Data from: The features of muscle activity during chair standing and sitting motion in submerged condition

This study aimed to measure muscle activity and motion kinematics during chair-based exercises under submerged and non-submerged conditions. Twelve healthy men performed chair-based standing and sitting movements. Surface electrodes were attached at the tibialis anterior, gastrocnemius, rectus femoris, biceps femoris, rectus abdominis, and erector spinae. The ankle, knee, and hip joint angles and forward inclination angle of the trunk segment in the sagittal plane were calculated. The mean muscle activities during both movements in the submerged condition for the entire motion were lower than those in the non-submerged condition except in the tibialis anterior and biceps femoris during the sitting movement (in the standing exercise, rectus femoris: 14.1% and 5.2%; and erector spinae: 18.3% and 13.6% in non-submerged and submerged conditions, respectively; and in the sitting exercise, rectus femoris: 12.1% and 4.5% and erector spinae: 12.9% and 9.9% in the non-submerged and submerged conditions, respectively). However, the integrated muscle activity in submerged conditions was similar or higher to that in non-submerged conditions during both movements, except for the rectus femoris. This was mainly due to the increased duration of motion (44.3% and 39.9% longer for standing and sitting exercises in submerged conditions, respectively, compared with non-submerged conditions; p < 0.01 for both). The hip joint flexion at the beginning and end of movement and forward inclination angles of the trunk segment at the beginning of the movement in the submerged condition were larger than those in the non-submerged condition during both movements (hip: 126.1° and 111.5° at the beginning, 182.3° and 178.4° at the end and trunk: 2.7° and 17.4° at the beginning in non-submerged and submerged conditions for the standing exercise, respectively; hip: 182.4° and 178.0° at the beginning, 125.9° and 111.1° at the end and trunk: 2.2° and 16.9° at the end in non-submerged and submerged conditions for the sitting exercise, respectively). Reduced or similar muscle activity but similar or higher muscular effort was observed in the submerged condition for all the muscles except the rectus femoris, with the upper body inclined forward. These findings could have beneficial implications for the prescription of exercise and rehabilitation regimens.本研究旨在探究椅上训练（chair-based exercises）在水下环境（submerged condition）与非水下环境（non-submerged condition）中的肌肉活动与运动学（kinematics）指标。招募12名健康男性受试者完成椅上站起与坐下动作，将表面电极（surface electrodes）分别附着于胫骨前肌（tibialis anterior）、腓肠肌（gastrocnemius）、股直肌（rectus femoris）、股二头肌（biceps femoris）、腹直肌（rectus abdominis）与竖脊肌（erector spinae）。计算矢状面（sagittal plane）内踝、膝、髋关节角度，以及躯干节段的前倾角。整体运动周期内，水下环境下两项动作的平均肌肉活动水平均低于非水下环境，但坐下动作中的胫骨前肌与股二头肌除外：站姿训练中，非水下与水下环境的股直肌活动度分别为14.1%与5.2%，竖脊肌分别为18.3%与13.6%；坐姿训练中，非水下与水下环境的股直肌活动度分别为12.1%与4.5%，竖脊肌分别为12.9%与9.9%。不过，除股直肌外，水下环境下两项动作的积分肌肉活动量（integrated muscle activity）与非水下环境相比相近甚至更高。这一现象主要源于水下环境下动作时长显著延长：站姿与坐姿训练的动作时长分别较非水下环境增加44.3%与39.9%，两组均满足p<0.01。两项动作中，水下环境下动作起始与结束时的髋关节屈曲角度，以及站姿训练起始时、坐姿训练结束时的躯干前倾角，均大于非水下环境。具体参数如下：站姿训练中，非水下与水下环境的起始髋关节角度分别为126.1°与111.5°，结束时分别为182.3°与178.4°；躯干起始前倾角分别为2.7°与17.4°。坐姿训练中，非水下与水下环境的起始髋关节角度分别为182.4°与178.0°，结束时分别为125.9°与111.1°；躯干结束前倾角分别为2.2°与16.9°。除股直肌外，水下环境下所有受试肌肉的平均肌肉活动水平降低或与非水下环境相近，但肌肉总负荷却相似甚至更高，且躯干呈现前倾状态。本研究结果可为运动处方与康复方案的制定提供有益参考。