Nutritional knowledge, attitudes and behaviours in rugby league; influences of age, body composition and ancestry.

INTRODUCTION: Rugby league is a physically demanding sport that necessitates considerable nutritional intake, focusing on quality and type, in order to optimize training and competition demands. However, rugby league athletes are reported to have inadequate nutrition intake to match these demands. Some factors that may determine an athlete's nutrition intake have been reported in other sports, including (but not limited to, knowledge, time, cooking skills, food costs, income, belief in the importance of nutrition, body composition goals, and family/cultural support). However, these potential factors are relatively unexplored in rugby league, where a range of personal (age, body composition) or social (ancestry) influences could affect nutritional intake. Further exploration of these factors is warranted to understand the knowledge, attitudes and behavior underlying rugby league athletes' nutritional intake that can provide practitioners with a more detailed understanding of how to approach nutrition behaviors and attitudes in rugby league athletes. OBJECTIVES: The primary aim was to describe the nutrition behaviors and knowledge of rugby league athletes. A secondary aim was to compare nutrition knowledge and behavior based on age, body composition and self-identified ancestry. METHODS: Fifty professional rugby league athletes anonymously completed a seventy-six-question online survey. The survey consisted of three sections : 1) sports nutrition knowledge, 2) attitudes toward nutrition on performance , and 3) nutrition behaviors. All participants completed the online survey without assistance using their own personal device, with data entered via REDCap during pre-season. Nutrition knowledge was compared based on age (years), body composition (body fat percentage (%)) and ancestral groups (Pasifika, Aboriginal and/or Torres Strait Islander (ATSI) and Anglo- European).Pearson correlation was used for the relationship between nutrition knowledge, age and body composition. An Analysis of Covariance (ANCOVA) was used to determine nutrition knowledge differences between ancestral groups with age and body composition as covariates. Attitudes and behaviors were compared based on age groups (<20, 20-24 and >25 y), ancestry and body composition. Attitudes and behaviors were analyzed by Pearson correlation for body composition, one-way ANOVA for age groups and ANCOVA for ancestry with covariates age and body composition. RESULTS: Overall athletes' nutrition knowledge score was reported as 40 ± 12% (overall rating "poor"). Nutritional behaviors were significant for body composition, as those with lower body fat percentage had higher intakes of vegetables and dairy products (p = 0.046, p = 0.009), and ate more in the afternoon (lunch p = 0.048, afternoon snack p = 0.036). For ancestry, after adjustment for both age and body composition, Pasifika athletes were more inclined to miss breakfast and lunch compared to their Anglo-European (p = 0.037, p = 0.012) and ATSI (p = 0.022, p = 0.006) counterparts and ate more fruit than Anglo-Europeans (p = 0.006, p = 0.016). After adjustment for body composition, ATSI athletes also viewed the impact of nutrition on mental health and well-being significantly lower than Pasifika (p = 0.044). CONCLUSION: These findings suggest differences exist within rugby league athletes based on ancestral backgrounds and body composition for nutrition attitudes, behaviors and knowledge. Such outcomes could be used when designing nutrition education interventions, with consideration given to these factors to optimize long-term positive behavior change.

The influence of age, sex and player position on skill demands in junior Australian football.

This study aimed to investigate how ecological constraints influence individual player skill demands in community-level junior Australian Football (AF). Footage from 68 junior AF games, incorporating 1874 unique players, were analysed for individual skill demands such as disposals, kicks, handballs, tackles, marks, and shots at goal per player per game. Multiple linear mixed effect models were created for each skill, using player as a random effect. The impact of age, relative area per player (RAPP), number of players on the team, quarters in midfield, and weather on skill demands was assessed in U9-U14 boys. Finally, the influence of sex on the same skills was explored in U11-U14 boys and girls. Younger players were found to have fewer disposals and handballs, but more tackles, per player than older players (all p < 0.05). Further, more quarters in the midfield increased all skill demands (all p < 0.001). Finally, girls had fewer disposals and marks, but more tackles, per player than boys (all p < 0.05). Overall, age, sex, and position significantly impacted players' exposure to skills in junior AF. Game designers should consider methods to improve skill involvement and reduce tackling exposure early in the junior pathway, with further emphasis on the girls' game.

The influence of external loads on post-match neuromuscular fatigue in international rugby union: A partial least squares correlational analysis.

