Scientist have know for some time that exercise can affect one's brain in positive ways. Trends in Neuroscience reports that "exercise increases synaptic plasticity by directly affecting synaptic structure and potentiating synaptic strength, and by strengthening the underlying systems that support plasticity including neurogenesis, metabolism and vascular function."
A study released today by Pediatrics, a medical journal, documents cases of ADHD children improving their attention span as a result of exercising. Here's the study. This article in The Atlantic has an excellent electrophysiological graph of brains with and without exercise.
The New York Times reported on several findings that highlight the benefit of exercising in enhancing information recall from our memory.
What does all this mean for instructional technologists? It's certainly beneficial to keep in mind the positive effects of exercise on learners' abilities. Suggestive breaks and exercise recommendations might be warranted in materials that are lengthy and challenging.