Ipreviously discussed whether running on hard surfaces is hard on your joints.
Will it wear out your joints prematurely?
I also discussed how our legs have the ability to adjust to the softness or hardness of the surface by becoming stiffer or less stiff as the type of surface changes.
The “spring” properties of our legs (resulting from the elastic and force absorption of muscle, tendon and cartilage) and the adjustment of our stride (varying the degree of bend in our hips, knees and ankles) are prime mechanisms we use to cope with different surfaces.
Humans and other running animals are able to make these adjustments within one or two strides when encountering a new surface.
Does research support the commonly held idea that running on hard surfaces actually wears out your joints, especially the cartilage in your knees, or predispose you to other injuries compared to running on a softer surface?
In one study in 2008, published in Foot and Ankle International, the incidence of tendonitis (inflammation of the tendon) was the predominate injury encountered and actually increased on the softer surface and decreased on the harder surface.
In fact, the study showed that Achilles tendon injuries increased tenfold when running on sand compared to pavement.
As far as wear and tear on the cartilage in the knee, there have been a few large, long-term studies done in the past 10 years on this and they all show that running does not promote premature arthritic changes, and may help prevent these changes in the knee.
In the Stanford University study, which tracked 1,000 runners and non-runners over 21 years, the authors found that the incidence of knee osteoarthritis was the same for both groups despite how little or how much the runners ran. Presumably the majority of these runners ran on pavement since that is the trend in the majority of recreational runners. The other remarkable finding of this study was that the runners had less physical disability and a mortality rate which was 39% lower that the non-runners. The journal Arthritis and Rheumatism published a study which demonstrated that vigorous exercisers had thicker and healthier knee cartilage than their sedentary counterparts. However, keep in mind that there are risk factors for osteoarthritis – another famous long-term study with a similarly large population was the Framingham study showed that previous cartilage injury, aging and obesity are risk factors for accelerated knee osteoarthritis
Of course, any physical exercise has risks for injury. Runners can get a variety of injuries from stress fractures in bones to tendon inflammation to sprained ankles.
So what are some ways we can reduce this risk?
Since we use our muscles and tendons as force dampers (like shock absorbers in our cars), it would seem that if we strengthened the muscles in our legs, they would have greater capacity to absorb the force of running on any surface and that the strength training would help increase bone density, too.
As it turns out, studies like the one done at the University of Minnesota supports this idea. Researchers found that competitive female runners who had larger and stronger calf muscles had a reduced incidence of stress fractures in the tibia (shin bone). More experienced runners are beginning to incorporate weight training into their routines, but not enough of them consider this preventative strategy, and most novice runners don’t either.
Another strategy to help reduce the risk of injury is changing stride length. It turns out that lighter, faster, elite runners have a long stride length than heavier, non-elite runners. Where beginner runners tend to get into trouble is that some can take longer strides than appropriate for their fitness level and muscle strength and land with more force than their legs can withstand. So simply by shortening the stride length a little, this can help reduce the force their legs endure.
Cross-training on different surfaces and with different types of exercise (cycling, classes, sports) will also help to decrease the chance of an over-use injury.
And as always, be aware of the grand-daddy of most overuse injuries – doing too much, too soon.