I was recently asked what the difference is between intense training (HIIT) and other types of training. Almost everyone has now heard of HIIT - high intensity training, where you go really hard for 20-30 seconds then rest for 10-20 seconds, then repeat for anything up to 20 minutes.
It sounds ideal, doesn't it? Get a better workout and burn more fat in a short period of time?
So, is it all its cracked up to be and whats the difference between HIIT and moderate-intensity continuous training (MICT)?
HIIT all started with a 1996 study by Professor Izumi Tabata et al. initially involving Olympic speed skaters.The study used 20 seconds of ultra-intense exercise (at an intensity of about 170% of VO2max - very hard!) followed by 10 seconds of rest, repeated continuously for 4 minutes (8 cycles). The exercise was performed on a mechanically braked cycle ergometer. In the original study, athletes using this method trained 4 times per week, plus another day of steady-state training, and obtained gains similar to a group of athletes who did steady state training (70% VO2max) 5 times per week. The steady state group had a higher VO2max at the end, but the Tabata group had started lower and gained more overall. Also, only the Tabata group had gained anaerobic capacity benefits.
It is important to note that in the original study, participants were disqualified if they could not keep a steady cycling pace of 85RPM for the full 20 seconds of work.Its also important to note the extreme high intensity of the work, and the fact that this evidence comes from Olympic athletes - something of which most of us are not!
"Tabata training" has now come to refer to a wide variety of HIIT protocols and exercise regimens that may or may not have similar benefits to those found in Tabata's original study.
A more recent study comparing the effects of HIIT and MICT in the Journal of Diabetes research concluded that after 12 weeks of training, both HIIT (at 90% VO2 max) and MICT (at 60% VO2max) groups of 52 females produced significant results in all measures of body fat and aerobic fitness. The theory is that HIIT training causes you to burn calories after the exercise has finished (EPOC), whereas MICT does not.
So the question I would ask is "can you achieve a high enough intensity for that short space of time to achieve the results produced in laboratory experiments?".
My experience is that many untrained clients cannot, therefore the outcome cannot be comparable. The majority of non-athletes do not have the aerobic capacity or mental strength to push themselves to high enough intensity to get the benefits of HIIT. There is a risk of injury and also non-compliance due to the higher motivation levels required to maintain the increased intensity.
In sport, we mix up both types of training. 1) MICT to build the aerobic engine and 2) HIIT in terms of interval training to increase the lactate threshold and therefore fitness/speed.
In life in general, and for the general exerciser, a mix of both types of training is important. We need to challenge ourselves to ensure change and improvement, so the moment you do the same thing for weeks and months on end, you will reach a plateau and stop seeing results.