Scientific Manuscript Excellence Honor: Dr. Gary A. Dudley Memorial Paper
BODY COMPOSITION AND BONE MINERAL
DENSITY OF NATIONAL FOOTBALL LEAGUE
PLAYERS
DONALD R. DENGEL,1,2 TYLER A. BOSCH,1 T. PEPPER BURRUSS,3 KURT A.
FIELDING,3 BRYAN E. ENGEL,3 NATE L. WEIR,3 AND TODD D. WESTON4
1
Dr. Gary A. Dudley
1952-2006
School of Kinesiology, University of Minnesota, Minneapolis, Minnesota; 2Department of Pediatrics,
University of Minnesota Medical School, Minneapolis, Minnesota; 3Green Bay Packers Professional
Football Team, Green Bay, Wisconsin; and 4GE Healthcare, Madison, Wisconsin
ABSTRACT
INTRODUCTION
Dengel, DR, Bosch, TA, Burruss, TP, Fielding, KA, Engel, BE,
Weir, NL, and Weston, TD. Body composition and bone mineral
density of national football league players. J Strength Cond Res
28(1): 1–6, 2014—The purpose of the present study was to
examine the body composition of National Football League
(NFL) players before the start of the regular season. Four hundred eleven NFL players were measured for height, weight and
lean, fat, and bone mass using dual-energy x-ray absorptiometry
(DXA). Subjects were categorized by their offensive or defensive
position for comparison. On average, positions that mirror each
other (i.e., offensive lineman [OL] vs. defensive lineman [DL])
have very similar body composition. Although OL had more fat
mass than DL, they were similar in total and upper and lower lean
mass. Linebackers (LB) and running backs (RB) were similar for
all measures of fat and lean mass. Tight ends were unique in that
they were similar to RB and LB on measures of fat mass; however, they had greater lean mass than both RB and LB and
upper-body lean mass that was similar to OL. Quarterbacks
and punters/kickers were similar in fat and lean masses. All positions had normal levels of bone mineral density. The DXA allowed us to measure differences in lean mass between arms and
legs for symmetry assessments. Although most individuals had
similar totals of lean mass in each leg and or arms, there were
outliers who may be at risk for injury. The data presented demonstrate not only differences in total body composition, but also
show regional body composition differences that may provide
positional templates.
here is a general perception that National Football
League (NFL) players are bigger and carry more
fat compared with NFL players from previous decades. Part of this statement may be true if we only
use body mass index (BMI) to examine these players.
Although players may have greater body mass, they may
actually be leaner than players from previous decades.
The interest in the body composition of professional
football players initially started over 40 years ago (14). Previous studies have reported that body composition is related
to position (3,4,6,12,14). As advancements in methodology to
examine body composition have developed, these newer
methods have been applied to the study of NFL players. To
date, most studies (6,14) have involved methods that use
a 2-compartment model of body composition (i.e., fat mass
and fat-free mass) and have only been able to focus on total
body composition. The use of hydrostatic weighing through
water or air displacement has long been considered to be the
gold standard for determining body composition. However,
the development of dual-energy x-ray absorptiometry (DXA),
which is a 3-compartment model (i.e., fat mass, lean mass, and
bone mass) is now considered the gold standard for measurement of total body composition (8). Until recently DXA
devices could not accommodate individuals .350 lbs, which
limited their use to measure body composition in NFL players. Recent improvements in technology allow newer DXA
devices to accommodate individuals who weigh 450 lbs. This
study examined body composition in a number of NFL players and prospects before summer training camp. This study is
the first to examine not only fat and lean tissue mass, but also
determine bone mass and examine regional body composition. In addition, we performed segmental analysis of lean
tissue, fat masses, and bone mineral density (BMD).
KEY WORDS dual-energy x-ray absorptiometry,
composition, NFL, athletics, percentage fat
body
T
Address correspondence to Donald R. Dengel, [email protected].
