From all we know about health and fitness we believe that the answer very much depends on what sort of competition and how we mentally and physically prepare / react to it. Depending on the psychological and physiological impacts of such competition we can either be doing damage or helping our own survival.
If we mentally and physically prepare for the competition and also allow ourselves to 'wind down' after then the impacts can be positive. It encourages mental clarity and focus on a goal (whether that's a literal goal or a different type of target like a promotion) which has been shown to improve performance. Improvement in performance comes along with a short term improvement in mental and physical fitness.
The difficulty is when the competition becomes chronic and 'too intense'. Chronic competition has similar problems to chronic stress. Our bodies would've evolved to survive short bouts of competition - running away from a wild animal, hunting to catch one, fights within a group etc... But, and it's a big one, when we expose ourselves to competition that has no end, no realistic goal in sight we build our mind and bodies up to an event that just doesn't come. We increase stress levels chronically over a period of time, which we've discussed many times and this isn't healthy. Intense competition (truly intense competition) can have detrimental effects too. High levels of stress over a shorter period of time is probably more like our evolution but at the same time if this competition is too intense it can cause a response in our bodies that is too intense to be classed as healthy. It can lead to acute health problems - injuries, stroke, heart problems - that are all bad for us.
We hope today we've given you some good reasons to go away and engage is competition, but also the knowledge that you need to control the intensity, exposure and end of the competition in order to get he health benefits without the negative impacts.