Comparison of physical and performance characteristics of NCAA Division I football players: 1987 and 2000

The purpose of this study was to compare normative data from present Division I National Collegiate Athletic Association football teams to those from 1987. Players were divided into 8 positions for comparisons: quarterbacks (QB), running backs (RB), receivers (WR), tight ends (TE), offensive linemen (OL), defensive linemen (DL), linebackers (LB), and defensive backs (DB). Comparisons included height, body mass, bench press and squat strength, vertical jump, vertical jump power, 40-yd-dash speed, and body composition. Independent t-tests were used to analyze the data with level of significance set at p < 0.01. Significant differences (p < 0.01) were found in 50 of 88 comparisons. From 1987 until 2000, Division I college football players in general have become bigger, stronger, faster, and more powerful. Further research is warranted to investigate if these trends will continue.     

Physical and performance characteristics of Japanese division 1 collegiate football players

Iguchi, J, Yamada, Y, Ando, S, Fujisawa, Y, Hojo, T, Nishimura, K, Kuzuhara, K, Yuasa, Y, and Ichihashi, N. Physical and performance characteristics of Japanese division 1 collegiate football players. J Strength Cond Res 25(12): 3368-3377, 2011-This study aimed to establish the physical and performance characteristics of football players in the Japanese Division 1 collegiate football program and perform a comparison of these characteristics between Japanese (n = 208) and US Division 1 football players (n = 797). The following comparisons were made: (a) between a higher-ranked university team vs. a lower-ranked university team in Japan, (b) between different playing positions in Japan, (c) between starters and nonstarters in Japan, and (d) between playing positions in Japan vs. those in the United States. The results of this study suggest that players in the higher-ranked university team were heavier, stronger in back squat, jumped higher, and had greater power than those on the lower-ranked team. Furthermore, linemen were generally characterized by larger size, greater strength, and more fat as compared with backs. On the other hand, backs tended to be faster, smaller in physical size, have higher vertical jump height, and show greater relative strength than linemen did. Starters were taller, heavier, stronger, had more powerful, and more fat-free mass than nonstarters. Finally, our results revealed that players in the United States were superior to players in Japan in all body status comparisons (p < 0.01). This study revealed that performance and superior body composition are essential for the success of a football player. Power and strength seem to be key factors in defining good football performance.     

Physical demands of National Collegiate Athletic Association Division I football players during preseason training in the heat

The purpose of this study was to evaluate physical demands of football players during preseason practices in the heat. Furthermore, we sought to compare how physical demands differ between positions and playing status. Male National Collegiate Athletic Association Division 1 football players (n = 49) participated in 9 practice sessions (142 ± 16 minutes per session; wet bulb globe temperature (WBGT) 28.75 ± 2.11°C) over 8 days. Heart rate (HR) and global positioning system data were recorded throughout the entirety of each practice to determine the distance covered (DC), velocity (V), maximal HR (HRmax), and average HR (HRavg). The subjects were divided into 2 groups: linemen (L) (N = 25; age: 22 ± 1 years, weight: 126 ± 16 kg, height: 190 ± 4 cm,) vs. nonlinemen (NL) (N = 24; age: 21 ± 1 years, weight: 91 ± 11 kg, height: 183 ± 8 cm) and starters (S) (N = 17; age: 21 ± 1 years, weight: 118 ± 21 kg, height: 190 ± 7 cm) vs. nonstarters (NS) (N = 32; age: 20 ± 1 years, weight: 105 ± 22 kg, height: 185 ± 7 cm) for statistical analysis. The DC (3,532 ± 943 vs. 2,573 ± 489 m; p = 0.001) and HRmax (201 ± 9 vs. 194 ± 11 b·min(-1); p = 0.025) were significantly greater in NL compared with that in L. In addition, NL spent more time (p < 0.0001) and covered more distance (p = 0.002) at higher velocities than L did. Differences between S vs. NS were observed (p = 0.008, p = 0.031), with S obtaining higher velocities than NS did. Given the demands of their playing positions, NL were required to cover more distance at higher velocities, resulting in a greater HRmax than that of L. Therefore, it appears that L engage in more isometric work than NL do. In addition, the players exposed to similar practice demands provide similar work output during preseason practice sessions regardless of their playing status.     

