We recently published a paper in the Journal of Strength and Conditioning Research (Bosch et al., 2019) on body composition measures in over 467 NCAA Division 1 collegiate football players. This paper is a companion paper to the series of papers we published on body composition in National Football League (NFL) players (Bosch et al., 2014; Dengel et al., 2014). Those two studies reported body composition measures on 342 NFL players. I thought it would be fun to compare these collegiate football players to our NFL football players. All three of these studies used the same model of dual X-ray absorptiometer (DXA) so it allows us to make comparisons between these two groups of football players without having to worry about differences in DXA scanners. To make looking at the data easier I have decided to split this topic into two separate blog posts.  The first blog post will deal with offensive players (i.e., offensive lineman, tight ends, running backs, quarterbacks and wide receivers).  In the second blog post, we will compare the defensive players (i.e., defensive lineman, linebackers and defensive backs).  

Physical characteristics of collegiate and NFL football players.
In the table below, you will find the physical characteristics of our two groups of offensive football players.  The table has the mean values plus the standard deviation for each variable.  The ranges for each variable can be found in parentheses next to the mean. The offensive players are grouped by position.  What is interesting about the table below is that, besides age, the mean values for height, weight, and body mass index (BMI) are very similar between college and professional football players. What is different for the two groups is the range for these values.  On average, collegiate football players have a greater range of values when compared to the professional football players. Another interesting aspect of the table are the mean values for BMI for both college and professional football players.  BMI is a measure of body composition based on height and weight. Using this measure of body composition, all of the offensive positions would be overweight (BMI 25-29.9 kg/m2) and some positions (i.e., offensive lineman, tight ends and running backs) would be classified as obese (BMI of 30 kg/m2 or greater). These data demonstrate the weakness of using BMI to assess body composition in college and professional football players.

Percent total body fat
Now let us look at percent fat for our two groups of football players.  In the figure below, I have graphed total percent body fat for both NFL (blue bars) and collegiate football players (red bars).  Again, the means for the different offensive positions are very similar.  Unlike height and weight, percent total body fat ranges (located above the bars) are similar in their magnitude.  In addition, professional as well as collegiate wide receivers had the lowest percent total body fat for offensive positions.

What does it all mean?
So what does it all mean? First, the data presented here provide trainers and coaches who use DXA to examine the body composition of their players a place to look at normative data by position for both professional and collegiate football players. Secondly, it is clear that using simple height, weight, and BMI will miss classifying athletes and that the use of more accurate methods such as DXA are needed in athletic populations.  Finally, the data presented here demonstrate how close collegiate football players are to their professional counterparts.  For those that want more detailed information found in this blog post, please contact the corresponding author Dr. Don Dengel (e-mail: denge001@umn.edu).

Bosch TA, Burruss TP, Weir NL, Fielding KA, Engel BE, Weston TD, Dengel DR: Abdominal body composition difference in NFL football players. Journal of Strength and Conditioning Research 28(12):3313-3319, 2014.
Bosch TA, Carbuhn A, Stanforth PR, Oliver JM, Keller KA, Dengel DR: Body composition and bone mineral density of division 1 collegiate football players: a consortium of college athlete research study. Journal of Strength and Conditioning Research 33(5):1339-1346, 2019. 
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.

Read Part 2 - Defense
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