RESUMO
Training and assessment of agility is often prioritised by soccer coaches and practitioners aiming to develop multi-directional speed. Although the importance of agility is advocated throughout childhood and adolescence, limited data evidence agility performance at different stages of adolescence. The purpose of this study was to examine differences in multi-directional speed performance in youth soccer players spanning an entire soccer academy. A total of 86 male junior-elite soccer players volunteered to participate. Anthropometric data were collected, alongside performance data from a battery of physical tests including sprinting, jumping, change of direction, reaction time, and agility. Bayesian models using log-likelihoods from posterior simulations of parameter values displayed linear or curvilinear relationships between both chronological and biological age and performance in all tests other than agility and reaction time. For agility and reaction time tests, performance improved until ~14 years of age or the estimated age of peak height velocity whereby arrested development in performance was observed. Our results demonstrate that while most performance skills improve as chronological or biological age increases, measures of agility and reaction time may not. These findings support the notion that agility performance is complex and multifaceted, eliciting unique, challenging physical demands and non-linear development.
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Desempenho Atlético , Destreza Motora , Tempo de Reação , Futebol , Humanos , Futebol/fisiologia , Adolescente , Masculino , Desempenho Atlético/fisiologia , Destreza Motora/fisiologia , Tempo de Reação/fisiologia , Criança , Corrida/fisiologia , Teorema de Bayes , Fatores Etários , Teste de Esforço , AntropometriaRESUMO
ABSTRACT: Brown, F, Jeffries, O, Gissane, C, Howatson, G, van Someren, K, Pedlar, C, Myers, T, and Hill, JA. Custom-fitted compression garments enhance recovery from muscle damage in rugby players. J Strength Cond Res 36(1): 212-219, 2022-to evaluate the effects of custom-fitted compression garments (CG) on recovery from muscle damage in rugby players. Forty-five players were tested for lower-body strength, power, and indices of muscle damage before completing a damaging protocol (20 × 20-m sprints with 5-m deceleration, 100 drop jumps). Players were randomly assigned to wear either custom-fitted (CF, n = 13), or standard-sized CG (SSG, n = 16), or to receive sham ultrasound therapy (CON, n = 16) immediately after exercise. Players were retested immediately, then after 24 and 48 hours. Strength recovery was significantly different between groups (F = 2.7, p = 0.02), with only CF recovering to baseline values by 48 hours (p = 0.973). Time × condition effects were also apparent for creatine kinase activity (χ2 = 30.4, p < 0.001) and midthigh girth (F = 3.7, p = 0.005), with faster recovery apparent in CF compared with both CON and SSG (p < 0.05). Custom-fitted CG improved strength recovery and indices of muscle damage in rugby players, compared with controls and standard-sized garments. Athletes and coaches would be advised to use appropriately fitted CG to enhance strength recovery after damaging exercise.
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Traumatismos do Joelho/prevenção & controle , Músculo Esquelético , Rugby , Meias de Compressão , Atletas , Vestuário , Futebol Americano , Humanos , Força Muscular , Músculo Esquelético/fisiologiaRESUMO
To optimize use of available resources, professional academies develop strategies to assess, monitor, and evaluate players as they progress through adolescence toward adulthood. However, few published reports exist using longitudinal study designs to examine performance throughout adolescence and the transition from youth to professional soccer. We examined differences in the age of player recruitment alongside longitudinal performance differences on field-based fitness tests of successful vs. unsuccessful graduates across the entire age spectrum recruited by a professional soccer academy. Altogether, 537 youth soccer players volunteered to participate. We recorded the age of recruitment, biannual fitness test performance, and subsequent success in attaining a senior professional contract at the club across a period of 12 years. Only 53 (10%) of players were successful in obtaining a professional contract, with 68% of players who became professional being recruited at 12 years of age or older. Individuals recruited at an earlier age did not display a higher probability of success in attaining a professional contract. Bayesian regression models reported a consistent interaction between age and group for data on all performance measures. Moreover, "successful" academy graduates only physically outperformed their "unsuccessful" counterparts from age ~13-14 years onward, with either no differences in performance, or performance on physical fitness tests favoring "unsuccessful" players prior to this age. Findings suggest that high achievers during childhood and early adolescence may not develop into successful senior professionals, raising concerns about the predictive utility of talent identification models.
