Last New Year’s I wrote a post entitled My Scientific/Personal Advice for Running on a Treadmill. That advice is based on my years of research studying gait as well as my own personal advice, having logged many a mile on a treadmill.

Whether or not you are contemplating the inclusion of a treadmill in your New Year’s Resolutions, the post is still, a year later, very much a worthwhile read. I discussed how the biomechanics between walking or running on a treadmill and walking or running over ground are essentially the same. Our biomechanical studies have dispelled a number of myths including “the treadmill belt propels you forward so that you do less work,” or “the treadmill belt pulls your leg through, resulting in a relatively passive extension of the hip, which reduces conditioning of the hip extensors.”

The post was picked up by Amby Burfoot, Senior Editor of Runners World who wrote an article for Runners World entitled “Biomechanics Expert Debunks Treadmill Running Myths”. From that, Mark Remy, also of Runners World, wrote a super funny piece entitled “12 More Treadmill Myths…Busted!”, which are all, still, must reads.

In my original post, I mentioned how treadmills provide a beneficial compliance or “springiness,” compared to running overground. This point subsequently spurred a lot of inquiries into the difference between “cushioning” and “springiness” particularly in regards to choosing which is the best treadmill.

Treadmills are often advertised to cushion impact, which would be all well and good if injuries were to occur at impact when the foot first strikes the ground. But the moment of impact is NOT when injuries occur. Counter to what many have believed, our biomechanical studies have shown that the peak forces associated with injury occur not at impact, but later when the foot is fully planted. Osteoarthritis of the knee, for example, is associated NOT with the tiny force that occurs at impact, but with the major force that occurs when the foot is fully planted, in midstance, when all the body weight is over the foot. And studies show that attempting to cushion impact results in increasing, rather than decreasing, the major forces at the knee that are associated with osteoarthritis.

Just as cushioning or “dampening” has a negative effect on the joints in the body, compliance or “springiness” has a positive effect. A truly springy interface that compresses and releases in response to when forces are at their peak can in fact reduce peak joint forces. And most treadmills that are built upon a compliant deck, usually plywood, in fact provide such an interface.

I like running on any treadmill, whether it’s at a gym, health club, or hotel. But I especially love our 21 year-old treadmill and have been resistant to getting a new one, even though it must have over 50,000 miles and has had to be re-built several times. It was made by “Trotter,” a company that is now owned by “Cybex” and is straightforward in design in that it has a plywood deck that compresses and releases in response to when the body weight forces are at their peak. I see many new treadmills advertised to cushion impact, via some type of foam cushioning or an alteration in how the deck is supported. Since anything that cushions the forces at impact just increases the peak joint loads, the best treadmill design would be one that has no cushioning or padding, but rather has a simple plywood deck supported in all four corners, just like our good old tried-and-true 21 year-old treadmill.

As I said last year, “Running on a treadmill is a great way to either get into or stay in shape during the winter. It’s so great in fact that you may find you like running on a treadmill year-round.” A lot of people do. I won’t because I love running outside, too. But this time, early in the New Year, I will be doing most of my miles on a treadmill.

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