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.