Why is it that running is seemingly “short” and limited compared to the other disciplines? IOW why is it that you can seem to continually add onto cycling and swimming well beyond that of teh disatnce of the race but so many people reccommend against doing that for the run?
My main question is why would the body not adapt to the rigors of running 20+ miles eventually? Certainly it may not be the most ideal situation for IM training but if one were strictly training for running or ultra running wouldn’t one be able to eventually adapt to 25-30+ mile runs as a regular workout? And if you could for Ultra, why not for IM?
Weight bearing exercise is just harder on the body than other kinds of exercise. Lots of pounding on the bones and joints.
5-6 hour training days in the pool really aren’t that physically hard on you if you’re reasonably fit. Seems like the same is true for cycling. But for most people, 5-6 hours of running results in too much pounding and is going to lead to injuries really really quick.
You can train to the point where you can run a lot of miles and still recover. How do you think elite runners can run 160 miles per week? I even made it to the point where I once ran 15 miles on a Wednesday and 24 the next day as part of a 70 mile week. The body does adapt, but when I did it I was riding five hours a week on the indoor bike. Once your bike time reaches a decent proportion to run time (for me about 2/1) then it just becomes harder to recover. The buildup to a lot of run miles needs to be the work of year, but most people only have the patience for months or even weeks. Thus they become injured by forcing the body to attemp to adapt too quickly. Very efficient runners can also increase more quickly. If you are overweight then it needs to be a very conservative process. Running is limited by the pounding on the joints, bones, little micro-tears in the muscle. Cycling tends to be limited by only your
I have found that for me a lot of run miles is not key to triathlon performance. Reasonable run miles (40-60) and more time on the bike made me faster. I do run my long run on Friday and do the long ride on Saturday (no Sunday training), and after a few months of that you can adapt as well.
So wouldn’t it be a beneficial thing to “slowly build” up to that mileage and be able to handle a 24 mile run without undo or overly taxing fatigue so you can work a regular 24 miler into your IM training plan without issue? Or are even the elite IM guy’s hitting the wall of human endurance and simply can’t get a 24 miler in and necessary bike mileage?
Certainly I’m not talking about us mere mortals as the benefits fo a 24 vs a 20 miler are far outweighed by the risk. But at some level you’d think a 24 miler woudl be appropriate, they seem to be for elite marathoners.