In an effort to improve performance, competitive athletes devote considerable time and effort into mastering a sport by practicing and developing a set of skills required for the sport. Athletes also participate in extensive training and conditioning in an effort to maximize fitness and develop appropriate body size and body composition for successful performance. In many competitive sports, it is easy to visually observe that athletes appear much larger in body size than in past years. This is particularly noticeable in American football. Of all the position players, offensive and defensive linemen tend to be the tallest, heaviest, and have the highest percentage of body fat. Other position players such as linebackers, fullbacks, and tight ends appear to have had significant body mass changes and show impressive musculature compared with previous generations of players. Wide receivers, running backs, and defensive backs appear to have the least significant alterations in body size but still have visually noticeable changes in body composition compared with those who have played the position many years ago. The changes in body size and body composition are in part because of improved strength and conditioning programs, better overall training practices, enhanced nutritional intake, and possibly even the use of performance enhancing drugs.
Overall body size has always played an important role in American football, but anecdotally there seems to be a dramatic change in the size of present day American football players. Although numerous studies have documented the body size and body composition of American football athletes of various playing positions from both college and professional players in different time periods, only a few studies have reported the body size and body composition of players over time (24,44,51). Furthermore, we have found no studies that documented the changes in body size and body composition over the past 70 years. Through a systematic data collection process using peer-reviewed journals, the changes in height, body weight, and body composition for American football players over the past 70 years can be recorded and evaluated over time.
The purpose of this study was to document the changes in height, body weight, and body composition of American football players from the years 1942 to 2011. We provide this information for use by athletic coaches and trainers, strength and conditioning specialists, and sports science researchers. This information should serve as a reference for the changes in body height, weight, and composition that have occurred over time, as well as a reference for what the average body height, weight, and composition of football athletes may be for positions at the college and professional level. The primary hypothesis was that college and professional level players would have a significant increase in height and body weight over the observed time period. The secondary hypothesis was that offensive and defensive lineman would have a significant increase in body composition over the observed time period.
Experimental Approach to the Problem
Intuitively, it seems that the body height, weight, and composition of an American football player have noticeably changed from the early playing days to the present time. However, there has been no systematic documentation of any possible changes. The playing career of a college football player is typically limited to 4–6 years, whereas the playing career of a professional player is highly variable and can typically last between 1 and 15 years. Consequently, a longitudinal prospective study of individual changes in body height, weight, and composition would be challenging and be limited to the time period studied. Therefore, this cross-sectional study was designed to investigate, by the playing level and playing position, the differences in body height, weight, and composition for college and professional football players over the past 70 years through a systematic review of data reported in academic journal articles.
Detailed searches were performed using Sport Discus and Index Medicus for English language studies from September 1, 1971 to August 1, 2011. Words and phrases used in searches included “football,” “height,” “body weight,” and “body composition.” Cross-referencing of bibliographies from previously retrieved studies and articles was conducted. Seventy-five studies were identified for review. A total of 55 studies were selected for inclusion and data analyses. Studies selected met the requirements of (1) having at least 2 of the 3 dependent variables (body height, body weight, and body composition) reported in the Results section; (2) containing a reported skill level of either college or professional; (3) providing measured data, not self-reported data; and (4) published studies in English language journals only.
Data were recorded in a Microsoft Excel spreadsheet. Each data entry represented a group of subjects from a study in which there was a measurement of a dependent variable. Variables recorded from each study were the following: body height (cm), body weight (kg), body composition (%fat), method of obtaining body composition, number of subjects in calculated mean, skill level (college, professional), and football playing position (quarterback, running back, wide receivers, defensive backs, tight ends, linebackers, offensive linemen, and defensive linemen).
For statistical analyses and presentation, the data were split into 2 groups based on skill level (college and professional). In each skill level, all players were grouped together and then each of the playing positions were grouped into 3 different categories: mixed linemen (offensive and defensive linemen, tight ends, and linebackers), mixed offensive backs (quarterback and running backs), and mixed skilled players (defensive backs and wide receivers). We also combined all data together for both college and professional players. R-software for statistical computing (http://www.r-project.org/) was used to generate scatterplots and compute simple linear regression slopes and corresponding 95% confidence intervals (CI) by regressing 3 primary variables (body height, body weight, and body composition) against year for college and professional football players’ data. To determine whether the individual regression slope was significantly different from zero, a t-test for simple linear regression was used at 5% significance level. Statistical significance was set at p < 0.017, to correct for multiple testing.
