Influence of playing position on the site, nature, and cause of rugby league injuries

This study investigated the influence of playing position on the site, nature, and cause of injuries in rugby league. The incidence, site, nature, and cause of playing injuries was prospectively studied in 156 rugby league players over 2 seasons. An injury was defined as any pain or disability suffered by a player during a match that resulted in the player missing a subsequent match. The hooker (101 per 1,000 playing hours) and prop (92 per 1,000 playing hours) positions had the highest incidence of injury. Injuries sustained by the fullback (32 per 1,000 playing hours) and halfback (44 per 1,000 playing hours) positions were less common. Compared with other individual playing positions, props had a significantly higher incidence of overexertion injuries (22 per 1,000 playing hours), thigh and calf injuries (47 per 1,000 playing hours), and hematomas (19 per 1,000 playing hours), whereas the five-eighth position (31 per 1,000 playing hours) and the hookers and halves positional group (17 per 1,000 playing hours) had a significantly higher incidence of falling and stumbling injuries. These results demonstrate that the hooker and prop positions have higher injury rates than other rugby league positions. Furthermore, the site, type, and cause of injuries are different among individual playing positions and playing groups. These findings suggest that individual position training for injury prevention is warranted in rugby league.     

Somatotypes of male and female competitive Ju-Jutsuka

31 men and 10 women of the German national cadre or cadres of the federal states (average age 22.3+/-6.1 years), who practised the still relatively new martial arts sports Ju-Jutsu for 8.9+/-4.3 years with 6.2+/-3.6 h training/week, were investigated by means of kinanthropometric methods and compared to 31 male and 10 female hobby martial arts athletes (average age 29.2+/-7.0 years), who practised Jeet Kune Do, Ju-Jutsu or Wing Chun since 8.2+/-7.8 years with 4.1+/-1.7 training hours/week. In the somatochart after Parnell the fighters were placed more endomesomorphic than the hobby sportsmen. In Conrad's chessboard sample graphics the fighters concentrate on the leptomorph half including the metromorph corridor. Remarkable above all is here a placement of the weight class average values toward the pyknomorph hyperplastic quadrant. Also in Knussmann's body build typognosis the weight classes reveal a clear tendency from the coordinates -13/0.5 to -8.3/6.5 in the superleptomorph area. The body fat percentage varies from 17.4 % (male competitors) to 21.8 % (male non-competitors) and 21.2 % (female competitors) to 23.6 % (female non-competitors), which appears still optimizable in comparison to other martial arts collectives.     

The application of training to failure in periodized multiple-set resistance exercise programs

Few studies and reports in the body of literature have directly addressed the issue of whether resistance exercise sets should be performed to failure. Research has clearly demonstrated the superiority of performing multiple sets vs. single sets for increases in maximal strength. However, there is little direct evidence to decide conclusively whether or not multiple sets should be performed to failure. Therefore, the purpose of this research note was to discuss what is currently known concerning the application of training to failure and to stimulate further research on this topic. Although not essential for increases in muscular characteristics such as strength and hypertrophy, training to failure might allow advanced lifters to break through training plateaus when incorporated periodically into short-term microcycles. Because muscular hypertrophy is a key contributor to long-term increases in maximal strength, advanced lifters should consider training to failure occasionally. The potential mechanisms by which training to failure might provide an advantage are through greater activation of motor units and secretion of growth-promoting hormones. However, training to failure is not an effective stimulus without lifting at a sufficient intensity (percentage of 1 repetition maximum). Furthermore, training to failure should not be performed repeatedly over long periods, due to the high potential for overtraining and overuse injuries. Therefore, the training status and the goals of the lifter should guide the decision-making process on this issue.     

