Jaskólska Anna, Kisiel Katarzyna, Brzenczek Wioletta, Jaskólski Artur
Department of Kinesiology, University College of Physical Education, ul. Rzeźbiarska 4, 51-629 Wrocław, Poland.
Eur J Appl Physiol. 2003 Sep;90(1-2):58-68. doi: 10.1007/s00421-003-0859-6. Epub 2003 Jun 13.
The aim of the study was to estimate the influence of force changes during relaxation from maximal voluntary contraction (MVC) of elbow flexors on electrical (EMG) and mechanical (MMG) activity of synergists and antagonists at different joint angles. Repeated studies were conducted on 22 young female students to estimate the EMG and MMG activity of the biceps brachii (BB), brachioradialis (BR), and triceps brachii (TB) muscles during relaxation from MVC at an optimal angle (the angle at which a subject achieved MVC=Lo), as well as at angles that were smaller (Ls=Lo-30 degrees ) and bigger (Ll=Lo+30 degrees ). Four testing sessions consisted of 2-s or 3-s MVC at each angle with simultaneous recording of EMG and MMG signals from BB, BR, and TB muscles. The EMG/MMG probes were used to record EMG and MMG signals. The results showed that the slow relaxation rate was related to a percentage decrease of the EMG amplitude (as measured by root mean square; EMG RMS) of the synergists, while the fast relaxation was related to the EMG RMS of the antagonist, independent of the joint angle. The MMG amplitude (MMG RMS) increased gradually during slow and fast relaxation (compared to the MMG RMS at MVC), indicating a bigger muscle oscillation during relaxation; the changes were related to the muscle tested and joint angle. It was found that, during the slow relaxation, the MMG RMS reflects the force amplitude changes in the BB muscle and the velocity of force changes in the BB and TB muscle (but not in the BR). During the fast relaxation, the MMG amplitude reflects a change in muscle force in the TB and BB muscles (but not in the BR), and the velocity of force changes in the synergists (not in the antagonist). The different contribution of the force and velocity of force changes during slow and fast relaxation to the MMG signal in the three muscle tested can be related to the different deactivation time of each muscle. In conclusion, the present results indicate that MMG recordings might be useful to measure the fast relaxation of individual muscle during voluntary contraction, but this needs be tested on isolated muscle.
本研究的目的是评估肘关节屈肌从最大自主收缩（MVC）放松过程中力的变化对不同关节角度下协同肌和拮抗肌的电活动（EMG）和机械活动（MMG）的影响。对22名年轻女学生进行了重复研究，以评估肱二头肌（BB）、肱桡肌（BR）和肱三头肌（TB）在从MVC以最佳角度（受试者达到MVC时的角度=Lo）放松过程中的EMG和MMG活动，以及在较小角度（Ls=Lo - 30度）和较大角度（Ll=Lo + 30度）时的情况。四个测试环节包括在每个角度进行2秒或3秒的MVC，并同时记录来自BB、BR和TB肌肉的EMG和MMG信号。使用EMG/MMG探头记录EMG和MMG信号。结果表明，缓慢放松速率与协同肌的EMG振幅（以均方根测量；EMG RMS）百分比下降有关，而快速放松与拮抗肌的EMG RMS有关，与关节角度无关。在缓慢和快速放松过程中，MMG振幅（MMG RMS）逐渐增加（与MVC时的MMG RMS相比），表明放松过程中肌肉振荡更大；这些变化与所测试的肌肉和关节角度有关。研究发现，在缓慢放松过程中，MMG RMS反映了BB肌肉中的力振幅变化以及BB和TB肌肉中的力变化速度（但不是BR肌肉）。在快速放松过程中，MMG振幅反映了TB和BB肌肉中的肌肉力变化（但不是BR肌肉）以及协同肌中的力变化速度（不是拮抗肌）。在缓慢和快速放松过程中，力和力变化速度对所测试的三块肌肉中MMG信号的不同贡献可能与每块肌肉不同的失活时间有关。总之，目前的结果表明，MMG记录可能有助于测量自愿收缩过程中单个肌肉的快速放松，但这需要在离体肌肉上进行测试。
