Neuromuscular Adaptations to Unilateral vs. Bilateral Strength Training in Women

Abstract

Botton, CE, Radaelli, R, Wilhelm, EN, Rech, A, Brown, LE, and Pinto, RS. Neuromuscular adaptations to unilateral vs. bilateral strength training in women. J Strength Cond Res 30(7): 1924-1932, 2016-Considering the bilateral deficit, the sum of forces produced by each limb in a unilateral condition is generally greater than that produced by them in a bilateral condition. Therefore, it can be speculated that performing unilateral strength exercises may allow greater training workloads and subsequently greater neuromuscular adaptations when compared with bilateral training. Hence, the purpose of this study was to compare neuromuscular adaptations with unilateral vs. bilateral training in the knee extensor muscles. Forty-three recreationally active young women were allocated to a control, unilateral (UG) or bilateral (BG) training group, which performed 2 times strength training sessions a week for 12 weeks. Knee extension one repetition maximum (1RM), maximal isometric strength, muscle electrical activity, and muscle thickness were obtained before and after the study period. Muscle strength was measured in unilateral (right + left) and bilateral tests. Both UG and BG increased similarly their unilateral 1RM (33.3 ± 14.3% vs. 24.6 ± 11.9%, respectively), bilateral 1RM (20.3 ± 6.8% vs. 28.5 ± 12.3%, respectively), and isometric strength (14.7 ± 11.3% vs. 13.1 ± 12.5%, respectively). The UG demonstrated greater unilateral isometric strength increase than the BG (21.4 ± 10.5% vs. 10.3 ± 11.1%, respectively) and only the UG increased muscle electrical activity. Muscle thickness increased similarly for both training groups. Neither group exhibited pretesting 1RM bilateral deficit values, but at post-testing, UG showed a significant bilateral deficit (-6.5 ± 7.8%) whereas BG showed a significant bilateral facilitation (5.9 ± 9.0%). Thus, performing unilateral or bilateral exercises was not a decisive factor for improving morphological adaptations and bilateral muscle strength in untrained women. Unilateral training, however, potentiate unilateral specific strength gains.

Blood flow restriction attenuates eccentric exercise‐induced muscle damage without perceptual and cardiovascular overload

“…These results can be explained by our volunteers being regular practitioners of resistance exercise for at least 1 year. According to recent studies (Cornwell et al, 2012;Botton et al, 2016), the difference between arms decreases after training, equalling the strength and anthropometric characteristics between limbs. We also compared the BFR in both arms and no difference was observed.…”

The Effectiveness of Two Methods of Prescribing Load on Maximal Strength Development: A Systematic Review

“…Adaptations to the neural system, such as the recruitment of additional or higher threshold motor units [34,35], the recruitment of more fast twitch muscle fibres (type IIx), greater synchronisation of discharge of motor units [38,44], greater efferent drive [44], increases in corticospinal excitability coinciding with reductions in short-interval intracortical inhibition [47] or enhanced neural coordination [52,53], have all been suggested to underpin improvements in maximal strength. In contrast, increases in muscle cross-sectional area, the conversion of muscle fibre types from type IIa to type IIx, changes in pennation angle, and the secretion of growthpromoting hormones [37,43,45,48,51] have also been suggested to explain maximal strength improvements following training. Whilst disparity in explanations might exist in the literature, this does, however, highlight that maximal strength is a complex quality that can be influenced by both neurological and morphological adaptations.…”

“…11 studies employed between two and five exercises within the intervention [36-42, 46, 51, 52, 54], with two studies prescribing more than five [43,48]. Six studies employed single joint or isolated exercises only [33][34][35][49][50][51], with the rest prescribing multi-joint or a combination of the two. Maximal strength increased by 5.4% more in multi-joint, compound exercises compared to single-joint, isolation exercises (Table 4).…”

Muscular performance decreases with increasing complexity of resistance exercises in subjects with chronic obstructive pulmonary disease

“…Importantly, in healthy adults, one‐legged resistance training leads to similar improvements of muscle functions as two‐legged training, measured as strength and hypertrophy . For COPD patients, there seems to be “a threshold” of muscle mass that can be exercised before muscular performance is limited by the cardiopulmonary capacity.…”