McGuire Jessica, Green Lara A, Gabriel David A
Electromyographic Kinesiology Laboratory, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario, Canada.
Physiol Rep. 2014 Nov 26;2(11). doi: 10.14814/phy2.12218. Print 2014 Nov 1.
This study compared the effects of a simple versus complex contraction pattern on the acquisition, retention, and transfer of maximal isometric strength gains and reductions in force variability. A control group (N = 12) performed simple isometric contractions of the wrist flexors. An experimental group (N = 12) performed complex proprioceptive neuromuscular facilitation (PNF) contractions consisting of maximal isometric wrist extension immediately reversing force direction to wrist flexion within a single trial. Ten contractions were completed on three consecutive days with a retention and transfer test 2-weeks later. For the retention test, the groups performed their assigned contraction pattern followed by a transfer test that consisted of the other contraction pattern for a cross-over design. Both groups exhibited comparable increases in strength (20.2%, P < 0.01) and reductions in mean torque variability (26.2%, P < 0.01), which were retained and transferred. There was a decrease in the coactivation ratio (antagonist/agonist muscle activity) for both groups, which was retained and transferred (35.2%, P < 0.01). The experimental group exhibited a linear decrease in variability of the torque- and sEMG-time curves, indicating transfer to the simple contraction pattern (P < 0.01). The control group underwent a decrease in variability of the torque- and sEMG-time curves from the first day of training to retention, but participants returned to baseline levels during the transfer condition (P < 0.01). However, the difference between torque RMS error versus the variability in torque- and sEMG-time curves suggests the demands of the complex task were transferred, but could not be achieved in a reproducible way.
本研究比较了简单收缩模式与复杂收缩模式对最大等长肌力增加以及力变异性降低的获得、保持和转移的影响。对照组（N = 12）进行腕屈肌的简单等长收缩。实验组（N = 12）进行复杂的本体感觉神经肌肉促进（PNF）收缩，即在单次试验中，最大等长腕伸展后立即将力的方向反转至腕屈曲。连续三天每天完成10次收缩，两周后进行保持和转移测试。对于保持测试，两组按照各自分配的收缩模式进行，随后进行转移测试，转移测试采用交叉设计，即由另一种收缩模式组成。两组的力量均有相当程度的增加（20.2%，P < 0.01），平均扭矩变异性均降低（26.2%，P < 0.01），且这些变化都得到了保持和转移。两组的共激活比率（拮抗肌/主动肌活动）均下降，且得到了保持和转移（35.2%，P < 0.01）。实验组扭矩和表面肌电图时间曲线的变异性呈线性下降，表明向简单收缩模式发生了转移（P < 0.01）。对照组从训练第一天到保持阶段，扭矩和表面肌电图时间曲线的变异性有所下降，但在转移测试时参与者又回到了基线水平（P < 0.01）。然而，扭矩均方根误差与扭矩和表面肌电图时间曲线变异性之间的差异表明，复杂任务的要求发生了转移，但无法以可重复的方式实现。
