Running up hills burns energy but if we run hills conservatively fully aware of how far we still need to go and the nature of the hills to come. The steeper the hill the easier we need to ascend it. The length of the hill does not matter as the steepness of the hill. The first hill you run up, be it in a warm-up you need to respect. Once you have run up the first hill slowly and your legs have warmed up properly then you can run the next hill with a little more vigour. Running downhills on the other hand use very little energy but can damage your legs for later on in the run or race if not run correctly.
Posted In: Hills