> For the complete documentation index, see [llms.txt](https://strydtaiwan.gitbook.io/stryd/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://strydtaiwan.gitbook.io/stryd/master/stryd-metrics/gct.md).
# 觸地時間 (Ground Contact Time, GCT)
**什麼是觸地時間？**\
觸地時間是指每一步中，腳掌接觸地面的時間，以毫秒（ms）計算。觸地時間從腳掌接觸地面開始，並在腳趾離地進入擺動階段時結束
**觸**地時間與 **代謝功率 (Metabolic Power)** 呈反比關係，這意味著 **較低的觸地時間通常代表較高的代謝功率**（這種關係適用於同一跑者，而非不同跑者之間的比較）。
\
觸地時間最適合用來 **監測趨勢變化**，而不是設定特定目標值（例如：不應刻意追求觸地時間 165 毫秒）。
影響觸地時間的因素包括：
* **疲勞**：長跑後期，當跑者感到疲勞時，觸地時間可能會上升
* **訓練適應**：隨著訓練進展，跑者可能會發現觸地時間逐漸減少
* **跑鞋影響**：鞋子的緩震程度、足跟差（Heel-to-Toe Offset）
* **配速與步頻**：跑速越快，步頻越高，通常會導致觸地時間減少
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