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1.
Biol Sport ; 40(3): 775-785, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37398974

RESUMEN

Evaluating the relationships between physical-test and match performance in team sports could be useful for training prescription and athlete evaluation. Here we investigated these relationships in women's Rugby Sevens. Thirty provincial-representative players performed Bronco-fitness, countermovement-jump, acceleration, speed, and strength tests within two weeks before a two-day tournament. Match-running and match-action performance measures were provided by GPS units and video analysis. Generalised and general linear mixed models were employed to estimate the effect of a two standard-deviation difference in physical-test measures on match measures. Effect magnitudes were assessed via standardisation (using the between-player SD) and, for effects on tries scored, also via match winning (based on simulating matches). Evidence for substantial and trivial true magnitudes was provided by one-sided interval-hypothesis tests and Bayesian analysis. There was good evidence of positive effects of many physical-test measures on match high-intensity running, with large effects for jump height and acceleration. There was some evidence of small-moderate positive effects of speed and Bronco, and of small-moderate negative effects of maximal strength and jump height, on match total running and high intensity changes in speed. The evidence was generally inadequate for associations between physical-test measures and match actions, but there was good evidence of small-large positive effects of back squat and jump height on tries scored. Enhancing players' jump height and back-squat performance might therefore increase the likelihood of match success in women's Rugby Sevens.

2.
Scand J Med Sci Sports ; 32(4): 710-719, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34981575

RESUMEN

PURPOSE: Rowing instrumentation systems provide measures of stroke power, stroke rate, and boat velocity during rowing races, but how well these measures predict race performance has not been reported previously. METHODS: Data were collected per stroke from 45 2000-m races using Peach PowerLine and OptimEye S5 GPS units. The boat classes assessed were nine male singles, eight female singles, three male pairs, and six female pairs. Random effects and residuals from general linear mixed modeling of stroke velocity adjusted for stroke power, stroke rate, and mean headwind provided measures interpreted as technical efficiency, race conditions, and stroke-velocity variability. These measures, along with mean race power, mean stroke rate, and mean headwind were then included in multiple linear regressions to predict race velocity from official race times. Effects were assessed for 2 SD changes in predictors and interpreted using interval hypothesis tests. RESULTS: Effects of mean race power, mean stroke rate, and mean headwind on race velocity ranged from small to extremely large and were mostly decisively substantial. Effects of technical efficiency and race conditions ranged from trivial to extremely large but were generally unclear, while stroke-velocity variability had trivial-small and mostly unclear effects. Prediction error was small to moderate and decisively substantial. Men's pairs lacked sufficient data for analysis. CONCLUSION: On-water rowing race performance can be predicted with mean race values of power, stroke rate, and headwind. Estimates from stroke data are potentially useful predictors but require impractical numbers of boats and races to reduce their uncertainty.


Asunto(s)
Deportes , Deportes Acuáticos , Eficiencia , Femenino , Humanos , Masculino , Navíos , Agua
3.
Br J Sports Med ; 53(18): 1141-1153, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-30862704

RESUMEN

There is evidence from human twin and family studies as well as mouse and rat selection experiments that there are considerable interindividual differences in the response of cardiorespiratory fitness (CRF) and other cardiometabolic traits to a given exercise programme dose. We developed this consensus statement on exercise response variability following a symposium dedicated to this topic. There is strong evidence from both animal and human studies that exercise training doses lead to variable responses. A genetic component contributes to exercise training response variability.In this consensus statement, we (1) briefly review the literature on exercise response variability and the various sources of variations in CRF response to an exercise programme, (2) introduce the key research designs and corresponding statistical models with an emphasis on randomised controlled designs with or without multiple pretests and post-tests, crossover designs and repeated measures designs, (3) discuss advantages and disadvantages of multiple methods of categorising exercise response levels-a topic that is of particular interest for personalised exercise medicine and (4) outline approaches that may identify determinants and modifiers of CRF exercise response. We also summarise gaps in knowledge and recommend future research to better understand exercise response variability.


