As seen in Night Stick the official publication for New Hampshire Police Association (Volume 77 Spring 2012 edition)
As your brain is your most important weapon, the effects of physical stress is often underappreciated for its effects on cognition for those who go into harms way, such military personnel, law enforcement, and other groups.
It’s been a generally held belief that cerebral blood flow (CBF) remains relatively steady during exercise, but recent studies (1,2) suggest that’s not the case. CBF appears to depend on a multitude of factors, including exercise intensity. With lower intensity steady state forms of exercise – all things being equal, such as hydration, etc, – CBF may increase, but during high intensity intermittent forms of exercise (like wrestling with another human being in a life or death struggle for example), appears to decrease. This may partially explain the cognitive decline people experience during high intensity exercise.