Strength changes during an in-season resistance-training program for football

The purpose of this study was to examine the effects of both intensity and volume of training during a 2 d.wk(-1) in-season resistance-training program (RTP) for American football players. Fifty-three National Collegiate Athletic Association Division III football players were tested in the 1 repetition maximum (1RM) bench press and 1RM squat on the first day of summer training camp (PRE) and during the final week of the regular season (POST). Subjects were required to perform 3 sets of 6-8 repetitions per exercise. Significant strength improvements in squat were observed from PRE (155.0 +/- 31.8 kg) to POST (163.3 +/- 30.0 kg), whereas no PRE to POST changes in bench press were seen (124.7 +/- 21.0 kg vs.123.9 +/- 18.6 kg, respectively). Training volume and training compliance were not related to strength improvement. Further analysis showed that athletes training at >or=80% of their PRE 1RM had significantly greater strength improvements than athletes training at <80% of their PRE 1RM, for both bench press and squat. Strength improvements can be seen in American football players, during an in-season RTP, as long as exercise intensity is >or=80% of the 1RM.     

Performance changes during a college playing career in NCAA division III football athletes

The purpose of this study was to compare anthropometric and athletic performance variables during the playing career of NCAA Division III college football players. Two hundred and eighty-nine college football players were assessed for height, body mass, body composition, 1-repetition-maximum (1RM) bench press, 1RM squat, vertical jump height (VJ), vertical jump peak, and vertical jump mean (VJMP) power, 40-yd sprint speed (40S), agility, and line drill (LD) over an 8-year period. All testing occurred at the beginning of summer training camp in each of the seasons studied. Data from all years of testing were combined. Players in their fourth and fifth (red-shirt year) seasons of competition were significantly (p < 0.05) heavier than first-year players. Significant increases in strength were seen during the course of the athletes' collegiate career (31.0% improvement in the 1RM bench press and 36.0% increase in squat strength). The VJ was significantly greater during the fourth year of competition compared to in the previous 3 years of play. Vertical jump peak and VJMP were significantly elevated from years 1 and 2 and were significantly higher during year 4 than during any previous season of competition. No significant changes in 40S or LD time were seen during the athletes playing career. Fatigue rate for the LD (fastest time/slowest time of 3 LD) significantly improved from the first (83.4 ± 6.4%) to second season (85.1 ± 6.5%) of competition. Fatigue rates in the fourth (88.3 ± 4.8%) and fifth (91.2 ± 5.2%) seasons were significantly greater than in any previous season. Strength and power performance improvements appear to occur throughout the football playing career of NCAA Division III athletes. However, the ability to significantly improve speed and agility may be limited.     

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.     

Body composition and physical performance in men's soccer: a study of a National Collegiate Athletic Association Division I team

The purpose of this study was to examine the relationship between body composition (BC) and physical performance (PP) in male collegiate soccer players and differences among positions and between starters and non-starters. Twenty-seven male collegiate soccer players were tested at the beginning of the 2003-2004 season (age = 19.9 +/- 1.3 years, height = 177.6 +/- 6.3 cm, body mass = 77.5 +/- 9.2 kg, body fat (BF) = 10.6 +/- 5.8 kg, and %BF = 13.9 +/- 5.8%). BC, vertical jump (VJ), speed (S), lower-body and total body power production (TPW), and estimated Vo(2)max were measured. Values found for BC were similar than the ones in the literature. Significant correlations were found between BC and PP ranging from -0.38 to 0.61 for weight, VJ, S, TPW, and Vo(2)max. BF showed a positive correlation with S (r = 0.60) and a negative correlation with Vo(2)max (r = -0.67). The values for BC and PP were similar in starters and non-starters with only TPW showing a significantly greater value in starters. It is apparent that all members of a team train to play owing to the long seasons and substitutions, and a high level of excellence is demanded of both starters and non-starters alike. Training programs that equally benefit both groups are important in soccer.     