Asunto(s)
Capacidad Cardiovascular/fisiología , Metabolismo Energético/fisiología , Ejercicio Físico/fisiología , Medicina de Precisión , Animales , Metabolismo Energético/genética , Humanos , Modelos Estadísticos , Condicionamiento Físico Animal , Acondicionamiento Físico Humano , Proyectos de Investigación
4.
J Sports Sci ; 37(18): 2045-2050, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31109247

RESUMEN

Regular air travel is common in sport. The aim of this study was to understand the extent to which travel has affected Super Rugby teams' performance from 2006, the first season with available Key Performance Indicators (KPIs), to 2016. Data were analysed with mixed linear models for the effects of number of time-zones crossed (east or west), travel duration, the away-match disadvantage, difference in ranking, a set of amendments to the laws of Rugby Union in 2008, a change in competition format (introduction of a conference system) in 2011, and a secular trend. In 2006, the predicted combined effects of travelling 24 h across 12 time-zones and playing away were trivial or small and negative but generally unclear for most of the KPIs in both directions of travel. In 2016 more effects were clear, small and negative for westward travel, while most effects for eastward travel were clear, small to moderate and negative. Most KPIs showed small to moderate increases over the 11 years, while difference in ranking, the introduction of new rules and game format led to mostly small changes. Changes in the physical demands of the game, and inadequate recovery time for long-haul travel can explain these effects.


Asunto(s)
Viaje en Avión , Rendimiento Atlético , Fútbol Americano , Conducta Competitiva , Humanos
5.
J Sports Sci ; 37(18): 2051-2056, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31104575

RESUMEN

The extent to which travel has affected Super Rugby teams' performances was analysed using outcomes of all matches played from the beginning of the competition in 1996 to the end of the 2016 season. Points difference and matches won or lost were predicted with general and generalized mixed linear models. The predictors were the linear effects of number of time zones crossed and travel duration based on the teams' locations for each match and their locations in the previous week. The away-match disadvantage was also estimated, along with trends in all these effects. In 1996 the predicted combined effect of eastward travel across 12 time zones was a reduction of 5.8 points scored per match, resulting in 4.1 more matches lost every 10 matches. Corresponding effects for westward travel were 6.4 points and 3.1 matches. In 2016 effects travelling eastward were 3.7 points and 2.3 matches, whereas travelling westward the effects were 3.7 points and 1.5 matches. These travel effects were due mainly to the away-match disadvantage: 5.7 points and 3.2 matches in 1996; 5.2 points and 2.3 matches in 2016. Teams in Super Rugby are dealing successfully with long-haul travel and should now focus on reducing the away-match disadvantage.


Asunto(s)
Viaje en Avión , Rendimiento Atlético , Fútbol Americano , Conducta Competitiva , Humanos , Modelos Lineales
6.
Hum Reprod ; 31(11): 2619-2631, 2016 11.
Artículo en Inglés | MEDLINE | ID: mdl-27907900

RESUMEN

STUDY QUESTION: What is the degree of intrinsic insulin resistance (IR) in women with polycystic ovary syndrome (PCOS) and the relative contribution of BMI to overall IR based on meta-analysis of gold standard insulin clamp studies? SUMMARY ANSWER: We report an inherent reduction (-27%) of insulin sensitivity (IS) in PCOS patients, which was independent of BMI. WHAT IS ALREADY KNOWN: PCOS is prevalent, complex and underpinned by IR but controversies surround the degree of intrinsic IR in PCOS, the effect of BMI and the impact of the different diagnostic criteria (NIH versus Rotterdam) in PCOS. STUDY DESIGN, SIZE, DURATION: A systematic review and meta-analysis of Medline and All EBM databases was undertaken of studies published up to 30 May 2015. Studies were included if premenopausal women diagnosed with PCOS were compared with a control group for IS, measured by the gold standard euglycaemic-hyperinsulinaemic clamp. The systematic review adheres to the principles of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Meta-analyses were performed using mixed modelling and magnitude-based inferences expressed as mean effect ±99% CI. We inferred the effect was small, moderate or large relative to a smallest important change of -3.7% or 3.8% derived by standardisation. Effects were deemed unclear when the CI overlapped smallest important positive and negative values. Effects were qualified with probabilities reflecting uncertainty in the magnitude of the true value (likely, 75-95%; very likely, 95-99.5%; most likely, >99.5%). PARTICIPANTS/MATERIALS, SETTING, METHOD: A total of 4881 articles were returned from the search. Of these, 28 articles were included in the meta-analysis. MAIN RESULTS AND THE ROLE OF CHANCE: Overall IS was lower in women with PCOS compared with controls (mean effect -27%, 99% CI ±6%; large, most likely lower). A higher BMI exacerbated the reduction in IS by -15% (±8%; moderate, most likely lower) in PCOS compared with control women. There was no clear difference in IS between women diagnosed by the original National Institutes of Health  (NIH) criteria alone compared with those diagnosed by the Rotterdam criteria. Low levels of sex hormone-binding globulin (SHBG) were associated with reduced levels of IS (-10%, ±10%; small, very likely negative), which was not confounded by BMI. LIMITATIONS, REASONS FOR CAUTION: This systematic review and meta-analysis inherited the confounding problems of small sample sizes, missing data (e.g. some hormones, waist and hip girths) and the lack of Rotterdam criteria phenotype reporting, limiting the evidence synthesis and meta-analysis. WIDER IMPLICATIONS OF THE FINDINGS: BMI has a greater impact on IS in PCOS than in controls. SHBG appears a potentially valuable marker of IR in PCOS, whereas testosterone after adjustment for BMI demonstrated an unexpected interplay with IS which warrants further investigation. STUDY FUNDING/COMPETING INTERESTS: This work was supported by grants from the National Health & Medical Research Council (NHMRC), grant number 606553 (H.J.T., N.K.S.), as well as Monash University. H.J.T. is an NHMRC Research Fellow. N.K.S. is supported through the Australian Government's Collaborative Research Networks (CRN) programme. The funding bodies played no role in the design, methods, data management or analysis or in the decision to publish. All authors declare no conflict of interests. REGISTRATION NUMBER: N/A.