Investigation of the breathing pattern structure in competitive exercises of kettlebell lifters

The goal of the research was to determine the characteristics of the breathing pattern in kettlebell lifters. The following main indicators of external respiration were recorded during exercise performance: respiratory rate (RR, f), tidal volume (TV, V _T ), and respiratory minute volume (RMV, V _E ). The dependence of these parameters on the qualification of athletes and competitive exercise intensity was estimated. An SMP-21/01-“R-D” spirograph was used for qualitative and quantitative assessment of the main indicators of breathing patterns in kettlebell lifters. The characteristic changes in breathing of masters of sports (MS) and candidate masters of sport (CMS) were shown mainly for the three parameters, respiratory rate and tidal volume, as well as in the number of breathing cycles per cycle of exercise. Respiratory rate increases and tidal volume decreases at a high-intensity exercise. In international masters of sports (MSIC), the number of breathing cycles per cycle of competitive exercise and, consequently, respiratory rate remain constant independent of physical load. They show the predominance of only one index, tidal volume, which increases from 0.7 ± 0.1 L to 1.2 ± 0.1 L (p < 0.01) with increasing intensity of exercise. We have found transitional forms of breathing patterns in the competitive exercises of kettlebell lifting. The results lay the basis for the development of a novel concept of training and improvement of breathing technique in kettlebell lifting.     

Muscle fiber characteristics of competitive power lifters

To examine the skeletal muscle characteristics of power lifters, 5 competitive power lifters (PL; X +/- SE; age = 31.0 +/- 1.5 years, squat = 287.7 +/- 15.7 kg, bench press = 170.5 +/- 17.7 kg, and deadlift = 284.2 +/- 7.5 kg) and 5 untrained control subjects (CON; age = 27.3 +/- 3.3 years) served as subjects. Isokinetic squat force and power was greater (p < 0.05) for the PL at all bar velocities (0.20, 0.82, and 1.43 m;pd s(-1)), as was vertical jump height and estimated power. Muscle biopsies from the vastus lateralis m. revealed significant differences for percent fiber type (PL, IIA = 45.5 +/- 1.6%, IIB = 1.3 +/- 0.8%; CON, IIA = 33.4 +/- 3.1%, IIB = 12.0 +/- 2.4%); percent fiber type area (PL, IIA = 51.8 +/- 1.6%, IIB = 1.3 +/- 0.8%; CON, IIA = 43.5 +/- 3.4%, IIB = 12.4 +/- 2.6%); and percent myosin heavy chain isoform (PL, IIa = 59.5 +/- 6.1%; CON, 46.5 +/- 2.5%). Muscle fiber characteristics were significantly correlated (r = +/- 0.61) with numerous strength and power measures for the PL. These data illustrate the muscle fiber characteristics necessary for the maximal force production requirements of power lifting.     

Modeling the influence of body size on weightlifting and powerlifting performance

The purpose of this study was to examine 1) if lifting performance in both the weightlifting (WL) and powerlifting (PL) scale with body mass (M) in line with theory of geometric similarity, and 2) whether there are any gender differences in the allometric relationship between lifting performance and body size. This was performed by analyzing ten best WL and PL total results for each weight class, except for super heavyweight, achieved during 2000-2003. Data were analysed with the allometric and second-order polynomial model, and detailed regression diagnostics was applied in order to examine appropriateness of the models used. Results of the data analyses indicate that 1) women's WL and men's PL scale for M in line with theory of geometric similarity, 2) both WL and PL mass exponents are gender-specific, probably due to gender differences in body composition, 3) WL and PL results scale differently for M possibly due to their structural and functional differences. However, the obtained mass exponents does not provide size-independent indices of lifting performances since the allometric model exhibit a favourable bias toward middleweight lifters in most lifting data analyzed. Due to possible deviations from presumption of geometric similarity among lifters, future studies on scaling lifting performance should use fat-free mass and height as indices of body size.     

Adjusting powerlifting performances for differences in body mass

It has been established that, in the sports of Olympic weightlifting (OL) and powerlifting (PL), the relationship between lifting performance and body mass is not linear. This relationship has been frequently studied in OL, but the literature on PL is less extensive. In this study, PL performance and body mass, for both men and women, was examined by using data from the International Powerlifting Federation World Championships during 1995-2004. Nonlinear regression was used to apply 7 models (including allometric, polynomial, and power models) to the data. The results of this study indicate that the relationship between PL performance and body mass can be best modeled by the equation y = a - bx(-c), where y is the weight lifted (in kg) in the squat, bench press, or deadlift, x is the body mass of the lifter (in kg), and a, b, and c are constants. The constants a, b, and c are determined by the type of lift (squat, bench press, or deadlift) and the gender of the lifter and were obtained from the regression analysis. Inspection of the plots of raw residuals (actual performance minus predicted performance) vs. body mass revealed no body mass bias to this formula in contrast to research into other handicapping formulas. This study supports previous research that found a bias toward lifters in the intermediate weight categories in allometric fits to PL data.     

