American football players, in general, have a unique morphological profile. This is due to the nature of the sport, which is largely composed of brief sessions of extremely intense, powerful bodily movements, often against strong forces of resistance. In order for a player to be successful on the field of play, he must be able to undergo these highly exergonic sessions without succumbing to energy depletion and powerful opposing forces, which might result in injury or rapid fatigue. The successful athletes in this sport tend to be heavily muscled, a body type that is conducive to the development of explosive power. Indeed, modern strength and conditioning programs have been designed to facilitate the development of this body type for the athletes in competitive football programs on every level.
However, it has been suggested that while these body types contribute to success on the playing field, they may also contribute to the increased risk of cardiovascular disease (CVD). For instance, it was observed in a 1994 study that while professional football players in general do not have diminished life expectancies, those players grouped into the highest body mass index (BMI) category were estimated to be six times as likely to die from cardiovascular disease compared to the general population (3). Unfortunately, BMI measures do not differentiate between muscle and fat tissue. Thus, it is not clear what role body fat plays in the excess health risk of professional football athletes. It is well established in the general population that obesity is a strong CVD risk marker; there is no logical reason to suggest that this would not be true of football players as well. Because of (a) the established link between body size (or fatness) and CVD and (b) the identification of football players as a very specific “at-risk” population, it behooves the players, coaches, and associated health care providers to develop morphological profiles of football players on all competitive levels to identify those individuals who may be placed at the greatest risk of early mortality. Intervention strategies can then be initiated by conscientious medical personnel to reduce player health risk.
Between 2000 and 2005, we found only four studies in which morphological profiles were developed to characterize those football athletes skilled enough to compete at the collegiate and profession levels (6,10,12,13). We have been unable to identify a single published study in which physical profiles were completed on young football athletes before they began their first full season as National Collegiate Athletic Association (NCAA) Division I players. Also, it is widely accepted by coaches and spectators that the younger players of today are on average larger than their peers of just 10 to 20 years ago. This perception requires research verification. Thus, a need exists for more published data to characterize football athletes entering an NCAA Division I football program with respect to body size and composition, both factors that theoretically contribute to football game success and risk of CVD. It is also important to characterize football athletes by projected playing position. Such data can serve to benchmark performance and morphological changes as athletes mature and engage in intense physical conditioning throughout their collegiate careers.
Kraemer et al. (10) published body composition data from National Football League players and compared these data to those previously published by Wilmore and colleagues (16,17) and Snow et al. (15). These data represent football players considered successful in the sport so far as to secure a position on a professional football team. It is clearly of value to compare these data from professionals to corresponding data from younger football players who are just entering a collegiate strength and conditioning program. In addition to the importance of evaluating these data with respect to health risk as previously discussed, these comparisons can be used to benchmark training goals for the younger players as a function of playing position.
Considering the lack of recent published literature, especially in young players just entering an NCAA Division I football program, and the potential performance and health implications of research findings, additional research is warranted to determine the physiological and morphological characteristics of football athletes. The purposes of this study, therefore, were to (a) establish a position-by-position morphological profile of first-year players entering an NCAA Division I football program, (b) compare their physical profiles to those of established players on a professional level, and (c) characterize these first-year players based on known CVD risk factors.
Experimental Approach to the Problem
In order to determine the morphological characteristics of first-year collegiate football players, first-year recruits to an NCAA Division I football program were selected to undergo body composition measurements in an exercise physiology laboratory. These data were grouped by projected player position and compared to published data for professional football athletes. The first-year player morphological findings were also evaluated for body composition health risk as established by national normative data.
This sample group was composed of true freshman (n = 57) and transfer players (n = 8), primarily from junior college football programs. These players had been recruited into the football program at Texas A&M University. The tests by which the data were collected were conducted in early August of 2003 to 2005 just prior to the beginning of twice per day football practices. Listed in Table 1 are the abbreviations for player positions that were reported. Each of the participating players read and signed an informed consent form before tests were administered.
The morphological data were obtained by trained exercise physiologists and staff at the Sydney and J.L. Huffines Institute for Sports Medicine and Human Performance on the campus of Texas A&M University. Body morphological data included height, weight, and body fat analysis. Height was observed as the subject stood without shoes, with his back against a measurement tape placed vertically on a wall. Body mass was determined with the subject wearing workout shorts on a mechanical and calibrated weight scale immediately prior to assessment of body composition. Body composition analysis was obtained via the hydrostatic weighing technique at residual volume (9). In brief, our equipment for the hydrostatic procedure in this study used digital load cells fitted to an aluminum chair submerged in a tank filled with warm (34°-36°C) water. The load cells send output to a computer with a customized program installed to remove the wave artifact of the water and calculate body density, lean body mass, and fat percentages at residual volume. The subjects were instructed to fast for 4-6 hours prior to weighing, remove all jewelry, and void the bladder and bowels before entering the hydrostatic tank. Once seated on the weight chair in the tank, each subject was asked to bend forward at the waist until completely submerged, while exhaling to residual volume. This procedure was repeated until three recordings were obtained within 1% deviation; the average of these three values was considered the true hydrostatic value. Body mass index was calculated by dividing body mass (kg) by the square of the height (m2).
