Body Composition and Bone Mineral Density of.1

8/9/2019 Body Composition and Bone Mineral Density of.1

http://slidepdf.com/reader/full/body-composition-and-bone-mineral-density-of1 1/6

Scientific Manuscript Excellence Honor: Dr. Gary A. Dudley Memorial Paper

B ODY C OMPOSITION AND B ONE M INERAL

D ENSITY OF N ATIONAL F OOTBALL LEAGUE

P LAYERSD ONALD R. D ENGEL ,1,2 T YLER A. B OSCH ,1 T. P EPPER B URRUSS ,3 K URT A.F IELDING ,3 B RYAN E. E NGEL ,3 N ATE L. W EIR ,3 AND T ODD D. W ESTON 4

1 School of Kinesiology, University of Minnesota, Minneapolis, Minnesota; 2 Department of Pediatrics,University of Minnesota Medical School, Minneapolis, Minnesota; 3 Green Bay Packers Professional Football Team, Green Bay, Wisconsin; and 4 GE Healthcare, Madison, Wisconsin

A BSTRACT

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 Res28(1): 1–6, 2014—The purpose of the present study was toexamine the body composition of National Football League(NFL) players before the start of the regular season. Four hun-dred eleven NFL players were measured for height, weight andlean, fat, and bone mass using dual-energy x-ray absorptiometry(DXA). Subjects were categorized by their offensive or defensiveposition for comparison. On average, positions that mirror eachother (i.e., offensive lineman [OL] vs. defensive lineman [DL])have very similar body composition. Although OL had more fatmass than DL, they were similar in total and upper and lower leanmass. Linebackers (LB) and running backs (RB) were similar forall measures of fat and lean mass. Tight ends were unique in thatthey were similar to RB and LB on measures of fat mass; how-ever, they had greater lean mass than both RB and LB andupper-body lean mass that was similar to OL. Quarterbacksand punters/kickers were similar in fat and lean masses. All po-sitions had normal levels of bone mineral density. The DXA al-lowed us to measure differences in lean mass between arms andlegs for symmetry assessments. Although most individuals hadsimilar totals of lean mass in each leg and or arms, there wereoutliers who may be at risk for injury. The data presented dem-onstrate not only differences in total body composition, but alsoshow regional body composition differences that may providepositional templates.

K EY WORDS dual-energy x-ray absorptiometry, bodycomposition, NFL, athletics, percentage fat

I NTRODUCTION

There is a general perception that National FootballLeague (NFL) players are bigger and carry more

fat compared with NFL players from previous dec-ades. Part of this statement may be true if we onlyuse body mass index (BMI) to examine these players.Although players may have greater body mass, they mayactually be leaner than players from previous decades.

The interest in the body composition of professionalfootball players initially started over 40 years ago (14). Pre-vious studies have reported that body composition is relatedto position (3,4,6,12,14). As advancements in methodology toexamine body composition have developed, these newermethods have been applied to the study of NFL players. Todate, most studies (6,14) have involved methods that usea 2-compartment model of body composition (i.e., fat mass

and fat-free mass) and have only been able to focus on totalbody composition. The use of hydrostatic weighing throughwater or air displacement has long been considered to be thegold 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, andbone mass) is now considered the gold standard for measure-ment of total body composition (8). Until recently DXAdevices could not accommodate individuals . 350 lbs, whichlimited their use to measure body composition in NFL play-ers. Recent improvements in technology allow newer DXAdevices to accommodate individuals who weigh 450 lbs. Thisstudy examined body composition in a number of NFL play-ers and prospects before summer training camp. This study isthe rst to examine not only fat and lean tissue mass, but alsodetermine bone mass and examine regional body composi-tion. In addition, we performed segmental analysis of leantissue, fat masses, and bone mineral density (BMD).

M ETHODS

Experimental Approach to the ProblemPlayers were instructed to be at hemostasis before all testing sessions. Whenever possible, studies were done in the

Address correspondence to Donald R. Dengel, [email protected].

