Why intense cardio training usually doesn’t work

Fitness trainers probably do better by not getting unfit people to start doing very intensive exercise, but instead starting them off at a moderately intensive level. Sports scientists at the University of South Australia discovered that a moderately intensive training programme stimulates people to become physically active of their own accord, but that a high-intensity programme does not.

The danger of short high intensity workouts
People have less and less time to devote to training, so the fitness industry has developed shorter and shorter training programmes. In order to make these training programmes effective, their inventors have increased the intensity of the exercise. High intensity has become the norm in fitness-land.

Why intensive cardio training usually doesn’t work
Critics are not happy with this development though. Many people who lead a sedentary lifestyle can’t stand physical exercise anyway. The more intense the exercise, the more they hate it. So it may well be the case that short workouts don’t actually motivate people to get more exercise, and that in the longer term people may benefit more from less intensive exercise programmes.

The Australians wanted to find out whether the critics had a point.

The researchers got 84 unfit subjects to run for half an hour on a treadmill three times a week for eight weeks. Half of the subjects had to run at an intensity that they described as ‘a bit heavy going’. The subjects did moderately intensive training.

The other half had to train at “high” intensity.

In case you’re interested, the Australians used the Borg scale to measure the intensity of the exertion. This goes from 6 to 20 RPE. The subjects in the moderate-intensity group ran at an intensity of 13 RPE, and the subjects in the other group at 15 RPE.

The researchers measured how fit the subjects were before the programme started, just after it ended and again six months later. The last measurement indicated that the maximal oxygen uptake – the most important indicator of fitness – had remained stable in the subjects who had done moderate-intensity training. This was not the case for the subjects who had done the intensive training programme.


The moderately intensive training programme had encouraged the subjects to continue doing some exercise of their own accord once the eight weeks had ended, the researchers think.

That was not the case for the subjects who had felt overworked by the intensive training program.