Exercise of any kind is always good for you, but a report by the New York Times points out that getting out of the gym (or your house) adds a few subtle benefits. Your stride is different when running outside as opposed to running on a treadmill, and you're more likely to hit hills that add challenges to your workout.
Picture: lululemon athletica/Flickr
In some cases, it's all about just being outdoors. You'll also run into wind resistance on a bike outdoors, which means you burn calories faster because you're expending more energy. A few smaller studies also suggest we're willing to exercise more and for a longer period of time when we're outdoors. The New York Times explains why that might be:
Studies haven't yet established why, physiologically, exercising outside might improve dispositions or inspire greater commitment to an exercise program. A few small studies have found that people have lower blood levels of cortisol, a hormone related to stress, after exerting themselves outside as compared with inside. There's speculation, too, that exposure to direct sunlight, known to affect mood, plays a role.
It's still a lot of speculation at this point, but if you're having trouble sticking to an exercise routine it might be worthwhile to move those activities outdoors.
The Benefits of Exercising Outdoors [New York Times]