for the last couple of days, I've been trying to make up my mind about whether altitude training is beneficial for sea-level performance or not. I have dug up a ton of old threads, so don't forward me to those. I also am tired of reading inconclusive studies. just tell me this: does anyone have any sorts of facts or figures which reflect how many successful runners (at sea level) train at altitude always or regularly? I know there are a bunch of variables, but I don't want to lose my mind trying to think of all of them. let's keep it simple.