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Aptidão , Desempenho Atlético/fisiologia , Adolescente , Fatores Etários , Teorema de Bayes , Estatura , Índice de Massa Corporal , Teste de Esforço , Humanos , Estudos Longitudinais , Destreza Motora/fisiologia , Futebol/fisiologia , Adulto JovemRESUMO
In March 2020, the spreading Coronavirus (COVID-19) prompted the United Kingdom government to introduce a societal shutdown, accompanied by self-isolation and social-distancing measures to reduce virus transmission. In doing so, opportunities for physical activity were likely reduced, potentially causing detrimental effects to older adults. Therefore, the present study investigated the influence of the initial six weeks of lockdown on physical activity levels, perceived physical function and mood in older adults. A cross-sectional, mixed-methods, observational study was conducted using self-administered, fortnightly online surveys throughout the UK between 21st March-4 May 2020. A total of 117 participants (52 males [age: 76 ± 4 years] and 65 females [age: 76 ± 4 years]) completed all surveys. Despite lockdown restrictions, this group of older adults maintained their pre-lockdown physical activity levels, but also increased their self-reported sedentary time. Subsequently, perception of physical function was maintained across lockdown. With regards to mood; the only strong evidence for an increase in depression was for males (ps = 95.35%; >0.3 AU), although self-reported levels of depression were similar between sexes at week six. Given the link between sedentary behaviour and negative health outcomes in older adults, strategies to reduce sedentariness during the COVID-19 pandemic are required.
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Afeto , COVID-19/psicologia , Exercício Físico , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Feminino , Humanos , Masculino , Pandemias , Comportamento Sedentário , Inquéritos e Questionários , Reino UnidoRESUMO
This study identified key somatic and demographic characteristics that benefit all swimmers and, at the same time, identified further characteristics that benefit only specific swimming strokes. Three hundred sixty-three competitive-level swimmers (male [n = 202]; female [n = 161]) participated in the study. We adopted a multiplicative, allometric regression model to identify the key characteristics associated with 100 m swimming speeds (controlling for age). The model was refined using backward elimination. Characteristics that benefited some but not all strokes were identified by introducing stroke-by-predictor variable interactions. The regression analysis revealed 7 "common" characteristics that benefited all swimmers suggesting that all swimmers benefit from having less body fat, broad shoulders and hips, a greater arm span (but shorter lower arms) and greater forearm girths with smaller relaxed arm girths. The 4 stroke-specific characteristics reveal that backstroke swimmers benefit from longer backs, a finding that can be likened to boats with longer hulls also travel faster through the water. Other stroke-by-predictor variable interactions (taken together) identified that butterfly swimmers are characterized by greater muscularity in the lower legs. These results highlight the importance of considering somatic and demographic characteristics of young swimmers for talent identification purposes (i.e., to ensure that swimmers realize their most appropriate strokes).
