Initially, I wrote a blog that compared the muscle-to-bone ratio (MBR) in NCAA Division I College Football Players (n=553) to a group of healthy age-matched men (n=261). In both groups, we determined regional and total MBR using dual X-ray absorptiometry (DXA), which is the gold standard for determining bone, muscle, and fat masses. The data for that blog as well as the present blog came from a recent scientific publication from my laboratory that appeared in the Journal of Strength and Conditioning Research (Dengel et al., 2024). In that scientific paper [Dengel et al., 2024] we also examined total and regional MBR by position in the college football players. The college football players were categorized into one of nine position categories: defensive backs (DB, n=85), defensive lineman (DL, n=67), linebackers (LB, n=62), offensive lineman (OL, n=125), quarterbacks (QB, n=25), running backs (RB, n=48), tight ends (TE, n=38) and wide receivers (WR, n=90). Punters and placekickers were combined into one category named punters/kickers (PK, n=13). Total MBR, as well as regional (i.e., arm, leg, and trunk) MBRs, were calculated from DXA measures of muscle and bone masses. In this blog we will look at the total and regional MBR by position in this group of college football players.
So, let us look at the positional total and regional MBR data. If you look at the figure below, you will notice that above each player position there is an image that sort of looks like a violin. These “violins” depict distributions of the data for each group using what are called density curves. The width of each curve corresponds with the approximate frequency of data points, in this case, the number of players in each region. Above each violin image there is a letter or series of letters. Violin images (i.e., positions) that share a letter with another violin image are not significantly different from each other. On the other hand, violin images that do not share the same letter are significantly different from each other. If you look at the total, arms, legs, and trunk panels of the figure below you will notice that not all positions share the same letter. For example, in the arm MBR panel (upper left corner panel), DB and DL violin images do not share the same letter. Indicating that the arm MBR is significantly lower in DB than DL. That means DL have a greater amount of muscle mass per unit of bone mass than DB. Given the amount of grabbing and pushing that the DL position requires this is not too surprising. Further, looking at the arm MBR you will also see that OL, DL, RB, TE, PK, and QB all share the letter b indicating that they have similar arm MBRs. The trunk MBR (lower left corner panel) shows OL, DL, LB, TE, and QB all having similar trunk MBR. The same can be observed between DL, LB, RB, TE, WR, DB, PK, and QB. Leg MBR (upper right corner panel) shows the greatest various between positions with OL having the greatest leg MBR and WR, DB, PK, and QB having the lowest leg MBR. Total MBR (lower right corner panel) shows that OL, DL, RB, TE, PK, and QB all had similar values. While DL, RB, TE, PK, and QB have similar total MBRs. Similarly, LB, RB, TE, PK and QB also had similar total MBRs. You may notice that offense and defensive positions that mirror each other such as WR and DB as well as OL and DL have similar total and regional MBRs. This was expected as we have previously reported [Dengel et al., 2014; Bosch et al., 2019]; offensive and defensive positions that mirror each other have similar total and regional measures of fat, lean, and bone masses.
What does it all mean?
As we pointed out in our first blog examining data from this published paper, the DXA provides coaches and athletic trainers with a method to determine total as well as regional MBRs. In addition, the DXA measures of MBR are much faster and more accurate than anthropometric methods to calculate MBR.
The data found in this manuscript [Dengel et al., 2024] also creates templates for comparison of total as well as regional MBR values for college football players at various positions. Future studies are needed to investigate the relationship between MBR and performance metrics (e.g., power, strength, and game performance), as well as to determine if changes in MBR are related to changes in physiological and mechanical loading.
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.
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, Evanoff NG. Positional Differences in Muscle-to-bone ratio in National Football League Players. International Journal of Sports Medicine 44:720-727, 2023.
Dengel DR, Studee HR, Juckett WT, Bosch TA, Carbuhn AF, Stanforth PR, Evanoff NG: Muscle-to-bone ratio in NCAA division I collegiate football players by position. Journal of Strength and Conditioning Research 38(9): 1607-1612, 2024.
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.