EPO and HGH will provide a huge advantage in triathlon. Anabolic steroids could be of some benefit to swimming performance. In a study of ~3000 amateur triathletes in Germany, 13% admitted to doping. 15% admitted to taking banned cognitive enhancers like modafinil.

http://www.irishtriathlon.com/wp-content/uploads/2014/01/iro...

doping is ALWAYS userful, doping allows the biggest advantage you can have: you can train more at higher intensities because your recovery is a lot quicker and you get injured less.

This of course also helps with the narrative of "I won because I trained super hard", some people are genetically blessed to be able to absorb large training volumes without getting injured or burning out, for the others there are plenty of things one can use to achieve similar effects

This is also why unfortunately some coaches seem to go through athletes quite a bit until they find some that can take the workload, and focus on those, not so good though for the ones that ended up getting injured and out of the sport though.

I do think the news tend to portray doping too much as "race day doping" when the biggest gains are made in the offseason, and this is why there are rules like offseason testing where athletes have to inform the anti-doping agencies where they are at all times, and why it raises a lot of questions when some countries don't seem to have effective offseason anti-doping controls.

Not as useful as in professional cycling but its still an endurance sport and, of course, the recovery benefits etc. etc.