The best part about running (in my opinion, at least) is that you can do it pretty much anytime and anywhere, at your own discretion and with minimal equipment. Of course, there are always conditional factors to consider when planning a run. No, I’m talking about matching your shoes to your outfit or vice versa. For the most part, as long as you have two feet and ground to run on, you are off to a good start.
What factors are you considering when you run? Strength and flexibility? Warming up? I’m sure you’re thinking about temperature or wind. Maybe the surface you run on? Most of these factors are out of our control. RunSmartOnline.com has plenty of content about how you can leverage your strength and flexibility, so let’s talk about a factor you can manipulate to optimize running economy and minimize risk of injury: the best ground surface to run on.
Running economy is the idea of harnessing and directing energy to maximize running performance. One external factor that can affect running economy is the ground reaction force (GRF). GRF is simply the force that the ground exerts on the body. GRF between runners differs largely based on running style, shoe-wear, body shape and size, and differences in forces produced by the muscles in your legs. Recent research has shown that runners are able to subconsciously adjust their leg stiffness to accommodate changes in surface. The softer the surface, the stiffer a runner’s legs are during the stance phase of the running. Based on this knowledge, Ferris, Louie and Farley have suggested that distance runners and runners with preexisting joint pain may benefit from training on softer ground due to decreased joint compression on impact.1
Asphalt is a hard(er) running surface that, for most recreational runners, is even harder to avoid. Running on asphalt is certainly less forgiving than the much softer gravel. In a black-and-white world, there would be no need for this discussion; the way to prevent injury would be to always run in the grass, period. The list of best (soft) to worst (hard) surfaces would read as follows: trails, gravel, cinders, synthetic tracks, treadmills, asphalt, and finally cement. Like always, there’s a caveat. Nothing is ever simply black and white. There are always other factors to consider.
Although a softer surface may be easy(ier) on your joints, running on softer surfaces can increase energy cost by 1.2–1.6 times that of running on a firm surface. Softer surfaces produce challenges to stability, resulting in an increase in muscle activity. Grass or trail running often results to increased fatigue for newcomers. That once forgiving “softer surface” could transform to a liability and eventually–an injury. It’s always important to remember that your body craves consistency. Something as simple as an occasional dabble in trail running or running through slushy, snow covered streets could tip the scales. Your body (mainly ankles) are simply not accustomed to soft or slippery surfaces. From an running efficiency standpoint, softer surfaces result in increased stance time, cadence, and decreased stride length leading to decreased running economy.2
So what about running on a track? Tracks tend to be more forgiving than running on a treadmill or asphalt. Similar to above, there are cons when running on a track vs. the road. Other than the mind-numbing hamster wheel sensation the track offers; a larger con includes continuous left turns.
For anyone heading to the track, think about the counter-clockwise direction for all warm ups and cool downs. It will help you avoid asymmetry that is bred with continuous left turns. The same applies to running on cambered surfaces (most roads). It may be wise to switch sides of the road periodically throughout a training run to avoid injury. You could also hop onto a sidewalk, as the sidewalk slants opposite of the road.
Running indoors is another adventure that most of us (but not all) in the Northeast have learned to tolerate. Running on the treadmill provides a softer surface than asphalt and it can be helpful if you’re working toward pace maintenance or through injury recovery. On the downside -you won’t get the benefit of having a natural breeze while running indoors, which is a trade-off to avoid lousy weather.
The take home point is that there’s always a trade-off. Running injuries can be caused by a variety of factors and it is important to train under similar conditions that you plan to confront on race day. If you’re race has a long downhill section, plan and train for it. If you’re going to be running on the right side of the road for 26.2 miles, train for it. Trail race? Train for it.
Your body will adapt to stressors applied to it, the key is to do so in a progressive manner (mileage, running surface, etc.). In essence this is why we slowly build our mileage—to let our body adapt and strengthen.
1. Ferris DP, Louie M, Farley CT. Running in the real world: adjusting leg stiffness for different surfaces. Proceedings of the Royal Society of London. Series B: Biological Sciences. 1998;265:989-994.
2. Pinnington HC, Lloyd DG, Besier TF, Dawson B. Kinematic and electromyography analysis of submaximal differences running on a firm surface compared with soft, dry sand. European Journal of Applied Physiology. 2005;94:242-253.