As crazy as it may seem, this is often one of the most important things I tell my patients. As the saying goes, “the devil is in the details.” I have been able to collect some valuable information from 4,000 patients who have come to me over the last 32 years.
During that time I have been responsible for ordering, evaluating and the computations of more than 4,000 X Rays of my patients’ legs, their femurs and tibias. I, along with other medical researchers, have concluded that 95% of us have about ¼ inch or 5 to 6 millimeters difference in the longitudinal length of our legs.
If this abnormal difference is more in the femur (the thigh bone), the difference in the weight of an average adult male’s longer femur could be 5 to 20 pounds more than the leg with the shorter femur! This is because of the extra body mass, more bone mass, including the bigger and stronger muscles in the buttocks and upper leg of the longer femur, especially the glutes, quads and hamstrings. Ever wonder why one glute, hamstring, quad, and/or calf always gets tighter or is more symptomatic than the other one? This is probably because of this elementary imbalance. Some dedicated runners, hikers and walkers have noticed they feel better exercising on one side of the road more than the other side and consequently use one side more to their benefit.
The only way to know for sure what this finite leg length difference number is with a special life size X Ray of the femurs and tibias—what is referred to in medicine and sports science as a scanogram or orthoroengtenogram of the femurs and tibias. A bone scan of the bones can be done as well, but I feel lacks the accuracy of a scanogram.
You might say this leg length difference number is the answer to the $40,000 question. But in the case of a professional athlete, it could be the security of the team owner’s $40M investment.
Once you know which leg is longer, you know what side of the road to run and/or walk on, depending on whether you’re running on the pavement or the sidewalk. The longer leg’s foot should always be lower than the shorter leg’s foot. For instance, if your right leg is longer, running on the right side of a crowned, paved street should feel better than running on the left side… and vice versa if your left leg is longer. If you’re running on the sidewalk, it is the opposite because sidewalks always slope toward the road. This means left long leg people should feel better running and/or walking on sidewalk on the right side of the street, or with the traffic if your right long leg is longer.
It should be noted that even if you correct the short leg length deformity with custom orthotics, or place an extra insole in your short leg shoe, the longer leg will still weigh more than the shorter leg. As a result, you will probably still feel better exercising on the side of the road that addresses your long leg imbalance. This leg length imbalance is also the reason you’ll want to stretch your long leg’s hamstrings, glutes, ITB, calf and quads more than the corresponding muscles on the shorter leg, especially after you exercise.
I believe that this leg length information will help extend your body’s physical longevity. We now know the elderly usually break the neck of their femur bone in the long leg about 90% of the time after putting 200,000 miles on their legs. The fall usually occurs after the femur breaks, and it is not the fall that causes the break in the leg. This does not discount the fact that any fall may result in a fracture for a geriatric.
Dr. Paul R. Copeskey, D.C., C.C.F.C.