The impact of the mechanical whole-body vibration experienced during military land transit on the physical attributes underpinning dismounted combatant physical performance: A randomised controlled trial

ObjectivesThe aim of this randomised controlled trial was to explore the impact of the mechanical WBV experienced during simulated military land transit on the physical attributes that underpin tasks performed by dismounted combatants.DesignThis study used a parallel group randomised control trial design.MethodsSixty participants were randomly assigned to one of four, 2-h laboratory-based simulations (restricted posture, sealed road, cross country or a control condition). A smaller sample of 16 Australian Defence Force infantry personnel served as a validation group and were exposed to the same conditions. Neither the restricted posture nor the control conditions were exposed to any WBV, but the former were secured in place using the built-in seat harness. Prior to, and following the assigned condition, participants performed a series of battlefield relevant physical performance tests including; drop jump, 20-m sprint, reactive agility, arm-hand steadiness, isometric mid-thigh pull, and sit-and-reach.ResultsMedium decreases in the drop jump were observed for both the sealed road (effect size [ES] = 0.53) and cross-country (ES = 0.97) simulation conditions indicating a decrease in performance of the jump phase. A large decrease in 20-m sprint performance was observed in both the sealed road (ES = 1.37) and cross-country (ES = 0.88) exposure conditions. Additionally, a large decrease in 20-m sprint performance was observed for the restricted posture (ES = 1.02) exposure condition.ConclusionsThese findings indicate that exposure to WBV experienced during motorised land transit has a negative influence on aspects of lower body explosive strength.     

Transitioning from club to national teams: Training and match load profiles of international footballers

ObjectivesTo quantify and profile the training and match loads of international footballers as they transition from club-to-camp-to-tournament contexts during multiple international tournaments.DesignRetrospective single-cohort observational study.MethodsExternal (session duration and count) and internal (session Rating of Perceived Exertion [s-RPE]) load data of all outfield players from the same national team were compared between club, pre-tournament camp and initial tournament phases of 3 recent international competitions. Further, load profiles were compared between each phase based on the acute:chronic (A/C) ratio using a 7 to 21-day ratio.ResultsModerate-to-large effect sizes existed for increased number of sessions (ES = 1.92; 90% CI: 1.56, 2.27) and s-RPE training load (ES = 1.16; 0.84, 1.48) from club to camp. Conversely, transitioning from camp-to-tournament showed very large effects for decreased number of training sessions (ES = −3.17; −3.47, −2.86) and s-RPE training load (ES = −2.05; −2.35, −1.75), alongside increased number of matches (ES = 1.87; 1.55, 2.18) and s-RPE match load (ES = 1.57; 1.25, 1.89). Consequently, a moderate effect was evident for increased A/C ratio during the club-to-camp transition (ES = 1.02; 0.70, 1.33), while a moderate decrease in the A/C ratio occurred during the tournament (ES = −0.76; −1.06, −0.46).ConclusionsInternational footballers showed expected increased training load when entering into pre-tournament camps, predominately via increased number of training sessions. Subsequent reductions in training volume coincide with increased match volume, though total load decreases. Such profiles provide insight into load accumulation transitioning from club to national teams in international footballers.     

Influence of an intensified competition on fatigue and match performance in junior rugby league players