Evaluation of dietary practices of National Collegiate Athletic Association Division I football players

The objective of this study is to evaluate the dietary practices of 28 football athletes on a National Collegiate Athletic Association (NCAA) Division I team using 3-day diet records. Student athletes completed 3-day diet records at 2 individual points of time, when no training table was available. Diet records were evaluated and were compared with the Third National Health and Nutrition Survey (NHANES III) data for the same ages and gender group. No differences in dietary practices of collegiate football athletes were observed when compared with data for the same ages and gender group culled from NHANES III. Inadequacies in energy intake for activity level were significant (p < 0.05). Influences of fad dieting trends were noted when the diets were mapped onto the United States Department of Agriculture (USDA) food guide pyramid. Changes in diet would be necessary to sustain the activity level of these athletes.     

Upper extremity sensorimotor control among collegiate football players

Injuries stemming from shoulder instability are very common among athletes participating in contact sports, such as football. Previous research has shown that increased laxity negatively affects the function of the sensorimotor system potentially leading to a pathological cycle of shoulder dysfunction. Currently, there are no data detailing such effects among football players. Therefore, the purpose of this study was to examine the differences in upper extremity sensorimotor control among football players compared with that of a control group. Forty-five collegiate football players and 70 male control subjects with no previous experience in contact sports participated. All the subjects had no recent history of upper extremity injury. Each subject performed three 30-second upper extremity balance trials on each arm. The balance trials were conducted in a single-arm push-up position with the test arm in the center of a force platform and the subjects' feet on a labile device. The trials were averaged, and the differences in radial area deviation between groups were analyzed using separate 1-way analyses of variance (p < 0.05). The football players showed significantly more radial area deviation of the dominant (0.41 ± 1.23 cm2, p = 0.02) and nondominant arms (0.47 ± 1.63 cm2, p = 0.03) when compared with the control group. These results suggest that football players may have decreased sensorimotor control of the upper extremity compared with individuals with no contact sport experience. The decreased upper extremity sensorimotor control among the football players may be because of the frequent impacts accumulated during football participation. Football players may benefit from exercises that target the sensorimotor system. These findings may also be beneficial in the evaluation and treatment of various upper extremity injuries among football players.     

Effects of beta-hydroxy beta-methylbutyrate on power performance and indices of muscle damage and stress during high-intensity training

Twenty-six members of a collegiate football team were randomly assigned to either a supplement (S) (3 g of beta-hydroxy beta-methylbutyrate [HMB] per day) or placebo (P) group. Testing occurred before (PRE) and at the end of 10 days of preseason football training camp (POST). During each testing session, subjects performed an anaerobic power test, and blood samples were obtained for testosterone, cortisol, creatine kinase, and myoglobin analysis. No differences in anaerobic power were seen between PRE and POST in either group. Cortisol concentrations were significantly decreased from PRE (333 +/- 81 nmol.L(-1)) to POST (246 +/- 79 nmol.L(-1)), and a sixfold increase was seen in creatine kinase concentrations at POST. However, no significant differences between the groups were seen. No significant time or group effects were observed in testosterone or myoglobin concentrations. Results suggest that short duration HMB supplementation does not provide any ergogenic benefit in collegiate football players during preseason training camp.     

Physical characteristics that predict functional performance in Division I college football players

Strength and conditioning professionals who work with collegiate football players focus much of their time and effort on developing programs to enhance athletic performance. Although there has been much speculation, there is little scientific evidence to suggest which combination of physical characteristics best predicts athletic performance in this population. The purpose of this investigation was to examine the relationship among 6 physical characteristics and 3 functional measures in college football players. Data were gathered on 46 NCAA Division I college football players. The 3 response variables were 36.6-m sprint, 18.3-m shuttle run, and vertical jump. The 6 regressor variables were height, weight, percentage of body fat, hamstring length, bench press, and hang clean. A stepwise multiple regression analysis was performed to screen for variables that predict physical performance. Regression analysis revealed clear prediction models for the 36.6-m sprint and 18.3-m shuttle run. The results of this investigation will help strength and conditioning specialists better understand the variables that predict athletic performance in Division I college football players.     