The aims were to determine the relationship(s) between match-play external load and post-match neuromuscular fatigue as latent constructs, the contribution of the specific measured variables to these latent constructs, and how these differ between forwards and backs in elite rugby union. Forty-one elite male rugby union players (22 forwards and 19 backs) from the same international rugby union team were tested, with data included from the 2020 and 2021 international seasons (11 matches; 146 player appearances). Player's match-play external loads were quantified using microtechnology (for locomotor activities) and video analysis (for collision actions). Neuromuscular fatigue was quantified using countermovement jump tests on force plates which were conducted ~ 24 to 48 hours pre- and post-match. Partial least squares correlation (PLSC) leave one variable out (LOVO) procedure established the relative variable contribution to both external load (X matrix) and neuromuscular fatigue (Y matrix) constructs. Linear mixed-effects models were then constructed to determine the variance explained by the latent scores applied to the variables representing these constructs. For external load, both locomotor and collision variables were identified for the forwards and the backs, although the identified variables differed between groups. For neuromuscular fatigue, jump height was identified as a high contributor for the forwards and the backs, with concentric impulse and reactive strength index high contributors only for the backs. The explained variance between the external load and neuromuscular fatigue latent constructs at the individual player level was 4.4% and 32.2% in the forwards and the backs models, respectively. This discrepancy may be explained by differences in match-play external loads and/or the specificity of the tests to measure indicators of fatigue. These may differ due to, for example, the activities undertaken in the different positional groups.

Perceptions of menstrual cycle tracking among elite rugby players.

The purpose of the current study was to understand female rugby players' perceptions of menstrual cycle (MC) tracking and identify the impact of MC tracking for the players. Interpretive descriptive methodology was adopted. Interviews were conducted with 12 elite female rugby players (age 25.2 ± 4.3 years), who were all naturally menstruating. Data were analysed following the four stages recommended within Interpretive Description. Results identified that athletes obtain personal benefits from MC tracking by; enhancing understanding of their MC and symptoms, and responding to their MC and symptoms. Athletes also reported that the process of tracking their MC enhanced relationships by; improving communication and interactions with coaches and support staff, and by facilitating team support. Specifically, using tracking increased the opportunities for open conversations with coaches, support staff and teammates regarding their MC. Overall, the findings highlight benefits of menstrual cycle tracking within this group of naturally menstruating rugby players, particularly in helping players and coaches understand the individual nature of the MC, engage in conversations, and establish support from teammates.

Energy Balance and Dietary Intake in Young Rugby Players during a Pre-Season Micro-Cycle: A Cluster Analysis.

Rugby players must develop excellent levels of conditioning during adolescence. However, this pivotal period of life is also characterized by a surge in biological growth, which further increases the energy and nutritional requirements of this population. This study examined within-individual differences in energy intake (EI) and energy balance (EB) of 46 young rugby players during a pre-season micro-cycle. Two clusters were identified with significantly different characteristics and EB states, suggesting that young rugby players adjust their EI to match their body composition goals. The first cluster is characterized by players with a low body fat% (12.87 ± 2.53). They had a positive EB (330 ± 517 kcal), suggesting a goal of increasing muscle mass. Conversely, the second cluster is characterized by a higher body fat% (23.1 ± 1.6, p < 0.005) and reported a negative, lower EB (-683 ± 425 kcal, p < 0.005), suggesting a goal focused on reducing fat mass. Although our study provides more optimistic results than previous ones regarding the high risk of inadequate EI in young rugby players, we emphasize the importance of rigorous nutritional support, especially for players aiming to lose weight, to avoid severe caloric restriction, as well as the downstream effects of such practices on their nutritional status, given the higher risk of macro- (e.g., CHO < 6 g/kg/d) and micronutrient (e.g., iron < 11 mg/d, calcium < 1300 mg/d, vitamin D < 5 mg/d) deficiencies.

Contemporary Themes in Dietary Intake in Rugby Union Players: A Narrative Review.

