Your mitochondria are small, hard-working organelles deep in your cells that are largely responsible for transforming the substrates your body deposits from the food you eat into energy. When it comes to metabolism, it is the mitochondria that actually perform the crucial action of “burning off” – taking in calories and turning them into heat. They are also the reason why exercise and muscle growth are crucial for sustained weight loss and health, as your muscles are the body’s hot beds of mitochondria. Simply put: The more muscle you have, the more mitochondria you need to burn calories.
But according to a new study that was just published last week in the journal Cell metabolism, if you are engaged in the wrong form of exercise, you can actually damage your mitochondria’s ability to do its job effectively. Read on for more about this study, and for more news from the forefront of fitness science, make sure you are aware of the great side effect of sitting on the couch too much, says new study.
The research was led by Filip Larsen from the Swedish Sports and Health School, who wanted to study the effects of overtraining on the body. He and his colleagues tested 11 young people for four weeks with a stationary bike, which increased the training intensity as they developed. During the experiment, the researchers monitored their insulin resistance and the body’s mitochondrial function.
During week one, the participants completed light interval training with high intensity for a total of 36 minutes. During week two, they went up to 90 minutes. During week three, they went up to a bone-melting 152 minutes. Week four was a recovery period with only 53 minutes of training.
During the first two weeks of the study, participants experienced all the usual effects one would expect from high-intensity exercise. Their mitochondrial function improved, among other things.
However, during the third training week, the participants’ mitochondrial function decreased by an average of 40% compared to week two. “After the week with the highest exercise load, we found a striking decrease in internal mitochondrial function that coincided with a disturbance in glucose tolerance and insulin secretion,” says the study.
That’s right: the subjects’ insulin resistance actually went down up. “It’s similar to the changes you see in people who start to develop diabetes or insulin resistance,” Larsen explained The scientist.
The volunteers’ ability to generate power on their cycles was also plateaued.
After the difficult third week of the study, participants entered a recovery phase. During this period, during which they only completed 53 minutes of exercise, their bodies largely returned to normal, but mitochondrial function remained 25% less than it was during the second week of the study. For more news from the forefront of science, see why drinking these 30 minutes before exercise flares fat, says new study.
Although the study was relatively small and the long-term effects of hardcore training are not clear, the researchers conclude: “HIIT training should not be excessive if increased health is a desired result”, Mikael Flockhart, researcher and doctoral student at the Swedish School of Sports and health sciences, explained for The New York Times.
According to the Mayo Clinic, you should exercise about 150 minutes with moderate exercise or 75 minutes with vigorous exercise each week. If you are a strong practitioner, this new study shows the benefits of reaching 90 minutes per week. If you walk as high as 152 minutes, you can do more harm than good. And if you are looking for more moderate exercise routines, check out what goes on for just 20 minutes a day according to your science.
