At least in the academic environment a lot of people are aware that, by exercising, they can then concentrate at a task for longer (hours instead of half-hour) and tackle harder problems.
That biological research could not figure out and test such simple truth until now does not mean it was not a widely adopted working hypothesis for a very long time.
What I would like to see is how are mental abilities affected by sporting conditions, for example a dull TV-ruled noisy gym with threadmills versus a soccer game in a sports field outdoors, and mindless, reflect-oriented sports such as Squash versus brainy, strategy-oriented sports such as team-sports or golf.
The difference is growing new neurons. Adult neurogenesis was always thought to be very limited (e.g., the myth about "killing" brain cells). Now we know it's much more common than ever thought.
That biological research could not figure out and test such simple truth until now does not mean it was not a widely adopted working hypothesis for a very long time.
What I would like to see is how are mental abilities affected by sporting conditions, for example a dull TV-ruled noisy gym with threadmills versus a soccer game in a sports field outdoors, and mindless, reflect-oriented sports such as Squash versus brainy, strategy-oriented sports such as team-sports or golf.