Asunto(s)
Resistencia a la Insulina/fisiología , Síndrome del Ovario Poliquístico/metabolismo , Índice de Masa Corporal , Femenino , Técnica de Clampeo de la Glucosa , Humanos
7.
J Phys Act Health ; 21(4): 323-332, 2024 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-38194951

RESUMEN

BACKGROUND: Although 24-hour movement behaviors are known to be interconnected, limited knowledge exists about whether change in one behavior during the COVID-19 pandemic (eg, increased screen time) was associated with change in another (eg, reduced physical activity or sleep). This review estimates mediational associations between changes in children's physical activity, screen time, and sleep during the COVID-19 pandemic. METHODS: We included studies published between January 1, 2020 and June 27, 2022, in the PubMed/MEDLINE, Embase, PsycINFO, SPORTDiscus, and Web of Science databases. Summary data were extracted from included studies and analyzed with random-effects meta-regression. RESULTS: This review included 26 studies representing 18,959 children across 18 mid-high-income countries (53% male; mean age, 11.5 [2.9] y). There was very good evidence of decreased total daily physical activity (factor change, 0.62; 90% CI, 0.47-0.81) and strong evidence of increased screen time (1.56; 90% CI, 1.38-1.77). There was very good evidence of decreased moderate to vigorous physical activity (0.75; 90% CI, 0.62-0.90) and weak evidence of increased sleep (1.02; 90% CI, 1.00-1.04). Mediational analysis revealed strong evidence that most of the reduction in total daily physical activity from before, to during, the pandemic was associated with increased screen time (0.53; 90% CI, 0.42-0.67). We observed no further mediational associations. CONCLUSION: Increased reliance on and use of screen-based devices during the COVID-19 pandemic can be linked with reduced child and adolescent physical activity. This finding links COVID-related restrictions to potential displacement effects within child and adolescent 24-hour movement behavior.


Asunto(s)
COVID-19 , Niño , Humanos , Masculino , Adolescente , Femenino , COVID-19/epidemiología , Ejercicio Físico , Pandemias , Conducta Sedentaria
8.
Int J Sports Physiol Perform ; 18(9): 968-981, 2023 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-37474117

RESUMEN

The aim of this investigation was to quantify professional rugby union player activity profiles after the most intense (peak) passages of matches. Movement data were collected from 30 elite and 30 subelite professional rugby union athletes across respective competitive seasons. Accelerometer-derived PlayerLoad and global navigation satellite system-derived measures of mean speed and metabolic power were analyzed using a rolling-average method to identify the most intense 5- to 600-second passages (ie, worst-case scenarios) within matches. Player activity profiles immediately post their peak 5- to 600-second match intensity were identified using 5 epoch duration-matched intervals. Mean speed, metabolic power, and PlayerLoad declined sharply (∼29%-86%) after the most intense 5 to 600 seconds of matches. Following the most intense periods of rugby matches, exercise intensity declined below the average match-half intensity 81% of the time and seldom returned to or exceeded it, likely due to a host of individual physical and physiological characteristics, transient and/or accumulative fatigue, contextual factors, and pacing strategies. Typically, player exercise intensities after the most intense passages of matches were similar between match halves, positional groups, and levels of rugby competition. Accurate identification of the peak exercise intensities of matches and movement thereafter using novel methodologies has improved the limited understanding of professional rugby union player activity profiles following the worst-case scenarios of matches. Findings of the present study may inform match-representative training prescription, monitoring, and tactical match decisions (eg, substitutions and positional changes).


