Does the Surface Affect How Fast a Person Will Run?

You might encounter a number of surfaces during the course of your daily runs. If you run on different surfaces frequently, you may notice that your running speed seems faster on some surfaces than it does on others. The running surface you choose can affect how fast you run, though a few factors determine exactly how much of an effect the surface has on your speed.

Some surfaces slow down your running speed by increasing your ground contact time, meaning that your feet stay in contact with the ground for longer than they do on other surfaces. Surfaces that have a lot of give or malleability, such as sand beaches and soft soil, can increase ground contact time significantly as they actually deform when you make contact with them and your body can't stabilize itself and continue its stride until the surface is solid and stable again. While differences in ground contact time may not be noticeable while you are running, these small differences can have a large impact on your overall speed.

One important factor in how much a surface affects your running speed is how well the surface absorbs the shock from your strides. Surfaces that absorb a large amount of the shock from your stride are often softer and springier, while surfaces that absorb very little shock are hard and rigid. Softer surfaces such as grass, sand and soft soil slow you down slightly because they conform more to your feet when you make contact while more rigid surfaces such as concrete and asphalt may speed you up by allowing more of your force to propel you forward. Surfaces that are firm without being hard may offer a happy medium between the two; they are soft enough so as not to be jarring to your joints while you run but are hard enough that a large portion of your impact force is still used to propel your stride.

The texture of a surface can have a significant impact on how fast you can run across it. Surfaces that offer more grip such as rough-textured concrete and synthetic running track surfaces allow you to stabilize your body faster and provide you with sufficient friction to make your next stride quickly; this results in a lower ground contact time and a faster overall running speed. Smoother or slicker surfaces such as some types of packed earth and snow-covered ground may be harder to stabilize your body on, increasing your ground contact time and slowing you down.

Angled surfaces can slow you down more than flat surfaces depending on the specific angle and the direction in which the surface angles. As you run on an angled surface your body has to work to climb or descend the surface as well as maintain your running technique. If you are running up an angled surface like a hill, then this means your muscles work harder and your running speed slows down. Running down an angled surface provides the opposite effect; your muscles don't have to work as hard because gravity and momentum carry you slightly farther, resulting in a faster running speed. The greater the angle of the surface is, the more prominent this effect will be when running up or down the surface.

Some running surfaces that negatively impact your speed can increase your likelihood of becoming injured as well. Surfaces that are smooth or that deform easily take longer for your body to stabilize itself on, increasing the likelihood of losing your balance and slipping or falling. Angled surfaces can also contribute to injury, by causing you to overwork your muscles without realizing it or causing you to trip when your running speed increases faster than you can adjust your stride to compensate.