ObjectivesThe aim of this study was to assess the physiological responses to an intensified rugby league competition and explore the relationships between fatigue and match performance.DesignProspective cohort study.MethodsFifteen junior rugby league players (n = 8 forwards, 7 backs; mean ± SE, age 16.6 ± 0.2 years; body mass 81.6 ± 3.0 kg; and height 178.9 ± 1.8 cm) competed in five 40 min games over 5 days (two games each on days 1 and 2, one game on day 4, and no games on days 3 and 5). Over the competition, players performed a countermovement jump to assess neuromuscular fatigue, provided a fingertip blood sample to measure blood creatine kinase, and completed a questionnaire to monitor perceived wellbeing; ratings of perceived effort were recorded following each game. Global positioning system and video analysis of each game were used to assess match performance.ResultsOver the first 3 days, there were progressive and large increases in neuromuscular fatigue which peaked 12 h after game 4 (forwards ES = 4.45, p = 0.014; backs ES = 3.62, p = 0.029), and muscle damage which peaked 1 h post game 4 (forwards ES = 4.45, p = 0.004; backs ES = 3.94 p = 0.012), as well as reductions in perceived wellbeing. These measures gradually recovered over the final 2 days of the competition. Compared to the backs, the forwards experienced greater increases in creatine kinase following game 2 (ES = 1.30) and game 4 (ES = 1.24) and reductions in perceived wellbeing (ES = 0.25–0.46). Match intensity, high-speed running, and repeated-high intensity effort bouts decreased in games 4 and 5 of the competition. Small to large associations were observed between the changes in fatigue, muscle damage and match performance, with significant correlations between creatine kinase and repeated high-intensity effort bout number (r = ?0.70, p = 0.031) and frequency (r = 0.74, p = 0.002) and low-speed activity (r = ?0.56, p = 0.029).ConclusionsFatigue and muscle damage accumulate over an intensified competition, which is likely to contribute to reductions in high-intensity activities and work rates during competition.     

The effect of physical fatigue on tackling technique in Rugby Union

ObjectivesTo measure the change in tackling technique of rugby union players following an acute bout of physically fatiguing exercise.DesignRandomised cross-over study design with a physical fatigue condition and no-physical fatigue condition (control).MethodsNineteen male amateur club rugby union players (n = 19) and a total of 887 tackles were analysed. During each condition, each player performed four sets of six tackles (three dominant and three non-dominant shoulder) on a contact simulator. Between each set of tackles in the physical fatigue condition, players performed the prolonged high-intensity intermittent running ability test. Using video, player's tackling proficiency for each tackle was measured by awarding either one point or zero points depending on whether a particular technique was performed or not. The sum of these points represents player’s tackling proficiency (score out of 9, measured in arbitrary units).ResultsIn the non-dominant shoulder, a difference between fatigue and control was found at set two (Fatigue 7.3 [7.1–7.6] AU vs. Control 7.6 [7.4–7.9] AU, p = 0.06, ES = 0.3 small) and set three (Fatigue 7.3 [7.0–7.5] AU vs. Control 7.7 [7.5–7.9] AU, p = 0.006, ES = 0.5 small). During the control condition, tackling proficiency scores improved from baseline for non-dominant tackles (Baseline 7.4 [7.2–7.6] AU, vs Set two 7.6 [7.4–7.9] AU, p = 0.08 ES = 0.3 small; vs Set three 7.7 [7.5–7.9] AU, p = 0.05, ES = 0.4 small).ConclusionsIn conclusion, this study shows that physical fatigue can potentially affect rugby union players’ tackling technique. Therefore, players should develop technical capacity to resist the effects of physical fatigue during the tackle.     

An integrative test of agility,speed and skill in soccer: Effects of exercise

ObjectivesThe aim of this study was to evaluate the effect of 45 min of soccer-specific exercise in the reactive motor skills test (RMST); a novel test which measures sprint, passing and reactive agility (RAT) performance.DesignA repeated-measures design was used to collect performance data.MethodsForty-two high-level amateur male soccer players (age 18.5 ± 3.5 years) were recruited. Participants were familiarised with the RMST prior to initial testing. Participants undertook 10 repetitions of the RMST before and after 45 min of soccer-specific exercise using the Loughborough Intermittent Shuttle Test. Eighteen of these participants repeated the RMST for test re-test reliability determination. Paired t-tests and effect size statistics were used to determine the effect of 45 min of intermittent exercise on RMST performance. Reliability was assessed using the standard error of measurement.ResultsThe exercise protocol resulted in moderate decreases of sprint (3.0 ± 0.9%, mean ± SD; 1.030 ± 0.09 ES ± 90% Confidence Intervals; p < 0.00001) and RAT performance (1.5 ± 1.1%; 1.015 ± 0.011; p < 0.05), but improved passing task time (?2.7 ± 1.2%; 0.973 ± 0.012; p < 0.001) and passing accuracy (3.6 ± 3.3%; 1.036 ± 0.33). Change in total test time was trivial. The test-retest coefficient of variation for the test was 2.4 ± 0.8%.ConclusionsSoccer-specific exercise decreased sprint and reactive agility performance but improved technical skill performance on a novel, integrative and reliable test of soccer skill performance. Overall RMST performance time was largely unchanged.     

