HIIT Timer
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High-Intensity Interval Training (HIIT) alternates short bursts of maximum-effort exercise with brief recovery periods. Unlike steady-state cardio, HIIT elevates your heart rate rapidly, then allows partial recovery — repeated cycles that create a powerful metabolic stimulus. The default 40:20 ratio (40 seconds work, 20 seconds rest) is a proven HIIT standard used in commercial fitness programs worldwide.
A 2:1 work-to-rest ratio provides enough time to build intensity during the work phase while the rest period is short enough to prevent full cardiovascular recovery. This sustained elevated heart rate is what triggers the afterburn effect (EPOC) that makes HIIT so effective for fat loss.
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