Will Running on Cement Injure Me?
Many runners run in urban settings for years, logging mile after mile on cement and other hard surfaces without any apparent problems. Other runners swear by the trail and believe it has prolonged a running career and mitigated many risks of injury. Still others do the exact same thing, and still fight injury after injury. Who is right?
Force = mass x acceleration
Conventional wisdom would indicate that the hard surfaces found in cement (your average city sidewalk), or asphalt (black top road surface) would increase the risk of injury for runners. After all, the body creates 2-3x its actual weight in force just during the heel off phase while walking. This increases to 5-8x body weight during running due to the increase speed and the fact you are (for some of us, very briefly!) completely airborne before each foot lands. Cement is about 10x harder than asphalt so it seems reasonable that cement would be an absolutely horrible surface on which to run.
If all your concerns related to problems that occurred due to force alone, then perhaps abstinence from cement would be a wise idea, and indeed, many runners opt for the street instead of the sidewalk, or go long ways out to find trails and grass surfaces. However, many of the injuries runners suffer have a more complicated genesis. Are your shoes appropriate for you? Does your foot strike the ground efficiently? Are you hips in alignment or do you have muscle imbalances and weaknesses that have left your joints and ligaments vulnerable to forces that your body has not been able to dissipate? All of these factors come into play, and have been much more easily researched as injury culprits than the surface itself.
What is good for the bones might be tough on the ligaments
Likewise, the even, but forgiving surface of a golf fairway (when rarely available) might provide a luxuriously feeling run, as does a well- manicured forest trail. But when does that desired effect dwindle when the trail become rocky and uneven, or muddy and slippery? When the grass is long and mushy, or the bark trail too soft, such that you sink perceptibly on each step, or the blacktop road so cambered that you are running on a slant instead of a flat sidewalk next to you, do you receive the same benefit?
While these surfaces might provide relief from the abrupt forces of cement, they often demand a great deal more from stabilizing muscles and ligaments and present their own challenges to your goal of staying injury-free. If tendonitis, muscle strains, or other soft tissue ailments are your kryptonite, you might risk more by continuing to run on these surfaces all the time and may benefit from a steadier ride on a hard surface.
Running is healthy for the spirit as well as the body
One of the reasons pavement and cement may get the blame for many maladies is the correlation with the environment where these surfaces are typically found. Not many runners would prefer the start and stop of a sidewalk interrupted every hundred yards with a stoplight, complete with honking, speeding cars and loud noises, crowds, and the like. The peaceful environment of a trail deep in the forest, around a lush and green grass field, or along the ridge of a slowly descending dirt path sounds much more reparative to the soul. Studies show that the body is best prepared to run hard late in the afternoon, or early in the evening. Potentially a study might show that those who run along peaceful dirt paths can extend their running careers later into middle age and beyond. But just as not everyone has the luxury to knock off work or family obligations for a 60 minute run in the hills at 4pm, not everyone can get to an idyllic nature setting for their daily run, whenever it occurs. For them, running along a busy street or the best bike path available most definitely is better than not running at all, and that may mean running on cement or non-ideal surfaces.
Look at the whole picture
Rather than automatically assume the risk of the surface one way or the other, a more thoughtful approach is in order. Consider your problem areas, where injury trouble tends to start or flourish, and then work through each of the other variables: shoes, foot striking pattern, known muscle weaknesses or misalignment issues, sleep, stress, nutrition, hydration, etc. It may be that a change to soft surfaces may be in order, but the investigation may uncover other areas where change may eliminate the risk or problem, even if the ground under your feet remains the same.