28(1)/1–6 Journal of Strength and Conditioning Research

2013 National Strength and Conditioning Association

Dr. Gary A. Dudley1952-2006

VOLUME 28 | NUMBER 1 | JANUARY 2014 | 1

Co ri ht © National Stren th and Conditionin Association Unauthorized re roduction of this article is rohibited.



morning on off days during physical examinations or beforepractice. Height and weight were measured by a standardwall stadiometer and medical beam scale, respectively. Bodymass index was calculated as weight in kilograms divided bythe square of height in meters. Total body imaging wasacquired using a GE Healthcare Lunar iDXA (GE Health-

care Lunar, Madison, WI, USA) DXA and analyzed using enCore software version 13.6, revision 2. No hardware orsoftware changes were made during the duration of thestudy. Participants were scanned using standard imaging andpositioning protocols.

SubjectsWe assessed NFL players from the Green Bay Packersprofessional football team from 2006 to 2011. Players wereeither active on the roster, free agents, or prospective draftchoices. Four hundred eleven NFL players (age 20-38 yrs)were measured just before draft or before the start of thesummer training camp. This informed consent of participants

was obtained by the Green Bay Packers professional footballteam. Approval was granted by the University of Minnesota’sInstitutional Review Board for statistical analysis of preexisting data that had been collected by the Green Bay Packers pro-fessional football team over a 6-year period.

Statistical AnalysesParticipants were categorized by position into 1 of 9categories 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 1category named punters/kickers (PK). Descriptive statisticswere calculated using mean6 SD by position. An analysis of variance was used to test if positional mean was equal toeach other. The TukeyHSD (honest signicant different)method was used to compare each positional mean againstthe next to correct for type I error from performing multiplecomparisons. Boxplots were used to present median (black line) and variation of 6 measurements by position (i.e., per-cent fat, total lean mass, lean mass ratio, difference in leanmass between legs and spinal BMD, and total mass-leanmass ratio). On each boxplots, the middle 50% of the data (box), range of the data (dashed lines), and possible outliersfor each measure (open circles) were displayed. All analysiswas completed using R (R Foundation for Statistical Com-

puting, Vienna, Austria).R ESULTS

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 signi-cant difference ( p . 0.05) between them. According to stan-dard BMI categories, 2 positions OL and DL are classied asseverely obese (BMI . 35 kg $m2 ). Three positions RB, LB,and TE are classied as moderately obese (BMI, 30–34.9kg $m2 ). The remaining positions, DB, QB, PK, and WR,

T A B L E

1 .

M e a n 6 S D f o r p h y s i c a l c h a r a c t e r i s t i c s o f p r o f e s s i o n a l f o o t b a l l p l a y e r s b y p o s i t i o n .

P o s i t i o n

O L ( n = 6 5 )

D L ( n = 5 8 )

T E ( n = 3 1 )

L B ( n = 5 5 ) R B ( n = 3 6 ) P K ( n = 1 9 )

Q B ( n = 2 2 )

D B ( n = 6 9 ) W R ( n = 5 6 )

A g e ( y )

2 4 . 1 A B

6

2 . 6

2 3 . 9 A

6

2 . 3

2 3 . 9 A B

6 2 . 1

2 3 . 5 A

6

1 . 9 2 4 . 1 A B

6

2 . 7 2 5 . 5 A B

6

3 . 7

2 5 . 9 B

6

4 . 6

2 3 . 6 A

6

2 . 1

2 3 . 6 A

6

1 . 8

H e i g h t ( c m )

1 9 2 . 8 D

6

4 . 1 1 9 0 . 9 B

6

2 . 9

1 9 2 . 9 D

6 3 . 6

1 8 6 . 7 C

6

3 . 9 1 8 1 . 5 E

6

4 . 1 1 8 7 . 4 C

6

4 . 6 1 8 8 . 5 C

6

3 . 6

1 8 2 . 2 A

6

3 . 1 1 8 5 . 7 C

6

3 . 9

W e i g h t ( k g )

