Intervals (HIIT)

Intervals give a lot of fitness for little time, but they’re hard. Once or twice a week is plenty alongside lifting.

Intervals alternate hard efforts with easy recovery, e.g. 30 seconds fast, 90 seconds easy, repeated. Vigorous minutes count double toward the weekly cardio guideline [1].

A simple session (about 20 minutes)

1. 5 minutes easy (walk, bike, row).
2. 6–8 rounds: 30 seconds hard (you can say only a few words), then 90 seconds easy.
3. 5 minutes easy.

A bike or rowing machine is gentler on the joints than sprinting. Start with 4 rounds.

Pros

• Time-efficient
• Improves fitness quickly
• Many options: bike, rower, hill walks, running

Cons

• Hard, so it’s easy to skip or overdo
• Adds fatigue that can cost reps on leg day (see pairing cardio with lifting)
• Not a good first step if you’re new to exercise; start with walking

Check with a doctor first

If you have heart disease, high blood pressure, chest pain with exertion or other conditions, ask before doing vigorous exercise.

General information, not medical advice. If you have a health condition, are pregnant or take medication, check changes with your doctor.