Rugby union is an intermittent team sport with variability in body composition and match-play demands between positions which requires careful consideration for individual dietary requirements. While previous reviews have detailed the macronutrient intake in rugby players, none have discussed the further determinants of dietary intake in this population. Therefore, the purpose of the current review was to summarise the current evidence detailing dietary intake in rugby union players, report on contemporary nutritional research themes, and provide recommendations for athletes, nutritionists, and other stakeholders. In total, eighteen articles report on dietary intake in rugby players, with only one of these detailing dietary intake in female athletes. Recent studies have reported on both protein and carbohydrate periodisation practices in rugby union players; however, there is currently limited evidence as to the influence of these on performance, recovery, and well-being. Factors influencing eating patterns, the impact of sports nutritionists on dietary intake, and food consumption in catered and non-catered environments has been explored in isolated studies. Nutrition knowledge levels in rugby players have been reported in several studies; however, the influence this has on dietary intake in rugby players is unknown. Collectively, despite new contemporary themes emerging in the literature concerning dietary intake in rugby players, the studies are isolated; as such, there is limited scope to the translatability of information due to heterogeneity in sex, level of play, and location of participants. Given this, future research should aim to build upon the themes identified in this review in combination to support practitioners working within their specific environments. This will subsequently build towards the generation of rugby-specific recommendations.

Energy expenditure of international female rugby union players during a major international tournament: a doubly labelled water study.

The purpose of this study was to quantify the total energy expenditure (TEE) of international female rugby union players. Fifteen players were assessed over 14 days throughout an international multi-game tournament, which represented two consecutive one-match microcycles. Resting metabolic rate (RMR) and TEE were assessed by indirect calorimetry and doubly labelled water, respectively. Physical activity level (PAL) was estimated (TEE:RMR). Mean RMR, TEE, and PAL were 6.60 ± 0.93 MJ·day-1 (1578 ± 223 kcal·day-1), 13.51 ± 2.28 MJ·day-1 (3229 ± 545 kcal·day-1), and 2.0 ± 0.3 AU, respectively. There was no difference in TEE (13.74 ± 2.31 (3284 ± 554 kcal·day-1) vs. 13.92 ± 2.10 MJ·day-1 (3327 ± 502 kcal·day-1); p = 0.754), or PAL (2.06 ± 0.26 AU vs. 2.09 ± 0.23 AU; p = 0.735) across microcycles, despite substantial decreases in training load (total distance: -8088 m, collisions: -20 n, training duration: -252 min). After correcting for body composition, there was no difference in TEE (13.80 ± 1.74 (3298 ± 416 adj. kcal·day-1) vs. 13.16 ± 1.97 (3145 ± 471 adj. kcal·day-1) adj. MJ·day-1, p = 0.190), RMR (6.49 ± 0.81 (1551 ± 194 adj. kcal·day-1) vs. 6.73 ± 0.83 (1609 ± 198 adj. kcal·day-1) adj. MJ·day-1, p = 0.633) or PAL (2.15 ± 0.14 vs. 1.87 ± 0.26 AU, p = 0.090) between forwards and backs. For an injured participant (n = 1), TEE reduced by 1.7 MJ·day-1 (-401 kcal·day-1) from pre-injury. For participants with illness (n = 3), TEE was similar to pre-illness (+0.49 MJ·day-1 (+117 kcal·day-1)). The energy requirements of international female rugby players were consistent across one-match microcycles. Forwards and backs had similar adjusted energy requirements. These findings are critical to inform the dietary guidance provided to female rugby players.

Validation of field-based running tests to determine maximal aerobic speed in professional rugby league.

Practitioners place importance on high-speed running (HSR) to monitor training practice and match-play demands, whilst attempting to maximise fitness and minimize the risk of injury occurrence. Practitioners apply various methods to quantify HSR, such as absolute thresholds, percentage of maximum sprint speed and maximal aerobic speed (MAS). A recent survey demonstrates the 5-minute run and 1200m shuttle test (ST) to be implemented among rugby league practitioners to quantify HSR by incorporating MAS. However, it is unclear as to how valid these methods are to accurately quantify MAS. Therefore, the aim of this study was to assess the validity of the 5-minute run and 1200m ST when compared to a gold standard measure for MAS. Twenty 1st team professional rugby league players competing in the European Super League participated in this study. Players were required to complete an incremental treadmill test, 5-minute run and 1200m ST over a two-week period in pre-season. MAS, peak heart rate (HRmax), peak lactate (Lapeak) and rating of perceived exertion (RPE) where collected upon completion of each test. Results demonstrated the 1200m ST to have a higher correlation for MAS than the 5-minute run (1200m ST: r = 0.73, 5-minute run: r = 0.64). However, when assessing validity using the level of agreement between data, the 5-minute run underreported MAS by 0.45 m·s-1 whereas the 1200m ST underreported MAS by 0.77 m·s-1. Ultimately, both field-based tests used in this study underreport MAS when compared to an incremental treadmill test, although the 5-minute run provides a closer agreement and therefore a more valid measurement for MAS than the 1200m ST.