Countermovement vertical jump with drop step is higher than without in collegiate football players

The vertical jump is a performance test commonly used to assess explosive power and predict athletic ability. Typically, the vertical jump is performed with a countermovement from a stationary stance. We hypothesized that taking a quick step back before initiating the jump, known as the drop-step technique, would result in a higher vertical jump. The purpose of this study was to compare countermovement vertical jumps (CMJs) done from the stationary-stance position to CMJs performed with the drop-step with trained athletes. NCAA Division I football players (N = 56) performed 3 trials each of stationary-stance and drop-step CMJs in a random order. A paired t test revealed that a significantly (p < 0.01) higher jump height was achieved with the drop-step CMJ (69.3 +/- 8.0 cm) compared to the stationary-stance CMJ (66.5 +/- 8.0 cm). The 2 jump conditions were highly related (r = 0.95), and the rank order of the athletes tended to be similar from 1 condition to the other (rho = 0.94). Trial-to-trial reliability was similar for each condition (coefficient of variation [CV] = 3.5% stationary stance; CV = 4.1% drop step). It is important to standardize CMJ testing procedures because a significant difference in the height achieved exists between the stationary-stance and drop-step techniques.     

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.     

Lower-body power,linear speed,and change-of-direction speed in Division I collegiate women’s volleyball players

Volleyball players need to sprint and change direction during a match. Lower-body power, often measured by jump tests, could contribute to faster movements. How different jumps relate to linear and change-of-direction (COD) speed has not been analyzed in Division I (DI) collegiate women’s volleyball players. Fifteen female volleyball players completed the vertical jump (VJ), two-step approach jump (AppJ), and standing broad jump (SBJ). Peak power and power-to-body mass ratio (P:BM) were derived from VJ and AppJ height; relative SBJ was derived from SBJ distance. Linear speed was measured via a 20-m sprint (0–10 and 0–20 m intervals); COD speed was measured using the pro-agility shuttle. Pearson’s correlations (p < 0.05) calculated relationships between the power variables, and speed tests. There were no significant relationships between the power variables and the 0–10 m sprint interval. Greater VJ height (r = -0.534) and P:BM (r = -0.557) related to a faster 0–20 m sprint interval. This be due to a greater emphasis on the stretch-shortening cycle to generate speed over 20 m. However, although a 20-m sprint may provide a measure of general athleticism, the distance may not be specific to volleyball. This was also indicated as the AppJ did not relate to any of the speed tests. Nonetheless, VJ height and P:BM, and SBJ distance and relative SBJ, all negatively correlated with the proagility shuttle (r = -0.548 to -0.729). DI women’s collegiate volleyball players could develop absolute and relative power in the vertical and horizontal planes to enhance COD speed.     

Occlusion training increases muscular strength in division IA football players

The purpose of this study was to investigate the effectiveness of 4 weeks of low-intensity resistance training with blood-flow occlusion on upper and lower body muscular hypertrophy and muscular strength in National Collegiate Athletic Association Division IA football players. There were 32 subjects (average age 19.2 ± 1.8 years) who were randomized to an occlusion group or control group. The athletes performed 4 sets of bench press and squat in the following manner with or without occlusion: 30 repetitions of 20% predetermined 1 repetition maximum (1RM), followed by 3 sets of 20 repetitions at 20% 1RM. Each set was separated by 45 seconds. The training duration was 3 times per week, after the completion of regular off-season strength training. Data collected included health history, resting blood pressure, pretraining and posttraining bench press and squat 1RM, upper and lower chest girths, upper and lower arm girths, thigh girth, height, and body mass. The increases in bench press and squat 1RM (7.0 and 8.0%, respectively), upper and lower chest girths (3 and 3%, respectively), and left upper arm girth were significantly greater in the experiment group (p < 0.05). Occlusion training could provide additional benefits to traditional strength training to improve muscular hypertrophy and muscular strength in collegiate athletes.     

Evaluation of the BOD POD for estimating percent body fat in collegiate track and field female athletes: a comparison of four methods

