Training & Fitness - Cardio & HIIT
Cardio fitness: easy work, intervals and weekly targets
Last reviewed 3 August 2026. How we write this.
Cardiorespiratory fitness is trainable through regular moderate and vigorous activity, built from a manageable starting point.
Cardio trains the heart, circulation and working muscles to deliver and use oxygen. Walking, cycling, swimming, running and many sports can all contribute.
Easy and hard work have different jobs
- Moderate work builds volume with manageable fatigue.
- Hard intervals provide a strong stimulus in less time but cost more recovery.
- Everyday movement reduces the amount of the day spent inactive.
WHO guidance for adults includes 150–300 minutes of moderate activity or 75–150 minutes of vigorous activity weekly, plus muscle strengthening on at least two days.
This lesson is general education, not an individual training, nutrition or medical prescription. Adapt activity to your experience and health, and seek qualified advice for symptoms, injury, pregnancy or a medical condition.
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Educational content only. Not medical advice, diagnosis or treatment. Always consult a qualified healthcare professional before changing your health regimen.