舞台表現仰賴理想的體能與精神狀態，而這些狀態在某種程度上受到女性月經周期過程性荷爾蒙波動的影響。女性月經周期的長短反映了身體新陳代謝的速度。本追蹤性研究目的在瞭解月經周期的長短與女性舞者肌力與心理安適程度的關連。這個短期追蹤研究針對月經周期短於28天的年輕女性舞者（short MC, n = 6），自周期第一天開始，每星期均進行一次下肢肌力與心理安適程度指標的測量，並與月經周期較長的女性（long MC, n = 6）比較其演變上的差異，除此之外自主神經系統的變化也同時被測量。研究結果顯示：短周期組的雌激素在月經第一天濃度最高、長周期組則發生在第21天；而長周期組的黃體素在第14與21天已明顯增加，但這個正常現象並未發生於短周期組。在我們預期以外的發現是短周期組的腿部肌力無論在屈與張的收縮力均較長周期組高，這個組間差異只有在排卵期時最小（第14天）。另外，短周期組女性舞者主觀疲勞感與心情干擾指數在整個月經周期中均明顯高於長周期組，顯示月經周期短的女性心理安適狀態較為不佳。雖短周期組舞者心率變異度與長周期組無明顯差異，但在經前交感神經明顯高於長周期組。本研究結論：本研究的原創性發現為月經周期較短的女性舞者其心理安適狀況明顯較差，然而卻有較高的肌力。這些研究結果可幫助我們瞭解舞者安排舞台表演的最佳時機。

Stage performance of dancers relies fundamentally on both physical and mental capabilities, which to some extent fluctuated with sex hormones across the menstrual cycle (MC) in young women. Length of menstrual cycle reflects metabolic pace for a woman. The purpose of this longitudinal study was to determine the role of MC length on muscle strength and mental wellbeing of young female dancers. This short-term longitudinal study was undertaken to tracked lower-body muscle strength and wellbeing variables every week for the young female dancers with MC length less than 28 days (short MC group, n = 6) against those with MC length greater than 28 days (long MC group, n = 6). Autonomic nervous activity among participants was also determined. Our result shows that estradiol levels were highest at day 1 for the short MC group and day 21 for the long MC group, respectively. Progesterone levels for the long MC group elevated at day 14 and day 21 during leuteal phase, but this normal trend was not observed not for the short MC group. Unexpectedly, muscle strength of the short MC group was significantly greater than that of the long MC group. This difference diminished around time of ovulation (day 14). In addition, subjective fatigue feelings and mood disturbance of the short MC group were significantly higher than those of the long MC group, indicating a relatively poor status of wellbeing. Despite heart rate variability was not significantly different throughout the MC period, premenstrual sympathetic power of the short MC group was higher than that of the long MC group at day 21 (premenstrual phase). Conclusion: The new finding of the study is that young women with shorter MC length exhibited poor status of mental wellbeing, but greater muscle strength. This result provides a ground for the time management to optimize the stage performance of female dancers.