METHODS
28(1)/1–6
Experimental Approach to the Problem
Journal of Strength and Conditioning Research
Ó 2013 National Strength and Conditioning Association
Players were instructed to be at hemostasis before all testing
sessions. Whenever possible, studies were done in the
VOLUME 28 | NUMBER 1 | JANUARY 2014 |
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Table 1 compares the physical characteristics (i.e., age,
height, weight, and BMI) of the participants by position. If
positions share a letter within each row, there is no significant difference (p . 0.05) between them. According to standard BMI categories, 2 positions OL and DL are classified as
severely obese (BMI .35 kg$m2). Three positions RB, LB,
and TE are classified as moderately obese (BMI, 30–34.9
kg$m2). The remaining positions, DB, QB, PK, and WR,
2
the
6
6
6
6
6
2.7 25.5AB
4.1 187.4C
8.5 98.4E
2.3 28.1AE
1.8
1.1A
6
6
6
6
6
2.1 23.5A 6 1.9 24.1AB
3.6 186.7C 6 3.9 181.5E
4.2 109.9C 6 4.3 105.4F
1.6 31.6C 6 1.6 32.0C
2.1
2.2A 6 2.0
2.3A
6
6
6
6
6
23.9AB
192.9D
113.9 G
30.6C
2.3AB
2.6 23.9A 6 2.3
4.1 190.9B 6 2.9
6.1 132.9B 6 14.7
2.1 36.5B 6 4.5
2.2
2.3A 6 2.4
6
6
6
6
6
PK (n = 19)
RB (n = 36)
LB (n = 55)
TE (n = 31)
DL (n = 58)
If positions share a letter within each row, they are not significantly different at p , 0.05.
OL = offensive lineman; DL = defensive lineman; TE = tight ends; LB = linebacker; RB running back; PK = punters/kickers; QB = quarterback; DB = defensive back; WR = wide
receivers; BMI = body mass index (kg$m2).
RESULTS
OL (n = 65)
Participants were categorized by position into 1 of 9
categories defensive backs (DB), defensive lineman (DL),
linebackers (LB), offensive lineman (OL), quarterbacks (QB),
running backs (RB), tight ends (TE), and wide receivers
(WR). Punters and place kickers were combined into 1
category named punters/kickers (PK). Descriptive statistics
were calculated using mean 6 SD by position. An analysis of
variance was used to test if positional mean was equal to
each other. The TukeyHSD (honest significant different)
method was used to compare each positional mean against
the next to correct for type I error from performing multiple
comparisons. Boxplots were used to present median (black
line) and variation of 6 measurements by position (i.e., percent fat, total lean mass, lean mass ratio, difference in lean
mass between legs and spinal BMD, and total mass-lean
mass ratio). On each boxplots, the middle 50% of the data
(box), range of the data (dashed lines), and possible outliers
for each measure (open circles) were displayed. All analysis
was completed using R (R Foundation for Statistical Computing, Vienna, Austria).
Position
Statistical Analyses
TABLE 1. Mean 6 SD for physical characteristics of professional football players by position.
We assessed NFL players from the Green Bay Packers
professional football team from 2006 to 2011. Players were
either active on the roster, free agents, or prospective draft
choices. Four hundred eleven NFL players (age 20-38 yrs)
were measured just before draft or before the start of the
summer training camp. This informed consent of participants
was obtained by the Green Bay Packers professional football
team. Approval was granted by the University of Minnesota’s
Institutional Review Board for statistical analysis of preexisting
data that had been collected by the Green Bay Packers professional football team over a 6-year period.
QB (n = 22)
Subjects
Age (y)
24.1AB
Height (cm)
192.8D
Weight (kg)
140.9D
BMI (kg/m2)
37.9D
Years played (y)
2.5A
DB (n = 69) WR (n = 56)
morning on off days during physical examinations or before
practice. Height and weight were measured by a standard
wall stadiometer and medical beam scale, respectively. Body
mass index was calculated as weight in kilograms divided by
the square of height in meters. Total body imaging was
acquired using a GE Healthcare Lunar iDXA (GE Healthcare Lunar, Madison, WI, USA) DXA and analyzed using
enCore software version 13.6, revision 2. No hardware or
software changes were made during the duration of the
study. Participants were scanned using standard imaging and
positioning protocols.
3.7 25.9B 6 4.6
23.6A 6 2.1 23.6A 6 1.8
4.6 188.5C 6 3.6 182.2A 6 3.1 185.7C 6 3.9
5.6 103.6F 6 13.9 90.8A 6 6.1 94.0E 6 6.0
2.3 29.2E 6 4.4
27.4A 6 1.8 27.3A 6 1.8
B
0.5
4.3 6 4.8
2.2A 6 2.3
1.9A 6 1.8
NFL and Body Composition
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TABLE 2. Mean (6SD) for body composition values of professional football players by position.