Comparison of selected physical fitness and performance variables between NCAA Division I and II football players

The purpose of this study was to compare selected physical fitness and performance variables between National Collegiate Athletic Association (NCAA) Division I and II football players. The subjects included offensive and defensive starters, excluding kickers and punters from 26 NCAA Division I and 23 Division II teams. Offensive players were grouped and compared by the following positions: quarterback, running back, wide receiver, tight end, and line. Defensive players were grouped and compared by the following positions: line, linebackers, and backs. Division I players were better in 58 of 117 comparisons (p < or = 0.01). Division II players were not found to be better in any of the variables studied.     

Equipment and running surface alter sprint performance of college football players

The purpose of this study was to determine the effect of football equipment and running surface on sprint performance in NCAA Division II football players (n = 68). Players were timed in the 40-yd sprint on an indoor rubberized track (Day 1) and on an outdoor, natural-grass football field (Day 2) wearing either regulation football equipment or shorts and a T-shirt. Each player was assigned randomly to perform 2 trials under each condition on each surface, and the average of the 2 trials was used for analysis. Offensive backs, defensive backs, and linebackers were significantly faster than were offensive and defensive linemen in all trials, and subjects were collapsed into 2 groups, backs and linemen. Football equipment significantly impaired performance on the track (-2.8% +/- 1.7%) and the field (-2.9% +/- 1.8%). The increase in body mass due to the football equipment was significantly greater for backs (7.2% +/- 0.7%) than for linemen (6.5% +/- 1.0%), but produced a significantly greater impairment in sprint performance in linemen (-3.3% +/- 1.1%) as compared with backs (-2.5% +/- 1.5%). Sprint performance was significantly and equivalently impaired when running on grass (backs: -2.5 +/- 1.1%; linemen: -2.8 +/- 1.4%) as compared with the track. Thus, running a 40-yd sprint in football equipment on a natural grass field impairs performance by an average of 5.5% (+/- 2.3%) compared with running indoors with minimal apparel. Football equipment and running surface significantly impair sprint performance in college football players, the effect being greater in linemen than in backs, and is likely related to differences in muscle strength/power and body fat.     

Body composition relates poorly to performance tests in NCAA Division III football players

We assessed body composition (height, body mass, body mass index, body fat by densitometry, fat mass, fat-free mass, and lean/fat ratio) and performance (10- and 40-yd sprints, pro shuttle run, vertical jump, sit and reach, and bench press) in 77 National Collegiate Athletic Association Division III football players. Data were analyzed by position and playing status. Significant differences (p 相似文献   

The relationship between core stability and performance in division I football players

The purpose of this study was to identify relationships between core stability and various strength and power variables in strength and power athletes. National Collegiate Athletic Association Division I football players (height 184.0 +/- 7.1 cm, weight 100.5 +/- 22.4 kg) completed strength and performance testing before off-season conditioning. Subjects were tested on three strength variables (one-repetition maximum [1RM] bench press, 1RM squat, and 1RM power clean), four performance variables (countermovement vertical jump [CMJ], 20- and 40-yd sprints, and a 10-yd shuttle run), and core stability (back extension, trunk flexion, and left and right bridge). Significant correlations were identified between total core strength and 20-yd sprint (r = -0.594), 40-yd sprint (r = -0.604), shuttle run (r = -0.551), CMJ (r = 0.591), power clean/body weight (BW) (r = 0.622), 1RM squat (r = -0.470), bench press/BW (r = 0.369), and combined 1RM/BW (r = 0.447); trunk flexion and 20-yd sprint (r = -0.485), 40-yd sprint (r = -0.479), shuttle run (r = -0.443), CMJ (r = 0.436), power clean/BW (r = 0.396), and 1RM squat (r = -0.416); back extension and CMJ (r = 0.536), and power clean/BW (r = 0.449); right bridge and 20-yd sprint r = -0.410) and 40-yd sprint (r = -0.435), CMJ (r = 0.403), power clean/BW (r = 0.519) and bench press/BW (r = 0.372) and combined 1RM/BW (r = 0.406); and left bridge and 20-yd sprint (r = -0.376) and 40-yd sprint (r = -0.397), shuttle run (r = -0.374), and power clean/BW (r = 0.460). The results of this study suggest that core stability is moderately related to strength and performance. Thus, increases in core strength are not going to contribute significantly to strength and power and should not be the focus of strength and conditioning.     