This investigation examined the accuracy of the BOD POD on a group of Division I collegiate track and field female athletes (N = 30). Hydrostatic weighing (HW) was used as the gold standard method. Body density (Db) values obtained from the BOD POD (Db BP) were compared with those determined by HW (Db HW). Both Db values were converted to percent body fat (%BF) using the Siri equation for comparison. Percent body fat values obtained from the BOD POD (BF BP) were also compared with those obtained from dual-energy X-ray absorptiometry (DXA, BF DXA) and skinfold (SF, BF SF). The validity of the BOD POD was assessed using repeated-measures analysis of variance (ANOVA), and the relationship between the methods was examined through Pearson correlation. Average Db BP was 0.00890 g x cm(-3) lower (p < 0.05) than Db HW, resulting in a significant overestimation of %BF (p < 0.05) by the BOD POD. Values for BFDXA and BFBP also differed significantly (p < 0.05). On the other hand, BFSF and BF BP were not significantly different. The correlation between percent body fat values obtained from HW (BFHW) and BF BP was good (r = 0.88, SEE = 2.30) as well as between BF SF and BF BP (r = 0.85, SEE = 2.05). Conversely, the correlation between BFDXA and BF BP was poor (r = 0.25, SEE = 5.73). The strong correlation between BF BP and BF HW presented here suggests that the BOD POD has the potential to be used as a body composition analysis tool for female athletes. The advantages of the BOD POD over HW encourage further investigation of this instrument. However, the fact that the BOD POD and SF results did not differ significantly might suggest that the SF could be used in its place until a better rate of accuracy for this instrument is established.     

Competition modeling of American football: observational data and implications for high school, collegiate, and professional player conditioning

In an effort to increase the transfer of training to sport performance, sport-specific training programs should be developed. Competition modeling has been proposed as a method for developing metabolic conditioning programs that mimic competition environments. This process involves both a qualitative and quantitative evaluation of competitive conditions of a sport. The purpose of this observational research was to construct a competition model of American football for 3 different levels: high school, collegiate, and professional. Observations of 30 football games at different levels were conducted and modeled with respect to length of play, length of recovery between plays, plays per series, and stoppages per series. The resultant data demonstrated that differences in these variables exist between levels of play. High school plays lasted, on average, 5.6 +/- 2.0 seconds and were slightly longer than college (+0.47 seconds) and professional (+0.44 seconds) plays. The average time for recovery between plays was longest in National Football League (NFL) games and shortest in high school. On average, the work to recovery ratio was most strenuous in high school (1:5.5), college (1:6.1), and NFL (1:6.2), respectively. Differences in the identified competitive conditions, although slight, do exist among high school, collegiate, and professional football. In order to design specific metabolic training programs for American football, coaches should consider the identified models. Exercise to rest ratios and volume of work performed in a training session should be designed to ensure that players are preparing specifically for identified game conditions.     

Determination of functional strength imbalance of the lower extremities

The purposes of this study were (a) to determine whether a significant strength imbalance existed between the left and right or dominant (D) and nondominant (ND) legs and (b) to investigate possible correlations among various unilateral and bilateral closed kinetic chain tests, including a field test, and traditional isokinetic dynamometry used to determine strength imbalance. Fourteen Division I collegiate women softball players (20.2 +/- 1.4 years) volunteered to undergo measures of average peak torque for isokinetic flexion and extension at 60 degrees .s(-1) and 240 degrees .s(-1); in addition, measures of peak and average force of each leg during parallel back squat, 2-legged vertical jump, and single-leg vertical jump and performance in a 5-hop test were examined. Significant differences of between 4.2% and 16.0% were evident for all measures except for average force during single-leg vertical jump between the D and ND limbs, thus revealing a significant strength imbalance. The 5-hop test revealed a significant difference between D and ND limbs and showed a moderate correlation with more sophisticated laboratory tests, suggesting a potential use as a field test for the identification of strength imbalance. The results of this study indicate that a significant strength imbalance can exist even in collegiate level athletes, and future research should be conducted to determine how detrimental these imbalances could be in terms of peak performance for athletes, as well as the implications for injury risk.     

Physiological and performance characteristics of adolescent club volleyball players