Asunto(s)
Rendimiento Atlético , Fútbol Americano , Carrera , Humanos , Fútbol Americano/fisiología , Carrera/fisiología , Rugby , Rendimiento Atlético/fisiología , Sistemas de Información Geográfica
9.
Appl Physiol Nutr Metab ; 48(11): 829-840, 2023 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-37390497

RESUMEN

Evaluating anatomical contributions to performance can increase understanding of muscle mechanics and guide physical preparation. While the impact of anatomy on muscular performance is well studied, the effects of regional quadriceps architecture on rapid torque or force expression are less clear. Regional (proximal, middle, and distal) quadriceps (vastus lateralis, rectus femoris, and vastus intermedius) thickness (MT), pennation angle (PA), and fascicle length (FL) of 24 males (48 limbs) were assessed via ultrasonography. Participants performed maximal isometric knee extensions at 40°, 70°, and 100° of knee flexion to evaluate rate of force development from 0 to 200 ms (RFD0-200). Measurements were repeated on three occasions with the greatest RFD0-200 and mean muscle architecture measures used for analysis. Linear regression models predicting angle-specific RFD0-200 from regional anatomy provided adjusted correlations (√adjR2) with bootstrapped compatibility limits. Mid-rectus femoris MT (√adjR2 = 0.41-0.51) and proximal vastus lateralis FL (√adjR2 = 0.42-0.48) were the best single predictors of RFD0-200, and the only measures to reach precision with 99% compatibility limits. Small simple correlations were found across all regions and joint angles between RFD0-200 and vastus lateralis MT (√adjR2 = 0.28 ± 0.13; mean ± SD), vastus lateralis FL (√adjR2 = 0.33 ± 0.10), rectus femoris MT (√adjR2 = 0.38 ± 0.10), and lateral vastus intermedius MT (√adjR2 = 0.24 ± 0.10). Between-correlation comparisons are reported within the article. Researchers should measure mid-region rectus femoris MT and vastus lateralis FL to efficiently and robustly evaluate potential anatomical contributions to rapid knee extension force changes, with distal and proximal measurements providing little additional value. However, correlations were generally small to moderate, suggesting that neurological factors may be critical in rapid force expression.


Asunto(s)
Articulación de la Rodilla , Músculo Cuádriceps , Masculino , Humanos , Músculo Cuádriceps/fisiología , Articulación de la Rodilla/diagnóstico por imagen , Articulación de la Rodilla/fisiología , Ultrasonografía , Torque
10.
Int J Sports Physiol Perform ; 17(5): 780-786, 2022 05 01.
Artículo en Inglés | MEDLINE | ID: mdl-35203051

RESUMEN

PURPOSE: Can power law models accurately predict the peak intensities of rugby competition as a function of time? METHODS: Match movement data were collected from 30 elite and 30 subelite rugby union athletes across competitive seasons, using wearable Global Navigation Satellite Systems and accelerometers. Each athlete's peak rolling mean value of each measure (mean speed, metabolic power, and PlayerLoad™) for 8 durations between 5 seconds and 10 minutes was predicted by the duration with 4 power law (log-log) models, one for forwards and backs in each half of a typical match. RESULTS: The log of peak exercise intensity and exercise duration (5-600 s) displayed strong linear relationships (R2 = .967-.993) across all 3 measures. Rugby backs had greater predicted intensities for shorter durations than forwards, but their intensities declined at a steeper rate as duration increased. Random prediction errors for mean speed, metabolic power, and PlayerLoad were 5% to 6%, 7% to 9%, and 8% to 10% (moderate to large), respectively, for elite players. Systematic prediction errors across the range of durations were trivial to small for elite players, underestimating intensities for shorter (5-10 s) and longer (300-600 s) durations by 2% to 4% and overestimating 20- to 120-second intensities by 2% to 3%. Random and systematic errors were slightly greater for subelites compared to elites, with ranges of 4% to 12% and 2% to 5%, respectively. CONCLUSIONS: Peak intensities of professional rugby union matches can be predicted with adequate precision (trivial to small errors) for prescribing training drills of a given duration, irrespective of playing position, match half, level of competition, or measure of exercise intensity. However, practitioners should be aware of the substantial (moderate to large) prediction errors at the level of the individual player.


