Exercise, visceral fat and the mitochondria

7 October 2015

Mitochondria and HIT

The mitochondria and High Intensity Exercise


The concept of how much time we need for exercise has begun to shift. Low-volume, high-intensity interval training, or HIT results in improved endurance capacity, lower body fat and higher lean mass and on a cellular level, the humble mitochondria is behind the positive effects.

Mitochondria, often called “the powerhouse of the cell” generate a cell’s supply of energy (ATP). The number of mitochondria per cell varies, depending on the tissue the cell comprises. VO2 max is a measurement of how much oxygen our mitochondria can consume and convert into ATP when we push ourselves to the limit.

ABCs Catalyst recently highlighted a modified version of HIT. The exercise program basically consisted of four 30-second sprints three times a week. With a 4.5 minute rest between each sprint, each session to 20 minutes total,(even though the total sprint time is two minutes).

The improvement in VO2 max is largely to do with how the mitochondria adapt with a rapid increase in the number and function mitochondria following sprints.

High-intensity exercise places enormous pressure on your system to produce high amounts of energy fast. Your mitochondria respond by being better able to take that oxygen out of the blood into the muscles and using that to produce energy.

“When you do low-intensity exercise, even though it might feel like it, you’re not actually using all of your muscle. You’re only using the amount of muscle that you need to do that particular type of exercise. Whereas when we do very high-intensity exercise, especially sprinting, then you need to recruit all of your muscle fibres at once. What we think is that with the high-intensity training, I think we’re probably replacing some of the older mitochondria with new, better-functioning mitochondria, and we think that may not be happening as much with the low-intensity exercise” Professor David Bishop

In addition, HIT switches on your flight-or-fight mode via the hormones adrenalin and noradrenaline, which recruit your muscles, vessels, heart and lungs. Interestingly, the receptors for these hormones are also found on fat cells, in particular, visceral fat, which explains the decrease in body fat after only weeks of training.

 Related links can be found here:

High-Intensity Intermittent Exercise and Fat Loss

  1. Thanks for publishing this article. It was very helpful.

    Comment by Mike on 14 October 2015 at 6:30 am