Department of Physical Education, University of South Carolina Upstate, Spartanburg, South Carolina, USA.
J Strength Cond Res. 2012 Sep;26(9):2394-400. doi: 10.1519/JSC.0b013e31823f8d11.
Recent research suggests that humans have some ability to selectively activate or relax some muscles during isometric or dynamic muscle actions without changing posture or position. This study sought to reveal whether trained athletes could isolate either the pectoral or triceps muscles, respectively, at different intensities when given verbal technique instruction. Eleven male Division III football players performed 3 sets of bench press at 50% 1-repetition max (1RM) and 80% 1RM while electromyographic (EMG) activity was recorded from the pectoralis major (PM), anterior deltoid (AD), and triceps brachii (TB). In the first set, the subjects performed the exercise without instruction. In the second set, the subjects were given verbal instructions to use only chest muscles. In the third set, the subjects were instructed to use only triceps muscles. Mean normalized root mean square EMG activity was calculated during 3 repetitions in each condition. Repeated-measures analysis of variance was used to detect differences from the preinstruction condition, with significance set to p ≤ 0.017 as indicated by a Bonferroni correction for multiple comparisons. During the 50% max lift with verbal instructions to focus on chest muscles, PM EMG activity increased by 22% over preinstruction activity (p = 0.005), whereas AD and TB activities were statistically unchanged. When the subjects were instructed to focus on only the triceps muscles, PM returned to baseline activity, whereas TB activity was increased by 26% (p = 0.005). When the lift was increased to 80% max, PM and AD activities were both increased with verbal instructions to use only chest muscles. The TB activity was unchanged during the 80% lifts, regardless of instructions. In conclusion, it is found that verbal technique instruction is effective in shifting muscle activity during a basic lift, but it may be less effective at higher intensities.
最近的研究表明，人类在进行等长或动力性肌肉活动时，具有选择性激活或放松某些肌肉的能力，而不会改变姿势或位置。本研究旨在揭示接受口头技术指导时，训练有素的运动员是否能够分别在不同强度下隔离胸肌或肱三头肌。11 名三级足球运动员分别在 50%和 80%的 1 次重复最大重量（1RM）时进行 3 组卧推，同时记录胸大肌（PM）、三角肌前束（AD）和肱三头肌（TB）的肌电图（EMG）活动。在第一组中，受试者在没有指导的情况下进行锻炼。在第二组中，受试者接受了仅使用胸部肌肉的口头指导。在第三组中，指导受试者仅使用肱三头肌。在每个条件下的 3 次重复中计算平均归一化均方根 EMG 活动。使用重复测量方差分析来检测与预指导条件的差异，通过 Bonferroni 校正多重比较，将显著性设置为 p≤0.017。在 50%最大重量的提升过程中，口头指示专注于胸部肌肉，PM 的 EMG 活动比预指导活动增加了 22%（p=0.005），而 AD 和 TB 的活动则没有统计学意义上的变化。当受试者被指示仅专注于肱三头肌时，PM 恢复到基线活动，而 TB 活动增加了 26%（p=0.005）。当提升到 80%最大重量时，口头指示仅使用胸部肌肉会增加 PM 和 AD 的活动。无论指示如何，TB 活动在 80%的提升过程中均保持不变。总之，研究发现口头技术指导在基本提升过程中有效转移肌肉活动，但在更高强度下效果可能会降低。