1 4 0 . 9 D

6

6 . 1 1 3 2 . 9 B

6

1 4 . 7

1 1 3 . 9 G

6 4 . 2

1 0 9 . 9 C

6

4 . 3 1 0 5 . 4 F 6

8 . 5

9 8 . 4 E

6

5 . 6 1 0 3 . 6 F 6

1 3 . 9

9 0 . 8 A

6

6 . 1

9 4 . 0 E 6

6 . 0

B M I ( k g / m 2 )

3 7 . 9 D

6

2 . 1

3 6 . 5 B

6

4 . 5

3 0 . 6 C

6 1 . 6

3 1 . 6 C

6

1 . 6 3 2 . 0 C

6

2 . 3 2 8 . 1 A E

6

2 . 3

2 9 . 2 E 6

4 . 4

2 7 . 4 A

6

1 . 8

2 7 . 3 A

6

1 . 8

Y e a r s p l a y e d ( y )

2 . 5 A

6

2 . 2

2 . 3 A

6

2 . 4

2 . 3 A B

6 2 . 1

2 . 2 A

6

2 . 0

2 . 3 A

6

1 . 8

1 . 1 A

6

0 . 5

4 . 3 B

6

4 . 8

2 . 2 A

6

2 . 3

1 . 9 A

6

1 . 8

I f p o s i t i o n s s h a r e a l e t t e r w i t h i n e a c h r o w , t h e y

a r e n o t s i g n i c a n t l y d i f f e r e n t a t p ,

0 . 0 5 .

O L = o f f e n s i v e l i n e m a n ; D L = d e f e n s i v e l i n e m a n ; T E = t i g h t e n d s ; L B =

l i n e b a c k e r ; R B r u n n i n g b a c k ; P K = p u n t e r s / k i c k e r s ; Q B = q u a r t e r b a c k ; D B = d e f e n s i v e b a c k ; W R = w i d e

r e c e i v e r s ; B M I = b o d y m a s s i n d e x ( k g $ m 2 ) .

NFL and Body Composition

2 Journal of Strength and Conditioning Researchthe TM






are all classied as overweight (BMI, 25–29.9 kg $m2 ). Weobserved no signicant differences in the number of yearsplayed in the NFL between positions, except QB. On aver-age, they had spent signicantly longer time in the NFL,before the scan, compared with other positions. Table 2compares the body composition data of the participants byposition. We observed that DB and WR were never signi-cantly different than each other. The OL had signicantlymore fat mass than DL, but the 2 positions were similar for

all measures of lean mass. Interestingly, we observed that LBand RB were not signicantly different from each other for allmeasures. Tight ends were signicantly different from OL onall measures except upper-body lean mass and the ratio of upper-body to lower-body lean mass. Table 3 presents theranges of the body composition data by position. Figure 1 isa boxplot of the data for percent fat by position. Figure 2presents the data for total lean mass by position. We observethat positions that typically mirror each other have very

Figure 3. Boxplot of ratio of U/L lean mass by position. DB = defensiveback; DL = defensive lineman; LB = linebacker; OL = offensive lineman;PK = punters/kickers; QB = quarterback; RB = running back; TE = tightends; WR = wide receivers.