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Destreza Motora/fisiologia , Natação/fisiologia , Adolescente , Aptidão , Braço/anatomia & histologia , Distribuição da Gordura Corporal , Tamanho Corporal , Criança , Comportamento Competitivo , Feminino , Quadril/anatomia & histologia , Humanos , Perna (Membro)/anatomia & histologia , Masculino , Músculo Esquelético/anatomia & histologia , Ombro/anatomia & histologia , Adulto JovemRESUMO
Subjective and objective assessments may be used congruently when making decisions regarding player recruitment in soccer, yet there have been few attempts to examine the level of agreement between these methods. Therefore, we compare levels of agreement between subjective and objective assessments of physical qualities associated with youth soccer performance. In total, 80 male youth soccer players (13.2 ± 1.9 years), and 12 professional coaches volunteered to participate. Players were objectively assessed using five fitness measures: Yo-Yo Intermittent Recovery Test Level 1; Countermovement vertical jump; Functional Movement Screen™; 5/20 m sprint; alongside anthropometric measures. Additionally, coaches subjectively rated each player on the same five physical qualities using 5-point Likert scales. Inter-rater agreement between ratings from lead and assistant coaches was established for each age group. Moreover, Bayesian regression models were fitted to determine how well coach ratings were able to predict fitness test performance. Although inter-rater agreement between lead and assistant coaches was moderate-to-substantial (ω = 0.48-0.68), relationships between coaches subjective rating's and corresponding fitness test performance were only highly related for the highest and lowest performing players. We suggest that while ratings derived from objective and subjective assessment methods may be related when attempting to differentiate between distinct populations, concerns exist when evaluating homogeneous samples using these methods. Our data highlight the benefits of using both types of measures in the talent identification process.
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Aptidão , Desempenho Atlético/fisiologia , Tutoria , Futebol/fisiologia , Adolescente , Adulto , Fatores Etários , Criança , Tomada de Decisões , Teste de Esforço/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Aptidão FísicaRESUMO
Taylor, RJ, Sanders, D, Myers, T, and Akubat, I. Reliability and validity of integrated external and internal load ratios as measures of fitness in academy rugby union players. J Strength Cond Res 34(6): 1723-1730, 2020-This study aimed to assess the relationships between integrated ratios of external and internal load measures and aerobic fitness in 3 different training exercise protocols. Twelve academy rugby union players (aged; 17.6 ± 0.44 years, height; 179.4 ± 6.3 cm, body mass 83.3 ± 9.7 kg) performed a lactate threshold/V[Combining Dot Above]O2max test (LT/V[Combining Dot Above]O2max) followed by 3 exercise protocols; 760 m continuous shuttle running (20 m shuttle run at 9 km·h), sprint interval training (SIT: 6 × 6 seconds sprint with 54 seconds recovery), and a small-sided game (SSG: 6 vs. 6, 10 minutes on a 39 × 51 m pitch) on 2 occasions. A LT/V[Combining Dot Above]O2max test was used to determine velocity at lactate threshold (vLT) and at the onset of blood lactate accumulation (vOBLA), maximal oxygen uptake (V[Combining Dot Above]O2max) and the heart rate-blood lactate profile for the calculation of internal load (individualized training impulse or iTRIMP). The total distance (TD), PlayerLoad, metabolic power (MP), high-speed distance >15 km·h (HSD), very high-speed distance >18 km·h (VHSD) and individualized high-speed distance based on each player's vOBLA (iHSD) for the 3 exercise protocols were measured using Micro Electro Mechanical Systems/Global Positioning System technology. Bayesian analysis was used to assess the ratios validity and reliability. Ratios demonstrated large-to-very large associations with vOBLA (Rho = 0.64-0.76), vLT (Rho = 0.63-0.71). Reliability of the ratios ranged from 7.06 to 36.28% (coefficient of variation [CV]%). The results suggest that integrated load ratios from the SIT and SSG protocols provide a measure which is reliable with large-to-very large associations to submaximal aerobic fitness in rugby union.
