Eh, there's no comparison. Playing most sports at a high level requires a massive amount of strength training and maintenance work just to keep your body functioning. I don't play darts, but from a purely physical aspect there is so much less potential for injury and less need to stay in superb physical condition across the entire body. Elite level athletes need to do everything from flexibility work, daily massage / myofascial release to promote blood flow and break up scar tissue, strengthen vulnerable areas like the neck to protect against concussions, careful nutrition, etc. If you don't train and do the work that accompanies training, you won't make it through half a season.