The Dose Makes The Poison

This is a principle of Mediterranean Wellness. That is, a little of some food may be good for you, but a ton of it is definitely not! 

A glass of wine may be good for your heart, but a bottle a day will turn your liver into a brick. You need sugar in your body to survive, but too much drives obesity, diabetes, and all the rest. Even water: you have to have it to be hydrated, but too much will give you a potentially life-threatening condition called hyponatremia.  

But is this principle also true for exercise?

In other words, as you get more and more and more exercise, could it become less and less good for your body?

New research out of the Swedish School of Sport and Health Sciences in Stockholm suggests the guy who came up with that maxim (Paracelsus, the Father of Toxicology) was even correct about exercise! You can read about Paracelsus here when you are totally out of other things to do in your day. 

I’m not sure who signed up for this study, but they were assigned to do 3 full weeks of strenuous exercise that got harder and harder over time. Even worse, the scientists had to snip out a piece of their muscle (a muscle biopsy) each week, to do tests on. It sounds awful (here’s the study reference for the oddly curious: Cell Metab. (2021))

In any case, the subjects’ performance did get better when the intensity progressed from LOW to MEDIUM strength, when it ramped up to the intensive strength, the subjects’ performance stopped improving.    

Remember those weekly muscle biopsies? They revealed that the energy-producing cells of the muscle did initially increase with exercise intensity. This finding matches the fact that the subjects improved their performance at first. But also like the performance, those same energy producing cells dropped drastically with vigorous training just like performance did.

But what about super endurance athletes? 

In the original study with non-athletes, they found that that drop in energy production happened right along with a lower ability to process the glucose in a glass of sugar water. 

After getting these results, the wanted to know if they’d see the same thing for super endurance athletes versus non-athletes. So they studied a separate group of 15 professional endurance athletes versus 12 non-athletes. They found that the average blood-sugar levels were nearly identical.

BUT, the professionals experienced longer periods of high and low blood sugar than the non-athletes. Blood sugar control was actually worse.

In other words, even for those who have already trained their body to run amazing lengths and times, there are metabolic consequences. In this case, their body has a harder time regulating blood sugar. 

What’s The Bottom Line?

Daily exercise is a great thing for your body. But pushing your body harder and harder can have diminishing returns (experiment 1). And even for long term training, highly intensive exercise can blunt your body’s ability to regulate blood sugar. 

Exercise, like wine, and water, and chocolate, and cheese, and sugar and everything else in the world is neither good for you nor bad for you until you make it that way.  Paracelsus was spot on: the dose makes the poison.

So control consumption, because moderation in all things will give you the best chance for optimal health.