Thermal responses and body fluid balance of competitive male swimmers during a training session

Thermoregulatory and body fluid balance (BFB) responses of competitive swimmers were studied during a typical interval training session under natural field conditions. Subjects were 9 males (18.0 +/- 1.7 years; VO(2)max = 3.8 +/- 0.9 L x min(-1)) who covered 9,000 m in 180 minutes in an outdoor pool (mean water temperature = 26.8 +/- 0.3 degrees C; mean wet bulb globe temperature = 29.8 +/- 2.8 degrees C). Mean body weight (BWt) decreased by 1.8 +/- 0.5 kg (P < 0.05), and rectal temperature increased by 1.0 +/- 1.0 degrees C (P < 0.05). Volitional water intake (WI) (0.1 +/- 0.2 kg) did not maintain BFB (-0.5 kg per hour) and plasma volume decreased 10.7 +/- 5.4%. During a typical training session, swimmers experienced significant body fluid losses, and WI was not enough to prevent involuntary dehydration. The magnitude of the fluid losses (2.5% of BWt) was sufficient to compromise convective thermoregulation because of the decreased plasma volume. Hence, to prevent involuntary dehydration, swimmers should be encouraged to consume an amount of fluids that equals losses throughout the training sessions.     

Snatch technique of collegiate national level weightlifters

Bar trajectory during weightlifting movements is related to the position of the body during the lift and the displacement of the feet during the drop-under phase. The purpose of this study was to examine anterior-posterior foot displacement and its relationship with performance in the snatch of collegiate weightlifters. Snatch attempts of men weightlifters from the 1998 U.S.A. Weightlifting Collegiate National Championships were analyzed for horizontal displacement of the feet by video analysis. Lifts were analyzed under 2 conditions: all lifts combined and the heaviest successful attempt for each lifter. Lifts (n = 74) were placed into 4 groups: forward displacement (FD, >2.5 cm); no displacement (ND, +/-2.5 cm); rearward displacement (RD, >2.5 cm); and those that showed asymmetric (AS, >7 cm difference in right and left foot) displacement of the feet. Chi-square revealed no significant difference in success rate between groups for all attempts. No statistically significant differences were noted between groups in body mass to bar mass ratio or Sinclair formula for heaviest successful attempts. Results indicate that foot displacement did not significantly affect snatch success or lifting ability in collegiate national level lifters.     

Epidemiology of training injuries in amateur taekwondo athletes: a retrospective cohort study

The objectives of this study were to estimate the incidence and describe the pattern and severity of training injuries in taekwondo, and to compare pattern and severity of training injuries with competition injuries. One hundred and fifty-two active Australian amateur taekwondo athletes, aged 12 years or over, completed an online survey comprising questions on training exposure and injury history over the preceding 12 months. The main outcome measures were: overall injury incidence rate per athlete-year; training injury incidence rate per athlete-year, per 1000 athlete-training-sessions, and per 1000 athlete-hours of training; injury severity; and injury proportions by anatomical region and by type of injury. Injury incidence rates were calculated with 95% confidence intervals using standard methods, while injury proportions were compared using Fisher''s exact test. The vast majority (81.5%) of taekwondo injuries in an average athlete-year occurred during training. The training injury incidence rate was estimated to be 1.6 (95% CI: 1.4, 1.9) per athlete-year, 11.8 (95% CI: 10.4, 13.4) per 1000 athlete-training-sessions, and 7.0 (95% CI: 6.1, 7.9) per 1000 athlete-hours of training. Among athletes with five or fewer injuries, the severity and injury pattern of training injuries were, by and large, the same as for competition injuries. Approximately sixty percent (60.3%) of training injuries required treatment by a health professional. Considering the burden of training injuries exceeds that of competition injuries, taekwondo governing bodies and stakeholders are encouraged to devote more efforts towards the identification of risk factors for, and prevention of, training injuries in the sport of taekwondo.     

