In my office as a Penn Hills Chiropractor, I see patients with a shortened leg all the time. It’s actually rare that a patient has an anatomically short leg. A short leg is usually most often seen as an over compensation resulting from a misaligned pelvis or low back.
But what does this short leg have to do with runners? In essence, it really puts a lot more of your total weight-bearing onto one side than the other. With a short leg, your weight is not at all evenly distributed and you can, and will, wear down one side of your body (specifically joints and muscles of the lower extremity, pelvis, and low back) much quicker.
Simply having a ¼ inch short leg adds 6% increased weight bearing to the long, unaffected side!
I used some very general numbers for these equations. Some runners will weigh more, some runners will weigh less. Some run more, some run less. Some will have longer strides, some shorter, but these general numbers will at least give you an idea of how the short leg can wear on you.
1. We’ll go with a 150 lb runner. A running heel strike is 5x body weight. So 150 x 5 = 750 lbs of heel strike per stride.
2. There are roughly 1800 strides per mile. So a runner running 10 miles per week (1800 x 10) is doing 18,000 strides per week.
3. 18,000 strides/week x 750 lbs of heel strike/stride = 13,500,000 lbs of heel strikes/week
4. 6% of 13,500,000 = 810,000 lbs.
So instead of evenly distributing your body weight in both lower extremities and your low back and pelvis, someone with a ¼ inch short leg in this example is putting 810,000 lbs more weight on the long leg in a week’s time!
And that’s the long and short of it!
– Dr. Brent Shealer — Monroeville, Penn Hills, Pittsburgh Chiropractor