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# 著地指數 (Duty Factor)

**什麼是**著地指數比**？**\
著地指數 (duty factor) 是指跑步過程中腳著地時間 (contact time) 、相對於騰空時間 (aerial time) 加上著地時間的比值。

**為何重要？**

* **低著地佔比（更多時間在空中）** → 速度較快，如短跑步態
* **高著地佔比（更多時間在地面）** → 速度較慢，如慢跑或耐力跑

**跑步與步行的著地佔比對比：**

* **跑步**：< 50%（有騰空階段）
* **步行**：> 50%（雙腳交替支撐）

**為何著地佔比會變化？**

* 速度變快 → 觸地時間減少 → 著地佔比降低
* 跑在不平或柔軟地面 → 觸地時間增加 → 著地佔比上升


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