Go Ask Alice
Okay, I ran my first race Sunday, and it felt *much* easier than running on the treadmill. I didn't feel nearly as tired. But I googled this question and found it on Go Ask Alice.
Here's what she had to say and it made a lot of sense. Especially the part about the boredom. Oh, and I ran faster outside than I do on the treadmill and still wasn't nearly as tired.
http://tinyurl.com/6l5uh
"Dear Alice,
Why is it I can always run a greater distance on a track than I can on a treadmill? On a track, I can run 5 or 6 miles, but on a treadmill, I can only go a maximum of 3 or 4, then I tucker out. Is it because I get more bored on a treadmill, or is there a more physical explanation?
Dear Reader,
First off, it's not clear if you are running on an indoor or outdoor track. For the sake of this answer, let's assume you run outdoors when you do your track runs.
Physically, there may be some slight differences between how your body expends energy running on a track versus a treadmill.
The treadmill belt offers some help by pulling your feet back underneath your body, so you are potentially exerting less energy to move your feet and legs than if you were not on a treadmill.
When you run indoors on a treadmill, you do not have to overcome wind resistance. The lack of wind means you'll spend less energy running four miles on a treadmill than you will running four miles outdoors. However, it may depend on how fast you are running. For the average person, running 5 - 9 miles per hour (mph) will result in little difference. Some studies say outdoor running expends up to 5 percent more calories; if you run faster than 9 mph, running outdoors could utilize up to 10 percent more calories because you are working harder against wind resistance. Other studies say there's no difference. One study demonstrated the way to balance energy use between indoor and outdoor running is to set the treadmill at an incline (or grade) of 1 percent.
Running indoors maintains or offers stable elements. Runners not only avoid wind, but also other potential natural elements, such as cold air, rain, or sand (if you run on a beach), which demand extra energy.
Running on a treadmill versus pavement (the composition of the track surface you run on is unclear) provides a softer surface, making it a little easier for your joints. People with knee pain or soreness might opt for a treadmill versus the road outside for this reason.
These explanations offer the argument that physically you should be able to run farther on a treadmill than on an outdoor track because a treadmill requires less energy.
Many people, though, do find running on a treadmill incredibly boring. Boredom lets someone think about how tired s/he is, perhaps more quickly than if s/he were not bored. Being distracted may help him/her run for a longer duration. Sports and exercise psychologists often refer to the "distraction hypothesis" as an explanation for the stress/anxiety reducing effects of exercise. Running, in this case, gives someone a time-out from daily stressors or worries, and allows him/her to be distracted. Some people enjoy running on a treadmill because they can watch television, listen to music, or just zone out and run. Others prefer running outdoors because they are distracted by the scenery, other people, the weather, varying terrain, and/or avoiding traffic. Perhaps getting outside onto a track gives you time outdoors to breathe fresh air and enjoy the sunshine. Maybe you are the sort of person who feels energized by being outdoors, for example, and that feeling and energy increase your endurance. The next time you run on a treadmill, if possible, position yourself in front of a television or listen to your favorite music to see if you can run for a longer period of time.
It's also unclear whether or not you are running at the same pace on the track versus the treadmill. If you haven't already done so, use a stopwatch to measure your running speed. Maybe you are running at a faster pace on the treadmill, and that's why you are tiring faster.
Other factors go into how a person feels when s/he runs, including the food(s) s/he has eaten, how well s/he has slept, and/or whether or not s/he is hydrated. Every day is a different day for our bodies. But if someone is a consistent runner, and has fairly consistent lifestyle behaviors, it may be that his/her enjoyment of the outdoors is what fuels his/her running.
Alice"