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Treino de força unilateral de baixa intensidade com restrição vascular vs. treino de força unilateral não restritivo de intensidade moderada : estudo comparativo sobre o impacto na taxa de produção de torque no membro treinado e não treinado
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Nas últimas décadas, vários estudos têm sugerido que o exercício de treino de força com intensidades moderadas-a-elevadas (>65% de 1 repetição máxima (1RM)) é fundamental para aumentar a massa e a força muscular. Contudo, mais recentemente, outros estudos têm demonstrado que o treino de baixa intensidade combinado com restrição vascular (TBIRV) apresenta resultados semelhantes e, em alguns casos, ainda mais eficazes do que o treino resistido de alta intensidade (TAI). Apesar de existir evidência de que o TAI induz ganhos de força, tanto nos membros treinados como nos membros não treinados, subsiste saber se o mesmo fenómeno também ocorre secundariamente ao TBIRV. Assim, o presente estudo pretendeu comparar o TBIRV vs. TAI relativamente aos seus efeitos nas medidas da contração voluntária máxima e da taxa de produção de torque quantificadas no membro treinado e no membro não treinado. Trinta e nove jovens voluntários (20 homens, 19 mulheres; idade: 22.1 ± 3.1 anos; altura: 168 ± 9 cm: massa corporal: 63.3 ± 9.3 kg; índice massa corporal 22.3 ± 2.2 kg/m² ) foram distribuídos aleatoriamente em dois grupos: 15 participantes no grupo TBIRV e 14 participantes no grupo TAI. Todos os participantes cumpriram o processo de intervenção que consistiu na execução de séries plantar-flexoras realizadas unilateralmente na posição sentada, 5 dias por semana durante quatro semanas (total de 20 unidades de sessão de treino por participante/grupo). A intensidade da carga de exercício foi calculada em função de uma repetição máxima (1RM) e fixada em 75% (4 séries de 10 repetições) e 20% de 1RM (4 séries de 30:15:15:15 repetições) para sessões TAI e TBIRV, respetivamente. A taxa máxima de produção de torque e a taxa de produção de torque sequencial (TPT0-30, TPT30-50, TPT50-100 e TPT100-150), foram determinadas a partir de contrações isométricas voluntárias máximas. Todas as medições foram repetidas bilateralmente em 3 momentos distintos: pré-treino (PRE), pós-treino (POS) e destreino (DES) - 4 semanas após conclusão do treino. O TBIRV foi realizado com restrição a 60% da pressão absoluta de oclusão por intermédio de um cuff colocado na porção mais proximal da coxa de cada participante. Recorreu-se à ANOVA de medidas repetidas de dois fatores (2 tipos de treino x 3 tempos) para avaliar os efeitos de cada regime de treino em todas as variáveis dependentes obtidas no membro treinado e não treinado. De acordo com os resultados obtidos, ambos os protocolos de treino induziram ganhos estatisticamente significativos na contração voluntária máxima do membro treinado (TBIRV: PRE = 54.3 ± 19.9, POS = 62.2 ± 23.2; TAI: PRE = 51.7 ± 14.6, POS = 58.4 ± 11.9 N.m; p = 0.025), tendo estes ganhos persistido durante o destreino. Ao contrário, no membro não treinado não se verificam ganhos estatisticamente significativos. A taxa máxima de produção de torque aumentou em ambas os membros com os dois protocolos de treino, tanto no membro treinado (TBIRV: PRE = 270.9 ± 112.7, POS = 318.2 ± 84.4; TAI: PRE = 269.6 ± 127.7, POS = 318.7 ± 120.8 N.m.s-1; p = 0.007), como não treinado (TBIRV: PRE = 253.6 ± 102.9, POS = 284.8 ± 93.0; TAI: PRE = 283.6 ± 102.8, POS = 331.8 ± 105.8 N.m.s-1; p = 0.013). Em ambos os casos, este efeito reverteu com o destreino. No membro treinado verificaram-se ainda ganhos na taxa de produção de torque sequencial (janelas temporais mais avançadas) decorrentes de ambos os protocolos (p < 0.05) – reverteram com o destreino. No membro não treinado, os ganhos verificados ao nível da taxa de produção de torque sequencial secundários a cada protocolo de treino foram mais incidentes sobre as janelas temporais mais iniciais (p < 0.05) – reverteram também com o destreino. Demonstrou-se que os ganhos na contração voluntária máxima, taxa máxima de produção de torque e taxa sequencial de produção de torque ao nível do membro treinado e não treinado são de magnitude semelhante entre o TBIRV quer com o TAI. No membro treinado, o ganho em janelas temporais mais tardias sugere uma adaptação primordialmente dependente dos ganhos de força máxima (que aumentou no decurso de ambos os protocolos de treino). No membro não treinado, a ausência de ganhos estatisticamente significativos na contração voluntária máxima, a par de melhorias observadas na taxa de produção de torque (principalmente nas janelas temporais mais iniciais), indica que a origem da adaptação contralateral se deve primordialmente a ganhos neurais.