Can We Just Play? Internal Validity of Assessing Physiological State With a Semistandardized Kicking Drill in Professional Australian Football.

PURPOSE: To examine associations between exercise heart rate (HRex) during a continuous-fixed submaximal fitness test (CF-SMFT) and an intermittent-variable protocol (semistandardized kicking drill [SSD]) in Australian Football athletes, controlling for external intensities, within-session scheduling, and environmental conditions. METHODS: Forty-four professional male Australian Football athletes (22.8 [8.0] y) were monitored over 10 sessions involving a 3-minute CF-SMFT (12 km·h-1) as the first activity and a SSD administered 35.7 (8.0) minutes after the CF-SMFT. Initial heart rate and HRex were collected, with external intensities measured as average velocity (in meters per minute) and average acceleration-deceleration (in meters per second squared). Environmental conditions were sampled. A penalized hierarchical linear mixed model was tuned for a Bayesian information criterion minima using a 10-fold cross-validation, with out-of-sample prediction accuracy assessed via root-mean-squared error. RESULTS: SSD average acceleration-deceleration, initial heart rate, temperature, and ground hardness were significant moderators in the tuned model. When model covariates were held constant, a 1%-point change in SSD HRex associated with a 0.4%-point change in CF-SMFT HRex (95% CI, 0.3-0.5). The tuned model predicted CF-SMFT HRex with an average root-mean-squared error of 2.64 (0.57) over the 10-fold cross-validation, with 74% and 86% of out-of-sample predictions falling within 2.7%-points and 3.7%-points, respectively, from observed values, representing the lower and upper limits for detecting meaningful changes in HRex according to the documented typical error. CONCLUSIONS: Our findings support the use of an SSD to monitor physiological state in Australian Football athletes, despite varied scheduling within session. Model predictions of CF-SMFT HRex from SSD HRex closely aligned with observed values, considering measurement imprecision.

Seasonal Muscular Power Changes: Considerations of Concurrent Resistance and Field-Based Training in Professional Rugby League.

ABSTRACT: Redman, KJ, Wade, L, Whitley, R, Connick, MJ, Kelly, VG, and Beckman, EM. Seasonal muscular power changes: considerations of concurrent resistance and field-based training in professional rugby league. J Strength Cond Res 38(9): 1620-1626, 2024-A rugby league player's ability to develop or maintain lower-body power will be significantly influenced by the resistance and field-based training loads completed. This study aimed to examine the power changes across a rugby league season and to investigate the relationship of concurrent training and training experience on power changes. Eighteen rugby league players participated in this study. Lower-body power was evaluated using a countermovement jump throughout the season. Four measures of external training loads were collected. A Friedman's test was used to assess differences in power throughout different phases of the season. A series of Spearman's rank-order correlations were conducted to assess the relationship between percentage changes in power during the training block, external training loads, and training experience. Countermovement jump peak velocity significantly decreased from the start ( p = 0.006) and end of pre-season ( p = 0.022) to the late competition. Correlation analysis revealed a large significant association between early competition field-based external loads (relative ( rs = -0.571) and total distance ( rs = -0.628)) and change in peak power. Very large significant negative relationships were also observed between mid-competition volume load with change in peak force ( rs = -0.825) and peak power ( rs = -0.736). Training experience was not significantly associated with changes in muscular power variables throughout this study. Coaches should seek to monitor changes in peak power when competition begins and to assist with decision-making for potential adjustments to running volume and intensity during field-based sessions.

Impact of Weekly Training-Load Structure and Content on the Risk of Injury in Professional Rugby Union Match-Play.