Asunto(s)
Rendimiento Atlético , Fútbol Americano , Carrera , Aceleración , Sistemas de Información Geográfica , Humanos , Rugby
11.
PLoS One ; 17(2): e0261517, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35134058

RESUMEN

Matches and travel, which are common in professional team sports, may have a negative impact on players. The aim of this study was to quantify the impact on sleep, wellness and training of Super Rugby players. Sleep of 122 players from four teams was monitored using activity monitors for up to three nights before and after matches played at home and overseas. Wellness and internal training load (questionnaires) and external training load (GPS/accelerometer) were also recorded. Separate analyses were performed for each team using a general linear mixed model to estimate the mean effects of travel (translocation overseas and return to the home country) on sleep, wellness and training. The mean effects of matches on sleep and wellness on the nights before, of and after matches. were also estimated. Teams generally experienced small to large reductions in sleep and wellness when overseas; on return, sleep and wellness recovered somewhat. The impact of matches on sleep and wellness differed in magnitude and direction (large reductions to small increases) between teams. External load overseas and upon return was reduced for three of the four teams, whilst internal load was reduced for the three teams that measured it. The changes in sleep, wellness and training can be explained by a combination of travel- and match-related stressors that differed between teams. Teams should consider remediation strategies to mitigate the effects of travel.


Asunto(s)
Atletas/psicología , Sueño/fisiología , Acelerometría , Adolescente , Adulto , Rendimiento Atlético , Humanos , Masculino , Rugby , Encuestas y Cuestionarios , Viaje , Adulto Joven
12.
Nutr J ; 10: 30, 2011 Apr 11.
Artículo en Inglés | MEDLINE | ID: mdl-21477383

RESUMEN

BACKGROUND: Probiotics purportedly reduce symptoms of gastrointestinal and upper respiratory-tract illness by modulating commensal microflora. Preventing and reducing symptoms of respiratory and gastrointestinal illness are the primary reason that dietary supplementation with probiotics are becoming increasingly popular with healthy active individuals. There is a paucity of data regarding the effectiveness of probiotics in this cohort. The aim of this study was to evaluate the effectiveness of a probiotic on faecal microbiology, self-reported illness symptoms and immunity in healthy well trained individuals. METHODS: Competitive cyclists (64 males and 35 females; age 35 ± 9 and 36 ± 9 y, VO2max 56 ± 6 and 52 ± 6 ml.kg-1.min-1, mean ± SD) were randomised to either probiotic (minimum 1 × 109 Lactobacillus fermentum (PCC®) per day) or placebo treatment for 11 weeks in a double-blind, randomised, controlled trial. The outcome measures were faecal L. fermentum counts, self-reported symptoms of illness and serum cytokines. RESULTS: Lactobacillus numbers increased 7.7-fold (90% confidence limits 2.1- to 28-fold) more in males on the probiotic, while there was an unclear 2.2-fold (0.2- to 18-fold) increase in females taking the probiotic. The number and duration of mild gastrointestinal symptoms were ~2-fold greater in the probiotic group. However, there was a substantial 0.7 (0.2 to 1.2) of a scale step reduction in the severity of gastrointestinal illness at the mean training load in males, which became more pronounced as training load increased. The load (duration×severity) of lower respiratory illness symptoms was less by a factor of 0.31 (99%CI; 0.07 to 0.96) in males taking the probiotic compared with placebo but increased by a factor of 2.2 (0.41 to 27) in females. Differences in use of cold and flu medication mirrored these symptoms. The observed effects on URTI had too much uncertainty for a decisive outcome. There were clear reductions in the magnitude of acute exercise-induced changes in some cytokines. CONCLUSION: L. fermentum may be a useful nutritional adjunct for healthy exercising males. However, uncertainty in the effects of supplementation on URTI and on symptoms in females needs to be resolved. TRIAL REGISTRATION: The trial was registered in the Australia and New Zealand Clinical Trials Registry (ACTRN12611000006943).