Training injuries in rugby league: an evaluation of skill-based conditioning games

This study investigated the site and nature of rugby league training injuries, and identified the training activities that were most likely to result in injury in rugby league players. The incidence of training injuries was prospectively studied in 60 semiprofessional rugby league players over 1 season. Injury data was collected from 72 training sessions, which included all preseason and in-season training sessions. Injuries were described according to site, type, and the training activity performed at the time of injury. The majority of injuries (90.9 per 1000 training hours, 37.5%) were sustained in traditional conditioning activities that involved no skill component (i.e., running without the ball). In contrast, the incidence of injuries sustained while participating in skill-based conditioning games (26.0 per 1000 training hours, 10.7%) was low. These results suggest that skill-based conditioning games offer a safe, effective method of conditioning for rugby league players.     

Personal best time and training volume, not anthropometry, is related to race performance in the 'Swiss Bike Masters' mountain bike ultramarathon

We investigated in 73 male ultraendurance mountain bikers, with (mean and SD) age 39.1 (8.6) years, weight 74.4 (8.3) kg, height 1.78 (0.07) m, and a body mass index of 23.3 (1.9) kg·m?2, whether variables of anthropometry, training, or prerace experience were associated with race time using bi and multivariate analysis. Our investigation was conducted at the "Swiss Bike Masters," which covers a distance of 120 km and an altitude of 5,000 m. In the bivariate analysis, body mass index (r = 0.29), circumference of upper arm (r = 0.28), sum of upper body skinfolds (r = 0.38), sum of lower body skinfolds (r = 0.25), sum of 8 skinfolds (r = 0.36), percent body fat (r = 0.41), total cycling kilometers per year (r = -0.47), yearly volume in both mountain bike (r = -0.33) and road cycling (r = -0.52), number of training units per week (r = -0.48), distance per unit in road cycling (r = -0.33), average speed during training in road cycling (r = -0.33), and personal best time in the "Swiss Bike Masters"(r = 0.67) were related to race time. In the multiple linear regression analysis, personal best time in the "Swiss Bike Masters" (p = 0.000), total yearly cycling kilometers (p = 0.004), and yearly training kilometers in road cycling (p = 0.017) were related to race time. When the personal best time was the dependent variable in a separate regression model, total yearly cycling kilometers (p = 0.002) remained the single predictor variable. We concluded that finishing a particular mountain bike ultramarathon does not seem to require a special anthropometry but rather a specific skill and experience for this selective kind of race coupled with a high training volume. For practical use, we concluded that successful athletes in a mountain bike ultramarathon, in a special environment and using sophisticated equipment, need prerace experience coupled with high training volume, rather than any special anthropometry.     

Serum and urinary markers of skeletal muscle tissue damage after weight lifting exercise

The purpose of this study was to determine whether high intensity weight lifting exercise produces elevations of urinary 3-methylhistidine (3-MH), serum creatine kinase activity (CK), and serum myoglobin concentration (MY), and whether trained weight lifters differed in such responses when compared to a group of untrained subjects. Ten experienced male weight lifters (EWL) and seven untrained male subjects (IWL) performed three sets of six weight lifting exercises at 70%-80% of 1 RM. All subjects consumed a meat-free diet. The 3-MH:creatinine (3-MH:CR) values decreased 24 h and 48 h following exercise (P less than 0.05). The 12-h and 24-h postexercise CK response and the 12-h postexercise MY response increased for both EWL and IWL (P less than 0.05). However, EWL had a lower 24-h postexercise CK response and lower 12-h and 24-h postexercise MY responses compared to IWL (P less than 0.05). Within 48 h following weight lifting exercise, skeletal muscle protein degradation (as assessed by 3-MH:CR values) decreased regardless of prior training experience whereas skeletal muscle tissue damage (as assessed by CK and MY responses) increased. However, prior weight lifting training appeared to diminish the extent of muscle tissue damage.     

