High Intensity Training also known as High Intensity Interval Training is high intensity exercise for short periods up to 30 seconds, interspersed with rest periods.
Its been around since the beginning of the 20th century in various forms, mainly used by elite athletes, but is now becoming increasingly popular as the science on its benefits continue to surprise with what seems like a lot of benefit for little exercise.
Anja Taylor in this episode of ABC TVs science program Catalyst investigates some of the current research and findings about High Intensity Interval Training.
To gain the benefits, the key seems to be to move your limbs fast during the high intensity interval, like you are running away from a dangerous animal. This seems to kick in a fight or flight mechanism that we have evolved to escape danger and the body responds by firing more muscle fibres synchronously for increased power than it does for normal exertion.
According to the researchers this in turn improves mitochondria function which is responsible for orchestrating many health and fitness benefits.
Mitochondria are the furnaces within all our cells where the body’s fuel is metabolised with oxygen to create the chemical energy that muscle fibres use. To measure mitochondrial function, a subjects oxygen consumption is measured while they do exercise during which they go as hard as they can for a short time. The mitochondria in the working muscles will be producing energy at their maximum capability which also means the oxygen consumption rate will also be maximum and this is the VO2 Max.
By measuring VO2 Max, a persons mitochondrial function can be monitored and so types of exercise program can be compared. The results seem to be that just short periods of high intensity exercise totalling 6 minutes a week delivers improvements just as good or better than 150 minutes a week of conventional endurance exercise. The 6 minutes is a total of three lots of three 20 second bursts, there is extra time in between for warm up and rest recovery.
Each cell contains many mitochondria and the total amount is a very surprising 10% of our body weight. Endurance and high intensity training both can increase the amount of mitochondria in cells but intriguingly only high intensity excercies improved mitochondrial function as well. It is thought this improvement results from some of the older mitochondria is replaced by better functioning new mitochondria.
As well as improving fitness in general, interval training and the improvement in mitochondrial function has many health benefits. It is potent at improving insulin sensitivity which is a factor for reducing obesity and type 2 diabetes. There is also evidence that the dermis with its collagen fibre thickens producing a more youthful skin.
Even elderly can access the benefits of improved mitochondrial function, but whatever your age you shouldn’t attempt it without the supervision of an exercise professional especially if you have a medical condition such as heart disease, diabetes etc.
Watch the full episode