Data for college football players were collected from the following articles for body height (1,4–15,18–20,22–28,30–35,38–41,43,44,46,47,49,52) (54,57–59), body weight (1,3–15,18–20,22–28,30–35,38–41,43–47,49,51,52) (54,57–59), and body composition (1,3–9,11,14,18,24,25,28,30–32,34,38–41,43–47,49,51,52) (54,57,58,60). Data for professional football players were collected from the following articles for height (2,29,48,50,55,58,61), body weight (2,17,29,48,50,55,58,61), and body composition (2,17,29,50,55,58,61).
Figures 1 and 2 illustrate the change in body height from 1959 to 2011 for college football players and from 1942 to 2011 for professional football lineman, respectively. The average change in body height for every year was between −0.048 and 0.502 cm for mixed offensive backs, 0.034–0.188 cm for mixed lineman, −0.073 to 0.119 cm for mixed skilled, and −0.011 to 0.112 cm for all positions combined. We can state with 95% confidence that these results are significantly different from zero for mixed lineman but not for mixed offensive backs, mixed skilled players, and all positions combined (Table 1). For professional football players, the average change in body height for every year is somewhere between −0.214to 0.316 cm for mixed offensive backs, −0.073to 0.096 cm for mixed lineman, −0.207 to 0.061 cm for mixed skilled, and −0.080 to 0.107 cm for all positions combined. We can state with 95% confidence that these results are not significantly different from zero for mixed offensive backs, mixed lineman, mixed skilled players and all players combined (Table 2).
Figures 1 and 2 illustrate the change in body weight from 1959 to 2011 for college football players and from 1942 to 2011 for professional football players. The average change in body weight for every year is somewhere between 0.089 and 0.208 kg for mixed offensive backs, 0.338–0.900 kg for mixed lineman, 0.078–0.334 kg for mixed skilled, and 0.160–0.570 kg for all positions combined. We can state with 95% confidence that these results are significantly different from zero for mixed lineman, mixed skilled players, and all players combined, but not for mixed offensive backs (Table 1). For professional football players, the average change in body weight for every year is somewhere between 0.180 and 0.545 kg for mixed offensive backs, 0.098–0.756 kg for mixed lineman, −0.015 to 0.305 kg for mixed skilled, and −0.046 to 0.570 kg for all positions combined. We can state with 95% confidence that these results are significantly different from zero for mixed offensive backs and mixed lineman, but not significantly different from zero for mixed skilled players and all players combined (Table 2).
Figures 1 and 2 illustrate the change in body composition from 1959 to 2011 for college football players and from 1942 to 2011 for professional football lineman. The average change in body composition for every year is somewhere between −0.133 and 0.127% fat for mixed offensive backs, 0.046–0.275% fat for mixed lineman, −0.053 to 0.164% fat for mixed skilled, and 0.030–0.278% fat for all positions combined. We can state with 95% confidence that these results are significantly different from zero for mixed lineman and for all players combined, but not for mixed offensive backs and mixed skilled players (Table 1). For professional football players, the average change in body composition for every year is somewhere between −0.071 and 0.236% fat for mixed offensive backs, −0.053 to 0.170% fat for mixed lineman, −0.065 to 0.139% fat for mixed skilled, and −0.082 to 0.142% fat for all positions combined. We can state with 95% confidence that these results are not significantly different from zero for mixed offensive backs, mixed lineman, mixed skilled players, and all players combined, respectively (Table 2).
The data used in this study cover 70 years and were derived from published journal articles in which a measured body height, body weight, and body composition were reported. Regression slopes were calculated for college and professional football players for each of the dependent variables for the following playing positions: mixed linemen, mixed offensive backs, mixed skilled players, and all positions combined. The results of this study show that over time there has been a significant increase in body weight for all college football players (mixed linemen, mixed offensive backs, mixed skilled, and all positions combined) and for profession football players (mixed linemen and mixed offensive backs). The results also show that there was a significant increase in percent body fat for college football players (mixed lineman and all positions combined). The obtained results also show that there has been no significant change in body height for college level players, whereas for professional level players there has been no significant change over time in both body height and body composition.
As the game of American football has evolved at the college and professional level with a greater demand for bigger athletes, there is greater emphasis on year-round training, proper nutrition, and the desire to be as physically large as possible while still maximizing running speed and quickness. This has led football players to use year-round advanced training programs, consume nutritionally appropriate diets, and use performance enhancing ergogenic aids to increase muscle size and strength.
