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Supplemental Digital Content is Available in the Text.Helme, M, Emmonds, S, Low, C, and Till, K. A novel case study approach to the investigation of leg strength asymmetry and Rugby League player's multidirectional speed. J Strength Cond Res38(5): 941–947, 2024—Leg strength and multidirectional speed qualities have repeatedly been linked with increased performance during Rugby League (RL) match play and associated with career attainment. However, very little of this evidence for strength has been gained through unilateral measurements with no study available that has examined the impact of strength asymmetry, in this population, on speed qualities in RL players. Therefore, this study examined the association between unilateral strength, and as a novel development, the subject with the most extreme asymmetry was identified for further analysis. Fifty RL players undertook the rear foot elevated split squat 5 repetition maximum, 20-m linear sprint, and modified 505 change of direction test. The mean leg strength for the group was 88.92 ± 12.59 kg; when divided by body mass, the mean relative strength (REL) was 1.03 ± 0.17 kg·kg−1, and the mean asymmetry was 3.21 ± 5.70%. The subject with the greatest asymmetry (subject A) had an imbalance of 33% and a mean leg strength of 75 kg (REL = 0.78 kg·kg−1) and a body mass 1 SDabove the group mean. Analysis of the group's data and that of subject A did not indicate that leg strength asymmetry was either frequent or harmful, with respect to speed performance. However, relative leg strength was associated with both improved linear and multidirectional speed. Practitioners are recommended to prioritize the development of relative leg strength and disregard the aspiration for between leg performance symmetry.

ABSTRACTThe aim of this study was to investigate the prevalence of oral contraceptive use in domestic rugby union, to compare symptomology by contraceptive use, and to determine symptom management strategies. Additionally, to characterise the perceived influence of oral contraceptive use and non-use on wellness and performance. A total of 238 Premiership and Championship women’s rugby union players completed an online questionnaire. The survey was comprised of questions relating to player characteristics, hormonal or non-hormonal contraceptive characteristics, perceived symptomology, symptom management strategies, and performance and wellness characteristics. The prevalence of oral contraceptive users was 26%. Non-hormonal contraceptive users reported greater perceived negative symptomology (i.e., back pain, nausea, sore breasts) and performance and wellness effects (i.e., fatigue, stress, mood, concentration, power, match-play) than oral contraceptive users. The most common symptom management strategies were medication (33%), nutritional interventions (20%), and training modulation (20%). Twelve percent of players had previously spoken to staff about their menstrual cycle (i.e., regular and irregular) or contraceptive use. The most common barriers to speaking to staff were ‘male staff’ (29%) and ‘club culture’ (24%). The importance of assisting non-hormonal contraceptive users in managing symptoms is evident. Emphasis on overcoming barriers to staff-player dialogue regarding menstrual/contraceptive cycle is required.

ABSTRACTObjectivesTo (i) quantify the differences in locomotor and technical characteristics between different drill categories in female soccer and (ii) explore the training drill distributions between different standards of competition.MethodsTechnical (ball touches, ball releases, high-speed ball releases) and locomotor data (total distance, high-speed running distance [>5.29 m∙s−1]) were collected using foot-mounted inertial measurement units from 458 female soccer players from three Women’s Super League (WSL; n = 76 players), eight Women’s Championship (WC; n = 217) and eight WSL Academy (WSLA; n = 165) teams over a 28-week period. Data were analysed using general linear mixed effects.ResultsAcross all standards, the largest proportion of time was spent in technical (TEC) (WSL = 38%, WC = 28%, WSLA = 29%) and small-sided extensive games (SSGe) (WSL = 20%, WC = 31%, WSLA = 30%) drills. WSL completed more TEC and tactical (TAC) training whilst WC and WSLA players completed more SSGe and possession (POS) drills. Technical drills elicited the highest number of touches, releases and the highest total distance and high-speed activity. Position-specific drills elicited the lowest number of touches and releases and the lowest total distance. When the technical and locomotor demand of each drill were made relative to time, there were limited differences between drills, suggesting drill duration was the main moderating factor.ConclusionFindings provide novel understanding of the technical and locomotor demands of different drill categories in female soccer. These results can be used by coaches and practitioners to inform training session design.

