緒論
了解運動肌肉疲勞背後的原因和機制是提高競走成績的重要方法。競走比賽需要專注於增加生物力學效率、配速策略和協調性。保持高速是競走成績的關鍵，因此比賽中生物力學效率和生理因素的相互作用可能會影響競走成績。過去研究顯示，呼吸肌疲勞會引起代謝反射，造成血液減少流入四肢，加速運動過程中運動肌肉的疲勞，造成生物力學 (動作) 的改變。然而，目前並無競走對呼吸肌疲勞的研究，因此我們希望探討長距離競走是否會造成呼吸肌疲勞。透過調查長距離競走下，呼吸肌力量、呼吸與運動強度自覺用力係數和心率的變化，評估競走時的呼吸肌疲狀態，進而提供增進競走成績的訓練新方向。

方法
本實驗招募條件為 (1) 15歲以上 (2) 競走距離不少於3公里 (3) 為仍有在比賽的選手。本試驗總共招募七名競走運動員並完成一次長距離競走，並於步行前後測量最大吸氣壓和血乳酸濃度。其中，透過測量最大吸氣壓評估吸氣肌的力量。此外，在步行過程中的五個距離點 (總步行距離的20%、40%、60%、80% 和 100%時) 收集呼吸自覺用力係數、運動強度自覺用力係數和心率，評估呼吸肌與運動肌肉的疲勞狀況。數據以無母數統計Wilcoxon signed-rank tests，比較競走前後，或倆距離點間各指數的差異。

結果
比較步行前後的數據後發現，步行後其最大吸氣壓顯著降低且血乳酸濃度顯著升高 (p < .05)。分析不同步行距離時的各項參數後可知，步行前段 (距離40%至20%) 時的呼吸自覺用力係數、運動強度自覺用力係數和心率同時顯著增加 (p < .05)；到步行中後段，80%步行距離時的呼吸自覺用力係數和運動強度自覺用力係數顯著高於60%步行距離時 (p < .05)，但心率沒有顯著變化 (p > .05)，如圖1所示。此外，兩名受試者的步行速度也隨著呼吸自覺用力係數的增加而下降，他們的呼吸自覺用力係數在步行距離的60 - 80%時上升了2分，而此區間的行走速度較前一區段低，如表1所示。

結論
長距離競走後，受測者最大吸氣壓顯著比運動前低，且呼吸自覺用力係數、運動強度自覺用力係數和心率的變化在早期步行距離 (20-40%距離間) 與後期 (60-80%距離間) 時顯著增加，顯示長距離競走會導致呼吸肌力量下降，出現呼吸肌疲勞。由於早期呼吸肌疲勞可能會延長運動開始時對呼吸頻率的調整，而晚期可能會擾亂步行者穩定的步行步態，導致步行步態變異從而影響競走表現，因此長距離競走不僅要注重運動肌肉訓練，還要注重呼吸肌的訓練。

Background: Understanding the causes and mechanisms of locomotor muscle fatigue is essential for enhancing race walking performance. Respiratory muscle fatigue induces metaboreflex, potentially inhibiting blood flow to the limbs and hastening locomotor muscle fatigue during exercise. The effects of race walking on respiratory muscle fatigue are still unclear. Purpose: The purpose of this study was to investigate the effects of long-distance race walking on respiratory muscle strength, rate of perceived exertion (RPE), and heart rate. Methods: Seven race walkers were recruited and completed a long-distance race walking. Maximal inspiratory pressure (MIP) and blood lactate concentration were measured before and after the walk. RPE for respiration (RPErespiratory), RPE for exercise intensity (RPEintensity), and heart rate were collected at five points during the walk (20%, 40%, 60%, 80%, and 100% of the total walking distance). Non-parametric statistical analysis was used for comparisons. Results: The MIP significantly reduced (p < .05) and blood lactate concentration significantly increased (p < .05) after the walk. Before reaching the half-way point, RPErespiratory, RPEintensity, and heart rate significantly increased between 20% and 40% of the walking distance (p < .05). After the half-way point, RPErespiratory and RPEintensity at 80% of the walking distance were significantly higher than those at 60% of the walking distance (p < .05), but not heart rate (p > .05). In addition, the walking speed also decreased along with the RPErespiratory of two subjects whose RPErespiratory increased by 2 points between 60% and 80% of the walking distance. Conclusions: Long-distance race walking led to a significant reduction in respiratory muscle strength. Moreover, the changes in RPErespiratory and RPEintensity occurred early in the race (between 20% and 40 % of the distance) and later (between 60% and 80% of the distance). The results indicate that long-distance race walking would induce respiratory muscles fatigue. These findings have implications for the training and performance of race walkers, emphasizing the importance of respiratory muscle conditioning.