Asunto(s)
Atletas , Enfermedades Gastrointestinales/microbiología , Limosilactobacillus fermentum , Probióticos/administración & dosificación , Infecciones del Sistema Respiratorio/microbiología , Adulto , Citocinas/metabolismo , Método Doble Ciego , Ejercicio Físico , Heces/microbiología , Femenino , Enfermedades Gastrointestinales/prevención & control , Tracto Gastrointestinal/microbiología , Humanos , Inmunidad , Masculino , Persona de Mediana Edad , Nueva Zelanda , Infecciones del Sistema Respiratorio/prevención & control , Autoinforme , Adulto Joven
13.
Front Physiol ; 12: 758015, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34867462

RESUMEN

Purpose: Instrumentation systems are increasingly used in rowing to measure training intensity and performance but have not been validated for measures of power. In this study, the concurrent validity of Peach PowerLine (six units), Nielsen-Kellerman EmPower (five units), Weba OarPowerMeter (three units), Concept2 model D ergometer (one unit), and a custom-built reference instrumentation system (Reference System; one unit) were investigated. Methods: Eight female and seven male rowers [age, 21 ± 2.5 years; rowing experience, 7.1 ± 2.6 years, mean ± standard deviation (SD)] performed a 30-s maximal test and a 7 × 4-min incremental test once per week for 5 weeks. Power per stroke was extracted concurrently from the Reference System (via chain force and velocity), the Concept2 itself, Weba (oar shaft-based), and either Peach or EmPower (oarlock-based). Differences from the Reference System in the mean (representing potential error) and the stroke-to-stroke variability (represented by its SD) of power per stroke for each stage and device, and between-unit differences, were estimated using general linear mixed modeling and interpreted using rejection of non-substantial and substantial hypotheses. Results: Potential error in mean power was decisively substantial for all devices (Concept2, -11 to -15%; Peach, -7.9 to -17%; EmPower, -32 to -48%; and Weba, -7.9 to -16%). Between-unit differences (as SD) in mean power lacked statistical precision but were substantial and consistent across stages (Peach, ∼5%; EmPower, ∼7%; and Weba, ∼2%). Most differences from the Reference System in stroke-to-stroke variability of power were possibly or likely trivial or small for Peach (-3.0 to -16%), and likely or decisively substantial for EmPower (9.7-57%), and mostly decisively substantial for Weba (61-139%) and the Concept2 (-28 to 177%). Conclusion: Potential negative error in mean power was evident for all devices and units, particularly EmPower. Stroke-to-stroke variation in power showed a lack of measurement sensitivity (apparent smoothing) that was minor for Peach but larger for the Concept2, whereas EmPower and Weba added random error. Peach is therefore recommended for measurement of mean and stroke power.

14.
Appl Physiol Nutr Metab ; 46(4): 368-378, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33058713

RESUMEN

The length-tension relationship affects knee extension performance; however, whether anatomical variations in different quadriceps regions affect this relationship is unknown. Regional (proximal, middle, distal) quadriceps thickness (MT), pennation angle, and fascicle length of 24 males (48 limbs) were assessed via ultrasonography. Participants also performed maximal voluntary isometric torque (MVIT) assessments at 40°, 70°, and 100° of knee flexion. Measures were recorded on 3 separate occasions. Linear regression models predicting angle-specific torque from regional anatomy provided adjusted simple and multiple correlations (√adjR2) with bootstrapped compatibility limits to assess magnitude. Middle vastus lateralis MT and MVIT at 100° (√adjR2 = 0.64) was the largest single correlation, with distal vastus lateralis MT having the greatest mean correlations regardless of angle (√adjR2 = 0.61 ± 0.05, mean ± SD). Lateral distal MT and architecture had larger (Δ√adjR2 = 0.01 to 0.43) single and multiple correlations with MVIT than the lateral proximal (√adjR2 = 0.15 to 0.69 vs -0.08 to 0.65). Conversely, middle anterior MT had greater (Δ√adjR2 = 0.08 to 0.38) single and multiple correlations than proximal MT (√adjR2 = 0.09 to 0.49 vs -0.21 to 0.14). The length-tension relationship was trivially affected by regional quadriceps architecture. The middle and distal quadriceps were the strongest predictors of MVIT at all joint angles. Therefore, researchers may wish to focus on middle and distal lateral quadriceps anatomy when performing ultrasonographic evaluations. Novelty: The length-tension relationship is minimally affected by regional quadriceps anatomical parameters. Middle and distal vastus lateralis and lateral vastus intermedius anatomy were consistently the best predictors of torque. Practitioners may focus their assessments on the middle and distal regions of the lateral quadriceps' musculature.