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Limiar Anaeróbio , Teste de Esforço , Futebol Americano/fisiologia , Ácido Láctico/sangue , Aptidão Física/fisiologia , Adolescente , Teorema de Bayes , Frequência Cardíaca , Treinamento Intervalado de Alta Intensidade , Humanos , Masculino , Reprodutibilidade dos Testes , Corrida/fisiologiaRESUMO
Sanders, D, Taylor, RJ, Myers, T, and Akubat, I. A field-based cycling test to assess predictors of endurance performance and establishing training zones. J Strength Cond Res 34(12): 3482-3488, 2020-This study evaluates the relationship between a field-based 8-minute time trial (8MTT) and physiological endurance variables assessed with an incremental laboratory test. Second, lactate thresholds assessed in the laboratory were compared with estimated functional threshold power (FTP) from the 8MTT. Nineteen well-trained road cyclists (aged 22 ± 2 years, height 185.9 ± 4.5 cm, body mass 72.8 ± 4.6 kg, V[Combining Dot Above]O2max 64 ± 4 ml·min·kg) participated. Linear regression revealed that mean 8MTT power output (PO) was strongly to very strongly related to PO at 4 mmol·L, PO at initial rise of 1.00 mmol·L, PO at Dmax and modified (mDmax) (r = 0.61-0.82). Mean 8MTT PO was largely to very largely different compared with PO at fixed blood lactate concentration of 2 mmol·L (ES = 3.20) and 4 mmol·L (ES = 1.90), PO at initial rise 1.00 mmol·L (ES = 2.33), PO at Dmax (ES = 3.47) and mDmax (ES = 1.79) but only trivially different from maximal PO (Wmax) (ES = 0.09). The 8MTT based estimated FTP was moderate to very largely different compared with PO at initial rise of 1 mmol·L (ES = 1.37), PO at Dmax (ES = 2.42), PO at mDmax (ES = 0.77) and PO at 4 mmol·L (ES = 0.83). Therefore, even though the 8MTT can be valuable as a performance test in cycling shown through its relationships with predictors of endurance performance, coaches should be cautious when using FTP and PO at laboratory-based thresholds interchangeably to inform training prescription.
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Ciclismo , Teste de Esforço , Adulto , Humanos , Ácido Láctico , Modelos Lineares , Estado Nutricional , Consumo de Oxigênio , Resistência Física , Adulto JovemRESUMO
Morris, RO, Jones, B, Myers, T, Lake, J, Emmonds, S, Clarke, ND, Singleton, D, Ellis, M, and Till, K. Isometric midthigh pull characteristics in elite youth male soccer players: Comparisons by age and maturity offset. J Strength Cond Res 34(10): 2947-2955, 2020-The purpose of this study was to (a) provide comparative isometric midthigh pull (IMTP) force-time characteristics for elite youth soccer players and (b) determine the effect of age and maturation on IMTP force-time characteristics. Elite male youth soccer players (U12 n = 51; U13 n = 54; U14 n = 56; U15 n = 45; U16 n = 39; and U18 n = 48) across 3 maturity offset groups (Pre n = 117; circa n = 84; and Post-peak height velocity n = 92) performed 2 maximal IMTP trials on a portable force platform (1,000 Hz). Absolute and relative values for peak force (PF) and impulse over 100 and 300 ms were analyzed. A full Bayesian regression model was used to provide probable differences similar to that of a frequentist p value. Advanced age and maturation resulted in superior IMTP force-time characteristics. Peak force demonstrated high probabilities of a difference between all consecutive age groups (p > 0.95). For absolute and relative impulse (100 and 300 ms), only 2 consecutive age groups (U14-15's and U16-18's) demonstrated high probabilities of a difference (p > 0.95) with large effects (d = 0.59-0.93). There were high probable differences between all maturity offset groups for PF and impulse with medium to large effects (d = 0.56-3.80). These were also reduced when expressed relative to body mass (relative PF and relative impulse). This study provides comparative IMTP force-time characteristics of elite male youth soccer players. Practitioners should consider individual maturation status when comparing players given the impact this has on force expression.
