Treadmill vs pavement running

A long time ago in a galaxy far far away (ok maybe not) I joined a gym....*waiting for applause* :-) At this gym, my favourite cardio machine was the treadmill. One day when walking on said treadmill, I realised that instead of listening to music I didn't like and breathing in recycled smelly air I could be outside with the birds and sunshine (and sunscreen) walking my dog, who gave me sad puppy eyes each time I left her to walk on said treadmill. So I didn't renew my membership.

Shortly thereafter I discovered one of the great disadvantages of not using a treadmill. At the peak of my gym going I could run for at least 25 minutes non-stop. I don't remember the distance or speed, but that effort made me immeasurably proud of myself. Unfortunately, it never translated to the street. There was absolutely no way I could run even half that time on the road. I always wondered why that was the case and now that I have started doing some running I thought I might search out the answer.

1. Wind resistance. Apparently even a slight breeze can make a big difference to the amount of effort required and I was shocked that this was one of the biggest reasons.
2. Uneven ground. It may look flat, but it is unlikely to be. Which is true if you have ever ridden a bike with loaded pannier bags. Plus you may be dodging puddles, dog poop, little kiddies on bicycles, parked cars or any number of things in your path which tends to vary your pace. And of course you might actually have to face a hill.
3. Propulsion. Unless living in an earthquake prone area or Godzilla is about, then the ground doesn't move underneath you. This is even addressed in shoe design as explained by Simon Bartold, International Research Consultant for ASICS. It's all about your centre of gravity which on the pavement which needs to be propelled forward by the leg muscles. On a treadmill however, the centre of gravity is static, being moved up an down on an unstable surface instead of forward.
   

The consequence is that research shows running on the road burns more calories than on a treadmill. But at the end of the day, it depends on what the desired outcome is. For example I'm not interested in the calories, but rather being able to run a 5K race therefore I choose to train outdoors, well that and I don't like gyms even though I no longer have a dog to walk. But if that's also your goal and regular outdoor runs aren't an option, then you can simulate the intensity of the outdoors with a 1 degree incline on the treadmill which will also provide a similar calorie burn.

But there are also plenty of reasons to stay on the treadmill if that's your thing. Often, they are padded so cushion your feet better putting less strain on your body. This translates to fewer injuries. Other advantages include avoid unpleasant weather (although I can testify that jogging in the rain on soggy grass is actually more fun than it would seem), safety, finding having a suitable place to run and convenience. On the forums where this seems a hotly debated topic, some argue that having a set pace on a treadmill means they can push themselves constantly at a steady pace whereas on the road they would be more likely to slow down.

So there you have it, an answer after all these years! What is your preference - hitting the pavement or the treadmill. Why do you choose one or the other for any form of exercise?