Exercise is good for you. You've heard that before, but probably not the way John J. Ratey, M.D. says it. According to him (and the many studies he cites), it's good for everything that ails your brain as well as your heart.

Dr. Ratey begins his tale of exercise's virtues with Naperville, Illinois School Distritct 203 and its "New PE." A revolutionary phys ed teacher named Phil Lawler decided to teach the kids something they could use for life: how to be physically fit. Instead of grading on performance and skill, he decided to grade the kids on their effort. If they work hard enough to keep their hearts in aerobic training range (70-80% of maximum heart rate), they get good grades.

What's most remarkable about the new PE is its correlation with test scores. Naperville consistently ranks among Illinois' top 10 school districts even though it not among the top spenders per pupil. What's more, struggling students who participate in gym before school raise their grades significantly.

It turns out exercise is good for learning. Why would this be? Because our biology evolved for the life of the hunter-gatherer, so now "the relationship between food, physical activity, and learning is hardwired into the brain's circuitry." Exercise also improves responses to stress, which is actually a necessary thing, in the right amount. It's like lifting weights for the brain. "Neurons get broken down and built up just like muscles — stressing them makes them more resilient."

In addition to learning and stress, Dr. Ratey has chapters on exercise's effects on anxiety, depression, ADHD, addiction, hormonal changes, and aging. He goes into a fair amount of detail about the structure, chemicals, and processes that make our brains tick, but don't expect to feel like you are sitting in biology class. Dr. Ratey and his coauthor Eric Hagerman adopt a conversational style that is easy to read and has momentum.

What stands out about this book is that it makes you want to start moving. Right now. A little preachy, a little reductionistic (exercise as cure-all), it is nevertheless effective. After just three chapters, I had to know: how much exercise do I need to get all these benefits? So, I skipped to the last chapter to find out.

I'm really glad I went back and read the rest, because it is interesting. I didn't always pay strict attention to the science — I figured I can look it up later if I need to know it. Plus the book includes a glossary for easy reference.

Spark is a great title, but it might have been called Run or Move, because that is its aim. In the chapter on aging, Dr. Ratey says, "My hope is that if you understand how exercise can also protect your mind, you'll take it to heart." I think he might just achieve his goal.