Book Review: Your Brain on Exercise

The gist of the book is – the way human beings evolved means that doing excessive exercise does more harm than good, and while doing aerobic exercise improves the cardiovascular health, and doing weight lifting improves the muscles and bones, there are no good correlations between exercise and brain health specifically.

What's really interesting was to know that brain specifically, and every other organ in the body generally, gets damaged by free radicals (Reactive Oxygen Species in the book). And while ROS are generated all the time in the body, their numbers go up with excessive exercise:

  1. We burn more Oxygen while exercising,
  2. Post-exercise we tend to eat more, sometimes to the tune of ~1000 extra calories, and burning this excess food burns more Oxygen.

The author argues that while excessive exercising doesn't make you sharp, being obese definitely makes your brain dull. And keeping fat away from the body can be achieved by moderate levels of exercise, moving more, and eating less.

How this compares to Outlive?

At the outset, the author called out that the studies correlating brain health with exercise suffer from biases. And the devil is in the details. Currently the culture is very much behind the idea that doing a ton of exercise makes us healthy. Couldn't this book be considered another meta-research which goes against the culture; couldn't it have it's own biases? I'm not sure.

Recently I finished Outlive (1)Attia, P. (2023). Outlive: The Science and Art of Longevity. , where Dr. Attia also supports having a good active lifestyle. His definition of active is slightly different though. Having suffered a lot of injuries by doing excessive sports like biking, swimming, weight lifting, in the book he recommends exercising in moderation.

While both the authors say that the literature is inconclusive, they still say it's inconclusive about different things. In Outlive, Dr. Attia says we can't really say anything for sure when it comes to diet, but exercise still is supposed to have a very tight positive correlation with healthspan. This book, on the other hand, says that the medical literature is, either inconclusive for exercise, or, at best, concludes that excessive exercise is bad.

Where both of these books have an overlap is the Zone-2 training. For cardiovascular exercise, Outlive suggests to do a majority of it in Zone2, and only once a week 30 mins of Zone4 (sprinting, biking, rowing). The moderation that this book defines is either walking in the woods, or exercising till point amel where you can talk but not sing.

Another interesting callout of this book is the fact that once you've got medical conditions like Alzheimer's or Parkinsons, starting exercise won't help you. This notion is also supported in Outlive where exercise is like a retirement account, and any additional muscle and VO2Max that you add helps during the retirement.

The points where these books diverge is that in this book ROS (and Oxygen) are seen as entirely evil entities. Having extra muscles is also going to burn more oxygen, and therefore produce more free radicals, and therefore cause more harm than good. Humans can live upto 117, but since we burn oxygen in our body, we die much early instead. But Outlive shows a positive correlation between VO2Max (the Oxygen that we burn at a maximum degree) and healthspan in the later decades of life (there was an old gentleman who improved his biking times in his eighties).

This book was a pretty nice read, and the fact that this comes from a neuroscientist means that he knows what he's talking about. It also has some sane overlaps with Outlive (although not too much of an overlap with The Comfort Crisis). Does that mean that I can take it a bit easy with my exercise routine? Maybe!