The effect of unilateral and bilateral strength training on the bilateral deficit and lean tissue mass in post-menopausal women

Abstract

Some have observed maximal strength of simultaneous bilateral homologous limb contraction is less than the sum of strengths of right and left limbs contracting alone; a phenomenon referred to as the bilateral deficit (BLD). There is controversy on whether there is a BLD for all exercises. We assessed whether a BLD occurs across different exercises (leg press, knee extension, and lat pull-down), whether the BLD could be altered with unilateral or bilateral training, and whether unilateral versus bilateral training was more beneficial for increasing lean tissue mass (LTM). Post-menopausal women (approximately 57 years) were randomized to bilateral (n=14) and unilateral (n=12) training, or non-training control (n=24) groups. Bilateral training involved seven exercises performed with bilateral contractions (two sets, 3 days week-1, 26 weeks). Unilateral training involved the same exercises performed with one limb at a time. A BLD was found for leg press and lat pull-down, but not for knee extension. Bilateral training decreased the BLD; whereas unilateral training had minimal effect on the BLD. The unilateral-training group had a greater increase in lower-body LTM compared to the control group (P<0.05); however, there were no differences between unilateral and bilateral training groups. Both training groups had greater increases in LTM of the upper- and whole-body compared to the control group. We conclude that the BLD is apparent for some exercises (i.e., the leg press and lat pull-down) but not others (i.e., knee extension). Bilateral training reduces the BLD; whereas unilateral training has minimal effect on the BLD.

Déficit bilateral em exercício multiarticular para membros superiores

“…The literature has not reached a consensus about the bilateral deficit phenomenon in multiarticular exercises for upper and lower limbs 5,20,21 . Our hypothesis was that a myoelectric deficit would not be evident for complex exercises such as converging articulated military press (i.e.…”

Déficit bilateral: origem, mecanismos e implicações para o treino de força.

“…Visto que o DB é causado por limitações neurais que reduzem o recrutamento de unidades motoras, o treinamento, que por sua vez tem como uma das adaptações neurais o aumento no recrutamento de unidades motoras, pode diminuir o DB quando executado bilateralmente [30][31][32] . Entretanto, são poucos os estudos encontrados na literatura que avaliam os diferentes efeitos da execução unilateral e bilateral, ao longo do tempo, na produção de força e na atividade elétrica.…”

“…Janzen et al 31 utilizaram Raio X para verificar as mudanças na massa muscular de mulheres pós menopáusicas que treinaram de forma ui ou bilateral. Em relação ao grupo controle, o grupo unilateral aumentou de forma significativa a massa muscular.…”

“…Assim como o estudo de Häkkinen et al 33 , o estudo de Janzen et al 31 foi realizado com idosos e possivelmente os efeitos deletérios do envelhecimento tenham dificultado a observação de diferenças no incremento de massa muscular. No caso do estudo de Janzen et al 31 , embora tenha ocorrido aumentos da massa muscular para o grupo unilateral, esses foram pequenos (4%) em relação aos aumentos na força (25%).…”

“…No caso do estudo de Janzen et al 31 , embora tenha ocorrido aumentos da massa muscular para o grupo unilateral, esses foram pequenos (4%) em relação aos aumentos na força (25%).…”