Asunto(s)
Músculo Cuádriceps/diagnóstico por imagen , Torque , Ultrasonografía , Adulto , Humanos , Masculino , Fuerza Muscular , Dinamómetro de Fuerza Muscular , Músculo Cuádriceps/anatomía & histología , Adulto Joven
15.
PLoS One ; 16(8): e0249122, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34415922

RESUMEN

PURPOSE: Boat acceleration profiles provide a valuable feedback tool by reflecting both rower technique and force application. Relationships between measures of boat acceleration and velocity to inform interpretation of boat acceleration profiles in rowing were investigated here. METHODS: Thirteen male singles, nine female singles, eight male pairs, and seven female pairs participated (national and international level, age 18-27 y). Data from each stroke for 74 2000-m races were collected using Peach PowerLine and OptimEye S5 GPS units. General linear mixed modelling established modifying effects on velocity of two within-crew SD of boat acceleration variables for each boat class, without and with adjustment for stroke rate and power, to identify potential performance-enhancement strategies for a given stroke rate and power. Measures of acceleration magnitude at six peaks or dips, and six measures of the rate of change (jerk) between these peaks and dips were analyzed. Results were interpreted using rejection of non-substantial and substantial hypotheses with a smallest substantial change in velocity of 0.3%. RESULTS: Several boat acceleration measures had decisively substantial effects (-2.4-2.5%) before adjustment for stroke rate and power. Most effect magnitudes reduced after adjustment for stroke rate and power, although maximum negative drive acceleration, peak drive acceleration, jerk during the mid-drive phase, and jerk in the late recovery remained decisively substantial (-1.8-1.9%) in some boat classes. CONCLUSION: Greater absolute values of maximum negative drive acceleration and jerk in the late recovery are related to improved performance, likely reflecting delayed rower centre-of-mass negative acceleration in preparation for the catch. Greater absolute values of peak drive acceleration, first peak acceleration, and jerk in the early and mid-drive are also associated with improved performance, likely reflecting propulsive force during the drive. These proposed mechanisms provide potential strategies for performance enhancement additional to increases in stroke rate and power output.


Asunto(s)
Rendimiento Atlético/fisiología , Deportes Acuáticos/fisiología , Aceleración , Adolescente , Adulto , Femenino , Humanos , Masculino , Fuerza Muscular/fisiología , Adulto Joven
16.
Front Sports Act Living ; 3: 681766, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33969301

RESUMEN

[This corrects the article DOI: 10.3389/fspor.2020.589013.].

17.
Sports Med Open ; 6(1): 23, 2020 Jun 03.
Artículo en Inglés | MEDLINE | ID: mdl-32495230

RESUMEN

BACKGROUND: A key tenet of sports performance research is to provide coaches and athletes with information to inform better practice, yet the determinants of athletic performance in actual competition remain an under-examined and under-theorised field. In cycling, the effects of contextual factors, presence of and interaction with opponents, environmental conditions, competition structure and socio-cultural, economic and authoritarian mechanisms on the performance of cyclists are not well understood. OBJECTIVES: To synthesise published findings on the determinants of cyclists' behaviours and chances of success in elite competition. METHODS: Four academic databases were searched for peer-reviewed articles. A total of 44 original research articles and 12 reviews met the inclusion criteria. Key findings were grouped and used to shape a conceptual framework of the determinants of performance. RESULTS: The determinants of cycling performance were grouped into four dimensions: features related to the individual cyclist, tactical features emerging from the inter-personal dynamics between cyclists, strategic features related to competition format and the race environment and global features related to societal and organisational constraints. Interactions between these features were also found to shape cyclists' behaviours and chances of success. CONCLUSION: Team managers, coaches, and athletes seeking to improve performance should give attention to features related not only to the individual performer, but also to features of the interpersonal, strategic, global dimensions and their interactions.

18.
Res Q Exerc Sport ; 91(1): 102-114, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31638482

RESUMEN

Purpose: Children with special educational needs and disabilities (SEND) are often excluded from physical education (PE). Opportunities exist to enhance the competence of trainee teachers, thus preparing them for the demands of inclusive PE (IPE). In this study, we examined the effect of IPE training workshops on trainee teachers' self-efficacy for including SEND children within PE. Method: Data was collection from 366 trainee teachers across 44 workshops (63% females; 57% primary-school trainees; age, 23 ± 5 y, mean ± standard deviation; age range 18-53 y). A pre-post design was used to assess the effect of the workshop and possible moderating factors. Data were analyzed using mixed modelling. Results: IPE training had a large beneficial effect on trainees' self-efficacy (1.61, ±0.21; standardized effect size, 99% confidence limits). Mixed modelling revealed substantial differences in the mean outcome between workshops. The standard deviation (SD) representing this variation between workshops was moderate-sized (SD = 0.30, ±0.30). We also found that trainees with an above average sense of self-efficacy at baseline (mean +1SD) were likely to benefit more. Workshop size (0.35, ±0.42) and trainees' perception of workshop quality (0.39, ±0.19) were substantial moderators of changes in self-efficacy. Other moderators with possible substantial effects were trainee specialization and completion of a school-based placement. Conclusion: This study supports the viability of embedding IPE within teacher training. Attention should be paid to trainees' starting points prior to scheduling training. The size of workshops and quality of delivery should also be considered when developing IPE competencies within trainees.