Comparison of loaded and unloaded jump squat training on strength/power performance in college football players

The purpose of this study was to explore the effects of 5 weeks of eccentrically loaded and unloaded jump squat training in experienced resistance-trained athletes during the strength/ power phase of a 15-week periodized off-season resistance training program. Forty-seven male college football players were randomly assigned to 1 of 3 groups. One group performed the jump squat exercise using both concentric and eccentric phases of contraction (CE; n = 15). A second group performed the jump squat exercise using the concentric phase only (n = 16), and a third group did not perform the jump squat exercise and served as control (CT; n = 16). No significant differences between the groups were seen in power, vertical jump height, 40-yd sprint speed and agility performance. In addition, no differences between the groups were seen in integrated electromyography activity during the jump squat exercise. Significant differences between the CE and CT groups were seen in Delta 1RM squat (65.8 and 27.5 kg, respectively) and Delta 1RM power clean (25.9 and 3.8 kg, respectively). No other between-group differences were observed. Results of this study provide evidence of the benefits of the jump squat exercise during a short-duration (5-week) training program for eliciting strength and power gains. In addition, the eccentric phase of this ballistic movement appears to have important implications for eliciting these strength gains in college football players during an off-season training program. Thus, coaches incorporating jump squats (using both concentric and eccentric phases of contraction) in the off-season training programs of their athletes can see significant performance improvements during a relatively short duration of training.     

Physiological characteristics of National Collegiate Athletic Association Division I ice hockey players and their relation to game performance

Previous ice hockey research has focused on physiological profiles and determinants of skating speed, but few studies have examined the association of preseason player evaluations with a measure of season-long performance. Understanding which tests are most predictive of player performance could help coaches organize practice and training more effectively. The purpose of this study was to describe physical characteristics and skill levels of 24 members of an NCAA Division I men's ice hockey team and relate them to game performance over the course of a season as measured by plus/minus (+/-) score. Subjects performed a battery of preseason tests including treadmill maximal aerobic capacity, body fat, leg press, push-ups, bench press, chin-ups, and sprinting ability both on and off ice. Pearson and Spearman correlations were used to examine correlations between preseason measures and +/- score. One coach also subjectively grouped the top and bottom 6 players, and analysis of variance was used to examine any differences in preseason measures and +/- score between these 2 groups. Leg press, chin-ups, bench press, and repeat sprint performance were significantly correlated with +/- score (r = 0.554, 0.462, 0.499, and -0.568, respectively). Teams with limited time and resources may choose to perform these tests to evaluate player potential efficiently. Only +/- score differed between top and bottom players suggesting that +/- accurately reflected the coach's perception of player success in this sample.     

Closed-kinetic chain upper-body training improves throwing performance of NCAA Division I softball players