Position
OL (n = 65) DL (n = 58) TE (n = 31)
Fat (%)
28.8D (3.7)
Fat mass (kg)
39.3D (6.0)
Lean mass (kg)
96.5B (4.5)
Total BMC (kg)
5.1B (0.35)
Upper lean mass (kg)
57.3B (3.5)
Lower lean mass (kg)
35.1B (2.3)
U/L lean ratio
1.64BC (0.17)
Total mass/lean mass ratio
1.41D (0.07)
Difference in leg lean mass 20.25 to
(kg) (Q1, Q3)
0.58
1.59B (0.13)
Spine BMD (g/cm2)
25.2B (7.6)
33.3B (12.3)
95.2B (5.5)
5.0B (0.36)
55.8B (3.3)
35.2B (3.6)
1.60B (0.19)
1.35B (0.13)
20.40 to
0.37
1.57B (0.13)
16.8C (3.8)
18.4C (4.5)
90.7D (4.0)
4.9BD (0.33)
54.5B (2.8)
32.2C (1.7)
1.69AB (0.09)
1.20C (0.06)
0.18 to 0.33
LB (n = 55)
17.0C (3.2)
17.9CD (3.8)
87.3C (3.5)
4.6CD (0.29)
51.9C (3.0)
31.5C (1.8)
1.66AB (0.14)
1.21C (0.05)
0.29 to 0.40
RB (n = 36) PK (n = 19) QB (n = 22) DB (n = 69) WR (n = 56)
16.0C (4.0)
16.3C (5.3)
84.5C (4.9)
4.5C (0.36)
50.0CD (3.1)
30.6C (2.7)
1.65AB (0.15)
1.19C (0.06)
0.32 to 0.35
19.2C (4.5)
18.2C (4.8)
76.1A (4.8)
4.1A (0.32)
46.2A (3.9)
26.2A (1.7)
1.77A (0.16)
1.24C (0.07)
0.14, 0.44
19.6C (4.6)
19.5C (6.0)
78.9A (5.1)
4.4AC (0.31)
47.8AD (3.5)
27.3A (2.5)
1.77A (0.17)
1.25C (0.07)
0.28 to 0.37
12.1A (3.3)
10.6A (3.5)
76.1A 6 4.2
4.2A (0.29)
45.4A (2.4)
27.0A (2.0)
1.69AC (0.10)
1.14A (0.05)
0.21 to 0.39
12.5A (3.1)
11.3A (3.4)
78.3A (4.3)
4.3A (0.38)
46.4A (2.9)
28.2A (2.1)
1.65AB (0.13)
1.14A (0.04)
0.24 to 0.43
1.52AB (0.12) 1.53AB (0.13) 1.51AB (0.11) 1.40C (0.13) 1.45AC (0.13) 1.47AC (0.11) 1.49AC (0.12)
If positions share a letter within each row, they are not significantly different at p , 0.05.
OL = offensive lineman; DL = defensive lineman; TE = tight ends; LB = linebacker; RB running back; PK = punters/kickers; QB = quarterback; DB = defensive back; WR = wide
receivers; BMC = bone mineral content; Upper/Lower Lean Ratio = the ratio of upper-body lean mass to lower-body lean mass; BMD = bone mineral density.
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TABLE 3. Range for body composition values of professional football players by position.
OL (n = 65) DL (n = 58) TE (n = 31) LB (n = 55)
Percent fat (%)
Fat mass (kg)
Lean mass (kg)
Total BMC (kg)
Upper lean mass (kg)
Lower lean mass (kg)
U/L lean ratio
Total mass/lean mass ratio
Difference in leg lean mass (kg)
Spine BMD (g/cm2)
14.3–35.8
18.1–52.4
87.5–108.7
4.2–5.9
50.2–68.4
27.5–41.1
1.38–2.32
1.17–1.56
22.1 to 1.5
1.3–1.9
12.1–39.1
12.8–62.5
81.5–109.0
4.2–5.8
46.7–63.6
24.2–44.7
1.28–2.44
1.14–1.64
23.7 to 1.6
1.3–1.8
RB (n = 36)
8.1–25.4
10.4–25.7
10.6–25.8
8.6–29.4
11.2–28.9
9.5–29.4
80.5–98.0
80.5–96.3
74.0–92.1
4.2–5.6
4.0–5.4
3.8–5.6
48.1–58.8
44.9–57.2
42.9–56.3
28.6–35.5
28.6–36.1
22.8–34.8
1.55–1.96
1.33–1.98
1.46–2.08
1.09–1.34
1.12–1.35
1.12–1.35
21.1 to 1.2 20.94 to 0.85 20.95 to 0.94
1.3–1.8
1.3–1.8
1.3–1.7
PK (n = 19) QB (n = 22) DB (n = 69) WR (n = 56)
10.9–27.9
10.4–29.4
68.2–84.7
3.5–4.7
39.9–54.0
23.3–30.6
1.54–2.26
1.12–1.39
20.45 to 1.7
1.2–1.6
11.3–30.5
11.1–34.3
70.3–91.8
3.9–5.3
41.3–54.9
23.9–35.0
1.51–2.30
1.13–1.45
20.86 to 1.1
1.2–1.7
7.1–23.9
7.7–22.1
5.9–23.1
6.2–23.1
68.5–89.6 71.1–88.7
3.4–4.8
3.6–5.3
40.5–54.9 42.0–52.2
22.2–33.1 24.5–32.8
1.53–1.93 1.42–1.88
1.08–1.31 1.08–1.28
21.1 to 1.4 20.88 to 1.2
1.3–1.7
1.2–1.8
3
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OL = offensive lineman; DL = defensive lineman; TE = tight ends; LB = linebacker; RB running back; PK = punters/kickers; QB = quarterback; DB = defensive back; WR = wide
receivers; BMC = bone mineral content; U/L lean ratio = the ratio of upper-body lean mass to lower-body lean mass; BMD = bone mineral density.
