A university academic conducted a series of physical and psychological tests to determine whether playing on computers could be defined as a sport.
Top gamers can earn tens of thousands of pounds a year in prize money and sponsorship but academics have warned the cost to their health could be devastating.
Dr Dominic Micklewright, from the University of Essex, put several ''elite cyber-sportsmen'' through their paces to see how they compared to professional athletes.
The head of Sport, Performance, and Fatigue Research Unit also wanted to determine whether video gaming should be classed as a sport.
The cyber-sportsmen had mental sharpness and psychological traits comparable to 'real' athletes, and reacted to visual stimuli almost as fast as fighter jet pilots.
But their fitness levels were shockingly low and comparable to people either much younger or much older than their actual age.
One leading gamer in his twenties appeared to be slim and healthy with a physique similar to an endurance athlete.
But tests revealed he in fact had the lung function and aerobic fitness of a heavy smoker in his sixties.
Dr Micklewright blamed the gaming lifestyle of spending 10 hours a day in front a computer screen and warned youngsters against such a sedentary lifestyle.
He said: ''Someone of this age should be much fitter, but perhaps this is the occupational hazard of the professional gamer who can spend around 10 hours a day in front of a screen.
''It is always difficult to say how these things will develop, but it could have long term health implications such as an increased risk of heart disease.
''Screen time with children has a very strong correlation with childhood obesity and risk factors with heart disease later in life.''
But Dr Micklewright was equally surprised by the number of characteristics gamers did share with top athletes.
He said: ''Their reaction time, motor skill, competitiveness and emotions were pretty close.
http://www.telegraph.co.uk/technology/video-games/7808860/Computer-gamers-have-reactions-of-pilots-but-bodies-of-chain-smokers.html