划船機氣壓坐墊對軀幹晃動與核心肌群之影響

Effects on trunk sway and core muscle activity when using a rowing machine with an air seat cushion

"緒論：划船是一項全身性且適合全民的健身運動。於划船機上添加不穩定表面或許可提高軀幹晃動並徵召更多的核心肌群以穩定身體姿勢，藉此促進動作控制與核心訓練。因此，本研究目的是要探討，於划船機上添加不同氣壓程度之坐墊對划船動作過程之軀幹晃動程度以及核心肌群活化的影響。方法：29位休閒運動者（14男、15女，23.1±7.8歲）隨機次序坐在三種坐墊氣壓（0、80、140mmHg）上，隨機進行三種划頻（18、30、36 strokes per minute [spm]）連續10下之划船運動。使用Delsys無線感測系統，分析第5-9下划船過程中，下背（L5）及上背（T1）在三軸方向的均方根角速度，以及腹直肌、腹外斜肌與豎脊肌之肌肉活化（EMGrms）。結果：經完全相依設計二因子變異數分析顯示，坐墊氣壓與划頻之間在各項依變數中皆無交互作用。坐墊主要效果顯示，拉槳期的下背水平（縱軸）與側向（矢狀軸）晃動在坐墊氣壓140mmHg時，顯著大於無氣壓坐墊（p＜.05）。上背晃動及所有核心肌群活化皆無隨坐墊氣壓顯著變化。划頻主要效果顯示，上、下背各軸向晃動在拉槳及回槳期皆隨划頻增加而顯著變大（18spm＜30spm＜36spm,p＜.05）；拉槳期所有肌肉及回槳期腹直肌活化，在划頻36spm及30spm皆顯著大於18spm（p＜.05）。結論：坐在氣壓坐墊上進行划船機運動時，可增加拉槳動作時下背的晃動，但其坐墊不穩定的程度不致於引起更多核心肌群的活化以維持平衡。相較於坐墊的影響，隨著划頻的增加，軀幹的晃動與核心肌肉活化會隨之提高，可做為調整划船運動對核心肌群負荷的控制因子。"

Introduction: Rowing is a whole-body exercise that is suitable for the general public. Adding an unstable surface to the rowing machine could increase trunk sway, resulting in increased core muscle activity to maintain body posture, promoting enhanced postural control and core training. Therefore, the purpose of this study was to investigate the effects of seats with different air pressures on trunk sway and core muscle activity during rowing machine use. Methods: Twenty-nine individuals who engage in recreational exercise (14 men, 15 women, mean age: 23.1 ± 7.8 years) were randomly assigned to three seat cushion conditions (0, 80, 140 mmHg air pressure) and performed ten strokes with three frequencies (18, 30, and 36 strokes per minute [spm]) in random order. The Delsys Trigno wireless sensing system was used to measure the root-mean-square angular velocity in three axis directions in the upper back (L5) and lower back (T1), as well as the muscle activity (EMGrms) of the rectus abdominis, external oblique, and erector spinae muscles. Results: The results, analyzed by two-way repeated-measures analysis of variance (ANOVA), showed no interaction effect between the seat cushion air pressure and stroke frequency conditions. A main effect of seat cushion was identified for horizontal (longitudinal axis) and lateral (sagittal axis) sway of the lower back, with significantly larger sway during the pull phase for the seat cushion with 140 mmHg pressure compared with 0 mmHg pressure (p <.05). Upper back sway and core muscle activity showed no change with different seat cushion air pressure levels. A main effect of stroke frequency was identified for the sway in the upper and lower back, which increased with stroke frequency (18 spm < 30 spm < 36 spm) during both the pull and return phases (p <.05). The muscle activity observed in all monitored muscles during the pull phase and the rectus abdominis during the return phase was increased during stroke frequencies of 36 spm and 30 spm compared with those at 18 spm (p <.05). Conclusion: Sitting on an air seat cushion to perform rowing machine exercises increased lower back sway during the pull phase, but the unstable seat cushion did not result in increased core muscle activity to maintain balance. Compared with the effects of the seat cushion, trunk sway and core muscle activity were more strongly affected by stroke frequency, which can be used to adjust the load on core muscles as a controlling factor.