On a rainy day (or up here in the north, a snowy or icy day), many athletes and coaches have wondered if treadmill running is a good replacement for road or trail work. For people with general fitness goals, anything that gets your heart rate up is almost certainly going to be effective. But treadmill running is different from ground running – different enough that it deserves a look, especially for those who are competitive runners or who wish to compete.
A treadmill has no twists, turns, or hills unless you adjust the incline, but let’s face it – the hills on a treadmill don’t feel the same as they do outside. That means the nature of the exercise is different from road or trail running. The surface and constant pace also make for potential alterations to running form. Because of these differences, we might wonder if the treadmill is actually an effective training tool for competitive runners. A study this month in the Journal of Strength and Conditioning addresses that question.
It was a simple study. The researchers analyzed the gaits of runners on a treadmill with a constant pace over time to see if there were any changes as the runners ran. They found the gait of the runners was consistent with outdoor running except for one variable: stride length. Over time in a given session of exercise, the stride length of the runners actually increased on the treadmill.
For form work, the change over time in stride length might make some important differences. Longer strides at a given speed could move some of the effort toward the back of your legs. It also tends to shift foot strike toward the heel. On a treadmill, this might actually reserve energy because the treadmill continues to pass under you as you spend time in the air. The greater vertical distance would be advantageous on a treadmill, but detrimental when running on the ground.
The researchers determined that the treadmill was acceptable for technique development, as long as the trainers or athletes were aware of the longer stride and corrected for it when running outdoors. I think the shift in emphasis, especially in foot strike, might make a significant difference in injury profile, and could affect form on ground work. Countering this effect should be simple enough. As long as you are still working form on the road or trail primarily, your technique shouldn’t suffer, making the treadmill an effective substitute for road work.
On those rainy days or weeks that some of us have been having this summer, fear not! Treadmill running is a good substitute on those days when it is impossible to get outside. Just be certain to keep your outdoor running form sharp the rest of the time to prevent injuries and improve performance where it counts, and use the treadmill as a supplement.
1. Brian Hanley, et. al., “Changes in Gait During Constant Pace Treadmill Running,” Journal of Strength and Conditioning Research, DOI: 10.1519/JSC.0b013e3182a38796
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