Figure 4. Boxplot of difference in right and left leg lean mass byposition. 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 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 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.






similar lean mass. Offensive linemen are almost equal to DL.Running backs are similar to LB. Wide receivers are similar toDB. Tight ends were between DL and LB. Figure 3 presentsthe ratio of upper/lower lean mass (U/L ratio) by position.The lower the ratio, the greater amount of lower-body massthe athlete has. Defensive and offensive linemen have thelowest U/L ratio and the highest lower-body lean mass,whereas QB and PK had the highest U/L ratios and lowestlower-body lean mass. Tight ends, RB, and LB had similar

U/L ratios and lower-body lean mass. Figure 4 presents thedifferences in lean mass between each leg. This is the differ-ence between the left side minus the right side. The rst andthird quartiles are presented in Table 2 and are also shown bythe upper and lower edge of each box within each positionalboxplot. Players located outside the rst and third quartiles

should work to balance leg lean mass. Figure 5 presents thedata for spine BMD. Offensive lineman had the highest den-sity; however, this difference was not signicantly differentthan DL, LB, RB, or TE. Players with a density below therst quartile (bottom of box) may be at increased risk of fracture risk. Figure 6 presents the ratio of total body massto lean body mass by position. We observed that DB, WR,LB, and RB had the lowest ratios, whereas DL and OL hadthe highest ratios.

D ISCUSSION

Although there have been a few papers (3,4,12,14) that havebeen written on the body composition of professional foot-ball players, this study is unique that by using DXA, we arenot only able to characterize fat and lean tissue mass, butalso bone mass. In addition, the use of DXA allows us to alsoexamine regional body composition and total bodycomposition.

A number of studies (5,7,9,13) have suggested a high prev-alence 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 distinguishbetween fat and lean tissue. In these highly trained athletes,this typically results in the overstatement of disease risk. Instudies (6,14) that have used more advance methods to mea-sure body composition so that lean and fat tissue can bedetermined, most professional football players are consid-ered to have healthy body composition when using percentfat mass. This study supports these other studies in thatalthough the average BMI for most positions shows theathlete to be overweight or obese, when the percent fat isused, these athletes are actually lean. The only exception tothis are the OL and DL, who even when using percent fatwould considered overweight or obese in some cases.

Kraemer et al. (6) suggested that offensive and defensivepositions that mirror each other, such as OL and DL or DBand WR would have similar body compositions values. Inthis study, we also observed similar overall patterns of body

compositions in individuals who played offensive or defen-sive that mirrored each other. Although OL had a higheroverall percent fat and total fat mass than DL, the 2 positionswere similar in overall bone and lean mass. They also hadsimilar amounts of upper and lower lean mass. Therefore,their U/L ratio was also similar for OL and DL. Thesepositions are meant to be anchors; neither player wants togive up position, so a lower U/L ratio would provide a betteranchor than a player, that is, top heavy (high U/L ratio).

Tight ends proved to be a unique position having anoverall percent fat similar to RB and LB, but having an

Figure 5. Boxplot of spine BMD by position. BMD = bone mineraldensity; 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 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.

Journal of Strength and Conditioning Researchthe TM

| www.nsca.com

VOLUME 28 | NUMBER 1 | JANUARY 2014 | 5




overall lean body mass greater than both RB and LB.Regionally, the TE had more upper-body lean mass thanboth RB and LB, but the lower-body lean mass was similarfor the 3 positions. Tight ends had as much upper-body leanmass as both OL and DL. This may be because of thedemands of the position in having to block DL players, but

having to run routes against LB and DB. This may also bea result of TE being used more as a receiver than a blocker.There is more emphasis placed on speed and elusivenessthan being an anchor position.

As expected, DB and WR had similar overall percentbody fats and similar total lean body mass. Their distributionof lean body for DB and WR was also very similar with thesame distribution of lean body mass in the upper and lowerregions. Speed is a priority for these positions, so it is notsurprising that there total mass to lean mass ratios weresignicantly lower than all other positions.

To our knowledge, this is the rst article to present bodycomposition data as determined using DXA on professionalfootball players. Our data create templates for body dimen-sions of NFL players at different positions. The use of theDXA provides new data on body composition such as bonemass and regional assessments of fat, lean, and bone mass.