Asunto(s)
Integración Escolar , Educación y Entrenamiento Físico , Maestros/psicología , Autoeficacia , Formación del Profesorado/métodos , Adolescente , Adulto , Educación Continua , Inglaterra , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven
19.
Front Sports Act Living ; 2: 589013, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33345160

RESUMEN

Purpose: Research establishing relationships between measures of rowing technique and velocity is limited. In this study, measures of technique and their effect on rowing velocity were investigated. Methods: Ten male singles, eight female singles, three male pairs, and six female pairs participated. Data from each stroke for forty-seven 2,000 m races were collected using Peach PowerLine and OptimEye S5 GPS units. General linear mixed modeling established modifying effects on velocity of two within-crew SD of predictor variables for each boat class, with subsequent adjustment for power, and for power and stroke rate in separate analyses. Twenty-two predictor variables were analyzed, including measures of boat velocity, gate force, and gate angle. Results were interpreted using superiority and inferiority testing with a smallest important change in velocity of 0.3%. Results: Substantial relationships with velocity were found between most variables assessed before adjustment for power, and for power and stroke rate. Effect magnitudes were reduced for most variables after adjustment for power and further reduced after adjustment for stroke rate and power, with precision becoming inadequate in many effects. The greatest modifying effects were found for stroke rate, mean and peak force, and power output before adjustment, and for catch angle after adjustment for stroke rate and power. Substantial between-crew differences in effects were evident for most predictors in some boat classes before adjustment and in some predictors and some boat classes after adjustment for stroke rate and power. Conclusion: The results presented reveal variables associated with improvements in rowing performance and can be used to guide technical analysis and feedback by practitioners. Higher stroke rates and greater catch angles should be targeted to improve rowing performance, and rower force development for the improvement of power output. Relationships between rowing technique and velocity can be crew-dependent and are best assessed on an individual basis for some variables.

20.
PLoS One ; 15(7): e0236024, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32687507

RESUMEN

Training prescription and monitoring of team-sport athletes rely on accurate quantification of player movement. Our aim was to determine the sensitivity, reliability and construct validity of measures derived from a wearable device incorporating Global Positioning System (GPS) and accelerometer technology to quantify the peak periods of rugby competition. Match movement data were collected from 30 elite and 30 sub-elite rugby union players across respective competitive seasons. Accelerometer and GPS measures were analysed using a rolling average to identify peak movement for epochs ranging from 5 to 600 seconds. General linear mixed modelling was used to quantify the effects of playing position and match-half on the peak movement and variabilities within and between players represented reliability of each measure. Mean positional differences and match-half changes were assessed via standardisation and magnitude-based decisions. Sensitivity of measures was quantified via evaluation of ("signal") and typical error of measurement ("noise"). GPS and accelerometer measures had poor sensitivity for quantifying peak movement across all epochs and both levels of rugby union competition (noise 4× to 5× the signal). All measures displayed correspondingly low reliability across most epochs and both levels of competition (ICC<0.50). Construct validity was evident in mean differences between playing positions and match halves that were consistent with expected activity profiles in rugby union. However, it was clear from the pattern of differences across epoch durations and levels of competition that GPS and accelerometer measures provided different information about player movement. The poor sensitivity and low reliability of GPS and accelerometer measures of peak movement imply that rugby union players need to be monitored across many matches to obtain adequate precision for assessing individuals. Although all measures displayed construct validity, accelerometers provided meaningful information additional to that of GPS. We recommend using accelerometers alongside GPS to monitor and prescribe match respresentative training.


Asunto(s)
Acelerometría/métodos , Atletas/estadística & datos numéricos , Rendimiento Atlético/fisiología , Fútbol Americano/fisiología , Sistemas de Información Geográfica/instrumentación , Carrera/fisiología , Análisis y Desempeño de Tareas , Adulto , Humanos , Masculino , Curva ROC , Reproducibilidad de los Resultados
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