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Training insights, coaching tips, and endurance sport science.

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Heart Rate Zones vs Power Zones Explained

Two systems, one goal: understanding intensity. Here's when to trust your heart rate, when to trust your power meter, and how 400WFTP brings them together.

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Understanding CTL, ATL, and TSB: Your Training Load Dashboard

Three numbers quietly shape every peak performance and every burnout. Learn how Chronic Training Load, Acute Training Load, and Training Stress Balance work together as your personal training dashboard — and how to read them before they read you.

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Understanding CTL, ATL, and TSB: Your Training Load Dashboard

A deep dive into the mathematical foundations and practical applications of Chronic Training Load, Acute Training Load, and Training Stress Balance — the three metrics that transform training from guesswork into science.