Our expert says:

FitnessDoc

Hi Kitty

If you do them at the SAME intensity, then they are the same. It's a bit like asking whether a kilogram of feathers weighs more or less than a kilogram of rocks!! And I don't mean to be funny about it, but it's important to realise that on average, people who are untrained tend to exercise at the same relative intensity regardless of the activity. However, in general, running will burn more calories because it uses more muscles. And that means more energy gets burned running at a given speed compared to cycling at a power output that is similar. But here's the crux - some people just cannot run, others cannot cycle. I know people who, if you asked them, would be unable to cycle for 20 minutes. In that case, they should not try to cycle. Others can't run. So it's irrelevant whether running burns more to these people - they can't run, and that's all that matters. So it's really important that you don't get caught in a numbers game, and instead, you just do whatever you can do and enjoy doing. So honestly, and trust me on this one, forget about the "best one" - there is no such thing, it's a theoretical concept.

Good luck