Assuntos
Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Maturidade Sexual/fisiologia , Futebol/fisiologia , Adolescente , Fatores Etários , Desempenho Atlético , Teorema de Bayes , Índice de Massa Corporal , Pesos e Medidas Corporais , Criança , Estudos Transversais , Humanos , Perna (Membro) , MasculinoRESUMO
This study investigated the effects of complete and partial sleep deprivation on multiple aspects of athletic performance. Ten males completed a cognitive function test, maximal handgrip strength, countermovement jump (CMJ) and a 15 min all out cycling test to assess aerobic performance. These tests were performed following 3 different sleep conditions; normal sleep (CON), a 4 hr sleep opportunity (PART) and complete sleep deprivation (DEP). Data were analysed using a Bayesian multi-level regression model to provide probabilities of impairment (p = %). Aerobic performance, CMJ and handgrip strength were impaired by 11.4% (p = 100%), 10.9% (p = 100%) and 6% (p = 97%) following DEP, while aerobic performance and CMJ were highly likely impaired by 4.1% (p = 90%) and 5.2% (p = 94%) following PART. Cognitive reaction time was not impacted by PART or DEP. In contrast the accuracy of responses was highly likely impaired by 2% (91) following DEP, while there was less certainty of impaired accuracy following PART (-1%, p = 73). Multiple aspects of physical and cognitive performance were impacted by sleep deprivation. The greatest detrimental effects were seen for aerobic performance and CMJ. Partial sleep deprivation equating to 4 hrs of sleep causes subtle, but potentially important negative impairments on athletic performance.
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Desempenho Atlético/fisiologia , Desempenho Atlético/psicologia , Cognição/fisiologia , Privação do Sono/fisiopatologia , Adulto , Teorema de Bayes , Teste de Esforço/métodos , Força da Mão , Humanos , Masculino , Exercício Pliométrico , Adulto JovemRESUMO
The aims of this study were to estimate the walking cadence required to elicit a VO2reserve (VO2R) of 40% and determine if fitness status moderates the relationship between walking cadence and %VO2R. Twenty participants (10 male, mean(s) age 32(10) years; VO2max 45(10) mL·kg-1·min-1) completed resting and maximal oxygen consumption tests prior to 7 x 5-min bouts of treadmill walking at increasing speed while wearing an Apple Watch and measuring oxygen consumption continuously. The 7 x 5-min exercise bouts were performed at speeds between 3 and 6 km·h-1 with 5-min seated rest following each bout. Walking cadence measured at each treadmill speed was recorded using the Apple Watch "Activity" app. Using Bayesian regression, we predict that participants need a walking cadence of 138 to 140 steps·min-1 to achieve a VO2R of 40%. However, these values are moderated by fitness status such that those with lower fitness can achieve 40% VO2R at a slower walking cadence. The results suggest that those with moderate fitness need to walk at ~40% higher than the currently recommended walking cadence (100 steps·min-1) to elicit moderate-intensity physical activity. However, walking cadence required to achieve moderate-intensity physical activity is moderated by fitness status.
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Aptidão Física , Velocidade de Caminhada , Caminhada/fisiologia , Adulto , Estudos Transversais , Teste de Esforço , Feminino , Humanos , Masculino , Consumo de Oxigênio , Adulto JovemRESUMO
This study evaluated the changes in ratios of different intensity (rating of perceived exertion; RPE, heart rate; HR, power output; PO) and load measures (session-RPE; sRPE, individualized TRIMP; iTRIMP, Training Stress Score™; TSS) in professional cyclists. RPE, PO and HR data was collected from twelve professional cyclists (VO2max 75 ± 6 mlâminâkg-1) during a two-week baseline training period and during two cycling Grand Tours. Subjective:objective intensity (RPE:HR, RPE:PO) and load (sRPE:iTRIMP, sRPE:TSS) ratios and external:internal intensity (PO:HR) and load (TSS:iTRIMP) ratios were calculated for every session. Moderate to large increases in the RPE:HR, RPE:PO and sRPE:TSS ratios (d = 0.79-1.79) and small increases in the PO:HR and sRPE:iTRIMP ratio (d = 0.21-0.41) were observed during Grand Tours compared to baseline training data. Differences in the TSS:iTRIMP ratio were trivial to small (d = 0.03-0.27). Small to moderate week-to-week changes (d = 0.21-0.63) in the PO:HR, RPE:PO, RPE:HR, TSS:iTRIMP, sRPE:iTRIMP and sRPE:TSS were observed during the Grand Tour. Concluding, this study shows the value of using ratios of intensity and load measures in monitoring cyclists. Increases in ratios could reflect progressive fatigue that is not readily detected by changes in solitary intensity/load measures.
