It's amazing how many teenagers have the ability to "turn on and off their adrenaline"-must be the hormones.
Why do I want to control the adrenaline? Well here are a couple of reasons:
1. The heart rate is an indictor of stress level as the heart rate increases from stress chemicals certain physical, mental and perceptual changes can occur.
Beats per Minute
115-Reduction in the ability to perform fine motor skills
145-Reduction of the ability to perform complex motor skills-like joint locks and take downs
170-Tunnel vision, auditory exclusion, things going into slow motion start to occur-gross motor skills get stronger
above 170 you get a shift from the forebrain where all your logic and learning is stored to the mid-brain what some refer to as the survival brain, mammallian brain, reptilian brain etc. Your ability to cognitively process falls through the floor. You can have a complete mental melt down-fight, flight or freeze.
By controlling the breathing as already suggested-inhale through the nose using the abdomen for a slow 4 count
-hold for 4
-exhale through the mouth for 4
-hold for 4
-repeat 4 times
This reduces the heart beat and attempts to keep you perceptually unimpaired, cognitivley processing the situation, at your peak heart rate range 140bpm for physical performance.
The technique is taught to the military, police, etc. and in numerous studies has shown to be benefitial.