Closed-kinetic chain resistance training (CKCRT) of the lower body is superior to open-kinetic chain resistance training (OKCRT) to improve performance parameters (e.g., vertical jump), but the effects of upper-body CKCRT on throwing performance remain unknown. This study compared shoulder strength, power, and throwing velocity changes in athletes training the upper body exclusively with either CKCRT (using a system of ropes and slings) or OKCRT. Fourteen female National Collegiate Athletic Association Division I softball player volunteers were blocked and randomly placed into two groups: CKCRT and OKCRT. Blocking ensured the same number of veteran players and rookies in each training group. Training occurred three times weekly for 12 weeks during the team's supervised off-season program. Olympic, lower-body, core training, and upper-body intensity and volume in OKCRT and CKCRT were equalized between groups. Criterion variables pre- and posttraining included throwing velocity, bench press one-repetition maximum (1RM), dynamic single-leg balance, and isokinetic peak torque and power (PWR) (at 180 degrees x s(-1)) for shoulder flexion, extension, internal rotation, and external rotation (ER). The CKCRT group significantly improved throwing velocity by 2.0 mph (3.4%, p < 0.05), and the OKCRT group improved 0.3 mph (0.5%, NS). A significant interaction was observed (p < 0.05). The CKCRT group improved its 1RM bench press to the same degree (1.9 kg) as the OKCRT group (p < 0.05 within each group). The CKCRT group improved all measures of shoulder strength and power, whereas OKCRT conferred little change in shoulder torque and power scores. Although throwing is an open-chain movement, adaptations from CKCRT may confer benefits to subsequent performance. Strength coaches can incorporate upper-body CKCRT without sacrificing gains in maximal strength or performance criteria associated with an athletic open-chain movement such as throwing.     

Lower-body work capacity and one-repetition maximum squat prediction in college football players

The purpose of this study was to assess lower-body muscular strength and work capacity after off-season resistance training and the efficacy of predicting maximal squat strength (1 repetition maximum [1RM]) from repetitions to fatigue. National Collegiate Athletic Association Division-II football players (n = 58) were divided into low-strength (LS, 1RM < 365 lb, n = 32) and high-strength (HS, 1RM ≥ 365 lb, n = 26) groups before training based on median 1RM squat performance. Maximal repetitions to failure (RTFs) were performed with a relative load of 70% of 1RM before training and 60, 70, 80, and 90% of 1RM after 12 weeks of a linear periodization resistance training program. As a team, 1RM squat (32 ± 27 lb), 70% RTF (4.5 ± 4.5 reps), and work capacity at 70% 1RM load (1,482 ± 1,181 lb reps) increased significantly after training. Likewise, training resulted in significant increases in 1RM, RTF at 70% 1RM, and work capacity (load × reps) in both LS (8 ± 33 lb, 3.9 ± 4.7 reps, 1,736 ± 1,521 lb reps, respectively) and HS (27 ± 21 lb, 4.9 ± 4.4 reps, 2,387 ± 1,767 lb reps, respectively), with no significant difference between groups. There was no relationship between the change in work capacity and the change in muscular strength for either the LS (r = 0.02) or HS (r = 0.06) group. Predicted 1RMs were best when RTFs were performed using 80% 1RM (5-17 RTFs), with an error of ±5% in 95% of the subjects. In conclusion, the changes in muscular strength associated with an off-season training program appear to have a positive influence on squat work capacity at 70% of 1RM and allow favorable prediction of 1RM using submaximal loads.     

Job analysis of college Division I-A football strength and conditioning coaches

This investigation consisted of a job analysis of 6 National Collegiate Athletic Association Division I-A strength and conditioning coaches (SCC). All the subjects in the study were primarily responsible for providing strength and conditioning services to their institution's football programs. The procedures used for the gathering of data consisted of 3 questionnaires and a semi-structured interview. The questionnaires were followed up by the semi-structured interview. The purpose of this format was to use the semi-structured interview to delve more deeply into the issues raised by the questionnaires. The major job responsibilities and tasks are highlighted. These included conducting training session for athletes, disciplining athletes for infractions of team rules, on campus recruiting, and professional scout liaison to the National Football League. These coaches' perceptions concerning their profession, work environment, relationships with supervisors and co-workers, and the effect the job has on their spouses and other family members are also emphasized.     