ABSTRACTObjectiveQuantifying differences in locomotor characteristics of training between two competition levels and between training days within elite female soccer players.MethodsFoot-mounted inertial measurement unit (Playermaker) data were collected from 293 players from three Women’s Super League (WSL; n = 76) and eight Women’s Championship (WC; n = 217) teams over a 28-week period. Data were analysed using partial least squares correlation analysis to identify relative variable importance and linear mixed effects models to identify magnitude of effects.ResultsWSL players performed more high-speed running distance (HSR; >5.29 m∙s−1), sprint distance (SpD; >6.26 m∙s−1), acceleration (ACC; >3 m∙s−2) and deceleration (DEC; <-3 m∙s−2) distance than WC players. The largest difference between WSL and WC in HSR and HSR per minute occurred on MD-4, (354.7 vs. 190.29 m and 2.8 vs. 1.7 m∙min−1). On MD-2, WSL players also covered greater SpD (44.66 vs. 12.42 m), SpD per minute (0.38 vs. 0.11 m∙min−1) and HSR per minute (1.67 vs. 0.93 m∙min−1). Between training days both WSL and WC teams reduced HSR and SpD but not ACC and DEC distance from MD-4 to MD-2, with MD-4 the highest training day of the week.ConclusionMD-4 is a key training day discriminating between competitive level. HSR and SpD volume and intensity is tapered in WSL and WC players, however there is less clear taper of ACC or DEC. As such, WC teams could increase the volume and intensity of HSR on MD-4 to mimic locomotor activities of those at a higher standard.

ABSTRACTPurpose:This study aimed to establish age-specific velocity thresholds for Under (U)14 and U16 elite youth female soccer players. Methods:Data was collected using 10 Hz GPS units during 50 matches from 187 players (U14 n = 89; U16 n = 98). Spectral clustering identified velocity thresholds for high-speed running (HSR), very high-speed running (VHSR), and sprinting (SPR), for 699 half-match observations (U14 n = 369; U16 n = 330). Linear mixed modelling determined youth (U14 and U16) and age-group (U14 or U16) velocity thresholds, and compared distances covered between these and existing senior thresholds. The effect of playing position and playing half on velocity thresholds was also quantified. Results:Youth velocity thresholds of HSR (≥3.00 m·s−1), VHSR (≥4.83 m·s−1), and SPR (≥5.76 m·s−1) were estimated from the model. Age-group and playing position influenced velocity thresholds but playing half did not. Adoption of youth and age-group velocity thresholds resulted in greater distance covered at HSR, VHSR, and SPR (p < 0.001; moderate-large effect size [ES] = 0.86–1.97) compared to senior thresholds. Both age-groups covered similar distances (trivial-small ESs = 0.002–0.23) when adopting youth and age-group velocity thresholds. Conclusion:These youth thresholds provide an alternative to arbitrary velocity thresholds within the literature, and thresholds derived from senior players or other populations, to inform appropriate quantification and interpretation of physical data within this population.

ABSTRACTThis study aimed to investigate the incidence, severity and burden of injury in English elite youth female soccer players. Qualified therapists at six English girls’ academies prospectively recorded all injuries that required medical attention or caused time loss for matches and training in 375 elite youth female soccer players (under-10 [U10], U12, U14 and U16) during the 2019/2020 season. One hundred- and eleven time-loss injuries (52 from training, 59 from matches) were sustained, resulting in 1,946 days absent (779 days from training injuries, 1,167 days from match injuries) from soccer activities. The injury incidence for matches (9.3/1000 hours, 95% CIs: 7.2–11.9) was significantly greater than training (1.1/1000 hours, 95% CIs: 0.9–1.5, p < 0.001). Additionally, the injury burden for matches (183 days lost/1000 hours, 95% CIs: 142–237) was significantly greater than training (17 days lost/1000 hours, 95% CIs: 13–22, p < 0.001). Injury incidence and burden were greatest in the U16 age group and were found to increase with age. Whilst injury incidence and burden are greater in matches than training, a large proportion of preventable injuries, soft-tissue and non-contact in nature, were sustained in training. Findings provide comparative data for elite youth female soccer players.