ABSTRACT: Chéradame, J, Loursac, R, Piscione, J, Carling, C, Decq, P, and Jacqmin-Gadda, H. Impact of weekly training-load structure and content on the risk of injury in professional Rugby Union match-play. J Strength Cond Res 38(9): 1613-1619, 2024-The aim of this study was to investigate the impact of different components of daily training load during the week preceding the match on the risk of sustaining a match injury in professional rugby union. A cohort of 72 players from a single professional French club participated. Global positioning system-derived data including total distance (TD) and high-speed distance in addition to ratings of perceived effort (RPE) for both on- and off-pitch (gym-based strength conditioning work) training were collected for each training session over 3 seasons (2017-2020). The association between the daily measures of external and internal training load over the week preceding the day of the match (MD) and the subsequent risk of injury in match-play was estimated using a mixed-effects logistic model adjusted for contextual and individual factors. A total of 184 injuries were sustained in 128 matches (incidence: 81.2 injuries per 1,000 player hours). Higher RPE values for the strength conditioning session on MD-5 ( p < 0.001) and for the on-pitch session on MD-1 ( p = 0.04) were associated with an increased risk of injury in matches. On MD-2, a higher TD covered and that run at high speed (>MAS) were, respectively, associated with a higher ( p = 0.03) and lower risk ( p = 0.02) of injury in matches played. This study in professional rugby union shows that different components of external and internal load had varying influences on injury risk and particularly in relation to the day on which these were performed in the week leading up to the next match. At MD-2, training load favoring intensity rather than volume could reduce the risk of match-play injury.

Muscle-to-Bone Ratio in NCAA Division I Collegiate Football Players by Position.

ABSTRACT: Dengel, DR, Studee, HR, Juckett, WT, Bosch, TA, Carbuhn, AF, Stanforth, PR, and Evanoff, NG. Muscle-to-bone ratio in NCAA Division I collegiate football players by position. J Strength Cond Res 38(9): 1607-1612, 2024-The purpose of this study was to compare the muscle-to-bone ratio (MBR) in National Collegiate Athletic Association Division I football players (collegiate football players [CFP]) to healthy, age-matched controls. In addition, we examined MBR in CFP by position. A total of 553 CFP and 261 controls had their total and regional lean mass (LM), fat mass (FM), and bone mineral content (BMC) determined by dual x-ray absorptiometry (DXA). College football players were categorized by positions defined as offensive linemen (OL), defensive linemen (DL), tight end, linebacker (LB), running back (RB), punter or kicker, quarterback (QB), defensive back (DB), and wide receiver (WR). There were significant differences between CFP and controls for total LM (80.1 ± 10.0 vs. 56.9 ± 7.8 kg), FM (22.2 ± 12.5 vs. 15.2 ± 7.1 kg), and BMC (4.3 ± 0.5 vs. 3.1 ± 0.5 kg). Although there were significant differences in body composition between CFP and controls, there was no significant differences in total MBR between CFP and controls (18.6 ± 1.4 vs. 18.8 ± 1.7). Regionally, CFP had significantly lower trunk MBR than controls (26.7 ± 2.7 vs. 28.7 ± 4.2), but no difference was seen in leg or arm MBR. Positional differences in CFP were noted as total MBR being significantly higher in DL (19.0 ± 1.4) than in DB (18.1 ± 1.3), WR (18.1 ± 1.3), and LB (18.2 ± 1.3). OL had a significantly higher total MBR (19.2 ± 1.3) than DB (18.1 ± 1.3), LB (18.2 ± 1.3), QB (18.1 ± 1.0), and WR (18.1 ± 1.3). In addition, RB had significantly higher total MBR (18.8 ± 1.3) than DB (18.1 ± 1.3) and WR (18.1 ± 1.3). This study may provide athletes and training staff with normative values when evaluating total and regional MBR with DXA.

Different humidity environments do not affect the subsequent exercise ability of college football players after aerobic high-intensity interval training.

