肩・肘関節の肢位と負荷量の違いによる手関節自動運動改善の即時効果の比較検討

無作為に選択した健常者10名を対象に,上肢静止性収縮時における肩・肘関節の肢位と負荷の相違が,手関節屈曲の自動関節可動域と手関節屈曲の主動筋と拮抗筋の表面筋電図に及ぼす影響を検討した.肩・肘関節の肢位は固有受容性神経筋促通(PNF)肢位(肩135°屈曲,45°内転,中等度外旋位,肘軽度屈曲,前腕90°回外)の上肢PNF肢位と非PNF 肢位(肩90°屈曲,内外旋中間位,肘伸展,前腕90°回内)の2種を選択し,負荷はピンチ力の最大随意収縮の30～40%(軽負荷)および70～80%(重負荷)の2種とした.重負荷・PNF 肢位の組み合わせによる静止性収縮後の手関節屈曲の自動関節可動域改善率が重負荷・非PNF 肢位の自動関節可動域改善率より有意に大きかった(p < 0.05).軽負荷と比較し重負荷で主動筋の積分筋電図値が有意に大きな値を示したが,PNF 肢位では認められなかった.積分筋電図値の指標と自動関節可動域改善との関連性は認められなかった.

This study aimed to compare the effects of sustained contractions in different positions of the upper extremity and different degrees of load on both the active range of motion (AROM) of wrist flexion and the surface electromyographic (EMG) activity of wrist agonist and antagonist for ten healthy subjects randomly selected. The positions of the upper extremity were the non-PNF position (shoulder flexion (90°) and elbow extension with forearm pronation) and the PNF position (shoulder flexion-adductionexternal rotation and elbow extension with supination). The target loads by fingertip force spanned a range from 30% to 40% of maximal voluntary contraction (light load) to 70% to 80% (heavy load). The improvement percentage of AROM after each sustained contraction was calculated in comparison with AROM before the contractions, and each integrated EMG (IEMG) ratio was normalized to the IEMG of each maximal voluntary contraction. The results of this study showed that the improvement of AROM by a sustained contraction combined with the PNF position and a heavy load was significantly larger (P < 0.05) compared with the non-PNF position combined with a light load. The IEMG ratio of the agonist during heavy load was greater than for the light load, which may be explained by the observation that the facilitation of the agonist in the heavy load, but there was no facilitation of the agonist in the PNF position of the upper extremity. Because of the non-significant correlation coefficient between improvement of AROM and IEMG, there was no relation between AROM and facilitation of the agonist activity.