In recent decades, several studies have suggested that strength training exercise at moderate-to-high intensities (>65% of 1 repetition maximum (1RM)) is critical for increasing muscle mass and strength. However, more recently, other studies have shown that low intensity training combined with vascular restriction (TBIRV) shows similar and, in some cases, even more effective results than high intensity resistance training (TAI). Although there is evidence that TAI induces strength gains in both trained and untrained limbs, it remains unclear whether the same phenomenon also occurs secondarily to TBIRV. Thus, the present study, intended to compare the TBIRV vs. TAI regarding its effects on the measurements of maximal voluntary contraction and torque production rate quantified in the trained and untrained limb. Forty young volunteers (20 males, 19 females; age: 22.1 ± 3.1 years; height: 168 ± 9 cm: body mass: 63.3 ± 9.3 kg; body mass index 22.3 ± 2.2 kg/m² ) were randomly assigned to two groups: 15 participants in the TBIRV group and 14 participants in the TAI group. All participants followed the intervention process that consisted in the execution of plantar-flexor series performed unilaterally in the sitting position, 5 days a week for four weeks (total of 20 units of training session per participant/group). Exercise load intensity was calculated as a function of one repetition maximum (1RM) and set at 75% (4 sets of 10 repetitions) and 20% of 1RM (4 sets of 30:15:15 repetitions) for TAI and TBIRV sessions, respectively. Maximum torque production rate and sequential torque production rate (TPT0-30, TPT30-50, TPT50-100 and TPT100-150) were determined from maximal voluntary isometric contractions. All measurements were repeated bilaterally at 3 different times: pre-training (PRE), post-training (POS) and de-training (DES) - 4 weeks after completion of training. The TBIRV was performed with restriction at 60% of the absolute occlusion pressure through a cuff placed on the most proximal portion of the thigh of each participant. A two-way repeated measures ANOVA (2 types of training x 3 times) was used to assess the effects of each training regimen on all dependent variables obtained in the trained and untrained limb. According to the results, both training protocols induced statistically significant gains in maximum voluntary contraction in the trained limb (TBIRV: PRE = 54.3 ± 19.9, POS = 62.2 ± 23.2; TAI: PRE = 51.7 ± 14.6, POS = 58.4 ± 11.9 N.m; p = 0.025), and these gains persisted during detraining. In contrast, in the untrained limb, no statistically significant gains were observed. The maximum torque production rate increased in both limbs with the two training protocols, both in the trained limb (TBIRV: PRE = 270.9 ± 112.7, POS = 318.2 ± 84.4; TAI: PRE = 269. 6 ± 127.7, POS = 318.7 ± 120.8 N.m.s-1; p = 0.007), and untrained (RBIRV: PRE = 253.6 ± 102.9, POS = 284.8 ± 93.0; TAI: PRE = 283.6 ± 102.8, POS = 331.8 ± 105.8 N.m.s-1; p = 0.013). In both cases, this effect was reverted with the de-training. In the trained limb there were also gains in the rate of sequential torque production (more advanced temporal windows) resulting from both protocols (p < 0.05) - reverted with the de-training. In the untrained limb, the gains in sequential torque production rate secondary to each training protocol were more incident on the earlier temporal windows (p < 0.05) - they also were reverted with the de-training. Gains in maximal voluntary contraction, maximal rate of torque production and sequential rate of torque production at the trained and untrained limb level were shown to be of similar magnitude between TBIRV and TAI. In the trained limb, the gain in later time windows suggests an adaptation primarily dependent on maximal strength gains (which increased over the course of both training protocols). In the untrained limb, the absence of statistically significant gains in maximal voluntary contraction, along with improvements observed in the rate of torque production (mainly in the earlier time windows), indicate that the origin of the contra-lateral adaptation is primarily due to neural gains.
