Let me take a stab at translating. "Executive function" is a catch-all term for mental skills that are required for complex behavior. This includes things like

Let me take a stab at translating. "Executive function" is a catch-all term for mental skills that are required for complex behavior. This includes things like working memory, selective attention, cognitive flexibility, and response inhibition. Toddlers have terrible executive function: they get distracted constantly and can't help themselves not do something. The stereotypical cool, collected NASA Mission Controller has great executive function: they identify and remember important details, juggle multiple tasks, etc. A number of brain diseases impair executive function, so we'd like to find ways to restore or improve it. Exercise seems to help, but why? One hypothesis is that exercise literally gets the blood moving in the brain, and thereby changes neural function. Exercise does a lot of other things too though, by increasing metabolic demands, ventilation, and the like. In this experiment, they try to dissociate the effects of exercise generally and improved cerebral blood flow by comparing three conditions: a) Active Exercise - pedal a stationary bike like at the gym b) Passive Exercise - a motor moves the pedals--and thus your legs--for you without you doing much work c) Control - do nothing. In the first part of the paper, they show that the Passive Exercise does increase cerebral blood flow, but doesn't engage the muscles or make you breathe hard. Thus, comparing the three conditions is a good way to isolate the role of cerebral blood flow. If muscle activation or metabolic demands mattered, you'd expect only the active condition to show an effect, but if exercise were totally ineffective, you'd expect all three to be similar. Next, they ask how these conditions affect executive function. There are lots of ways to test executive function, but here they use an eye movement task. The participant looks straight ahead, and is then shown a dot to the left (or right) of their gaze. They need to make an eye movement ("saccade") in the opposite direction ("anti"); that is they need to look away from the cue. This is unnatural--you need to inhibit your natural instinct to look at the new thing--and so subjects with impaired executive function are slower and more error-prone on the task. This paradigm has been studied a lot (my group uses it to look at Parkinson's disease and how various treatments affect it) and is nice because it's fairly standardized. They find that participants make anti-saccades faster after both forms of exercise vs. the control condition, though the effect of real Active Exercise is bigger. Thus, they conclude that increasing cerebral blood flow improves executive function, and that passive exercise may be one way to do so. As with most papers, it's one more piece of evidence, rather than a complete and final story, but it's kind of neat.