The objective of this investigation was to examine the physical and performance characteristics of adolescent club volleyball players. Twenty-nine adolescent girls, aged 12 to 17 years (14.31 +/- 1.37) were participants in this investigation. All athletes were members of a competitive volleyball club. The following group values were obtained: height (HT) = 1.69 +/- 0.08 m, weight (WT) = 59.6 +/- 8.2 kg, body fat percentage (BF%) = 20.9 +/- 4.5, lean body mass (LBM) = 46.7 +/- 4.9 kg, modified sit-and-reach (MSR) = 38.7 +/- 7.1 cm, shoulder rotation (SR) = 29.4 +/- 5.6 cm, isometric hand grip (IHG) = 34.5 +/- 5.5 kg, isometric leg strength (ILS) = 77.4 +/- 18.1 kg, vertical jump (VJ) = 35.5 +/- 6.2 cm, standing broad jump (SBJ) =178.8 +/- 20.3 cm, 1-minute sit-ups (SU) = 47.0 +/- 6.7, T-test (TT) = 11.2 +/- 0.8 seconds., shuttle test (SHT) = 9.7 +/- 0.4 seconds, stork stand (SS) = 8.1 +/- 4.1 seconds, serving velocity (SVV) =16.1 +/- 4.5 m.s(-1), and spiking velocity (SKV) = 16.9 +/- 2.4 m.s(-1). For purposes of analysis, players were divided into 2 age groups: 12 to 14 years (group A) and 15 to 17 years (group B). Significant differences (p < 0.05) were found between age groups for the following values: HT, WT, LBM, IHG, ILS, SBJ, and SVV. Values for group B were greater for each variable. Significant correlations include age and IHG (r = 0.75), age and ILS (r = 0.51), age and SBJ (r = 0.67), age and SVV (r = 0.71), LBM and IHG (r = 0.90), LBM and ILS (r = 0.62), LBM and SVV (r = 0.58), SVV and IHG (r = 0.60), and SKV and SS (r = 0.60). Our results suggest that age, experience, LBM, shoulder, hip, and thigh girths, strength, and balance are key physical performance characteristics of adolescent girls who play volleyball. Potentially, this type of information will allow coaches and athletes to identify physical and performance data specific to age groups for purposes of evaluation and player development.     

Noncompatibility of power and endurance training among college baseball players

Exercise professionals seeking to develop evidence-based training programs rely on several training principles demonstrated through research and professional experience. In an effort to further research examining these principles, an investigation was designed and completed to evaluate the compatibility of cardiovascular endurance and neuromuscular power training. Sixteen Division-I collegiate baseball players were divided into two training groups with lower body power measured before and after their college playing season. The two groups differed in training in that one group performed moderate- to high-intense cardiovascular endurance training 3-4 days per week throughout the season, while the other group participated in speed/speed endurance training. A significant difference between groups (P < .05) was identified in the change in lower body power during the baseball season. During the season, the endurance training group decreased an average of 39.50 +/- 128.03 watts while the speed group improved an average of 210.63 +/- 168.96 watts. These data demonstrate that moderate- to high-intense cardiovascular endurance and neuromuscular power training do not appear to be compatible when performed simultaneously. For baseball players, athletes who rely heavily on power and speed, conventional baseball conditioning involving significant amounts of cardiovascular endurance training should be altered to include more speed/power interval training.     

The combined effects of protein intake and resistance training on serum osteocalcin concentrations in strength and power athletes

The purpose of the present investigation was to examine the combined effects of protein intake and resistance training on a blood marker of bone osteogenesis, serum osteocalcin, in Division III football players. Thirty-three resistance-trained football players (age = 20.4 +/- 1.8 years; height = 180.9 +/- 7.0 cm; body mass = 97.2 +/- 12.6 kg) were evaluated on their protein intake and subsequently underwent 10 weeks of periodized heavy resistance training during the off season. Subjects were then placed into 1 of the following 3 groups based on relative protein intake and were instructed to maintain their diets throughout the experimental period: (a) low protein intake (<1.2 g per kilogram of body mass), (b) moderate protein intake (1.21 to 1.90 g per kilogram of body mass), or (c) high protein intake (>1.91 g per kilogram of body mass). Blood sampling occurred prior to and following the 10-week resistance training period to determine resting serum osteocalcin concentrations. A significant main effect was observed following training such that only the group who consumed <1.2 g per kilogram of body mass of protein shown significant elevations in serum osteocalcin in response to resistance training (26.8 +/- 6.4 to 33.4 +/- 6.6 ng.ml(-1)). In addition, absolute protein intake was significantly correlated to serum osteocalcin concentrations (r = 0.39). The results of the present investigation demonstrated relationships between protein intake and serum osteocalcin concentrations. In addition, the osteocalcin response to short-term resistance training appeared to be affected by protein intake.