Originally Posted by
wphamilton
You're in a BF thread that asks what the difference is in training adaptations for the heart. If most people here find running painful at any pace, they probably aren't right that there's no difference because "all out is the same".
If you want to know what *my* point is, go back to my first post. It's what everyone is arguing with, and I haven't said "it is harder on the body" because I don't necessarily believe that, if you're talking about injuries. More stress yes, which produces different training adaptations. That's what this thread is about.
I suppose I simply disagree with you that an intense interval on the bike is somehow less stressful on the heart than running. Your only evidence seems to be that running all-out for one minute feels harder for you than cycling all-out for a minute.
The reason running is often touted as being more efficient (better bang for your buck) is that the floor of intensity for running is higher than cycling. I've not seen any evidence that running at high intensity is more stressful on the cardiovascular system than cycling at the same intensity. Personally, a 5k running race doesn't feel any harder on the heart and lungs than a short TT on a bike. Lots of other parts hurt when running as the stress on ligaments and tendons is much higher than in cycling but that's not what this thread is about.