Have a question or a request? We love to hear from you!

In cases where we’ve already covered something, we might link to what we wrote before, but will always be happy to revisit any of our topics again in the future too—there’s always more to say!

As ever: if the question/request can be answered briefly, we’ll do it here in our Q&A Thursday edition. If not, we’ll make a main feature of it shortly afterwards!

So, no question/request too big or small 😎

❝Why do I get tired much more quickly running outside, than I do on the treadmill? Every time I get worn out quickly but at home I can go for much longer!❞

Short answer: the reason is Newton’s laws of motion.

In other words: on a treadmill, you need only maintain your position in space relative the the Earth while the treadmill moves beneath you, whereas on the road, you need to push against the Earth with sufficient force to move it relative to your body.

Illustrative thought experiment to make that clearer: if you were to stand on a treadmill with roller skates, and hold onto the bar with even just one finger, you would maintain your speed as far as the treadmill’s computer is concerned—whereas to maintain your speed on a flat road, you’d still need to push with your back foot every few yards or so.

More interesting answer: it’s a qualitatively different exercise (i.e. not just quantitively different). This is because of all that pushing you’re having to do on the road, while on a treadmill, the only pushing you have to do is just enough to counteract gravity (i.e. to keep you upright).

As such, both forms of running are a cardio exercise (because simply moving your legs quickly, even without having to apply much force, is still something that requires oxygenated blood feeding the muscles), but road-running adds an extra element of resistance exercise for the muscles of your lower body. Thus, road-running will enable you to build-maintain muscle much more than treadmill-running will.

Some extra things to bear in mind, however:

1) You can increase the resistance work for either form of running, by adding weight (such as by wearing a weight vest):

Weight Vests Against Osteoporosis: Do They Really Build Bone?

…and while road-running will still be the superior form of resistance work (for the reasons we outlined above), adding a weight vest will still be improving your stabilization muscles, just as it would if you were standing still while holding the weight up.

2) Stationary cycling does not have the same physics differences as stationary running. By this we mean: an exercise bike will require your muscles to do just as much pushing as they would on a road. This makes stationary cycling an excellent choice for high intensity resistance training (HIRT):

HIIT, But Make It HIRT

3) The best form of exercise is the one that you will actually do. Thus, when it’s raining sidewise outside, a treadmill inside will get exercise done better than no running at all. Similarly, a treadmill exercise session takes a lot less preparation (“switch it on”) than a running session outside (“get dressed appropriately for the weather, apply sunscreen if necessary, remember to bring water, etc etc”), and thus is also much more likely to actually occur. The ability to stop whenever one wants is also a reassuring factor that makes one much more likely to start. See for example:

How To Do HIIT (Without Wrecking Your Body)

Take care!