The body and mind react to stress. Were as stress can be anything from a person yelling at you up to a life threatning situation were a gun is placed into your face. An indication on how the stressful situation is influencing you can be seen by monitoring your heart rate. 

 

A high heart rate by itself as in running, isn't enough to simulate the stress the body and mind undergoes. The surge of adrenalin can litteraly sweep your mind away.

 

Studies have shown that heart rates can be classfied into three groups:

 

    Fine motor skills:  up to around 120 bpm (beats pr. min) were it starts to fall at 110bpm

    Complex motor skills: up to around 175 bpm, were it starts to fall at 135 bpm

    Gross motor skills: can be held to max bpm

 

The body increases the production of adrenalin, which increases the blood flow to the extremities and in the end encreasing strenght, but will in the end interfere with the fine motor skills.

 

All is not lost, in the sense that only gross motor skills can work at high levels of stress. By utillizing scenario training, to understand, cope and learn how selfdefence situations will influence you, you'll become more familiar  and be able to push the limit of when fine and complex motorskills will cease to function.