Previous studies have explored the effect of differing heat and relative humidity (RH) environments on the performance of multiple anaerobic high-intensity interval training (HIIT). Still, its impact on physiological responses and performance following aerobic HIIT has not been well studied. This study examined the effects of differing RH environments on physiological responses and performance in college football players following HIIT. Twelve college football completed HIIT under four different environmental conditions: (1) 25 °C/20% RH (Control group); (2) 35 °C/20% RH (H20 group); (3) 35 °C/40% RH (H40 group); (4) 35 °C/80% RH (H80 group). The heart rate (HR), mean arterial pressure (MAP), lactate, tympanic temperature (TT), skin temperature (TS), thermal sensation (TS), and rating of perceived exertion (RPE) were recorded continuously throughout the exercise. The heart rate variability (HRV): including root mean squared differences of the standard deviation (RMSSD)、standard deviation differences of the standard deviation (SDNN)、high frequency (HF), low frequency (LF), squat jump height (SJH), cycling time to exhaustion (TTE), and sweat rate (SR) were monitored pre-exercise and post-exercise. The HR, MAP, lactate, TT, Ts, TS, and RPE in the 4 groups showed a trend of rapid increase, then decreased gradually. There was no significant difference in HR, MAP, TT, or RPE between the 4 groups at the same time point (p > 0.05), in addition to this, when compared to the C group, the lactate, Ts, TS in the other 3 groups significant differences were observed at the corresponding time points (p < 0.05). The RMSSD, SDNN, HF, and LF levels in the 4 groups before exercise were not significantly different. The RMSSD and HF in the H40 and H80 groups were significantly decreased and other HRV indicators showed no significant difference after exercise. In sports performance measurement, the SJH and TTE were significantly decreased, but there was no significant difference in the 4 groups. The SR was no significant difference in the 4 groups after exercise. In conclusion, heat and humidity environments elicited generally greater physiological effects compared with the normal environment but did not affect sports performance in college football players.

Predicting Sprint Performance From the Vertical and Horizontal Jumps in National Football League Combine Athletes.

ABSTRACT: Agar-Newman, DJ, MacRae, F, Tsai, M-C, and Klimstra, M. Predicting sprint performance from the vertical and horizontal jumps in National Football League Combine athletes. J Strength Cond Res 38(8): 1433-1439, 2024-Identifying fast athletes is an important part of the National Football League (NFL) Combine. However, not all athletes partake in the 36.58-m sprint, and relying on this single test may miss potentially fast athletes. Therefore, the purpose of this study was to determine whether sprinting times can be predicted using simple anthropometric and jumping measures. Data from the NFL Combine between the years 1999-2020 inclusive were used (n = 4,149). Subjects had a mean (±SD) height = 1.87 ± 0.07 m and body mass = 111.96 ± 20.78 kg. The cross-validation technique was used, partitioning the data into a training set (n = 2,071) to develop regression models to predict time over the 9.14-, 9.14- to 18.29-, 18.29- to 36.58-m, and 36.58-m segments using vertical jump, broad jump, height, and mass as the independent variables. The models were then evaluated against a test set (n = 2,070) for agreement. Statistically significant (p < 0.01) models were determined for 9.14-m time (adjusted R2 = 0.76, SEE = 0.05 seconds), 9.14- to 18.29-m time (adjusted R2 = 0.74, SEE = 0.04 seconds), 18.29- to 36.59-m time (adjusted R2 = 0.79, SEE = 0.07 seconds), and 36.58-m time (adjusted R2 = 0.84, SEE = 0.12 seconds). When evaluated against the test set, the models showed biases of -0.05, -0.04, -0.02, and -0.02 seconds and root-mean-square error of 0.07, 0.05, 0.07, and 0.12 seconds for the 9.14-, 9.14- to 18.29-, 18.29- to 36.58-m, and 36.58-m segments, respectively. However, 5-6% of the predictions lay outside of the limits of agreement. This study provides 4 formulae that can be used to predict sprint performance when the 36.58-m sprint test is not performed, and practitioners can use these equations to determine training areas of opportunity when working with athletes preparing for the NFL Combine.

Heading during the season and its potential impact on brain structure and neurocognitive performance in high-level male football players: An observational study.

OBJECTIVES: To investigate potential effects of heading on the neurocognitive performance and the white matter (WM) of the brain in high-level adult male football players. DESIGN: Prospective longitudinal. METHODS: Football players engaging in the highest football leagues in Germany were included. Neurocognitive performance tests and diffusion tensor imaging (DTI) were executed before and after the observation period. Video recordings of each training session and each match play during the observation period were analyzed regarding heading exposure and characteristics. Four DTI measures from tract-based spatial statistics (fractional anisotropy, mean, axial, and radial diffusivity) were investigated. Associations between heading variables and DTI and neurocognitive parameters were tested subsequently. RESULTS: 8052 headers of 22 players (19.9 ±â€¯2.7 years) were documented in a median of 16.9 months. The individual total heading number ranged from 57 to 943 (median: 320.5). Header characteristics differed between training sessions and matches. Neurocognitive performance (n = 22) and DTI measures (n = 14) showed no significant differences from pre- to post-test. After correction for multiple comparisons, no significant correlations with the total heading number were found. However, the change in fractional anisotropy in the splenium of the corpus callosum correlated significantly with the total amount of long-distance headers (Pearson's r = -0.884; p < 0.0001). CONCLUSIONS: Over the median observation period of 16.9 months, DTI measures and neurocognitive performance remained unchanged. To elucidate the meaning of the association between individual change in fractional anisotropy and long-distance headers further investigations with larger samples, longer observations, and various cohorts regarding age and level of play are required.