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Position
NFL and Body Composition
Figure 1. Boxplot of percent fat by position. DB = defensive back; DL =
defensive lineman; LB = linebacker; OL = offensive lineman; PK =
punters/kickers; QB = quarterback; RB = running back; TE = tight ends;
WR = wide receivers.
Figure 3. Boxplot of ratio of U/L lean mass by position. DB = defensive
back; DL = defensive lineman; LB = linebacker; OL = offensive lineman;
PK = punters/kickers; QB = quarterback; RB = running back; TE = tight
ends; WR = wide receivers.
are all classified as overweight (BMI, 25–29.9 kg$m2). We
observed no significant differences in the number of years
played in the NFL between positions, except QB. On average, they had spent significantly longer time in the NFL,
before the scan, compared with other positions. Table 2
compares the body composition data of the participants by
position. We observed that DB and WR were never significantly different than each other. The OL had significantly
more fat mass than DL, but the 2 positions were similar for
all measures of lean mass. Interestingly, we observed that LB
and RB were not significantly different from each other for all
measures. Tight ends were significantly different from OL on
all measures except upper-body lean mass and the ratio of
upper-body to lower-body lean mass. Table 3 presents the
ranges of the body composition data by position. Figure 1 is
a boxplot of the data for percent fat by position. Figure 2
presents the data for total lean mass by position. We observe
that positions that typically mirror each other have very
Figure 2. Boxplot of total lean mass by position. DB = defensive back;
DL = defensive lineman; LB = linebacker; OL = offensive lineman; PK =
punters/kickers; QB = quarterback; RB = running back; TE = tight ends;
WR = wide receivers.
Figure 4. Boxplot of difference in right and left leg lean mass by
position. DB = defensive back; DL = defensive lineman; LB = linebacker;
OL = offensive lineman; PK = punters/kickers; QB = quarterback; RB =
running back; TE = tight ends; WR = wide receivers.
4
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U/L ratios and lower-body lean mass. Figure 4 presents the
differences in lean mass between each leg. This is the difference between the left side minus the right side. The first and
third quartiles are presented in Table 2 and are also shown by
the upper and lower edge of each box within each positional
boxplot. Players located outside the first and third quartiles
should work to balance leg lean mass. Figure 5 presents the
data for spine BMD. Offensive lineman had the highest density; however, this difference was not significantly different
than DL, LB, RB, or TE. Players with a density below the
first quartile (bottom of box) may be at increased risk of
fracture risk. Figure 6 presents the ratio of total body mass
to lean body mass by position. We observed that DB, WR,
LB, and RB had the lowest ratios, whereas DL and OL had
the highest ratios.
DISCUSSION
Figure 5. Boxplot of spine BMD by position. BMD = bone mineral
density; DB = defensive back; DL = defensive lineman; LB = linebacker;
OL = offensive lineman; PK = punters/kickers; QB = quarterback; RB =
running back; TE = tight ends; WR = wide receivers.
similar lean mass. Offensive linemen are almost equal to DL.
Running backs are similar to LB. Wide receivers are similar to
DB. Tight ends were between DL and LB. Figure 3 presents
the ratio of upper/lower lean mass (U/L ratio) by position.