The relationship between preseason range of motion and muscle strain injury in elite soccer players

The purpose of the study was to determine the influence of preseason lower-extremity range of motion (ROM) on the risk of muscle strain injury during a competitive season for elite soccer players. Thirty-six elite male soccer players (age, 25.6 +/- 4.7 years) had maximum static ROM for 6 movements of the lower extremity measured prior to the 2003-2004 English Premier League season. Player age, body size, dominant limb, and playing position were documented also. All lower-extremity muscle strain injuries were recorded prospectively during the competitive season, as was the total amount of time spent in training and games for each player. Soccer players sustaining a muscle strain injury in the hip flexors or knee flexors had lower preseason ROM (p < 0.05) in these muscle groups compared with uninjured players. Similar trends were observed for the remaining muscle groups, but all failed to reach statistical significance (p > 0.05). Most significantly, soccer players with lower preseason ROM in the hip flexors and knee flexors had a statistically higher risk for a muscle strain injury to these muscle groups during a competitive season. Age, body size, limb dominance, and playing position were not significant intrinsic risk factors for the development of muscle strain injuries. Screening of flexibility for soccer players should be conducted during preseason, and flexibility training should be prescribed to players with reduced ROM to lower the risk of developing a muscle strain injury.     

Effects of a competitive wrestling season on body composition, strength, and power in National Collegiate Athletic Association Division III college wrestlers

The purpose of this study was to investigate the effects of a competitive wrestling season on body composition, muscular strength, and muscular power in National Collegiate Athletic Association (NCAA) Division III college wrestlers. A total of 10 wrestlers were assessed throughout 2 consecutive wrestling seasons in late October, late January (midseason), and late March (postseason). Measurements included body weight, body composition (6-site skinfold), muscular strength (back squats and bench press), and muscular power (e.g., power cleans, vertical jump, seated medicine ball put). A repeated-measures analysis of variance (ANOVA) showed no significant changes in body weight, percentage of body fat, or fat-free mass (FFM) from pre- to mid- to postseason (body weight, 77.9 +/- 12.4, 75.7 +/- 11.0, and 79.9 +/- 12.8 kg; percentage of body fat, 11.6 +/- 3.9, 10.5 +/- 3.0, and 12.0 +/- 3.4; FFM, 68.5 +/- 8.7, 67.5 +/- 8.2, and 70.0 +/- 9.0 kg). A statistically significant main effect of time (p < 0.01) was observed for muscular strength, as both the back squat and bench press measures were lower at midseason (back squat, 150.8 +/- 25.2 kg; bench press, 98.3 +/- 25.4 kg) than at pre- and postseason (back squat, 157.9 +/- 25.5 and 161.4 +/- 25.6; bench press, 103.4 +/- 25.5 and 106.4 +/- 26.0). Muscular power did not change significantly throughout the wrestling season. These data indicate that Division III college wrestlers remain relatively weight stable with little change in body composition during a competitive wrestling season. While muscular power is apparently maintained, muscular strength may decline slightly. Our findings suggest that these wrestlers benefit from a training program that emphasizes in-season strength maintenance.     

Changes in physiological and anthropometric characteristics of rugby league players during a competitive season

This study investigated the physiological and anthropometric characteristics of rugby league players during a competitive season. Sixty-eight rugby league players were allocated into training (n = 52) and nonexercise control (n = 16) groups. The training group participated in 2 field-training sessions per week, with training loads, match loads, and injury rates recorded. Subjects performed measurements of standard anthropometry (height, body mass, and sum of 7 skinfolds), muscular power (vertical jump), speed (10-, 20-, and 40-m sprint), agility (L run), and maximal aerobic power (multistage fitness test) in December (off-season), March (preseason), May (midseason), and August (end season). Increases in maximal aerobic power and muscular power and reductions in skinfold thickness were observed during the early phases of the season when training loads were highest. However, reductions in muscular power and maximal aerobic power and increases in skinfold thickness occurred toward the end of the season, when training loads were lowest and match loads and injury rates were highest. These findings suggest that high overall playing intensity and match loads in end-season matches increase in injury rates in the latter half of the season, and residual fatigue associated with limited recovery between successive matches may compromise the physical development of rugby league players.     