Normal hip strength and range of motion values in youth and adult female national football teams: Data from 504 assessments.

OBJECTIVES: To determine normal hip adduction- and abduction strength and range of motion (ROM) values for youth and adult female national team football players, and evaluate if increasing age, playing position and leg dominance were associated with these strength and ROM values. DESIGN: Cohort study. SETTING: National football center. PARTICIPANTS: 344 unique asymptomatic female football players. MAIN OUTCOME MEASURES: Hip internal/external rotation (°), Bent Knee Fall Out test (cm), hip adduction/abduction strength(N) and ratio, and normalised hip adduction/abduction torque (Nm/kg). RESULTS: A total of 504 assessments were performed. A total of 107 players underwent two (n = 67), three (n = 27) or four (n = 13) assessments. Mean peak hip adduction strength was 39% greater in 20 + Y old players 170 (±53 N) than in 13Y old players 122 (±28 N). Normalised hip adduction torque was 9% greater: 2.5 (±0.8Nm/kg) versus 2.3 (±0.5Nm/kg). A positive association between age and all strength measurements was found, while a negative association between age and hip external rotation and total hip rotation was found. No clinically relevant differences were found for the associations between playing position, leg dominance and hip strength- and ROM values. CONCLUSION: Normal values for hip strength and range of motion in youth and adult female national football players are presented that can be used as clinical reference values.

Minimal influence of the menstrual cycle or hormonal contraceptives on performance in female rugby league athletes.

We examined performance across one menstrual cycle (MC) and 3 weeks of hormonal contraceptives (HC) use to identify whether known fluctuations in estrogen and progesterone/progestin are associated with functional performance changes. National Rugby League Indigenous Women's Academy athletes [n = 11 naturally menstruating (NM), n = 13 using HC] completed performance tests [countermovement jump (CMJ), squat jump (SJ), isometric mid-thigh pull, 20 m sprint, power pass and Stroop test] during three phases of a MC or three weeks of HC usage, confirmed through ovulation tests alongside serum estrogen and progesterone concentrations. MC phase or HC use did not influence jump height, peak force, sprint time, distance thrown or Stroop effect. However, there were small variations in kinetic and kinematic CMJ/SJ outputs. NM athletes produced greater mean concentric power in MC phase four than one [+0.41 W·kg-1 (+16.8%), p = 0.021] during the CMJ, alongside greater impulse at 50 ms at phase one than four [+1.7 N·s (+4.7%), p = 0.031] during the SJ, without differences between tests for HC users. Among NM athletes, estradiol negatively correlated with mean velocity and power (r = -0.44 to -0.50, p < 0.047), progesterone positively correlated with contraction time (r = 0.45, p = 0.045), and both negatively correlated with the rate of force development and impulse (r = -0.45 to -0.64, p < 0.043) during the SJ. During the CMJ, estradiol positively correlated to 200 ms impulse (r = 0.45, p = 0.049) and progesterone to mean power (r = 0.51, p = 0.021). Evidence of changes in testing performance across a MC, or during active HC use, is insufficient to justify "phase-based testing"; however, kinetic or kinematic outputs may be altered in NM athletes.

A kinetic analysis of four high velocity, horizontally focused step-up variations for acceleration training.