Combining higher-load and lower-load resistance training exercises: A systematic review and meta-analysis of findings from complex training studies

ObjectivesThe aim of the present meta-analytical review was to determine the effectiveness of training programmes combining higher-load and lower-load exercises in one workout (i.e. complex training [CT]) on lower-body performance.DesignSystematic review and meta-analysis.MethodsA search of five electronic databases (PubMed, Web of Science, SportDiscus, CINAHL and Scopus) was conducted to identify all publications up to 7 March 2018. Meta-analyses were performed using a random-effects model with the dependent variables countermovement jump (CMJ) height, squat jump (SJ) height, one-repetition maximum (1-RM) squat performance and sprint time for 5 m, 10 m, 20 m, 30 m and 40 m, respectively.ResultsThe analysis comprised 33 studies and a total of 1064 healthy participants. The meta-analysis revealed that CT is effective in improving CMJ (95% confidence interval [CI] 5.6%–12.3%), SJ (95% CI 8.0%–17.4%), 1-RM squat (95% CI 16.4%–30.7%) and sprint performance (5 m = 95% CI −14.8% to −0.9%, 10 m = 95% CI −6.0% to −2.1%, 20 m = 95% CI −7.4% to −1.4%, 30 m = 95% CI −8.0% to −0.6%). However, when directly compared to traditional training methods, only 1-RM squat strength performance and 20 m sprint time were superior following CT interventions (95% CI 0.2%–13.7% and 95% CI −1.6% to −0.1%, respectively)ConclusionsCT is an acceptable method for improving jump, strength and sprint performance in athletes. Compared to traditional training methods, CT seems to produce superior training effects only for 1-RM squat and 20 m sprint performance; however, these findings were influenced by single studies and should be therefore interpreted with circumspection.     

Will the real leaders please stand up? The emergence of shared leadership in semi-professional soccer teams

ObjectivesHigh-quality leadership is often regarded as one of the main sources of competitive advantage. Especially within sport teams, a team’s leadership structure has historically been considered to be stable across the season, with the coach and team captain as the formal, and often sole, leaders. In line with recent organizational research, the present study aims to broaden this perspective by also taking informal leaders into account and exploring how leadership structures among athletes within sport teams evolve over the course of a season.DesignUsing social network analysis, we analyzed the leadership structure of 20 semi-professional soccer teams (N = 460 players, M_age = 23.50 years; SD = 4.55) at the start of the season and then again halfway through the season. More specifically, for each team we constructed a leadership network for four leadership roles (task, motivational, social, and external leadership) at these two time points.ResultsFindings suggest that leadership structures in sport teams can change considerably over the course of the competitive season, thereby challenging the classic view of stable, vertical leadership structures. The transition to more shared forms of leadership can be attributed to the emergence of informal leaders over time as players engage more strongly in leadership roles. Furthermore, our results suggest that as teams evolve towards shared leadership their functioning and performance benefits from these changes.ConclusionsBased on these findings, we recommend that coaches actively implement a structure of shared leadership and seek to develop the leadership qualities of formal and informal athlete leaders.     

The relationship between pre-season fitness testing and injury in elite junior Australian football players

ObjectivesAustralian Football (AF) is a collision sport containing high injury rates in junior competition. Successful performance at the elite junior level not only requires superior specific football knowledge and skills, but also well developed fitness qualities. However, no studies have examined the link between physical fitness qualities and injury in AF.DesignProspective cohort.MethodsInjury data were collected through the use of a Player Movement Record (PMR) and a standardized Injury Report Form (IRF). Fitness test data was collected during the pre-season of the 2010 and 2011 seasons.Results382 players consented to participate in the study. The cohort experienced an injury incidence rate of 24.29/standardized club (40 players/club). A faster 5-m sprint was associated with ‘injury status’ (p = 0.016) and a ‘knee’ region (p ≤ 0.001) injury. A faster planned agility score was associated with an increased risk of a ‘hip/groin/thigh’ region (p = 0.010) injury, and specifically a ‘quadriceps strain’ (p = 0.005). A lower 20-m shuttle run was associated with an increased risk of a ‘shin/ankle/foot’ (p = 0.045) injury. Increased injury severity was associated with a higher left foot running vertical jump (VJ) (p = 0.040), and faster 5-m sprint (p = 0.043).ConclusionsLower aerobic endurance, faster 5-m acceleration and greater planned agility were associated with an increased risk of various injury types in elite junior AF players. Furthermore, a higher left foot running VJ and faster 5-m acceleration were associated with injury severity. These results may largely relate to a greater work capacity placing a higher load upon the musculoskeletal system in contact and non-contact situations.     