Physical training is an important component for the development of muscle size. Early in the history of football, there was little training performed for the specific purpose of increasing body size. Training regimens consisted of callisthenic types of activities and little formal resistance exercise training (personal correspondence with older former college and professional players). Furthermore, off-season training was often limited to a short time period before the start of the season. Over time, a transition to year-round training using exercises specifically designed to increase muscle size and strength has occurred. These new and improved programs have helped athletes increase their body weight during training. Additionally, the prevalence of professionally educated and trained strength and conditioning coaches has increased so that all college and professional football teams have individuals working in these positions. For example, the founding of the National Strength and Conditioning Association in 1978 gave rise to knowledgeable professionals helping athletes increase body size through proper training and conditioning programs. All these training factors have probably contributed to the increase in body weight and body composition.
Another factor contributing to the changes observed in body weight and body composition over time is the use of improved nutritional intake. This is especially true as it relates to adequate carbohydrate and protein intake during training (53). Numerous studies have demonstrated the importance of adequate carbohydrate and protein intake during training for the purpose of increasing body weight and muscle mass (53). Furthermore, an appropriate macronutrient intake is especially important during periods of heavy training when attempting to increase muscle mass (53).
The use of performance enhancing ergogenic aids designed to increase muscle strength and size may also be a likely contributor to the change in body weight observed among college and professional football players. Several ergogenic aids have been shown to significantly increase body weight and muscle mass: creatine (56), beta-hydroxy-beta-methylbutyrate (36), and anabolic steroids (21). In particular, anabolic steroids, when combined with a resistance exercise training program, result in an increase in body weight and muscle mass (16,21,37). The use of anabolic steroids has been prevalent in football at many levels and may have also likely contributed to the changes in weight observed over the past 70 years. The use of anabolic steroids to increase muscle mass was first reported in the early 1940s (21,42). Although college and professional football governing bodies have outlawed the use of steroids, it has been reported that many players, particularly offensive and defensive linemen, use them in an effort to increase body size and muscular strength (21).
A number of rule changes may have also contributed to the change in body weight and body composition among college and professional American football players over the past 70 years. As the game of football developed, there have changes to the rules governing the sport. In 1951, a rule was implemented that no offensive guard or tackle including the center could catch the ball on a forward pass. This limited the offensive lineman's job to just blocking and took away the skilled aspect for that position group. Additionally, in 1971, a rule against blocking below the waist was implemented. This rule change took away the use of the chop block and scramble block, both of which provided an advantage for small and quick offensive linemen. As a consequence, there was an increased demand for larger and stronger linemen. It is also possible that different types of offensive and defensive schemes have contributed to the changes in body size and composition over the past 70 years. For example, larger offensive linemen provide better pass protection for the quarterback on a team that might use a passing offense. Additionally, larger defensive linemen, because of their large size, make effectively running the football in the middle of the line more difficult to accomplish.
There are several factors that could be considered as limitations to this study. First, the mixed levels (divisions 1, 2, and 3) of college football players reported in the research literature may have masked more profound changes in the division 1 level subjects. Although no published studies have directly compared height, body weight, and body composition across college level divisions, the larger, stronger, and faster players are more commonly found in the division 1 level. Second, the evolution of the game through various playing eras could result in one type of offensive or defensive strategy prevailing at a particular time or with a particular team and therefore influencing the results for a specific time period. Finally, combining the various positions together for the analysis could also influence the changes in the dependent variables. For example, wide receivers could get taller in height and defensive backs shorter in height. In a combined group, these changes would be diluted in the data set. However, despite these limitations, we feel confident that the data presented in this article supports what is intuitively known, that college and professional football players have increased body size during the past 70 years.
Results from this study could be used in a number of general ways as athletes and programs constantly change. The reported values may be representative of the body size and composition of college and professional football athletes. This would provide a standard size for comparing changes in body height, body weight, and composition in professional and collegiate football players per position. Coaches and athletes could use the results to set obtainable goals dealing with body size and composition. This study could also be used to examine the health implications of excessive weight gains in specific position groups. As observed in the study, there has been a significant increase in weight and a change in body composition in mixed linemen. These increases are seen as necessary in professional and collegiate football players, but for the nonathletic person in America, the weight and body composition values would be viewed as having a negative effect on health. Finally, this study can be used to provide a context for how American football has evolved over the past 70 years. The game has changed significantly and the changes in body size and composition have played a huge factor in how the game is played.
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