Ponderal somatograms assess changes in anthropometric measurements over an academic year in Division III collegiate football players

Ponderal somatograms evaluate body size and shape by converting muscular (shoulders, chest, biceps, forearm, thigh, calf) and nonmuscular (abdomen, hips, knee, ankle, wrist) girths into ponderal equivalent (PE) values. Anthropometric measurements, including stature, body mass, girths, and percent body fat by densitometry were collected in 54 Division III football players in preseason camp (fall) and at the beginning (winter) and end (spring) of the team strength and conditioning program. PE values were calculated for each girth as PE, kg = (girth, cm / k)(2) x stature, dm, where k = k constant from Behnke's reference man. PE values were compared to body mass to indicate overdevelopment (PE > body mass) and underdevelopment (PE < body mass) at specific girth sites. From fall to winter, body mass (+1.6 kg), percent fat (+1.3%), fat mass (+1.6 kg), nonmuscular abdominal and hip girths (+2.1 cm, +1.5 cm), and PE values (+5.3 kg, +2.6 kg) increased significantly (p < 0.05). From winter to spring, percent fat (-1.5%), fat mass (-1.4 kg), nonmuscular abdominal girth (-1.0 cm), and PE value (-2.5 kg) decreased significantly (p < 0.05). Fat-free mass (+1.5 kg), muscular biceps girth (+0.4 cm), and PE value (+2.6 kg) increased significantly (p < 0.05) from winter to spring. Ponderal somatogram muscular components were generally overdeveloped, with the greatest overdevelopment at the biceps in fall (+14.7 kg), winter (+14.9 kg), and spring (+17.4 kg). Nonmuscular components generally were underdeveloped, except abdomen and hips that were overdeveloped. The abdomen remained the greatest nonmuscular overdevelopment in fall (+6.8 kg), winter (+10.5 kg), and spring (+7.9 kg). Ponderal somatograms provide a relatively simple, practical method to track specific changes in body size and shape over time.     

Polymorphism of uncoupling protein genes in football players: Investigation of the functional role

We studied the polymorphism of uncoupling protein genes (UCP1, UCP2, and UCP3) and the FTO gene in 28 football players (team of masters) and compared the results with the data obtained in nonathletes. All these genes encode the proteins that are involved in the regulation of body mass. However, we observed an increased percentage of the carriers of “thrifty” allele of the UCP3 gene; the alleles frequency of other studied genes showed the same tendency. This finding can be partially explained by the fact that the organism of an athlete needs to spare energy. Spearman rank correlation analysis showed that there is a significant correlation between the UCP1 and FTO genes and the elastic component of explosive strength of leg muscles. No correlations were found with the body composition and fat distribution (except for the fat distribution in the pelvic area). The UCP2 gene correlated with the parameters of respiratory functions. The UCP3 gene correlated with the rate of energy production in ramp test and the ergometric parameters of efficiency. It was also found that the high rate of uncoupling of oxidation and phosphorylation in muscles results in an increase in the total energy consumption rate, but also improves the ergometric parameters of efficiency and intensity of muscle work corresponding to the anaerobic threshold. The obtained data were analyzed in the context of the possible role of uncoupling proteins in homeostasis during intense physical activities.     

Head impact exposure in collegiate football players

In American football, impacts to the helmet and the resulting head accelerations are the primary cause of concussion injury and potentially chronic brain injury. The purpose of this study was to quantify exposures to impacts to the head (frequency, location and magnitude) for individual collegiate football players and to investigate differences in head impact exposure by player position. A total of 314 players were enrolled at three institutions and 286,636 head impacts were recorded over three seasons. The 95th percentile peak linear and rotational acceleration and HITsp (a composite severity measure) were 62.7g, 4378rad/s(2) and 32.6, respectively. These exposure measures as well as the frequency of impacts varied significantly by player position and by helmet impact location. Running backs (RB) and quarter backs (QB) received the greatest magnitude head impacts, while defensive line (DL), offensive line (OL) and line backers (LB) received the most frequent head impacts (more than twice as many than any other position). Impacts to the top of the helmet had the lowest peak rotational acceleration (2387rad/s(2)), but the greatest peak linear acceleration (72.4g), and were the least frequent of all locations (13.7%) among all positions. OL and QB had the highest (49.2%) and the lowest (23.7%) frequency, respectively, of front impacts. QB received the greatest magnitude (70.8g and 5428rad/s(2)) and the most frequent (44% and 38.9%) impacts to the back of the helmet. This study quantified head impact exposure in collegiate football, providing data that is critical to advancing the understanding of the biomechanics of concussive injuries and sub-concussive head impacts.     

