Okay letsrun, seeking some help here.
I've been a competitive runner for over 20 years. I've never been out of shape and I've stayed very constant in my training, fitness-level, lifestyle, etc. throughout that time. Nothing special, just a steady 70 miles a week avg., consistent in workouts, long runs, core work, etc.
The other constant over all of those years is the fact that I get a deep side cramp on my right side after about 20-25 minutes of intense hard steady running/racing, etc. It's almost predictable. If I do fartlek or reps with any kind of short break of backing off of pace then I can hold it off, but racing 8k-10k all out generally almost brings it on, but never a 5k. But backing off just a bit even to say a 1/2 marathon pace can hold it off as well with no real problems. I don't know if the pace matters, but for 8k-10k we're talking 5:00 miles, for a 1/2 5:15-5:20.
I've tried about everything, different breathing patterns, changing stride-length going around turns/corners, etc.
Not sure it matters that I'm a taller runner or the impacts of the stress on the muscles, etc. compared to someone else more compact and shorter with less pounding and more effective leg turnover.
Thanks for any advice.