Whole-body vibration training improves flexibility,strength profile of knee flexors,and hamstrings-to-quadriceps strength ratio in females

ObjectivesShort-term whole-body vibration training (WBVT) has emerged as an exercise method for improving neuromuscular performance and has been proposed for injury prevention and rehabilitation. This study investigated the effects of a short-term (≤2 months) WBVT program using a side-to-side vibration on: (i) strength profile of knee extensors (KE) and flexors (KF), (ii) “functional” hamstrings-to-quadriceps ratio (ECC_KF/CON_KE), (iii) flexibility and (iv) vertical jumping performance (VJ). Furthermore, we explored the retention of performance gains 21 days following WBVT.DesignRandomized-controlled trial.MethodsTwenty-six moderately active females (20.40 ± 0.27 years) were assigned to a vibration (VG) or a control group (CG). The short-term WBVT program consisted of sixteen-sessions on a side-to-side vibration platform (frequency: 25 Hz, amplitude: 6 mm, 2 sets × 5 min). Isokinetic and isometric peak torque of KE and KF, ECC_KF/CON_KE, flexibility, and VJ were measured pre, 2 days post, and 21 days following the cessation of WBVT.ResultsPost-training values of flexibility, isokinetic and isometric peak torques of KF and ECC_KF/CON_KE ratio were higher than pre-training values in VG (p < 0.05); however, they remained unchanged in CG. Post-training values were greater in VG vs. CG (p < 0.05). Twenty-one days following WBVT, post-training values were no longer significantly different than pre-training values. The short-term WBVT program had no effect on strength profile of KE and on VJ.ConclusionsA short-term side-to-side WBVT program improved flexibility, the strength profile of knee flexors, and the “functional” hamstrings-to-quadriceps ratio in moderately active females. Coaches and clinical practitioners should consider this type of training as an effective exercise mode for improving the strength asymmetry of reciprocal muscles at the knee joint.     

Effect of concentric and eccentric hamstring training on sprint recovery,strength and muscle architecture in inexperienced athletes

ObjectivesTo investigate whether five-weeks of concentric (CON) or eccentric (ECC) hamstring strength training have different effects on recovery from sprint running, eccentric strength and architecture of the biceps femoris long head (BF_LH).DesignCohort study.MethodsThirty males (age, 22.8 ± 4.1 y; height, 180.1 ± 6.4 cm; weight, 85.2 ± 14.6 kg) were allocated into either a CON or ECC group, both performing nine sessions of resistance training. Prior to and immediately after the five-week intervention, each participant’s BF_LH fascicle length (FL), pennation angle (PA), muscle thickness (MT), peak isometric KF torque and Nordic eccentric strength were assessed. Post-intervention, participants performed two timed sprint sessions (10 × 80 m) 48 h apart. Blood samples and passive KF torques were collected before, immediately after, 24 h and 48 h after the first sprint session.ResultsAfter five-weeks of strength-training, fascicles lengthened in the ECC (p < 0.001; d = 2.0) and shortened in the CON group (p < 0.001; d = 0.92), while PA decreased for the ECC (p = 0.001; d = 0.52) and increased in the CON group (p < 0.001; d = 1.69). Nordic eccentric strength improved in both ECC (p < 0.001; d = 1.49) and CON (p < 0.001; d = 0.95) groups. No between-group differences were observed in peak isometric strength (p = 0.480), passive KF torques (p = 0.807), sprint performance decrements between sprint sessions (p = 0.317) and creatine kinase (p = 0.818).ConclusionsDespite inducing significant differences in BF_LH muscle architecture, there were no significant between group differences in sprint performance decrements across two sprint sessions.     

