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We investigated whether a single heart rate clamped cycling session under systemic hypoxia affects the recovery of physical and psycho-physiological responses from residual fatigue compared to normoxia. On separate occasions, twelve trained males performed a 3-d acute training camp scenario. On days 1 and 3, participants cycled for 60 min at a constant heart rate (80% of ventilatory threshold). On day 2, fatigue was induced through a simulated team game circuit (STGC), followed by a 60-min intervention of either: (1) heart rate clamped cycling in normoxia; (2) heart rate clamped cycling in hypoxia (simulated altitude ~ 3500 m); or (3) no cycling. Countermovement jump height and leg stiffness were assessed before and after every session. Perceptual fatigue was evaluated daily. Compared to baseline, jump height decreased at all timepoints following the STGC (all p < 0.05). Leg stiffness and cycling power output only decreased immediately following the STGC, with a 48% further decrease in cycling power output in hypoxia compared to normoxia (p < 0.05). Perceived fatigue, decreased sleep quality, and increased muscle soreness responses occurred on day 3 (p < 0.05). A single heart rate-clamped cycling session in hypoxia reduced mechanical output without affecting recovery of physical performance and perceptual measures from residual fatigue induced through team sport activity.
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Ciclismo , Frequência Cardíaca , Hipóxia , Humanos , Frequência Cardíaca/fisiologia , Masculino , Hipóxia/fisiopatologia , Ciclismo/fisiologia , Adulto Jovem , Fadiga/fisiopatologia , Mialgia/fisiopatologia , Mialgia/etiologia , Fadiga Muscular/fisiologia , Adulto , Percepção/fisiologia , Altitude , Sono/fisiologia , Esportes de Equipe , Desempenho Atlético/fisiologia , Perna (Membro)/fisiologiaRESUMO
We assessed the accuracy and inter-sessional reliability of traditional (manual) compared to automatic (AutoHR) heart rate (HR) clamping methods during submaximal intensity continuous cycling. On separate occasions, thirteen males cycled at an HR corresponding to 80% of the ventilatory threshold for 18 min. Cycling power output was adjusted using either manual or AutoHR methods, encompassing three trials per method. For the manual method, cycling power output was adjusted every 30 s by 0, 5 or 10 W at the experimenter's discretion. Conversely, AutoHR automatically adjusted power output based on the difference between target and actual HR. Participants' HR was measured at 1 Hz. Root-mean square error (RMSE) and intraclass correlation coefficients (ICC) were calculated from the difference between measured and target HR to represent accuracy and reliability of each method. The RMSE for the manual method (3.2 ± 2.6 bpm) was significantly higher compared to AutoHR (2.8 ± 2.3 bpm) (p < 0.01, r = 0.13); inter-day ICC were 0.92 and 0.89 for manual adjustment and AutoHR, respectively. Automatic methods to clamp HR are more accurate than manual approaches during submaximal intensity continuous cycling and can be easily implemented for uniform HR control in individual and group training sessions at minimal cost.
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Ciclismo , Ergometria , Frequência Cardíaca , Humanos , Masculino , Frequência Cardíaca/fisiologia , Ciclismo/fisiologia , Reprodutibilidade dos Testes , Adulto Jovem , Adulto , Ergometria/métodos , Ergometria/instrumentação , Teste de Esforço/métodos , Consumo de Oxigênio/fisiologiaRESUMO
We examined the sweat characteristics and fluid balance of elite female field hockey players during two heat training camps. Fourteen elite female field hockey players from the Australian national squad participated in two heat training camps held â¼6 months apart, following winter- (Camp 1) and summer-based training (Camp 2). Daily waking body mass (BM) and urine specific gravity (USG) were collected, along with several markers of sweat and fluid balance across two matches per camp. There was a 19% mean reduction in estimated whole-body sweat sodium concentration from Camp 1 (45.8 ± 6.5 mmol/L) to Camp 2 (37.0 ± 5.0 mmol/L; p < .001). Waking urine specific gravity ≥ 1.020 was observed in 31% of samples, with no significant differences in mean urine specific gravity or BM between camps (p > .05), but with substantial interindividual variation. Intramatch sweat rates were high (1.2-1.8 L/hr), with greater BM losses in Camp 1 (p = .030), resulting in fewer players losing ≥2% BM in Camp 2 (0%-8%), as compared with Camp 1 (36%-43%; p = .017). Our field data suggest that elite female field hockey players experience substantial sweat losses during competition in the heat regardless of the season. In agreement with previous findings, we observed substantial interindividual variation in sweat and hydration indices, supporting the use of individualized athlete hydration strategies.
