Data_Sheet_1_To Flex or Rest: Does Adding No-Load Isometric Actions to the Inter-Set Rest Period in Resistance Training Enhance Muscular Adaptations? A Randomized-Controlled Trial.PDF

We aimed to investigate the effects of resistance training (RT) combined with no-load isometric actions (iso-holds) during the inter-set recovery period versus RT that involves passive inter-set rest on muscular strength, muscular hypertrophy, and muscular endurance in resistance-trained men. Twenty-seven resistance-trained male volunteers were randomly assigned to either a traditional group (TRAD) that performed a hypertrophy-oriented RT routine with the rest intervals spent passively (n = 13) or to a group that supplemented traditional RT with iso-holds (ISO) for the working muscle group between each set (n = 14). Training for both routines consisted of three weekly sessions performed for 8 weeks. Three sets of 8–12 repetitions were performed per exercise. A 2-min rest interval was afforded between sets; the ISO group performed iso-holds for the first 30 s of each rest interval and then recovered for the final 90 s. Maximal strength was assessed using the one repetition maximum (1RM) tests in the leg press and bench press. Upper-body muscle endurance was assessed by performing the bench press to failure at 50% of 1RM. Muscle thickness (MT) of the elbow flexors, elbow extensors, mid-thigh, and lateral thigh was assessed using B-mode ultrasound. Results indicated a favorable effect of ISO on MT in the mid-thigh. Alternatively, there was a possible detrimental effect for ISO on leg press strength. No other notable differences were seen between conditions. In conclusion, the use of inter-set iso-holds may be a time-efficient strategy to enhance development of the quadriceps femoris; conversely, it may be detrimental to maximizing lower body strength.本研究旨在探究：在阻力训练（Resistance Training, RT）的组间恢复期加入无负荷等长保持动作（iso-holds），相较于采用被动组间休息的常规阻力训练，对具备阻力训练经验男性的肌力、肌肉肥大及肌肉耐力的影响。本研究共招募27名具备阻力训练经验的男性志愿者，通过随机分组将其分为两组：传统组（TRAD，n=13）采用以肌肉肥大为导向的阻力训练方案，组间休息采用被动恢复方式；等长组（ISO，n=14）则在传统阻力训练的基础上，于每组训练间隔期间针对训练肌群完成等长保持动作。 两组训练方案均为每周3次训练，持续8周。每项训练动作完成3组，每组8~12次重复；组间休息时长为2分钟，其中等长组需在每组休息的前30秒进行等长保持动作，剩余90秒进行常规被动恢复。 采用腿部推举与卧推的单次最大重复重量（one repetition maximum, 1RM）测试评估受试者的最大肌力；上肢肌肉耐力通过以50%1RM重量进行卧推至力竭的方式进行评估。采用B型超声测量肘屈肌、肘伸肌、大腿中部及大腿外侧的肌肉厚度（Muscle Thickness, MT）。 研究结果显示，等长组对大腿中部的肌肉厚度具有积极改善效果；但该组的腿部推举最大肌力可能存在一定负面影响。两组其余指标未观察到显著差异。 综上，在组间休息期间加入等长保持动作，或许是一种兼顾时间效率的股四头肌强化策略；但与此同时，该方式可能会对下肢最大肌力的最大化提升产生不利影响。