Helme, M, Emmonds, S, and Low, C. Is the rear foot elevated split squat unilateral? An investigation into the kinetic and kinematic demands. J Strength Cond Res36(7): 1781–1787, 2022—The purpose of the study was to determine the unilateral nature of the rear foot elevated split squat (RFESS). Specifically, the production of force by the rear leg was examined to better understand its role, if any, toward successful completion of the exercise. Male volunteers were recruited (n= 26, age = 23.8 ± 4.6 years, body mass = 88.1 ± 10.7 kg, and height = 1.79 ± 0.1 m), who were recreationally trained and engaged in a structured strength and conditioning program, including both bilateral and unilateral exercises, and had at least 2 years supervised training experience. Subjects participated in an incremental 5 repetition maximum protocol after familiarization. Kinetic data were recorded through 2 independent force plates, 1 integral to the floor and the second mounted on top of solid weightlifting blocks. Kinematic data were captured through 3-dimensional motion analysis. A total of 715 repetitions were analyzed, and the mean contribution of the lead foot to total vertical force production was 84.36 ± 3.6%. An almost certainly small positive correlation (rho = 0.25, confidence interval [CI] 0.18–0.33) was found between the percentage of force produced by the lead foot, with increasing exercise intensity. A most likely trivial, nonsignificant correlation (rho = −0.01, CI −0.09 to 0.06) with rear foot force production, representing the mass of the rear leg. Data from this study do not indicate that the rear foot contributes to the kinetic demands of the exercise and therefore suggests that the RFESS is a valid unilateral exercise.

The implementation of long-term athletic development (LTAD) aims to improve health, physical activity, and performance of all youth. Contemporary LTAD models suggest that a broad range of physical and psychosocial competencies should be developed in youth, but few resources are available for coaches that describe “how” to achieve these outcomes. This article overviews a coaching session framework built around the following components: raise, activate, mobilize, prepare, activity, games, evaluate (RAMPAGE). The framework provides practitioners with information on whatcan be planned and delivered and whenwithin a coaching session, across multiple ages and stages of development within multiple contexts (e.g., physical education and talent development).

ABSTRACTThe purpose of this study was to quantify the technical characteristics of U14 and U16 elite youth female soccer match-play and compare position-specific differences between and within these age groups. A total of 449 match observations from 45 matches were undertaken on 189 players representing Regional Talent Centres in The Football Association’s Girls’ England Talent Pathway league. Linear mixed modelling determined position-specific differences for 24 technical and 4 possession-based variables. Results showed similar team possession-based characteristics at both age groups. Interceptions (U14 = 4.6 ± 0.3, U16 = 3.9 ± 0.3) and tackles (U14 = 4.2 ± 0.3, U16 = 3.2 ± 0.3) were the most common defensive actions. Passes were the most common offensive action (U14 = 21.8 ± 1.8, U16 = 25.1 ± 1.9). In possession, U14 central players performed more actions than wide players, whilst actions were more evenly distributed amongst positions at U16, suggesting a variation in playing style between age groups. Technical performances of players were position-dependent, and differences in offensive and defensive variables were observed between age groups across all positions. These findings may assist practitioners in informing specific coaching practice, training programme design or talent identification processes within this population.

ABSTRACTPurposeUnderstanding differences in locomotor and collision characteristics between phases of play can help rugby league coaches develop training prescription. There are no data currently available describing these differences at the elite international level. The aim of our study was to determine the differences in average speed (m∙min−1), high-speed running (>5.5 m∙s−1) per minute and collision frequencies per minute (n∙min−1) between attack and defence during the 2017 Rugby League World Cup (RLWC). Methods:Microtechnology data were collected from 24 male professional rugby league players from the same international squad across six matches of the RLWC. Data were then subject to exclusion criteria and stratified into forwards (n= 9) and backs (n= 7) before being analysed with linear mixed-effects models. Results:When comparing attack with defence, forwards and backs had substantially slower average speeds (effect size [ES]; ±90% confidence limits: −2.31; ±0.31 and −1.17; ±0.25) and substantially greater high-speed distance per minute (1.61; ±0.59 and 4.41; ±1.19). Forwards completed substantially more collisions per minute when defending (2.75; ±0.32) whilst backs completed substantially more when attacking (0.63; ±0.70). There was greater within- and between-player variability for collision frequency (coefficient of variation [CV] range; 25–28%) and high-speed distance (18–33%) per minute when compared to average speed (6–12%). Conclusions:There are distinct differences in locomotor and collision characteristics when attacking and defending during international rugby league match-play, yet the variability of high-speed running and collisions per minute is large. These data may be useful to plan or evaluate training practices.

