Before we take a closer look at the benefits of High Intensity Interval Training, we need to consider what it is being compared to.

Research on HIIT has focused on comparing it with continuous aerobic training, which is defined as any exercise session which takes place at a continuous steady state – or below Functional Threshold Power or threshold heart rate.

Both types of exercise (HIIT and continuous aerobic training) have similar benefits, including increased cardiovascular capacity (increased stroke volume and an increased number of mitochondria – the power stations of your cells), increased skeletal muscle improvements (increased muscle force and power) and metabolic adaptations (greater use of fat as an energy source).

The key benefit of HIIT, then, is that it is said to bring about these adaptations in a shorter amount of time. Research has shown that HIIT sessions offer greater improvement across all three areas compared to the equivalent amount of continuous aerobic training. Again, more bang for your buck.

For example, research carried out on runners in 2007 by the Martin Luther University in Germany showed a ten per cent improvement in stroke volume (the amount of blood pumped per heart beat) in athletes doing three HIIT sessions per week for eight weeks compared with runners following a continuous aerobic training programme. So why does this happen?