We measured the medial joint distance (MJD), activity of muscles involved in medial elbow-joint support, and grip strength, aiming to examine the supportfunction of muscles.

MJD was measured in supinated and pronated positions of the forearm of 10 participants under three conditions: at rest (R), under valgus load on the elbow joint (L), and under valgus load on the elbow joint during the grip task (L-grip). Under the L-grip condition, electromyography was performed on flexor digitorum superficialis (FDS), pronator teres (PT), flexor carpi radialis (FCR), and flexor carpi ulnaris (FCU); subsequently, normalized integrated electromyograms (NIEMG) were calculated. Under the L-grip condition, MJD was shorter in the pronated position than in the supinated position (p < 0.001); however, grip strength was lower in the pronated position. NIEMG of FDS was 90% in both positions, and those of FCR and FCU were low at 10%. However, that of PT was 3.6% in the supinated position and 40.9% in the pronated position, showing higher NIEMG in the pronated position (p < 0.001). Medial support during grip tasks was higher in the pronated position probably because PT activity compensates for the decreased FDS activity.

我们测量了内侧关节距离（MJD）、参与内侧肘关节支撑的肌肉活动度和握力，旨在检查肌肉的支撑功能。

MJD 是在三种条件下测量 10 名参与者的前臂旋后和旋前位置：休息时 (R)、肘关节外翻负荷下 (L) 以及握力任务期间肘关节外翻负荷下 (L-紧握）。L握距条件下，对指浅屈肌（FDS）、旋前圆肌（PT）、桡侧腕屈肌（FCR）、尺侧腕屈肌（FCU）进行肌电图检查；随后，计算归一化积分肌电图（NIEMG）。在 L 型握把条件下，旋前位置的 MJD 比旋后位置的 MJD 短 (p < 0.001)；然而，旋前位置时握力较低。FDS 的 NIEMG 在两个位置上均为 90%，FCR 和 FCU 的 NIEMG 较低，为 10%。然而，旋后位的 PT 为 3.6%，旋前位的 PT 为 40.9%，显示旋前位的 NIEMG 较高（p < 0.001）。握力任务期间，旋前位置的内侧支撑较高，可能是因为 PT 活动补偿了 FDS 活动的减少。