I thought it was because you were actually doing "skipping" thinking it was "bounding"??? Just kidding; just giving you a hard time.

Didn't you say you actually had trouble downhill? Or did I misunderstand it?

Again, when people say, "Lydiard's schedule calls for 3 hill training days a week plus sprint work in between. If I do it that much, I'd break down." My advice would be; "then don't do it!" Still it would be interesting to get down on your issue and analyze why you'd have trouble doing hill exercises... Would you have been strong enough to handle them if you started them, say, 30 years ago? Or are you just structurely not suited for hill bounding? Or if you have some sort of muscle issue... Or simply doing them wrongly!?