P RACTICAL A PPLICATIONS

The DXA allows coaches and athletic trainers the opportunityto examine differences in muscle symmetry as a possibleprecursor to injury. For example, legs can be examined as leftvs. right leg. Large differences in lean mass between legs couldincrease the risk of noncontact injury. Several studies (1,2,11)have shown that strength imbalances have an association toincreased risk of noncontact injuries, although Shambaughet al. (10) observed leg girth differences are associated withincreased risk of noncontact injuries. There are limitations of these studies. The leg girth measurements cannot differentiatebetween fat and muscle, whereas the strength imbalances aremeasured using non–weight-bearing procedures (isokinetictorque). Dual-energy x-ray absorptiometry is able to differen-tiate leg mass into bone, muscle, and fat to determine muscu-lar imbalances. Players measured in the whiskers (dashedlines) of Figure 4 should address this difference. The DXAcould also be used in rehabilitation to examine differences inlean 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

BMD in the spine could indicate an increased risk for spinalinjury in a collision sport. Players identied with values belowthe rst quartile (bottom line of box) should address this lowvalue with supplementation and exercises to strengthen themuscles that support the spine.

R EFERENCES

1. Baumhauer, JF, Alosa, DM, Renstrom, AF, Trevino, S, andBeynnon, B. A prospective study of ankle injury risk factors. Am J Sports Med 23: 564–570, 1995.

2. Ekstrand, J and Gillquist, J. Soccer injuries and their mechanisms:A prospective study. Med Sci Sports Exerc 15: 267–270, 1983.

3. Fry, AC and Kraemer, WJ. Physical performance characteristics of American collegiate football players. J Appl Sport Sci Res 5: 126–138,1991.

4. Gleim, GW. The proling of professional football players. Clin Sports Med 3: 185–197, 1984.

5. Harp, JB and Hecht, L. Obesity in the National Football League.JAMA 293: 1061–1062, 2005.

6. Kraemer, WJ, Torine, JC, Silvestre, R, French, DN, Ratamess, NA,Spiering, BA, Hateld, DL, Vingren, JL, and Volek, JS. Body size andcomposition of National Football League players. J Strength Cond Res 19: 1061–1062, 2005.

7. Miller, MA, Croft, LB, Belanger, AR, Romero-Corral, A,Somers, VK, Roberts, AJ, and Goldman, ME. Prevalence of metabolic syndrome in retired National Football League players. Am J Cardiol 101: 1281–1284, 2008.

8. Oates, MK, Puhl, S, and Wacker, WK. Total body % fat—comparisonof DXA with other body composition methods. J Bone Miner Res 21:S117, 2006.

9. Selden, MA, Helzberg, JH, Waeckerle, JF, Browne, JE, Brewer, JH,Monaco, ME, Tang, F, and O’Keefe, JH. Cardiometabolicabnormalities in current National Football League players. Am J Cardiol 103: 969–971, 2009.

10. Shambaugh, JP, Klein, A, and Herbert, JH. Structural measures aspredictors of injury basketball players. Med Sci Sports Exerc 23: 522–527, 1991.

11. Soderman, K, Alfredson, H, Pietila, T, and Werner, S. Risk factors forleg injuries in female soccer players: A prospective investigationduring one out-door season. Knee Surg Sports Traumatol Arthrosc 9: 313–321, 2001.

12. Snow, TK, Millard-Stafford, M, and Rosskopf, LB. Bodycomposition prole of the NFL players. J Strength Cond Res 12: 146–149, 1998.

13. Tucker, AM, Vogel, RA, Lincoln, AE, Dunn, RE, Ahrenseld, DC,Allen, TW, Castle, LW, Heyer, RA, Pellman, EJ, Strollo, PJ Jr,Wilson, PWF, and Yates, AP. Prevalence of cardiovascular diseaserisk factors among National Football League players. JAMA 301:2111–2119, 2009.

14. Wilmore, JH and Haskell, WL. Body composition and endurancecapacity of professional football players. J Appl Physiol 33: 564–567,1972.



Documents

Body Composition and Bone Mineral Density of.1