Recently, I wrote a blog titled: “ASYMMETRY IN THROWING AND NON-THROWING ARMS OF NFL QUARTERBACKS”. That blog looked at data from my 2014 paper on body composition in NFL players (Dengel et al., 2014). In the blog, I examined the composition of throwing and non-throwing arms in NFL quarterbacks to see if there were asymmetries. 

I thought it would be interesting to apply this same analysis to the NFL punters and placekickers in the same study (Dengel et al., 2014) in regards to their kicking and non-kicking legs. We had data on the kicking and non-kicking leg for 18 NFL punters and placekickers. Ten were punters and eight were placekickers.  Four were left-footed and the remaining 14 were right-footed. The data on the kicking and non-kicking legs for these 18 individuals can be found in the table below.

In this group of NFL punters and placekickers there were no significant differences between the kicking and non-kicking legs in regards to total, muscle, or fat masses. These results are similar to what we found in the NFL quarterbacks where we found no significant differences between the throwing and non-throwing arms in regards to total, muscle, and fat masses. The punters and placekickers examined here showed the non-kicking leg had significantly more bone mineral content (BMC) and bone mineral density (BMD) than the kicking leg. This is different than what we found in the throwing and non-throwing arms of NFL quarterbacks where the throwing arm had more BMC and BMD than the non-throwing arm. 

You are probably wondering why the kicking leg has greater BMC and BMD compared to the non-kicking leg?  If we think of the kicking or punting motion a tremendous amount of force is placed on the non-kicking leg when it plants and provides the base for the kicking or punting motion. It is this “plant” force that probably accounts for the greater BMC and BMD in the non-kicking leg.  Even though the kicking leg is striking the ball the force being generated by the non-kicking leg with the playing surface is likely greater than the force developed in striking the ball.

What does it all mean?
So what does it all mean? First, there is the fact that NFL punters and placekickers had an increase in BMC and BMD in their non-kicking legs compared to their kicking legs.  This is opposite to what we reported in the throwing and non-throwing arms of NFL quarterbacks. This may seem usual until you stop and think about the kicking motion and the force placed on the non-kicking leg as it plants and serves as the base of support for the kicking motion. The fact that there was no corresponding difference in muscle mass in the kicking leg compared to the non-kicking leg may point to the strength training as well as other training that both legs participate in. The small, but significant differences between the two legs are not that concerning and should be expected due to the load placed on the non-kicking leg.  

References
Dengel DR, Bosch TA, Burruss TP, Fielding KA, Engel BE, Weir NL, Weston TD: Body composition of National Football League players. Journal of Strength and Conditioning Research 28(1):1-6, 2014.

About the Author
Donald Dengel, Ph.D., is a Professor in the School of Kinesiology at the University of Minnesota and is a co-founder of Dexalytics. He serves as the Director of the Laboratory of Integrative Human Physiology, which provides clinical vascular, metabolic, exercise and body composition testing for researchers across the University of Minnesota.