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Ciclismo/fisiologia , Fadiga/diagnóstico , Monitorização Fisiológica , Esforço Físico , Adulto , Frequência Cardíaca , Humanos , Masculino , Consumo de OxigênioRESUMO
Introduction: Participating in regular physical activity (PA) has numerous benefits, such as reducing obesity, chronic degenerative conditions, and depression. Despite many health-related benefits, physical inactivity is increasing in young people worldwide, especially in ethnic minority groups, such as British South Asians (BSAs). The aim of this study was to explore the PA levels of BSAs, specifically focusing on youth from Afghan, Pakistani, Bangladeshi, and Indian groups. Methods: A total of 191 (Afghans N = 44; Bangladeshi N = 39; Indian N = 56, Pakistani N = 52) youth from the West Midlands (UK) participated in this study (mean age 15.4 ± 0.5). The International Physical Activity QuestionnaireShort Form was used to measure PA levels. Data were modelled using a Bayesian approach to determine differences in PA levels. Results: The results indicated that 88.5% Afghans, 80% Bangladeshi, 78.6% Indians and 63% Pakistani reported engaging in <30 min of PA per day. Additionally, boys were more active than girls across all ethnic groups. Discussion: This study highlighted an alarmingly low proportion of young people from each BSA ethnic group meeting the PA guidelines. To the authors' knowledge, this is the first study to explore and compare PA levels of the young British Afghan population, thus contributing novel findings to the area of BSA PA. Conclusion: Overall, the vast majority of BSA young people failed to meet the recommended PA guidelines of 60 min per day. Future research could utilise objective methods, such as Global Positioning System, pedometers and accelerometery to track and monitor PA levels, and could adopt an ecological approach to explore determinants of PA within each ethnic and gender group.
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Etnicidade , Grupos Minoritários , Masculino , Feminino , Humanos , Adolescente , Estudos Transversais , Teorema de Bayes , Exercício Físico , Reino UnidoRESUMO
OBJECTIVES: To a) demonstrate that adopting 'at risk' waist-to-height ratio (WHTR) cut-off points, recently approved by National Institute for Health and Care Excellence (NICE) and the United States Department of Defense (USDoD), will unfairly penalize shorter individuals and will be too lenient for taller individuals, b) to confirm that waist circumference (WC) of a sample of US service personnel, scales to approximately height0.5, supporting the notion that WC, to be independent of height (HT), should be normalized using WC.HT-0.5 (WHTâ¢5R), and c) to identify the WHTâ¢5R cut-off points that will reduce or eliminate this unwanted bias. SUBJECTS/METHODS: We employed a three independent cross-sectional sample design. All n = 58,742 participants underwent anthropometric assessment of body mass, stature and waist circumference. RESULTS: The allometric power-law model WC=a.HT^b for US service personnel identified the height exponent to be b= 0.418 (95 % CI 0.251-0.585), confirming that the simple body-shape index for WC to be independent of HT, should be WC.HT-0.5. Chi-square tests of independence and for linear trend confirmed that by adopting WHTR cut-off point, shorter individuals (both service personnel and non-service participants) will be over penalized (classified as being 'at risk'). New WC independent-of-height ratio cut-off points were found to resolve this problem. CONCLUSIONS: Adopting WHTR cut-off thresholds (either 0.5 or 0.55) will lead to shorter adults being unfairly classified as being 'at risk' in terms of their central adiposity and general health status. Adopting new WHTâ¢5R cut-off point thresholds were found to greatly reduce or eliminate this bias.
