McGill Stuart M, Karpowicz Amy, Fenwick Chad M J, Brown Stephen H M
Department of Kinesiology, Faculty of Applied Health Sciences, Spine Biomechanics Laboratories, University of Waterloo, Waterloo, Canada.
J Strength Cond Res. 2009 Mar;23(2):455-64. doi: 10.1519/JSC.0b013e3181a0227e.
The purpose of this study was to document the muscle activity, spine motion, spine load, and stiffness during several movement-based or "functional" exercises and to assess the effect of technique change. Eight subjects, all healthy men from a university population, were instrumented to obtain surface electromyography of selected trunk and hip muscles, together with video analysis and electromagnetic lumbar spine position sensor to track spine posture. Exercises included a walkout in the sagittal plane that compared an upright form against a wall with those performed on the floor, overhead cable pushes, lateral cable walkouts, the good morning exercise, and the bowler's squat. Generally, muscle activation levels were quite modest even though the tasks were quite strenuous in many cases. Even though similar joint moments were required in different exercises, the pattern of activity between muscles was different. Abdominal bracing increased spine stiffness at the expense of more spine load. Thus, muscle activity seems to be constrained in "functional" exercises. There are several possible reasons for this. Single muscles cannot be activated to 100% of the maximum voluntary contraction in functional exercises because this would upset the balance of moments about the 3 orthopedic axes of the spine, or it would upset the balance of stiffening muscles around the spine required to ensure stability of the spinal column. The one exception was the floor walkout, which resulted in full activation of the rectus abdominis; however, this was a sagittal plane task without the joint moment constraints of multiplanar exercise. Therefore, maximal muscle activity is observed during single-plane tasks, but muscle activation levels were constrained during functional tasks. Thus, strength training muscles may not help in "functional multiplanar" tasks. These data can be used to assist decisions regarding the selection of exercises, specifically choices regarding the starting challenge, progression, exercise form, and possibly corrective technique for those who have spine concerns, or those simply looking for performance enhancement.
本研究的目的是记录在几种基于动作或“功能性”练习过程中的肌肉活动、脊柱运动、脊柱负荷和刚度，并评估技术改变的影响。八名受试者均为来自大学人群的健康男性，他们被安装仪器以获取选定的躯干和髋部肌肉的表面肌电图，同时进行视频分析和电磁腰椎位置传感器以跟踪脊柱姿势。练习包括矢状面的俯卧撑（比较靠墙直立姿势与在地板上进行的姿势）、头顶绳索推、横向绳索俯卧撑、早安式练习和保龄球深蹲。一般来说，尽管在许多情况下任务相当费力，但肌肉激活水平相当适度。即使不同练习需要相似的关节力矩，但肌肉之间的活动模式不同。腹部支撑以增加更多脊柱负荷为代价提高了脊柱刚度。因此，在“功能性”练习中肌肉活动似乎受到限制。对此有几个可能的原因。在功能性练习中，单个肌肉不能被激活到最大自主收缩的100%，因为这会打乱围绕脊柱三个骨科轴的力矩平衡，或者会打乱确保脊柱稳定性所需的脊柱周围加强肌肉的平衡。唯一的例外是地板俯卧撑，它导致腹直肌完全激活；然而，这是一个矢状面任务，没有多平面运动的关节力矩限制。因此，在单平面任务中观察到最大肌肉活动，但在功能性任务中肌肉激活水平受到限制。因此，力量训练肌肉可能对“功能性多平面”任务没有帮助。这些数据可用于协助有关练习选择的决策，特别是对于那些有脊柱问题的人或那些只是寻求提高表现的人，在起始挑战、进展、练习形式以及可能的纠正技术方面的选择。