The lower the ratio, the greater amount of lower-body mass
the athlete has. Defensive and offensive linemen have the
lowest U/L ratio and the highest lower-body lean mass,
whereas QB and PK had the highest U/L ratios and lowest
lower-body lean mass. Tight ends, RB, and LB had similar
Figure 6. Boxplot of ratio of total mass/total lean mass by position.
DB = defensive back; DL = defensive lineman; LB = linebacker;
OL = offensive lineman; PK = punters/kickers; QB = quarterback;
RB = running back; TE = tight ends; WR = wide receivers.
Although there have been a few papers (3,4,12,14) that have
been written on the body composition of professional football players, this study is unique that by using DXA, we are
not only able to characterize fat and lean tissue mass, but
also bone mass. In addition, the use of DXA allows us to also
examine regional body composition and total body
composition.
A number of studies (5,7,9,13) have suggested a high prevalence of obesity in professional football players. Most of
these studies have used BMI to categorize player’s level of
body composition. Unfortunately, BMI does not distinguish
between fat and lean tissue. In these highly trained athletes,
this typically results in the overstatement of disease risk. In
studies (6,14) that have used more advance methods to measure body composition so that lean and fat tissue can be
determined, most professional football players are considered to have healthy body composition when using percent
fat mass. This study supports these other studies in that
although the average BMI for most positions shows the
athlete to be overweight or obese, when the percent fat is
used, these athletes are actually lean. The only exception to
this are the OL and DL, who even when using percent fat
would considered overweight or obese in some cases.
Kraemer et al. (6) suggested that offensive and defensive
positions that mirror each other, such as OL and DL or DB
and WR would have similar body compositions values. In
this study, we also observed similar overall patterns of body
compositions in individuals who played offensive or defensive that mirrored each other. Although OL had a higher
overall percent fat and total fat mass than DL, the 2 positions
were similar in overall bone and lean mass. They also had
similar amounts of upper and lower lean mass. Therefore,
their U/L ratio was also similar for OL and DL. These
positions are meant to be anchors; neither player wants to
give up position, so a lower U/L ratio would provide a better
anchor than a player, that is, top heavy (high U/L ratio).
Tight ends proved to be a unique position having an
overall percent fat similar to RB and LB, but having an
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NFL and Body Composition
overall lean body mass greater than both RB and LB.
Regionally, the TE had more upper-body lean mass than
both RB and LB, but the lower-body lean mass was similar
for the 3 positions. Tight ends had as much upper-body lean
mass as both OL and DL. This may be because of the
demands of the position in having to block DL players, but
having to run routes against LB and DB. This may also be
a result of TE being used more as a receiver than a blocker.
There is more emphasis placed on speed and elusiveness
than being an anchor position.
As expected, DB and WR had similar overall percent
body fats and similar total lean body mass. Their distribution
of lean body for DB and WR was also very similar with the
same distribution of lean body mass in the upper and lower
regions. Speed is a priority for these positions, so it is not
surprising that there total mass to lean mass ratios were
significantly lower than all other positions.
To our knowledge, this is the first article to present body
composition data as determined using DXA on professional
football players. Our data create templates for body dimensions of NFL players at different positions. The use of the
DXA provides new data on body composition such as bone
mass and regional assessments of fat, lean, and bone mass.
PRACTICAL APPLICATIONS
The DXA allows coaches and athletic trainers the opportunity
to examine differences in muscle symmetry as a possible
precursor to injury. For example, legs can be examined as left
vs. right leg. Large differences in lean mass between legs could
increase the risk of noncontact injury. Several studies (1,2,11)
have shown that strength imbalances have an association to
increased risk of noncontact injuries, although Shambaugh
et al. (10) observed leg girth differences are associated with
increased risk of noncontact injuries. There are limitations of
these studies. The leg girth measurements cannot differentiate
between fat and muscle, whereas the strength imbalances are
measured using non–weight-bearing procedures (isokinetic
torque). Dual-energy x-ray absorptiometry is able to differentiate leg mass into bone, muscle, and fat to determine muscular imbalances. Players measured in the whiskers (dashed
lines) of Figure 4 should address this difference. The DXA
could also be used in rehabilitation to examine differences in
lean mass between arms or legs before and after rehabilitation.
Issues regarding bone density can also be examined, for
instance, Figure 5 presents the data for spine BMD. Low
6
the
BMD in the spine could indicate an increased risk for spinal
injury in a collision sport. Players identified with values below
the first quartile (bottom line of box) should address this low
value with supplementation and exercises to strengthen the
muscles that support the spine.
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