Step-up variations are frequently used in sports performance to develop coordinated and powerful movements that transfer to running. This study aimed to quantify the kinetic characteristics of the first foot contact of four different step-up variations. Ten professional rugby league players participated in this study and performed the Barbell One Box Step-Up with Catch (BB1), Barbell Two Box Step-Up (BB2), Vest Two Box Run (VEST) and Step-Up Jump (JUMP) as part of routine in-season strength training sessions during one season. Peak force, total impulse and maximal rate of force development (RFD) were measured from first foot contact on the step-up box. Significantly greater peak force and RFD were observed in JUMP than any other variation (standardized mean difference; SMD: 3.9-5.5; p < 0.001). Total impulse was equal between JUMP and BB1, and significantly greater in JUMP than BB2 and VEST (SMD: 1.3-2.3; p < 0.001), and in BB1 than BB2 and VEST (SMD: 1.8-2.8; p < 0.001). Significantly larger peak force and RFD were observed in BB2 and VEST than BB1 (SMD: 0.6-0.7) and in total impulse in BB2 than VEST (SMD: 1.6) (p < 0.05). The results of this study highlight that step-up exercise variations maximize different kinetic characteristics, which may transfer differently to athlete running performance.

Determining female-specific high-intensity activity GPS thresholds in women's rugby union: Use of current use of male-derived absolute speed thresholds underestimates true levels.

GPS speed thresholds in women's rugby union are usually based on data derived from the men's game. However, evidence suggests the maximum speeds achieved by female players are 2-8 km.h-1 slower and the volume of high-intensity running (HIR) in women's rugby may be underestimated. The aim of the study was to examine the effect of adjusting absolute thresholds on the volume of high-intensity locomotion. GPS units recorded movement data from 58 players across 18 English Premier15 s matches. Distance in HIR and sprint (Spr) zones were calculated using male-derived criteria: AbsMale (HIR >18 km.h-1; Spr ≥21 km.h-1). Two alternative thresholds were compared: AbsFVmax (HIR >16 km.h-1; Spr ≥19 km.h-1); AbsFemale (HIR >14 km.h-1; Spr ≥17 km.h-1). Data were analysed using one-way ANOVA and effect sizes to determine differences in distances between thresholds. AbsMale HIR and Spr distances were 63 ± 71 m and 30 ± 53 m. Significantly greater distances at higher-intensity speeds were observed with female-adjusted thresholds. AbsFVmax: HIR: 139 ± 116 m (p = 0.01, ES 0.80); Spr: 60 ± 90 m (p = 0.131, ES 0.41) and AbsFemale: HIR: 239 ± 157 m (p < 0.01, ES 1.45); Spr: 137 ± 152 m (p < 0.01, ES 0.94). 24 players (41%) achieved speeds greater than the 21 km·h-1 threshold with the male-derived thresholds. At AbsFVmax threshold this increased to 44 (76%) and 100% at the AbsFemale threshold. Existing male-derived thresholds appear to underestimate high-intensity locomotion of female players. With adjusted thresholds, specifically the AbsFemale, the proportional volume of high-intensity activity in the women's game (8.2% total distance) aligns more closely to that observed during men's match-play.

Anthropometric and performance changes in male college 15s Rugby Union student-athletes over 52 weeks using in-person training and online training supervision.

BACKGROUND: Although the physiological demands on 15s Rugby Union (RU) players have increased, researchers have suggested that the anthropometric and performance data from developing male college-age RU student-athletes remain limited. This prospective longitudinal repeated measures study aimed to examine the anthropometric and performance changes of male college-age New Zealand Rugby Otago Rugby Football Union (NZRORFU) Academy student-athletes (student-athletes), using in-person and online training supervision (IPTS and OTS, respectively). METHODS: NZRORFU recruited 20 student-athletes (aged 19 to 21 years) and nine were monitored over 52 weeks. During weeks 1 through 35 (in-season), the student-athlete's weekly schedule included 25 hours of IPTS. During the remaining 17 weeks (off-season), the student-athletes followed individualized training programs with OTS. Data were collected on two anthropometric variables and nine performance variables. RESULTS: Over the 52 weeks, using IPTS and OTS, led to increases in both anthropometric measurements with simultaneous significant performance improvements in vertical jump/lower-body power (7.1%, P=0.005, 95% confidence interval (95% CI) 54.4, 63.5), Cohen's effect size (ES) =medium, upper-body strength, bench-press (17.3%, P=0.005, 95% CI 107.4, 127.6, ES=large), and bench-pull (6.1%, P=0.034, 95% CI 90.4, 96.6, ES=large). Furthermore, performance improvements were observed in two anaerobic endurance variables, however, acceleration and speed results were slower. CONCLUSIONS: The use of IPTS and OTS for 52 weeks resulted in increases in body weight and skinfolds with concurrent significant improvements in the performance of VJ/lower-body power and upper-body strength, but changes in each performance variable occurred at different periods.