Real Or Simulated Combat May Cause Stress - Better For You Than You Think?

Kata and particularly kumite are not just physically demanding, they can be emotionally stressful since both are forms of simulated combat. Well what effect does this have on us? A 2012 paper published in Sports Science Health by Benedini et al found increases in glucose, epinephrine (adrenaline) and norepinephrine (noradrenaline) after 3 minutes of kata or kumite activity in elite karateka, with the greatest difference found following kumite.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3573715/

What is interesting about this is that firstly, it demonstrates the fast physiological changes that humans can display to appropriate mental and physical stress and that secondly, this is likely to be mediated by the sympathetic nervous system rather than hormonal systems. The levels of insulin and cortisol did not change over this time scale. The effects of this would be predicted to liberate glucose from liver glycogen for our muscles and brain to use. It would also stimulate the production of lactate from muscles which can be used by the liver to generate glucose by a separate pathway. This all makes perfect sense as a fast way for our nervous system to push out glucose to fuel a fight. However, the effects of these two neurotransmitters over a longer term on fat, muscle and other tissues, let alone their overall effect on metabolism is complex and unclear. It has been proposed that alterations in the sympathetic nervous system may predispose to metabolic disturbances such as types 2 diabetes and obesity and it is also known that exercise has a very beneficial effect on glycaemic (glucose) control in people with diabetes. Contrary to the conclusion of the authors that such activity may need to be avoided in 'dysmetabolic individuals', I suspect it may be more beneficial than most forms of exercise. See the review below if you have the strength.

http://link.springer.com/article/10.1007%2Fs001250051341

One of the things missing from Western life is real physical stress that you can physically respond to - really put the fight-or-flight response into action. We do have an abundance of other stress - stressful jobs, frustrating traffic queues, people we can't control who control us etc. etc. Their is no physiological outlet for this and it is widely acknowledged that this is generally bad for us. Perhaps stress you can respond to is less bad, or even good? I'm not aware of any definitive medical evidence for this yet, but there are interesting articles appearing.