Repeated high-speed running in elite female soccer players during international competition

The purpose of the present study was to provide a detailed analysis of the repeated high-speed demands of competitive international female soccer match-play. A total of 148 individual match observations were undertaken on 107 outfield players in competitive international matches during the 2011-2012 and 2012-2013 seasons, using a computerized tracking system (STATS, Leeds, England). High-speed activity was classified as either sprint activity (SA) or high-speed running (HSR), with thresholds of >25.1 km.h-1 or >19.8 km.h-1 applied respectively. Repeated sprint activity (RSA) was defined as a minimum of two sprints with 20 s or less recovery between sprints and repeated high-speed activity (RHSA) was defined as a minimum of two high-speed runs or sprints with 20 s or less recovery between efforts. HSR bouts occurred ~5 times more frequently than SA bouts. Central defenders completed 50-80 fewer HSR bouts (moderate count ratio (CR): range 0.61-0.70) and 10-20 fewer SA bouts (moderate CR: range 0.53-0.69) than all other playing positions. RSA bouts occurred less frequently than RHSA bouts (33 ± 10 v 1.1 ± 1.1) with 37 % of players failing to complete any RSA bouts. Central defenders completed fewer RHSA bouts compared to all other playing positions (moderate CR: range 0.57-0.69). Consideration of both RHSA and RSA bouts is necessary to ensure a comprehensive understanding of the demands of female match-play. Practitioners can utilise this information to construct position-specific training and testing programmes which are aligned to the RHSA demands of match-play for elite female players

Actinide Triamidoamine (Tren^R) Chemistry:Uranium and Thorium Derivatives Supported by a Diphenyl‐tert‐Butyl‐Silyl‐Tren Ligand

We report the synthesis and characterisation of thorium(IV), uranium(III), and uranium(IV) complexes supported by a sterically demanding triamidoamine ligand with N-diphenyl-tert-butyl-silyl substituents. Treatment of ThCl4(THF)3.5 or UCl4 with [Li3(TrenDPBS)] (TrenDPBS = {N(CH2CH2NSiPh2But)3}3-) afforded [An(TrenDPBS)Cl] (An = Th, 1Th; U, 1U). Complexes 1An react with benzyl potassium to afford the cyclometallates (TrenDPBScyclomet) [An{N(CH2CH2NSiPh2But)2(CH2CH2NSiPhButC6H4)}] (An = Th, 2Th; U, 2U). Treatment of 1An with sodium azide affords [An(TrenDPBS)N3] (An = Th, 3Th; U, 3U). Reaction of 3Th with potassium graphite affords 2Th. In contrast, 3Th reacts with cesium graphite to afford the doubly-cyclometallated (TrenDPBSd-cyclomet) ate complex [Th{N(CH2CH2NSiPh2But) CH2CH2NSiPhButC6H4)}2Cs(THF)3] (4). In contrast to 3Th, reaction of 3U with potassium graphite produces the uranium(III) complex [U(TrenDPBS)] (5), and 5 can also be prepared by reaction of potassium graphite with 1U. The loss of azide instead of conversion to nitrides contrasts to prior work when the silyl group is iso-propyl silyl, underscoring how ligand substituents profoundly drive the reaction chemistry. Several complexes exhibit T-shaped meta-C-H···phenyl and staggered parallel p-p-stacking interactions, demonstrating subtle weak interactions that drive ancillary ligand geometries. Compounds 1An-3An, 4, and 5 have been variously characterised by single crystal X-ray diffraction, multi-nuclear NMR spectroscopy, infrared spectroscopy, UV/Vis/NIR spectroscopy, and elemental analyses

Applied physiology of female soccer: an update

The popularity and professionalism of female soccer has increased markedly in recent years, with elite players now employed on either a professional or semiprofessional basis. The previous review of the physiological demands of female soccer was undertaken two decades ago when the sport was in its relative infancy. Increased research coupled with greater training and competition demands warrants an updated review to consider the effect on physical performance and injury patterns. The physical demands of match-play along with the influence of factors such as the standard of competition, playing position and fatigue have been explored. Total distance covered for elite female players is approximately 10 km, with 1.7 km completed at high-speed (>18 km·h-1). Elite players complete 28 % more high-speed running and 24 % more sprinting than moderate-level players. Decrements in highspeed running distance have been reported between and within halves, which may indicate an inability to maintain high-intensity activity. Although the physical capacity of female players is the most thoroughly researched area, comparisons are difficult due to differing protocols. Elite players exhibit maximal oxygen uptake (VO2max) values of 49.4–57.6 mL·kg-1·min-1, Yo Yo Intermittent Endurance test level 2 (YYIE2) scores of 1,774 ± 532 m [mean ± standard deviation (SD)] and 20 m sprint times of 3.17 ± 0.03 s (mean ± SD). Reasons for the increased prevalence of anterior cruciate ligament injuries in females (2–6 times greater than males) are discussed, with anatomical, biomechanical loading and neuromuscular activation differences being cited in the literature. This review presents an in-depth contemporary examination of the applied physiology of the female soccer player

Inconsistent effect of psychometric-scale familiarization on the relationship between ratings of perceived exertion and external load measures in elite youth soccer players

To examine the moderating effect of familiarization on the relationship between external load and ratings of perceived exertion (RPEs) in elite youth soccer players. Thirty-five elite male youth soccer players were monitored over a 31-week period. Players had no previous experience using the centiMax scale (arbitrary units [AU]). The final sample included familiarized (blackness test; n = 20) and nonfamiliarized players (n = 15) with the Borg centiMax scale. Players recorded a global RPE and differential RPEs (dRPE) for breathlessness (RPE-B) and leg-muscle exertion (RPE-L) 15 to 30 minutes following training sessions and competitive matches. Separate multivariable-adjusted random-effects generalized additive models with restricted maximum likelihood quantified familiarization versus no-familiarization differences in actual perceived exertion score (in AU) by number of accelerations, decelerations, and high-speed running distance (in meters) as predictor variables, respectively. Players improved their blackness test score from 39% to 78%. For explorations by number of accelerations, familiarization effects were not practically relevant for the RPE and RPE-B variables. The width and sign of the effects for the RPE-L variable at 30 efforts of 10 AU (95% CI, 4-16 AU) suggested that scores were lower for players who underwent familiarization versus players who did not. Familiarization effects were not practically relevant for any RPE variable irrespective of the number of deceleration efforts and high-speed running distance covered. Improved performance on the blackness test did not have a moderating effect on the relationship between proxy measures of external load and RPEs

Inter-methodological quantification of the target change for performance test outcomes relevant to elite female soccer players

Introduction: Valid and informed interpretations of changes in physical performance test data are important within athletic development programmes. At present, there is a lack of consensus regarding a suitable method for deeming whether a change in physical performance is practically relevant or not. Methods: We compared true population variance in mean test scores between those derived from evidence synthesis of observational studies to those derived from practioner opinion (n = 30), and to those derived from a measurement error (minimal detectable change) quantification (n = 140). All these methods can help to obtain ‘target’ change score values for performance variables. Results: We found that the conventional ‘blanket’ target change of 0.2 (between-subjects SD) systematically underestimated practically relevant and more informed changes derived for 5-m sprinting, 30-m sprinting, CMJ, and Yo-Yo Intermittent Recovery Level 1 (IR1) tests in elite female soccer players. Conclusions: For the first time in the field of sport and exercise sciences, we have illustrated the use of a principled approach for comparing different methods for the definition of changes in physical performance test variables that are practically relevant. Our between-method comparison approach provides preliminary guidance for arriving at target change values that may be useful for research purposes and tracking of individual female soccer player’s physical performance