The effect of warm-up on intermittent sprint performance and selected thermoregulatory parameters

ObjectivesTo investigate the effect of various warm-up intensities based upon individual lactate thresholds on subsequent intermittent sprint performance, as well as to determine which temperature (muscle; T_mu, rectal; T_re or body; T_b) best correlated with performance (total work, work and power output of the first sprint, and % work decrement).DesignNine male team-sport participants performed five 10-min warm-up protocols consisting of different exercise intensities on five separate occasions, separated by a week.MethodsEach warm-up protocol was followed by a 6 × 4-s intermittent sprint test performed on a cycle ergometer with 21-s of recovery between sprints. T_mu, T_re and T_b were monitored throughout the test.ResultsThere were no differences between warm-up conditions for total work (J kg^?1; P = 0.442), first sprint work (J kg^?1; P = 0.769), power output of the first sprint (W kg^?1; P = 0.189), or % work decrement (P = 0.136), respectively. Moderate to large effect sizes (>0.5; Cohen's d) suggested a tendency for improvement in every performance variable assessed following a warm-up performed at an intensity midway between lactate inflection and lactate threshold. While T_mu, T_re, T_b, heart rate, ratings of perceived exertion and plasma lactate increased significantly during the exercise protocols (P < 0.05), there were no significant correlations between T_mu, T_re, and T_b assessed immediately after each warm-up condition and any performance variable assessed.ConclusionsWarm-up performed at an intensity midway between lactate inflection and lactate threshold resulted in optimal intermittent sprint performance. Significant increases in T_mu, T_re and T_b during the sprint test did not affect exercise performance between warm-up conditions.     

Promoting lower extremity strength in elite volleyball players: Effects of two combined training methods

ObjectivesTo compare the impact of short term training with resistance plus plyometric training (RT+P) or electromyostimulation plus plyometric training (EMS+P) on explosive force production in elite volleyball players.DesignSixteen elite volleyball players of the first German division participated in a training study.MethodsThe participants were randomly assigned to either the RT+P training group (n = 8) or the EMS+P training group (n = 8). Both groups participated in a 5-week lower extremity exercise program. Pre and post tests included squat jumps (SJ), countermovement jumps (CMJ), and drop jumps (DJ) on a force plate. The three-step reach height (RH) was assessed using a custom-made vertec apparatus. Fifteen m straight and lateral sprint (S15s and S15l) were assessed using photoelectric cells with interims at 5 m and 10 m.ResultsRT+P training resulted in significant improvements in SJ (+2.3%) and RH (+0.4%) performance. The EMS+P training group showed significant increases in performance of CMJ (+3.8%), DJ (+6.4%), RH (+1.6%), S15l (?3.8%) and after 5 m and 10 m of the S15s (?2.6%; ?0.5%). The comparison of training-induced changes between the two intervention groups revealed significant differences for the SJ (p = 0.023) in favor of RT+P and for the S15s after 5 m (p = 0.006) in favor of EMS+P.ConclusionsThe results indicate that RT+P training is effective in promoting jump performances and EMS+P training increases jump, speed and agility performances of elite volleyball players.     

Movement pattern comparisons in elite (AFL) and sub-elite (WAFL) Australian football games using GPS

This study examined differences in movement patterns between AFL (elite) and WAFL (sub-elite) players using Global Positioning System (GPS) devices. Maximum speed data and totals of high intensity efforts (>15 km h^?1), sprint efforts (>20 km h^?1) and distance covered were collected on 41 players during the 2008 season. Data were expressed per min of game time played, separated into first and second halves, and also into positions, for both elite and sub-elite players. Overall, elite players had higher movement demands, including 9% more distance covered/min (128 ± 12 m min^?1 vs. 117 ± 15 m min^?1; p < 0.01, ES = 0.84), and 21% more high intensity efforts/min (2.9 ± 0.6 vs. 2.4 ± 0.6; p < 0.01, ES = 0.83). Movement demands significantly declined (p < 0.05–0.01) from first to second half, in both competition levels. For both leagues, Small Forwards/Small Backs and Midfield players covered significantly greater (p < 0.05–0.01) total distances and completed more high intensity efforts than other positions. Ruckmen recorded significantly lower (p < 0.05–0.01) movement demands than Small Forwards/Small Backs, Midfielders and Centre Half-Forwards/Centre Half-Backs over most variables. In conclusion, elite players recorded higher overall movement demands than sub-elite players. This information may be useful for coaches and conditioning staff in designing appropriate training drills for specific role requirements of individual players and assist in the progression of players from sub-elite to elite levels of competition.     