Muscle dysmorphia in elite-level power lifters and bodybuilders: a test of differences within a conceptual model

The purpose of this study was to determine if associated characteristics of muscle dysmorphia (MD) were different between elite-level competitive bodybuilders and power lifters. Elite-level competitive bodybuilders (n = 100) and power lifters (n = 68) completed the muscle dysmorphia inventory (MDI) at the time of or immediately before competition. A 2 x 6 (group x MDI subscales) multivariate analysis of variance indicated that bodybuilders were significantly more likely to report body size-symmetry concerns (F(1, 167) = 10.31, p < 0.001), physique protection (F(1, 167) = 10.27, p < 0.001), dietary behavior (F(1, 167) = 28.38, p < 0.001), and pharmacological use (F(1, 167) = 19.64, p < 0.001) than were power lifters. These results suggest that elite-level bodybuilders are significantly more likely to engage in characteristics associated with MD than are elite-level power lifters.     

Neuromuscular training and the risk of leg injuries in female floorball players: cluster randomised controlled study

Objective To investigate whether a neuromuscular training programme is effective in preventing non-contact leg injuries in female floorball players.Design Cluster randomised controlled study.Setting 28 top level female floorball teams in Finland.Participants 457 players (mean age 24 years)—256 (14 teams) in the intervention group and 201 (14 teams) in the control group—followedup for one league season (six months).Intervention A neuromuscular training programme to enhance players’ motor skills and body control, as well as to activate and prepare their neuromuscular system for sports specific manoeuvres.Main outcome measure Acute non-contact injuries of the legs.Results During the season, 72 acute non-contact leg injuries occurred, 20 in the intervention group and 52 in the control group. The injury incidence per 1000 hours playing and practise in the intervention group was 0.65 (95% confidence interval 0.37 to 1.13) and in the control group was 2.08 (1.58 to 2.72). The risk of non-contact leg injury was 66% lower (adjusted incidence rate ratio 0.34, 95% confidence interval 0.20 to 0.57) in the intervention group.Conclusion A neuromuscular training programme was effective in preventing acute non-contact injuries of the legs in female floorball players. Neuromuscular training can be recommended in the weekly training of these athletes.Trial registration Current Controlled Trials ISRCTN26550281.     

Physiological and anthropometric characteristics of junior rugby league players over a competitive season

This study investigated the physiological and anthropometric characteristics of junior rugby league players over a competitive season. Forty-five rugby league players were allocated into training (n = 36) and nonexercise control (n = 9) groups. The training group participated in 2 field-training sessions each week with training loads, match loads, and injury rates recorded. Subjects performed measurements of standard anthropometry (height, body mass, and sum of 7 skinfolds), muscular power (vertical jump), speed (10-, 20-, and 40-m sprint), agility ('L run'), and estimated maximal aerobic power (multi-stage fitness test) in December (off-season), March (preseason), May (midseason), and August (end-season). Training loads progressively increased in the general preparatory phase of the season (preseason period), and declined slightly during the competitive phase of the season. Match intensity and match loads decreased throughout the season. Increases in estimated maximal aerobic power and muscular power and reductions in skinfold thickness occurred during the general preparatory phase of the season, and were maintained throughout the competitive phase of the season. These findings suggest that high training loads in the general preparatory phase of the season and low match loads in the competitive phase of the season allow junior rugby league players to maintain a high level of fitness throughout an entire competitive season.     

The evolution of competitive strategies in annual plants

Annual plants are common in disturbed habitats. It is frequently assumed that because these habitats often have low-plant density, competition is not important in shaping the ecological strategies of annual plants. We test for competitive strategies in genotypes of the short-lived annual plant Arabidopsis thaliana. Genotypes were grown in treatments with or without conspecific competitors. We measured size at reproduction and fitness (fruit production) at final development. We estimated competitive ability in each genotype at first reproduction (the ability to maintain size in the presence of competitors) and at final development (the ability to maintain fruit production in the presence of competitors). Genotypes showed relatively high competitive ability measured as fruit production at final development, but most genotypes had low competitive ability measured as size at reproduction. Our results suggest that competition has been important in the evolution of strategies in these genotypes but vegetative size is not a strong predictor of competitive ability. Rather, competitive ability is determined by the capacity to reproduce efficiently in the presence of competitors. The competitive strategies expressed across these genotypes suggest that competition has been a selective force in these plants, and that a fast life history is not equivalent to an “r-strategy.”