In recent decades, several studies have suggested that strength training exercise at moderate-to-high intensities (>65% of 1 repetition maximum (1RM)) is critical for increasing muscle mass and strength. However, more recently, other studies have shown that low intensity training combined with vascular restriction (TBIRV) shows similar and, in some cases, even more effective results than high intensity resistance training (TAI). Although there is evidence that TAI induces strength gains in both trained and untrained limbs, it remains unclear whether the same phenomenon also occurs secondarily to TBIRV. Thus, the present study, intended to compare the TBIRV vs. TAI regarding its effects on the measurements of maximal voluntary contraction and torque production rate quantified in the trained and untrained limb. Forty young volunteers (20 males, 19 females; age: 22.1 ± 3.1 years; height: 168 ± 9 cm: body mass: 63.3 ± 9.3 kg; body mass index 22.3 ± 2.2 kg/m² ) were randomly assigned to two groups: 15 participants in the TBIRV group and 14 participants in the TAI group. All participants followed the intervention process that consisted in the execution of plantar-flexor series performed unilaterally in the sitting position, 5 days a week for four weeks (total of 20 units of training session per participant/group). Exercise load intensity was calculated as a function of one repetition maximum (1RM) and set at 75% (4 sets of 10 repetitions) and 20% of 1RM (4 sets of 30:15:15 repetitions) for TAI and TBIRV sessions, respectively. Maximum torque production rate and sequential torque production rate (TPT0-30, TPT30-50, TPT50-100 and TPT100-150) were determined from maximal voluntary isometric contractions. All measurements were repeated bilaterally at 3 different times: pre-training (PRE), post-training (POS) and de-training (DES) - 4 weeks after completion of training. The TBIRV was performed with restriction at 60% of the absolute occlusion pressure through a cuff placed on the most proximal portion of the thigh of each participant. A two-way repeated measures ANOVA (2 types of training x 3 times) was used to assess the effects of each training regimen on all dependent variables obtained in the trained and untrained limb. According to the results, both training protocols induced statistically significant gains in maximum voluntary contraction in the trained limb (TBIRV: PRE = 54.3 ± 19.9, POS = 62.2 ± 23.2; TAI: PRE = 51.7 ± 14.6, POS = 58.4 ± 11.9 N.m; p = 0.025), and these gains persisted during detraining. In contrast, in the untrained limb, no statistically significant gains were observed. The maximum torque production rate increased in both limbs with the two training protocols, both in the trained limb (TBIRV: PRE = 270.9 ± 112.7, POS = 318.2 ± 84.4; TAI: PRE = 269. 6 ± 127.7, POS = 318.7 ± 120.8 N.m.s-1; p = 0.007), and untrained (RBIRV: PRE = 253.6 ± 102.9, POS = 284.8 ± 93.0; TAI: PRE = 283.6 ± 102.8, POS = 331.8 ± 105.8 N.m.s-1; p = 0.013). In both cases, this effect was reverted with the de-training. In the trained limb there were also gains in the rate of sequential torque production (more advanced temporal windows) resulting from both protocols (p < 0.05) - reverted with the de-training. In the untrained limb, the gains in sequential torque production rate secondary to each training protocol were more incident on the earlier temporal windows (p < 0.05) - they also were reverted with the de-training. Gains in maximal voluntary contraction, maximal rate of torque production and sequential rate of torque production at the trained and untrained limb level were shown to be of similar magnitude between TBIRV and TAI. In the trained limb, the gain in later time windows suggests an adaptation primarily dependent on maximal strength gains (which increased over the course of both training protocols). In the untrained limb, the absence of statistically significant gains in maximal voluntary contraction, along with improvements observed in the rate of torque production (mainly in the earlier time windows), indicate that the origin of the contra-lateral adaptation is primarily due to neural gains.
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Kaatsu Força explosiva Ativação Muscular Propriedades Contracteis Unilateral Contralateral Explosive force Muscle Activation Contractile Proprieties Unilateral Contra-lateral