A 2006 Jason Polan cartoon from The New Yorker features two gerbils in conversation. In the background is one of those wire wheels you find in hamster/gerbil cages, and one of the two gerbils is saying with maybe a little more self-satisfaction than is warranted, "I usually do two hours of cardio and then four more of cardio and then two more of cardio." (You can see the cartoon, and obtain a copy of it in various forms, at The Cartoon Bank.)

It turns out that maybe the smug little creature was onto something after all (from "Lobes of Steel" in Play, The New York Times's "sports magazine"):

The Morris water maze is the rodent equivalent of an I.Q. test: mice are placed in a tank filled with water dyed an opaque color. Beneath a small area of the surface is a platform, which the mice can’t see. Despite what you’ve heard about rodents and sinking ships, mice hate water; those that blunder upon the platform climb onto it immediately. Scientists have long agreed that a mouse’s spatial memory can be inferred by how quickly the animal finds its way in subsequent dunkings. A “smart” mouse remembers the platform and swims right to it.

In the late 1990s, one group of mice at the Salk Institute for Biological Studies, near San Diego, blew away the others in the Morris maze. The difference between the smart mice and those that floundered? Exercise. The brainy mice had running wheels in their cages, and the others didn’t.

Oh, well, that's mice, you say. People are a lot different, right? Er, not necessarily:

[Scientists] have been finding more evidence that the human brain is not only capable of renewing itself but that exercise speeds the process.
[...]
This spring, neuroscientists at Columbia University in New York City published a study in which a group of men and women, ranging in age from 21 to 45, began working out for one hour four times a week. After 12 weeks, the test subjects, predictably, became more fit. Their VO2 max, the standard measure of how much oxygen a person takes in while exercising, rose significantly.

But something else happened as a result of all those workouts: blood flowed at a much higher volume to a part of the brain responsible for neurogenesis. Functional M.R.I.’s showed that a portion of each person’s hippocampus received almost twice the blood volume as it did before. Scientists suspect that the blood pumping into that part of the brain was helping to produce fresh neurons.

The article doesn't address research (if there has been any) on the effects of exercise in the TBI-afflicted. But it doesn't seem like much of a stretch (no pun intended) to imagine that working out can help, and perhaps help a lot. (We've seen this with Jack himself, who had dropped tennis for a while but has recently gotten back into it -- as TLS mentioned in a post back in July.)

Labels: brain growth, exercise, fitness, TBI