Data analysis was performed via analysis of variance (ANOVA) using SAS statistical analysis software. Descriptive statistics were performed to obtain means, SDs, and value ranges. Duncan's multiple range test was performed to compare dependent variables by player position. Significance was established as P ≤ 0.05.
For the results to follow by playing positions, “>” indicates significantly different, P ≤ 0.05 and “=” indicates nonsignificance. Note that the results presented below reflect comparisons of groups on opposing sides of “=” or “>” signs. See Table 2 for average values by position.
Offensive line (OL) = tight end (TE) = defensive line (DL) > quarterbacks (QBs) = linebackers (LBs) = kickers (Ks) = wide receivers (WRs) > defensive backs (DBs) = running backs (RBs).
OL = DL > TEs = LBs = RBs = QBs = WRs = Ks = DBs.
Body Fat Percentage
OL = DL = LBs = RBs = TEs = WRs = DBs = Ks = QBs.
Body Mass Index
OL = DL = RBs = TEs = LBs > QBs = DBs = WRs = Ks.
As shown in Table 2, the OL group tended to have the highest values for the morphological variables. The OL and TE players tended to be the tallest while OL and DL players were significantly the heaviest. The OL players tended to express the highest percentage of fat. The OL and DL players were also observed to have the highest BMI.
When the pooled data from our collegiate players were compared to those from professional players as reported by Kraemer et al. (10) (Table 3), the following tendencies were observed: freshmen were taller (189 cm > 188 cm), body masses were similar (107 kg = 107 kg), professional players were marginally leaner (14% < 15%), and the BMI values were only slightly greater in professional players (30 > 29.8).
When player positions were categorized with regard to BMI and body fat percentage to determine health status, there were conflicting results (Table 4). The collegiate players in our study, when judged by BMI, would be classified as overweight or obese. However, the average body fat percentages for all collegiate players by positions would be considered to be within an acceptable age- and gender-referenced normal range (2).
Profiles for football players have previously been reported for players on the professional (1,7,10,14,15,16) and collegiate (6,12,13) competitive levels. However, most of these profiles are rather dated and may not adequately reflect the profiles of today's players. For example, of the published studies that we have reviewed in which profiles of football players have been reported, 72% were published prior to 1995. In one of the more recent studies, Secora et al. (13) collected physical and performance profiles for collegiate football players from 37 NCAA Division I football programs to compare players from 1987 and 2000. However, their data were obtained via surveys sent to the universities to be completed by the strength and conditioning coaches of each university. Although their results contribute valuable information to the body of knowledge with respect to football athletes, the survey method has well-known methodological weaknesses. For example, the procedures used for obtaining body composition were not detailed in their methods, thus leaving open the possibility that there were different methodologies employed to measure body composition by the universities surveyed. Survey methods were also used by Garstecki et al. (6) in 2004. Noel et al. (12) determined the body composition of Division I football players experienced in the strength and conditioning program at Michigan State University. The previously referenced papers considered slightly older players (ages averaged 19-20 years) already experienced in a conditioning program at their respective universities. To our knowledge, these previously published studies did not include first-year players uninfluenced by a collegiate strength and conditioning regimen.
In 2005, Kraemer et al. (10) reported body composition data obtained from 53 professional football players who were members of the Indianapolis Colts football team (Table 3). Comparative values for variables from first-year players in our study and those reported by Kraemer et al. (10) for professional players are shown in Figures 1 to 4. Body fat analysis data in Kraemer et al. (10) were obtained via the BOD POD, an air displacement plethysmography system. Trends in body composition values relative to playing position were similar to what we report in our present study. With regard to height, with the exception of QBs and Ks (Ks/Ps), the first-year collegiate players tended to be taller than their professional counterparts (Figure 1). The most notable difference was observed in the WR group. The first-year collegiate wide receivers were 5.8 cm taller than professional WRs. The first-year collegiate players tended to have less body mass than the professional players (Figure 2). Of interest in these comparisons is the observation that the first-year LB, WR, DB, and RB players tended to have a higher percentage of body fat than did the professional players while the professional OL, TE, DL, and QB players tended to demonstrate comparatively greater body fat percentages. We cannot rule out the possibility that at least a portion of the differences noted in body composition are due to differences in the study methodologies (BOD POD versus hydrostatic) (4). However, it is likely that these differences predominantly reflect the maturity and training history of the professional athletes and also come about as a natural consequence of the highly selective process of the professional football draft system, in which only the very best collegiate athletes are chosen. The trends for BMI that were reported for professional players are mirrored in our first-year players as well (Figure 4). This would be expected, in light of the fact that similar trends in body mass were also observed in the two groups.