ABSTRACTPurpose:Longitudinal studies assessing the seasonal development of strength, speed and power qualities are limited in youth soccer players. The purpose of this study was to evaluate the seasonal changes in the physical development of elite youth soccer players across Pre-, Circa- and Post-Peak Height Velocity (PHV), against a similar age and maturity matched control groups. Methods:One-hundred and twelve male elite youth soccer players (Pre-PHV n = 55; Circa-PHV n = 21; Post-PHV n = 36) and 38 controls consisting of non-elite active participants (Pre-PHV n = 18; Circa-PHV n = 10; Post-PHV n = 10) all undertook isometric mid-thigh pull strength, 10–30 m sprints, change of direction speed (CODs) and countermovement jump (CMJ) tests pre- and post-season. Results:The elite Circa-PHV improved greater than the control group for all physical qualities between pre- and post-season. The elite Pre-PHV improved greater in sprints, CODs, CMJ jump height and strength while the elite Post-PHV group improved more in CODs and strength than their respective control groups. Conclusion:Findings suggest that systematic academy soccer training enhances the development of physical qualities in youth soccer players but maturity status may impact upon such adaptations.

ABSTRACTPurpose: Research has characterised the strength characteristics of elite youth male soccer players, although little is known about female players. This study investigated the influence of age and maturity status on strength characteristics of elite youth female soccer players. Methods: 157 female soccer players (U16; n = 46, U14; n = 43, U12; n = 38, U10; n = 30), recruited from three elite female soccer academies. Linear mixed models were used to determine the difference by age or maturation on maximum and explosive strength characteristics. Results: Peak force (PF) was possiblyand likelygreater for older age groups; however, differences in relative PF were most likely trivialbetween consecutive age groups. Relative impulse at 100 and 300 ms was very likelygreater at U12 than U10, likelyand possiblyless at U12 than U14 and most likelyless and possiblygreater at U16 than U14. Relative PF was likelyless at pre-peak height velocity (PHV) than circa and circa than post-PHV. Relative impulse at 100 and 300 ms was most likelylower for pre-PHV than circa and pre-PHV than post-PHV, and possiblegreater at circa than post-PHV. Conclusion: Age and maturation impact upon PF and impulse; thus, practitioners should account for individual maturation status when comparing players. These data provide reference strength data for elite youth female soccer players, which can be used when monitoring player development.

The article explores the benefits and challenges of physical performance support applied within the girls' regional talent clubs of the Football Association. Topics discussed include growing popularity in women's and girls' football, disparity in sport science/strength and conditioning research in elite male and female football, and different physiological changes that occur in girls and boys during maturation.

In recent years there has been an exponential rise in the professionalism and success of female sports. Practitioners (e.g., sport science professionals) aim to apply evidence-informed approaches to optimise athlete performance and well-being. Evidence-informed practices should be derived from research literature. Given the lack of research on elite female athletes, this is challenging at present. This limits the ability to adopt an evidence-informed approach when working in female sports, and as such, we are likely failing to maximize the performance potential of female athletes. This article discusses the challenges of applying an evidence base derived from male athletes to female athletes. A conceptual framework is presented, which depicts the need to question the current (male) evidence base due to the differences of the “female athlete” and the “female sporting environment,” which pose a number of challenges for practitioners working in the field. Until a comparable applied sport science research evidence base is established in female athletes, evidence-informed approaches will remain a challenge for those working in female sport.