本研究的目的在探討換氣閾值與運動時的生理反應是否會隨著月經週期而有所不同。 受試者為十名自願參與本研究且具有規律月經週期的大學女性運動員（年齡 21.7 ± 1.6 歲、身高 164.4 ± 4.3 公分、體重 53.0 ± 5.0 公斤）， 每位受試者分別在濾泡期及黃體期（由記錄基礎體溫、分析助孕素濃度加以確認）各進行一次遞增負荷的原地腳踏車最大攝氧量測量。測量過程中全程記錄心跳及採氣，測量前及測量後五分鐘各採血一次，藉以分析血乳酸濃度。本研究的結果發現，在最大運動負荷下受試者的最大心跳率、最大攝氧量、最大換氣量、衰竭時間及乳酸值皆沒有顯著差異（ p>.05 ）， 但在 100W 的非最大運動負荷時，黃體期的換氣量及攝氧量皆顯著的高於濾泡期（ p<.05 ）。 在 125W 的非最大運動負荷時，黃體期的換氣量仍顯著的高於濾泡期（ p<.05 ）。 另外，濾泡期的換氣閾值（ 75.8 ± 3.98 ％ VO2max ）則顯著的高於黃體期（ 73.4 ± 4.67 ％ VO2max； p<.05 ）。結論：換氣閾值及非最大運動負荷時的攝氧量及換氣量，會受到月經週期的影響而有所不同，因此，在以女性作為受試者，並進行與攝氧量及換氣量有關的研究，或以換氣閾值進行訓練強度設定時，將月經週期納入考慮是有必要的。

The purpose of this study was to examine the effects of menstrual cycle phase on ventilatory threshold (VT) and physiological responses to exercise. Ten university female students (age 21.7 ± 1.6 yrs, height 164.4 ± 4.3 cm, weight 53.0 ± 5.0 kg ) with eumenorrheic menstrual cycle were recruited for this study. Incremental cycle ergometer exercise tests were performed at the mid-follicular (FP) and mid-luteal (LP) phases in the menstrual cycle (confirmed by basal body temperature and progesterone hormone level) Ventilation (VE), oxygen consumption (VO2) and heart rate were monitored throughout the exercise test. The blood samples of lactate acid (LA), progesterone were collected before and 5 minutes after exercise test. The VT was determined by systematic increase in ventilatory equivalent for O2 with no change in the ventilatory equivalent for CO2. VEmax, VO2max, LAmax, HRmax and time to exhaustion did not show significant difference during LP and FP. For the 100 watts submaximal exercise intensities, the VE during LP (36.6 ± 6.89 1/min) was significantly higher (p<.05) than during FP (33.1 ± 4.91 1/min), the VO2 during LP (25.34 ± 3.18 ml/kg/min) was significantly higher (p<.05) than during FP (23.9 ± 2.83ml/kg/min). For the 125 watts submaximal exercise intensities, the VE during LP (44.2 ± 7.98 1/min) was significantly higher (p<.05) than during FP (40.1 ± 7.54 1/min). The VT during LP (73.4 ± 4.67%VO2max) ws significantly lower (p<.05) than during FP (75.8 ± 3.98 % VO2max; P<.05). These results indicate that menstrual cycle phase should be considered when utilize female subjects in ventilatory and oxygen consumption related studies.