The normalization of explosive functional movements in a diverse population of elite American football players

The objective of this study was to investigate the need to normalize, for body mass, explosive functional tasks in a population exhibiting diverse body masses. Measures investigated in elite college American football players attending the National Football League's annual combine (n = 1,136) were the 9.1-, 18.3-, and 36.6-m sprints, vertical and horizontal jumps, 18.3-m shuttle, and 3-cone drill. To determine the relationship between body mass and performance outcomes, Pearson's correlation coefficients (r) were generated using log-transformed data. Task-specific allometric exponents, accounting for body mass, were also determined. The strength of the correlations suggests that sprint and jump abilities are associated with body mass, whereas change-of-direction ability is not. The determined allometric exponents range between 0.296 and -0.463 for the sprint and jump tasks and are -0.022 and -0.006 for the 18.3-m shuttle and the 3-cone drill, respectively. In populations exhibiting relatively large variations in body mass, normalization of sprint and jump abilities is recommended, whereas normalization of change-of-direction ability is unwarranted. Novel suggestions derived from the present research are that sprint and jump abilities in diverse populations warrant normalization and that physical attributes associated with explosive functional movements deserve attribute-specific consideration when contemplating normalization.     

Relationships between isokinetic knee strength, single-sprint performance, and repeated-sprint ability in football players

Previous research has demonstrated that muscular strength of the knee extensors is related to the speed an athlete can produce during a single-sprint performance. Football players, as well as many other athletes on the field and the court, execute multiple sprints during the course of a match. The purpose of this study was to examine the relationships between leg strength, single-sprint speed, and repeated-sprint ability. Thirty-eight football players from 3 codes (soccer, rugby league, rugby union) completed a 12- x 20-m repeated-sprint protocol and were evaluated for peak isokinetic knee extension and flexion torque at 60 degrees .s(-1), 150 degrees .s(-1), and 240 degrees .s(-1). Although single-sprint performance correlated with peak extensor and flexor torque at all velocities, the strongest correlation was observed between relative knee extensor torque at 240 degrees .s(-1) and the initial acceleration phase (0-10 m) of the single-sprint performance (r = -0.714, p < 0.01). However, the data suggest that factors other than strength contribute to repeated-sprint ability. This finding provides new evidence in elucidating the relationship between strength and repeated-sprint performance.     

Anthropometric dimensions do not enhance one repetition maximum prediction from the NFL-225 test in college football players

The purpose of this study was to evaluate the contribution of anthropometric dimensions to improving the accuracy of repetitions-to-fatigue (RTF) using an absolute load of 225 lbs to predict 1 repetition maximum (1RM) bench press performance in college football players. Sixty-one players from an NCAA Division II team were evaluated for 1RM bench press performance, RTF using an absolute load of 225 lbs, and measured (5 skinfolds, 2 skeletal length, and 2 muscle circumferences). Anthropometric dimensions (percent fat, lean body mass, and arm cross-sectional areas) were derived at the conclusion of 8 weeks of heavy resistance training during the off-season. None of the anthropometric dimensions made a significant additional contribution to RTF (r = 0.96, SEE = 12.3 lbs) for predicting 1RM. Of the currently available NFL-225 prediction equations found in the literature nonsignificantly underestimated 1RM from RTF by an average of 1.1 lbs (+/-12.7 lbs), whereas 5 other RTF equations significantly overpredicted by 3.5-9.0 lbs (+/-12.2-14.1 lbs). Anthropometric dimensions neither reduced the error associated with prediction of 1RM bench press using the NFL-225 test in college football players nor do they explain why some players are significantly over- or underpredicted when using muscle endurance repetitions.