Physical exercise has many beneficial effects on human health, including the protection from stress-induced depression. In a new study, researchers at Karolinska Institutet in Sweden show that exercise training induces changes in skeletal muscle that can purge the blood of a substance that accumulates during stress, and is harmful to the brain.

The study provides an explanation for the protective biochemical changes induced by physical exercise that prevent the brain from being damaged during stress.

It was known that the protein PGC-1a1 increases in skeletal muscle with exercise, and mediates the beneficial muscle conditioning in connection with physical activity. In this study researchers used a genetically modified mouse with high levels of PGC-1a1 in skeletal muscle that shows many characteristics of well-trained muscles (even without exercising).These mice, and normal control mice, were exposed to a stressful environment, such as loud noises, flashing lights and reversed circadian rhythm at irregular intervals. After five weeks of mild stress, normal mice had developed depressive behavior, whereas the genetically modified mice (with well-trained muscle characteristics) had no depressive symptoms.

The research hypothesis was that trained muscle would produce a substance with beneficial effects on the brain. They actually found the opposite: well-trained muscle produces an enzyme that purges the body of harmful substances. So in this context the muscle’s function is reminiscent of that of the kidney or the liver,” says the lead researcher.

The researchers discovered that mice with higher levels of PGC-1a1 in muscle also had higher levels of enzymes called KAT. KATs convert a substance formed during stress (kynurenine) into kynurenic acid, a substance that is not able to pass from the blood to the brain. The exact function of kynurenine is not known, but high levels of kynurenine can be measured in patients with mental illness. In this study, the researchers demonstrated that when normal mice were given kynurenine, they displayed depressive behavior, while mice with increased levels of PGC-1a1 in muscle were not affected. In fact, these animals never show elevated kynurenine levels in their blood since the KAT enzymes in their well-trained muscles quickly convert it to kynurenic acid, resulting in a protective mechanism.

Skeletal muscle appears to have a detoxification effect that, when activated, can protect the brain from insults and related mental illness. Depression is a common psychiatric disorder worldwide. The World Health Organization (WHO) estimates that more than 350 million people are affected.



Dr. Keith & Laurie Nemec’s comments on “Physical exercise protects the brain from stress-induced depression”:

What an interesting study. Exercise acts like a detoxification organ similar to the liver or the kidneys in getting rid of waste products that would circulate to the brain and cause depression.


The mechanism is through an enzyme that is produced by the muscle when it is activated and that enzyme (KAT) converts brain toxic kynurenine to kynurenic acid which cannot pass the blood brain barrier thus the brain is protected. Also it was very interesting that there are high levels of kynurenine in mental patients.

What is the bottom line?

When you exercise the way you were designed by God to exercise,

When you eat what you were designed by God to eat,

When you drink the amount of water you were designed by God to drink,

When you go to sleep at the time you were designed by God to sleep and

When you live a life of prayer (listening to God speak to your heart) and

Fasting (a permanent Daniel fast of living/raw plant food)

Then the diseases that plague the world would by no more!

Rather than reaching for a medication or even a vitamin pill, why not try getting back to the BASICS you were created to do?

As we have told patients at Total Health Institute over the last 30 years. If you feel stressed then your body secretes stress hormones that have two major negative results:

  1. Stress hormones decrease your immune system function- they suppress your body’s ability to fight bacteria, viruses, parasites, fungi and cancer.
  2. Stress hormones break down your intestinal lining and cause “Leaky Gut Syndrome” which leads to inflammation throughout the body and also leads to malabsorption of nutrients so you become deficient even if you are overweight.

Remember if see a tiger coming towards you your body will secrete stress hormones that can cause damage to your body if they are secreted much longer than 15 minutes. So what do you do? You run! Or to put it another way you exercise to burn up these stress chemicals that you secrete from daily mental and emotional stresses.

You can swim, run, bike, do weight training or go up and down your stairs but you must exercise when you are feeling stressed because this will  protect your body and your brain.

To Your Total Health Always,

Dr. Keith & Laurie Nemec