HIIT/interval training (anaerobic power).

The idea

HIIT, or high-intensity interval training, alternates short maximal or near-maximal efforts with brief recovery periods. A typical session might use 30 s of sprinting followed by 30 s of walking, repeated across several rounds. The intense work bouts demand energy faster than aerobic metabolism alone can supply, so anaerobic power and anaerobic capacity improve, alongside aerobic fitness. Interval training more broadly uses planned work-to-recovery ratios; a shorter recovery keeps heart rate and oxygen demand high, while a longer recovery allows greater power in each repetition. Intensity, work duration, recovery duration and number of repetitions are the key variables. Because effort is high, performers need adequate warm-up, progression and recovery between sessions to reduce injury and overtraining risk.

What earns the marks

• HIIT alternates short periods of maximal or near-maximal work with brief recovery periods.
• The high-intensity work bouts rely heavily on anaerobic energy supply, developing anaerobic power.
• Repeated bouts with incomplete recovery also stress the aerobic system, improving aerobic fitness.
• Work-to-recovery ratio is a key variable: shorter recovery raises intensity and fatigue, longer recovery allows greater power output.
• Intensity, work duration, recovery duration and number of repetitions determine the training effect.
• High effort requires thorough warm-up, gradual progression and adequate rest between sessions to reduce injury and overtraining risk.

Common mistakes and how to put them right

• Treating HIIT as purely anaerobic.

  Put it right: Repeated bouts also develop aerobic fitness, so the answer should not exclude that benefit.

• Ignoring the recovery period.

  Put it right: Recovery length controls how much power can be produced in later repetitions.

• Assuming HIIT suits every performer immediately.

  Put it right: Beginners need progression and adequate recovery to avoid injury.

• Confusing HIIT with steady continuous training.

  Put it right: HIIT uses short intense bouts, not unbroken submaximal work.

Exam tips

• Identify the work and recovery variables in the question before selecting an answer.
• Link the short intense bouts to anaerobic power and the repeated nature to aerobic development.
• Reject options that describe continuous steady-state work as HIIT.