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Are Long Legs Really Better?

According to Herman Pontzer, Ph.D (Journal of Experimental Biology), fossil records show that 2 million yrs. ago, human leg length suddenly began to increase...presumably to conserve energy during long distance travel. Pontzer's model predicts the rate of energy use related to limb length, i.e., longer legs = less force production = lower energy cost.

To test his equation, Pontzer put people, dogs and goats on a treadmill and measured how much oxygen each used during walking and running at various speeds. "All things being equal, leg length is one of the major determinants of energy cost," says Pontzer, "If two animals are identical except for leg length, the animal with longer legs is more efficient."

Although his findings seem rational, my question is: "In humans, are the legs really designed to propel motion or do we possess a more complex "whole-body" antigravty "Spring System" which determines gait efficiency. See http://erikdalton.com/articleDontGetMarried_Part2.htm or some of Tom Myer's stuff at AnatomyTrains.com.

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Comment by Joseph Matties on April 1, 2010 at 8:36am: I would think it would take less energy to move a shorter/smaller leg, but then you would also travel a shorter distance. In my opinion it would balance out. My problem is you would have a hard time convincing me that we were around 2 million years ago.

Comment by Erik Dalton, Ph.D. on March 29, 2010 at 8:16am: Kelly> Don't despair, ballerinas have long lovely legs but so do some of our short-legged gymnasts. My wife has the opposite pattern -- short upper torso (not as much room for the viscera) -- and long legs (probably more vulnerability to knee and hip injury). Obviously, the better top to bottom balance one has, the greater mechanical advantage.

Personally, I believe the inability to recognize and adapt exercise programs to the genetic card you've drawn is a major no-no. For example Kelly, people with your body type typically have very little trouble forward bending and touching the floor. The hamstrings can easily accommodate this maneuver without straining the low back.

But how many time do we see 40+ year old men come in our office complaining of severe back pain and during the history exam they say, "It seemed to 'lock-up' following my yoga class".

Long-legged people with a short torso should beware of any type of stretching that includes straight-legged forward bending. If they are not taught to 'pull up' on their ischial tuberosities (stretch from the hams) while learning the maneuver, much of the strain must come from the posterior structures in the low back's osteoligamentous canal. Even greater stress can be placed on the intervertebral disc if sidebending or rotation is added while in the forward bent position. This is one of the primary reasons the L5-S1 disc is the most surgically repaired area in the body. Thx for the post :)

Comment by Kelly Grounds on March 28, 2010 at 11:45pm: If longer legs are better (and they probably are) I am so screwed. I have what is called a 'long waist' and short legs. ::sigh::