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HIIT: big fitness gains in little time

HIIT — big fitness gains in little time. High-intensity interval training produces cardiovascular benefits in sessions as short as 15 minutes. Short bursts of hard effort followed by recovery improve VO2 max and mitochondrial health efficiently. One to two sessions per week is enough; more is not always better and can raise injury risk. Research consistently links small improvements here to better metabolic and immune outcomes. The mechanism involves tighter control of blood sugar, cortisol and oxidative stress markers. Measure progress with a simple marker rather than a perfect outcome. For most adults, try 30 seconds hard, 90 seconds easy, repeated 8–10 times on a bike or rower. Sustainable change is built from boring, reliable repetition.