It is empirically evident to even the casual observer that the morphological characteristics of football athletes are rapidly changing. The rate of change within this sport warrants a periodic review and, if necessary, revision of the published normative data describing the athletes participating in professional and collegiate football programs. A descriptive profile of the football athletes is of value to exercise physiologists as well as strength and conditioning personnel as a benchmark for player position-by-position comparisons. As noted previously, there is also a deficiency of published data describing players entering an NCAA Division I football program. Anecdotal evidence suggests that the morphological characteristics of these relatively younger players are considerably different than they were 10 and 20 years ago. For instance, when our data are compared to those on experienced players described in other studies, our first-year players were larger than experienced position players of the past who actively participated on the playing field (6, 12, 13). However, because there are no previously published profiles for first-year collegiate players to which we can compare our findings, we cannot be certain of this perceived historical change in player physical characteristics. Thus, the data that we present here provide important new information that will serve as an historical benchmark to evaluate changes in the physical characteristics of first-year NCAA Division I football athletes of the future.
The body morphology results of the players in our study are consistent with the game-type player position specialization requirements. For example, the positions specialized for line-of-scrimmage blocking and tackling (OL and DL) were comparatively taller and heavier than players at other positions. The positions specialized for sprinting and dynamic agility (WR, RB, and DB) expressed lower height, weight, body fat percentages, and BMI compared to the overall group of players. The players in this group are required to be lighter and more agile in order to move quickly and rapidly change directions in various planes of motion.
Comparatively, our SDs (a measure of variance) for WT and BF were greater than those reported from professional players by Kraemer et al. (10). This would be expected because the professional athletes have been carefully selected in the football draft system from a larger pool of available collegiate players, therefore greatly reducing the variation from player to player at any one position. We also speculate that this greater variance may be due to the fact that our younger players had not been subjected to the rigors of a specialized strength and conditioning program, which might serve to uniformly mold the individuals within each player position into a more homogeneous morphology.
In light of recent publications reporting widespread obesity for retired professional football players (8) and the negative health implications of obesity for those retired from the sport (3), it was of interest to compare indices of obesity in our sample of young collegiate players to those in professional players. The observed group average BMI, body fat percentage, and obesity-related health risk of the young players in our study proved to be similar to those observed in the professional players. All players stratified by position would be classified as either overweight or obese based on BMI alone. However, with regard to body fat percentages, the averages of the first-year athletes in our study at all playing positions would classify them in an acceptable range compared to their age- and gender-matched norm values (11). This illustrates the disparity between two accepted methods of determining obesity-related health status of athletes. One may logically assume that BMI is the less precise predictor of cardiovascular risk because it does not account for the portion of the body mass that is composed of fat. It is apparent that despite being overweight as estimated by BMI, the young athletes in our study were not overly fat. Whether BMI is a valid predictor of cardiovascular risk in this population is open to question, a question that will require longitudinal research over many years to conclusively answer.
Our data are descriptive of first-year football recruits entering an NCAA Division I football program and will serve as a player position-specific baseline for comparisons among first-year football athletes at other NCAA Division I university programs. Our data also show that the body morphology trend across all playing positions for the first-year players generally mirrors that of the corresponding professional players, e.g., OL players are the tallest and heaviest, while DBs are the shortest and lightest, whether professional or amateur. This suggests that specific body types, whether in professional or amateur players, are related to success at specific playing positions. Our data also serve to benchmark obesity-related health risk in young football players. Although first-year football players are on average overweight and obese by BMI standards, a more precise measure of body composition demonstrates they are not overly fat. Longitudinal studies after the football athlete's competitive experience ends should be undertaken to determine the extent to which BMI and body fat predict future CVD morbidity and mortality in this population. It is possible that many of the aging players retain their high body masses with a change to a higher percentage of body fat after retirement; this would increase their CVD risk and mortality. Our data may also be used to assess the developmental and training-induced changes players experience as they progress through strength and conditioning programs specific for football. It should be noted that the profiles that we report in this study are reflective of the players recruited into the football program at a particular Division I university and may not represent players entering other Division I, II, or III universities. Fry and Kraemer (5) demonstrated that certain performance characteristics differentiated between football players of the different divisions. Thus, the morphological characteristics between the divisions of play may be differentiated as well and may reflect the collegiate recruiting process. Furthermore, morphology may vary in relation to the strategic systems employed in each football program, as well as in relation to the makeup of the recruiting population of any given university. If a team is built on a pass-oriented offensive scheme, it might be expected that the players recruited into these programs differ in morphology compared to those recruited to play in an offense oriented toward the running game. How these data relate to the ultimate success of the athletes on the football playing field has yet to be determined. Some data may not be completely indicative of the player's capacity to perform on the field of play and would be given better perspective when considered relative to the general population and relative to the general health of the athlete.
In our historical comparisons, we cannot rule out an effect of recent rule changes within the sport of football that may influence the morphological makeup of players who are successful at various positions. For example, rule changes that restrict below-the-waist blocking techniques have created a demand for a larger body size and mass in present-day compared to former offensive lineman. It follows that an emphasis on larger athletes may significantly increase CVD risk of these players, especially if the increase in mass during a player's active years is followed by an increase in body fat after retirement. As rule changes are made in the future, player morphological profiles will likewise change to optimize performance within the rules. Once again, our data presented here can serve as a historical benchmark to document changes in player morphology that may occur in response to future rule changes in the game.
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