This is a longform piece from the Canadian magazine The Walrus, by Alex Hutchinson, who blogs about exercise/performance and science at his very interesting Sweat Science.
The main topic of discussion is the brain's role in regulating the body during exertion. It's not clear at the point in time how or where in the brain this happens, but there's been some provocative research in the field.
How does this apply to horses? There is a comparison of horse racing to human racing in the article, but beyond that, there's the broader context of what eventers ask their horses to do, both in training and in competition. By understanding limits, fatigue and the role played by competition (even in training), maybe we'll come up with some new ideas on how to work with our horses.
The linked piece is also a very enjoyable read.
Note: I post articles like this one, and last week's post on hydration, because reading about exercise physiology has given me a lot of insight into horse and human fitness, and how to optimize my efforts. Magazine articles, while not double-blind controlled studies in peer-reviewed academic journals, often provide citations from studies of that variety, and thus can be an excellent springboard for learning more, either by accessing those studies or by contacting the people who do the research.