Thanks to Conditioning Research for finding this one.
A study was done on Tae Kwon Do practitioners that showed that sparring (essentially, live fighting practice) increased cortisol levels. Cortisol is a stress hormone that is generated by exercise. So far, so good.
The study further showed that sparring - 3 fights, 6 minutes each, 30 minutes between fights - lowered anabolic hormones (hormones that encourage muscle growth) in the fighters, and further lowered testosterone in males (but not females).
This isn't surprising. When you train, you increase the stress levels on your body. That's the point of training - you put stress on your body and it super-compensates and becomes stronger, better adapted, able to go longer or work harder.
Nicely they uses "elite" athletes - presumably actual competitors? And not just untrained people. So these folks should have been used to the stress of contact fighting.
My main questions here would be:
- What exactly did the fights involve? How much contact, how much force, how much protection? I'd say, odds-on, that the more contact the more stress. However, [i]any[/i] contact is going to ramp up the stress level, even if it's just light contact sparring. Why? Contact is contact, and risk of injury should put anyone into a slightly-higher stress level even if they've gotten to the point of considering routine.
- Was this an acute reaction only? Meaning, did they suffer a catabolic reaction immediately, but then later did it level off or taper off, or indeed result in an anabolic (muscle-building) reaction?
- A great study would be to do this on wrestlers and BJJ stylists and judoka - sports were all of your practice involves some contact. Does the stress level go up as the intensity goes up? Is live sparring always catabolic, or is that an acute response (meaning it happens immediately) that leads to a long-term anabolic effect? Hard to say, but if so it might explain why martial arts gets you a bit strong but despite all that hard grappling and pulling and straining, it's hard to get truly strong just on the mats or in the ring. You need higher-intensity exercise but presumably with less overall time and less psychological stress.
- Finally, if martial arts sparring is catabolic, what do we do about it? Post-sparring, should you act as if you just did a heavy weight training workout, which also increases your cortisol initially? If so, post-sparring you'd want to drink protein and simple, fast-digesting carbohydrates (i.e. sugar) and use any usual post-workout means to reverse that catabolic (tissue-burning) reaction and switch it back to an anabolic (tissue-building) reaction.
I'm very interested in the results of this study.