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Obesidade , Razão Cintura-Estatura , Humanos , Adulto , Fatores de Risco , Índice de Massa Corporal , Estudos Transversais , Circunferência da CinturaRESUMO
The National Institute for Clinical Excellence (NICE) has just released its latest guidelines to assess and predict health risk, such as type 2 diabetes, hypertension or cardiovascular disease. Their latest advice is "Keep the size of your waist to less than half of your height". We believe this advice is flawed and will seriously and unfairly penalize shorter people and lull taller people into a false sense of security. In this short communication, we provide this evidence. We consider this a serious oversight by NICE and feel strongly that this evidence needs to be made available in the public domain.
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Doenças Cardiovasculares , Diabetes Mellitus Tipo 2 , Estatura , Doenças Cardiovasculares/prevenção & controle , Humanos , Reino UnidoRESUMO
PURPOSE: To manage physical performance in soccer, practitioners monitor the training load (TL) and the resulting fatigue. A method frequently used to assess performance is the countermovement jump (CMJ). However, the efficacy of CMJ to detect fatigue from soccer matches and training remains uncertain, as does the relationship between TL and change in CMJ performance. The aims of the present study were 2-fold. One was to observe the changes of CMJ force-time components and jump height (JH). The second was to examine dose-response relationships between TL measures and CMJ over a 6-week preseason. METHODS: Twelve male academy soccer players (17 [1] y, 71.2 [5.6] kg, and 178 [5.8] cm) were recruited. Daily changes in CMJ were assessed against baseline scores established before preseason training, along with internal and external TL measures. A series of Bayesian random intercept models were fitted to determine probability of change above/below zero and greater than the coefficient of variation established at baseline. Jumps were categorized into match day minus (MD-) categories where the higher number indicated more time from a competitive match. RESULTS: JH was lowest on MD - 3 (28 cm) and highest on MD - 4 (34.6 cm), with the probability of change from baseline coefficient of variation highly uncertain (41% and 61%, respectively). Changes to force-time components were more likely on MD - 3 (21%-99%), which provided less uncertainty than JH. Bayes R2 ranged from .22 to .57 between TL measures and all CMJ parameters. CONCLUSIONS: Force-time components were more likely to change than JH. Practitioners should also be cautious when manipulating TL measures to influence CMJ performance.
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Desempenho Atlético , Futebol , Masculino , Humanos , Futebol/fisiologia , Desempenho Atlético/fisiologia , Teorema de Bayes , Fadiga Muscular/fisiologia , FadigaRESUMO
INTRODUCTION: A metabolic equivalent (MET) is one of the most common methods used to objectively quantify physical activity intensity. Although the MET provides an 'objective' measure, it does not account for inter-individual differences in cardiorespiratory fitness. In contrast, 'relative' measures of physical activity intensity, such as heart rate reserve (HRR), do account for cardiorespiratory fitness. The purpose of this systematic review with meta-regression was to compare measures of absolute and relative physical activity intensity collected during walking. METHODS: A systematic search of four databases (SPORTDiscus, Medline, Academic Search Premier and CINAHL) was completed. Keyword searches were: (i) step* OR walk* OR strid* OR "physical activity"; (ii) absolute OR "absolute intensity" OR mets OR metabolic equivalent OR actigraph* OR acceleromet*; (iii) relative OR "relative intensity" OR "heart rate" OR "heart rate reserve" OR "VO2 reserve" OR VO2* OR "VO2 uptake" OR HRmax* OR metmax. Categories (i) to (iii) were combined using 'AND;' with studies related to running excluded. A Bayesian regression was conducted to quantify the relationship between METs and %HRR, with Bayesian logistic regression conducted to examine the classification agreement between methods. A modified Downs and Black scale incorporating 13 questions relative to cross-sectional study design was used to assess quality and risk of bias in all included studies. RESULTS: A total of 15 papers were included in the systematic review. A comparison of means between absolute (METs) and relative (%HRR, %HRmax, %VO2R, %VO2max, HRindex) values in 8 studies identified agreement in how intensity was classified (light, moderate or vigorous) in 60% of the trials. We received raw data from three authors, incorporating 3 studies and 290 participants. A Bayesian random intercept logistic regression was conducted to examine the agreement between relative and absolute intensity, showing agreement in 43% of all trials. Two studies had identical relative variables (%HRR) totalling 240 participants included in the Bayesian random intercept regression. The best performing model was a log-log regression, which showed that for every 1% increase in METs, %HRR increased by 1.12% (95% CI: 1.10-1.14). Specifically, the model predicts at the lower bound of absolute moderate intensity (3 METs), %HRR was estimated to be 33% (95%CI: 18-57) and at vigorous intensity (6 METs) %HRR was estimated to be 71% (38-100). CONCLUSION: This study highlights the discrepancies between absolute and relative measures of physical activity intensity during walking with large disagreement observed between methods and large variation in %HRR at a given MET. Consequently, health professionals should be aware of this lack of agreement between absolute and relative measures. Moreover, if we are to move towards a more individualised approach to exercise prescription and monitoring as advocated, relative intensity could be more highly prioritised.