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Hóquei , Suor , Humanos , Feminino , Hóquei/fisiologia , Temperatura Alta , Ingestão de Líquidos/fisiologia , Austrália , Sudorese , Equilíbrio Hidroeletrolítico/fisiologia , DesidrataçãoRESUMO
ABSTRACT: Giles, B, Peeling, P, and Reid, M. Quantifying change of direction movement demands in professional tennis matchplay: An analysis from the Australian Open Grand Slam. J Strength Cond Res 38(3): 517-525, 2024-Change of direction (COD) contributes significantly to the movement repertoire of professional tennis players, yet the time-motion and degree demands of these changes are poorly understood. This study examines the velocity, acceleration, and angular displacement profiles of COD movements in modern professional tennis. One hundred eighty-two singles matches of Hawk-Eye player tracking data collected from the Australian Open Grand Slam were used for analysis. A novel COD classification algorithm was used to identify >120,000 medium and high-intensity CODs for analysis. Descriptive characteristics of the COD performance were calculated using player coordinate and time variables. Sex comparisons were analyzed using 2 mixed-effects models assessed for differences via likelihood ratios. Players performed 1.6 CODs per point. Both sexes executed, on average, 1.3-1.4 shots and covered 4.8 m per COD, with men performing changes every 2.7 seconds and women every 3.1 seconds. Medium-intensity COD comprised 88-94% of all identified changes. Approximately 2 in 3 CODs involved a degree of change >105°, whereas cutting maneuvers (<45°) were most commonly high-intensity COD. This study is the first to quantify the COD characteristics of professional tennis matchplay. Both sexes performed the same average number of CODs per point, however, men executed high-intensity changes twice as frequently as women, at an average of 1 every 5 points. These novel findings will help to improve the specificity of training interventions in elite tennis conditioning.
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Desempenho Atlético , Tênis , Masculino , Humanos , Feminino , Austrália , Movimento , Movimento (Física) , AlgoritmosRESUMO
ABSTRACT: Goods, PS, Appleby, B, Scott, BR, Peeling, P, and Galna, B. High-intensity running during international male field hockey involves frequent changes of direction and repeated accelerations but seldom reaches sprint velocities. J Strength Cond Res XX(X): 000-000, 2024-The aim of this investigation was to quantify the characteristics of high-intensity running in international male field hockey. Player movement data were collected through wearable player tracking devices across 3 tournaments (17 matches) from 27 members of the Australian male field hockey team (totaling 266 player matches). Active duration (minute), high-intensity efforts (>2.5 m·s-2 for >1 second), repeated high-intensity efforts (≥3 efforts with ≤45-second recovery between efforts), and sprints (>7 m·s-1) were extracted and aggregated for each player match. The duration, distance, mean and peak speed, mean change of direction and straightness for each high-intensity effort, and peak deceleration at the conclusion of each effort were calculated. Mixed-effects models were used to estimate the mean for each outcome (fixed effect), with random intercepts modeled for player and match. On average, players completed 42.2 high-intensity efforts and 2.1 sprints per match. High-intensity efforts were short (3.61 seconds, 12.9 m), failed to reach high velocities (average peak velocity: 4.8 m·s-1), and involved frequent changes of direction (56% of efforts were not straight). There were 4.7 bouts of repeated high-intensity efforts per player, per match (comprising 3.8 efforts, with 3.53 seconds per effort separated by 16.2-second recovery). Last, we also found that 29% of high-intensity efforts involved a high-speed deceleration (>3.5 m·s-2), and these occurred frequently when in conjunction with a >45° (86%) or >90° (89%) change of direction. We recommend practitioners focus on developing players' ability to repeatedly accelerate, decelerate, and change direction over short distances and adopt testing and monitoring programs that assess these qualities.
