I was thinking about the point made that running beats up the body more and the bike is a more efficient form of expending energy. I have a different perspective.
Running does not "beat up the body". It's a more high resistance/impact form of exercise that will strengthen ligament and bone (a good thing). You have to have a basic level of fitness to support that higher impact but, once there, the stress is a benefit, not a detriment.
Cycling has a lower impact which means one can actually lose bone density while doing it. One can do it longer because one is not stressing the body as much. It also has a lower entry point in terms of fitness requirement to begin (a good thing) which is why many people prefer cycling to running. You can be less fit and still do it.
To get an equivalent level of short duration workout than trail running I ride uphill mtb trails, usually 2-4 km's of sustained climbing. This is a pretty good cardio workout and the ride down also works upper body/core/agility/stress loading/resistance.
Last edited by Happy Feet; 09-29-21 at 08:38 AM.