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Teste de Esforço , Consumo de Oxigênio , Humanos , Consumo de Oxigênio/fisiologia , Estudos Transversais , Teorema de Bayes , CaminhadaRESUMO
PURPOSE: The purpose of this study was to assess the relationship between typical performance tests among elite and professional cyclists when conducted indoors and outdoors. METHODS: Fourteen male cyclists of either UCI (Union Cycliste Internationale) Continental or UCI World Tour level (mean [SD] age 20.9 [2.8] y, mass 68.13 [7.25] kg) were recruited to participate in 4 test sessions (2 indoors and 2 outdoors) within a 14-day period, consisting of maximum mean power testing for durations of 60, 180, 300, and 840 seconds. RESULTS: Across all maximum mean power test durations, the trimmed mean power was higher outdoors compared with indoor testing (P < .05). Critical power was higher outdoors compared with indoors (+19 W, P = .005), while no difference was observed for the work capacity above critical power. Self-selected cadence was 6 rpm higher indoors versus outdoors for test durations of 60 (P = .038) and 300 seconds (P = .002). CONCLUSIONS: These findings suggest that maximal power testing in indoor and outdoor settings cannot be used interchangeably. Furthermore, there was substantial individual variation in the difference between indoor and outdoor maximum mean powers across all time durations, further highlighting the difficulty of translating results from indoor testing to outdoor on an individual level in elite populations.
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Ciclismo , Adulto , Fenômenos Biomecânicos , Meio Ambiente , Humanos , Masculino , Adulto JovemRESUMO
INTRODUCTION: Handgrip strength (HGS) is an important indicator of health. Because HGS is strongly associated with body size, most investigators normalize HGS for some measure of body size as a more sensitive indicator of strength within a population. We aimed to 1) identify the optimal body size dimension to remove (normalize) HGS for differences in body size among adults and 2) generate norm-referenced centiles for HGS using the identified body size dimension. METHODS: Data were from the National Health and Nutrition Examination Survey, a representative sample of the US noninstitutionalized civilian population. Exclusions resulted in a final sample of 8690 adults 20 yr and older. HGS was measured using handheld dynamometry. Body size dimensions included body mass, height, and waist circumference. The most appropriate dimension(s) associated with HGS is identified using allometry. We fitted centile curves for normalized HGS using the generalized additive model for location, scale, and shape. RESULTS: Findings suggest that neither body mass nor body mass index is appropriate to normalize HGS. Incorporating all three body size dimensions of body mass, height, and waist circumference, or the reduced subsets of body mass and height, or height alone, suggests that the most appropriate normalizing (body size) dimension associated with HGS should be a cross-sectional or surface area measure of an individual's body size (i.e., L2, where L is a linear dimension of body size). Given that height was also identified as the signally best body size dimension associated with HGS, we recommend HGS be normalized by height2 (i.e., HGS/HT2). Centile curves for HGS/HT2 by age group and gender were therefore provided. CONCLUSIONS: Scaling adult HGS by height2 may help normalize strength for population-based research.