Treadmills allow you to run or walk indoors at any time. However, the impact of walking or running may lead to discomfort, pain or injury. While an exercise program may be modified to strengthen joints and modify intensity, another approach is to minimize joint shock. Many treadmills have special belts, decks and shock systems designed for this reason. Consult your doctor for recommendations and specific instructions before you start an exercise program.
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In a study published in the November 2000 issue of "Medicine and Science in Sports and Exercise," researchers found that harder running surfaces did not absorb as much shock as softer surfaces. The treadmill belt affects the overall running surface and is available in many materials and designs. While absorbent belts reduce impact, they may also increase wear on other parts of the treadmill.
The deck is directly under the moving belt and also affects shock absorption. Treadmill decks are usually made of wood or synthetic materials. Some decks only have shock absorption where the foot lands, so running or walking remains natural. The deck material and absorption design are listed in the machine features. Decks wear out over time, so choose a deck that is sturdy as well as absorbent.
Shocks and Springs
Shocks and springs are sometimes used for treadmill shock absorption. Air shocks carry some of the load of the machine and help to absorb impact every time the foot strikes. However, air shock systems may require more regular maintenance than other treadmills. For example, some manufacturers recommend servicing air shocks every 150 miles. Avoid springs because the absorbed shock is released directly back to you.
Woodway is the leading brand in absorbent and reliable treadmills. As of 2010, Woodway treadmills have been purchased by 97 percent of National Football League teams and 93 percent of Major League Baseball teams, as well as several universities, reality television shows and military organizations. This brand's patented belt is made of thick, rubber slats that slide on low friction ball bearings. Researchers at the Deutsche Sporthochschule in Germany determined that the softness of the Woodway belt is ideal for reducing shock without changing body mechanics.
A variety of Woodway models are available. Some have downhill and backward modes, as well as a nonmotorized setting that allows you to work harder by driving the treadmill belt yourself. This means that more work can be accomplished with less shock.