Dr. Matthew B. (Matt) (likely the presenter) - Unknown

high-intensity exercise, you then have more healthy functional mitochondria because you're just getting rid of the damaged part of the mitochondria.

If the mitochondria is dysfunctional enough, you're going to get rid of the whole mitochondria.

And by the way, the AMP kinase pathway, many of you are probably thinking, oh, well, that's a nutrient-sensing pathway.

It's activated during periods of fasting.

And that is true.

AMP kinase is activated during periods of fasting, and fasting is a powerful signal for inducing autophagy and mitophagy.

However, in this particular study, people that did this high intensity vigorous exercise for 30 minutes, it did not matter if they had fasted for 16 hours or not.

There was no difference in the mitophagy.

So in other words, the exercise itself was such a strong signal for activating mitophagy that it didn't matter if they had not fasted for 16 hours because it was so powerful.

On top of the repair process, high intensity interval training is one of the most robust exercise modalities that can increase mitochondrial biogenesis.

So the growth of new mitochondria, increasing mitochondrial volume.

So you're having this double whammy effect where you're getting repairing of the mitochondria, getting rid of the unhealthy parts, and then you're

increasing the growth of new mitochondria.

So one of the reasons high intensity interval training is very good at increasing mitochondrial biogenesis compared to, let's say, moderate continuous exercise is because lactate that's generated from that vigorous exercise is a signaling molecule to activate the protein that very much regulates mitochondrial biogenesis in skeletal muscle, PGC1 alpha.

So again, lactate is playing that signaling role.

It's generated by the muscle.

It's taken back up by the muscle.

And then it's communicating with the muscle and saying, hey, we can't make energy fast enough because this exercise is so intense.

We need more mitochondria to be able to do that.

So it's an adaptation to the vigorous intensity exercise.