The influence of passive heat maintenance on lower body power output and repeated sprint performance in professional rugby league players

Objectives: The pre-competition warm-up mediates many temperature related physiological changes which generally lead to an improvement in performance. However, after ceasing exercise body temperature declines rapidly, which reduces some of the benefits of the initial warm-up. We examined the effects of a passive heat maintenance strategy on post-warm-up core temperature (T_core) and performance in professional rugby league players. Design: Twenty professional rugby league players completed this randomised and counter-balanced study. Methods: After a standardised warm-up, players completed a countermovement jump (CMJ) before resting for 15 min wearing normal training attire (control) or wearing a passive heat maintenance jacket (PHM), players then completed another CMJ and a repeated sprint protocol (RSA). T_core was measured at baseline, post-warm-up, pre-RSA and post-RSA. CMJ were analysed for peak power output (PPO), and RSA for fastest, mean and total sprint time. Results: Post-warm-up T_core (mean ± SD; control 37.70 ± 0.28; PHM 37.70 ± 0.27 °C; p = 0.741) and PPO (control 5220 ± 353 vs. PHM 5213 ± 331 W; p = 0.686) were similar between conditions. At pre-RSA, PHM was associated with greater T_core (control 37.14 ± 0.31 vs. PHM 37.51 ± 0.30 °C; p < 0.001) and PPO (control 4868 ± 345 vs. PHM 5056 ± 344 W; p < 0.001) when compared to control. The decline in PPO from post-warm-up to pre-RSA was related to the drop in T_core (r = 0.71; p < 0.001). During the RSA, fastest, mean and total sprint time were all improved under PHM compared to control (p < 0.05). Conclusions: Passive heat maintenance is an effective method of attenuating the post-warm-up decline in T_core and improves PPO and repeated sprint ability in professional rugby league players.     

Monitoring of sport participation and injury risk in young athletes

ObjectivesCareful modulation of training characteristics in high-level sports optimizes performance and avoids inappropriate workloads and associated sports injury risk. The aims of this study were to compare sport participation characteristics in different youth sport categories and to investigate their relationship with injury.DesignProspective cohort follow-up.MethodsYoung (12–19 years) high-level athletes (n = 154) from a regional sport school were followed during 41 weeks regarding sport participation characteristics and traumatic and overuse sports injuries (time-loss definition). All data were self-recorded by the athletes in an electronic system “TIPPS” (Training and Injury Prevention Platform for Sports) and subject to a systematic data quality control. Volume and intensity (self-rated perceived exertion) of each sport session were used to compute weekly load, monotony and strain. Sport categories were defined as team, racket, and individual sports.ResultsAll sport participation characteristics were dependent on sport category (p < 0.05). Weekly intensity, load and strain were dependent on age (p < 0.05). Racket and individual sports were associated with lower injury risk (HR = 0.37 and 0.34, p = 0.001 and p < 0.001, respectively) compared to team sports. Average sport participation characteristics were not related to injury according to the survival analysis. However, intensity during the week prior to injury was significantly higher (p < 0.01) compared to that of the 4 preceding weeks.ConclusionsThis study investigated for the first time the relationship between sport participation pattern and injury risk in young athletes. The monitoring method was sensitive to variations according to pertinent variables and might help identify athletes with increased sports injury risk.     

Identifying risk factors for contact injury in professional rugby league players – Application of a frailty model for recurrent injury

