Eccentric training is pretty standard fitness protocol. When you're working out on weights (including gym machines), they always tell you to lift the weight slowly and (important) to let it down slowly as well - that's the eccentric part of the cycle.

You might have noticed hiking downhill can be hard on the knees, especially if you have a heavy load (like on a steep downhill portage). That's because you're forcing your quads to work eccentrically when they haven't been trained for it. Working extra-hard on concentric contraction (normal cycling, uphill hiking) really isn't a substitute.