (19.0 6 7.1%, p , 0.001) and was unchanged in the B group (3.4 6 8.4%, p = 0.80). Maximal isometric leg press force with both legs was increased similarly between groups (B: 20.1 6 6.5%, U: 19.9 6 6.2%). However, the sum of right- and left-leg max- imal force increased more in U compared with B group (23.8 6 9.1% vs. 11.9 6 6.2%, p = 0.009, respectively). Similarly, the sum of right- and left-leg RFD 0-50 and RFD 0-100 were improved only in the U group (34–36%, p , 0.01). Unilateral plyometric training was more effective at increasing both single- and double-leg jumping performance, isometric leg press maximal force, and RFD when compared with bilateral training. KEY WORDS eccentric training, training specificity, countermovement jump, reactive strength index, rate of force development INTRODUCTION D uring single- and double-leg muscle actions, the sum of force or power generated by each limb acting separately may be greater than the force or power produced when the muscles of both legs act simultaneously (3,6,13). This is termed the bilateral deficit and has been attributed to reduced neural drive and a failure to maximally activate the muscles of the 2 limbs when they contract simultaneously (30). Previous studies have shown that the maximal force bilateral deficit may be reduced signif- icantly or even eliminated, after bilateral strength training, because of the greater magnitude of improvement in bilateral compared with unilateral strength (12,14). By contrast, there is evidence from a cross-sectional (13) and a recent training study (5), suggesting that unilateral training may increase bilateral deficit, supporting the principle of training specificity. Based on the phenomenon of bilateral deficit, that also occurs in jumping (3), it is tempting to hypothesize that strength and power training performed with each leg sepa- rately (unilateral) may allow greater loads and thus greater adaptations compared with bilateral training. Earlier resis- tance training studies using middle-aged and elderly men and women (12), students (24), or postmenopausal women (14) have presented conflicting results regarding the effec- tiveness of unilateral and bilateral lower-limb training. For example, Taniguchi (24) reported that only bilateral leg extension training resulted in an increase in maximal force, whereas Ha ¨kkinen et al. (12) and Janzen et al. (14) reported strength gains that were specific to the training mode used (bilateral or unilateral). One recent study (5) using unilateral and bilateral knee extension strength training found that iso- metric strength gains were almost 2-fold greater after unilat- eral compared with bilateral training. The possibility that Address correspondence to Gregory C. Bogdanis, gbogdanis@ phed.uoa.gr. 33(3)/633–640 Journal of Strength and Conditioning Research Ó 2017 National Strength and Conditioning Association VOLUME 33 | NUMBER 3 | MARCH 2019 | 633 Copyright © 2017 National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.