While running on a treadmill is a great way to improve your cardiovascular fitness, stay warm indoors and watch TV which you are exercising. It does not provide you with the same workout that you would receive from running outdoors. This is due to the belt on the treadmill, as you place your foot down on the moving belt rather than having your glutes, hamstrings and quads propel you forward, the belt will move your foot back for you removing a lot of the hard work from running. As mentioned before you can still get a great cardio workout for the treadmill but if you are training for a running event, then just training on the treadmill is not the ideal way to prepare.
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