ObjectivesWell-developed physical qualities may protect against contact injuries. However, the potential contribution of physical qualities as risk or protective factors to contact injury risk is yet to be determined for rugby league. This study applied a frailty survival model that accounts for recurrent injury to identify risk factors for all physiotherapist-reported contact injury in professional rugby league players.DesignProspective cohort study.MethodsSixty-six professional rugby league players participated in this three successive year prospective study. At the start of each season, all players underwent measurements of standard anthropometry (height, body mass, and sum of seven skinfolds), speed (10 m and 40 m sprint), muscular strength (1 repetition maximum [RM] bench press, 1RM squat, 1RM weighted chin-ups), power (vertical jump, bench throw, 1RM power clean, jump squat), and endurance (maximum repetition bench press with 60 kg resistance), repeated-sprint ability (12 × 20 m sprints performed on a 20 s cycle), prolonged high-intensity intermittent running ability (8 × 12 s maximal effort shuttles performed on a 48 s cycle), and maximal aerobic power (multi-stage fitness test). Data was used to demonstrate the application of the frailty model extension of the Cox proportional regression model for recurrent events to identify factors associated with a high hazard ratio (HR) of injury.ResultsHeavier (body mass, HR = 2.6, 95% CI = 1.2–5.7), and faster (40 m sprint, HR = 2.1, 95% CI = 1.0–4.2) players, and those with poorly developed prolonged high-intensity intermittent running ability (HR = 2.9, 95% CI = 1.7–5.0) and upper-body strength (chin-up, HR = 2.2, 95% CI = 1.3–3.7) had a higher incidence of contact injuries.ConclusionsThis study demonstrates application of a novel statistical approach for the analysis of injury data that is recurrent in nature. This approach identified that the greater impact forces generated from heavier players with faster speed may result in an increase in recurrent contact injury rates. However, the development of prolonged high-intensity intermittent running ability and upper-body strength and power may assist to reduce the risk of contact injury in professional rugby league players.     

Use and perception of breast protective equipment by female contact football players

ObjectivesFemale contact football players sustain contact breast injuries that can negatively affect their sporting performance. This study investigated what female contact football players wear on their breasts during training and competition, and their perceptions on the protection provided by these garments against contact breast injury.DesignA custom-designed survey about breast injuries and prevention strategies was distributed via an online link to coaches and team staff of contact football teams throughout Australia. The fit and features of breast support and/or protection that players wore during training and competition were also directly assessed.Methods207 female Australian Football League (AFL), Rugby League, Rugby Union (XVs) and Rugby 7 s players completed the survey. The breast support of 112 of these players was also assessed.ResultsOnly 17% (n = 35) of players reported using breast protective equipment, of which 66% (n = 23) perceived it provided protection against contact breast injuries. Reasons reported for not using protective equipment included not knowing it existed (n = 79, 53%), it was too uncomfortable/hot (n = 50, 24%) and that it did not fit or was restrictive (n = 33, 22%). Although most players (n = 97, 87%) reported to wear a sports bra, 52% (n = 58) wore an ill-fitted bra and only 31% (n = 63) perceived it provided any protection against contact breast injuries.ConclusionsBreast protective equipment is not commonly worn by female contact football players reportedly due to a lack of awareness of its existence, discomfort or poor fit. Although most female contact football players usually wore a sports bra, most players perceived these bras did not provide breast protection.     

Negative effect of static stretching restored when combined with a sport specific warm-up component

There is substantial evidence that static stretching may inhibit performance in strength and power activities. However, most of this research has involved stretching routines dissimilar to those practiced by athletes. The purpose of this study was to evaluate whether the decline in performance normally associated with static stretching pervades when the static stretching is conducted prior to a sport specific warm-up. Thirteen netball players completed two experimental warm-up conditions. Day 1 warm-up involved a submaximal run followed by 15 min of static stretching and a netball specific skill warm-up. Day 2 followed the same design; however, the static stretching was replaced with a 15 min dynamic warm-up routine to allow for a direct comparison between the static stretching and dynamic warm-up effects. Participants performed a countermovement vertical jump and 20 m sprint after the first warm-up intervention (static or dynamic) and also after the netball specific skill warm-up. The static stretching condition resulted in significantly worse performance than the dynamic warm-up in vertical jump height (?4.2%, 0.40 ES) and 20 m sprint time (1.4%, 0.34 ES) (p < 0.05). However, no significant differences in either performance variable were evident when the skill-based warm-up was preceded by static stretching or a dynamic warm-up routine. This suggests that the practice of a subsequent high-intensity skill based warm-up restored the differences between the two warm-up interventions. Hence, if static stretching is to be included in the warm-up period, it is recommended that a period of high-intensity sport-specific skills based activity is included prior to the on-court/field performance.