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ABSTRACT: Snyder, L, Goods, PSR, Peeling, P, Balloch, A, Peiffer, JJ, Binnie, MJ, and Scott, BR. Contribution of physical characteristics to game performance in male wheelchair basketball athletes at the Tokyo Paralympic Games. J Strength Cond Res XX(X): 000-000, 2024-This investigation explored the physical characteristics of elite male wheelchair basketball (WCB) athletes and their association with game performance during the Tokyo 2020 Paralympic Games. Sixteen male athletes from the Australian national WCB squad were assessed for anthropometrics, speed, change of direction, aerobic power, and upper-body power during a training camp before the 2020 Paralympic Games. Athletes were grouped according to the International Wheelchair Basketball Federation disability classification system (1.0-4.5) as low- (≤2.5, more severe impairments) or high-point (≥3.0, less severe impairments) athletes. Physical and performance characteristics between groups were compared using independent-samples t-tests, and their relationship to game statistics (points, rebounds, assists, and steals) per minute played was explored through stepwise regression. High-point athletes were 13% taller (p = 0.001), 4-9% faster (p < 0.001-0.017), and demonstrated superior change of direction ability (15%, p < 0.001) compared with low-point athletes. Approximately 74% of the variance in points scored per minute was accounted for by athlete classification, whereas the most important modifiable physical characteristic was speed, which contributed significantly to steals (54% of variance) and assists (96% of variance when arm span and sitting reach height were also considered). Low-point athletes with spinal cord injuries generally have impaired trunk control, which is a likely explanation for performance differences between groups. A range of nonmodifiable (classification, sitting reach height, and arm span) and modifiable (speed) physical characteristics contribute to game performance outcomes and should therefore be considered when identifying, developing, and selecting WCB athletes for elite competition.
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This study analysed critical movement demands of tennis match-play to better inform contemporary approaches to athlete preparation and training. HawkEye data from matches during the 2021 and 2022 Australian Open were utilised. Distance was aggregated for movement cycles, points, games, sets, and matches, alongside total shots played. Data was collated for males (best-of-five sets) and females (best-of-three sets) allowing comparisons both within and between sexes. Overall, no differences within sexes were evident for total distance, however males traversed further per match than females (MDE = 809 ± 139m, ES = 0.86). Female players travelled further in their deciding (third) sets compared to set 1 (ES = 0.28) and while this effect wasn't as discernible for males, the deciding (fifth) set showed some evidence of elevated distance requirements and variability. Between sexes, only female set 3 was different to male set 3 (ES = 0.29). Female and male tiebreak games (i.e. game 13) required players travel further distance compared to other games (ES = ~1.45). Between sex differences were observed for tiebreak games compared to games 1 to 12 (female ES = 1.36 and male ES = 1.53). Players from both sexes generally covered similar distances during points and movement cycles, with between-shot distances of 4.2m-4.5m, notably longer than previous reports. Further, total shots and total match distance (r > 0.97; p < 0.01) shared similar linear relationships. These results highlight that the between shot or movement cycle demands of professional hard court tennis are substantially higher than described in the literature (Roetert et al., 2003). The findings also reveal competitiveness as a key influence on set level distance demands during professional tennis match-play, a consideration in player preparation programs.
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Desempenho Atlético , Tênis , Humanos , Masculino , Feminino , Austrália , Atletas , MovimentoRESUMO
PURPOSE OF REVIEW: This review examines recent developments in our understanding of iron regulation/absorption around exercise, with specific attention paid towards the female athlete. RECENT FINDINGS: Building on the well accepted knowledge that hepcidin concentrations increase in the 3-6âh period following an acute bout of exercise, recent studies have shown that this links to a reduced fractional iron absorption from the gut during feedings provided 2âh postexercise. Further, a window of enhanced iron absorption has recently been identified to occur 30âmin either side of exercise commencement/completion, which allows for strategic iron intake to optimize absorption around exercise. Finally, there is burgeoning evidence to show that iron status and iron regulation change throughout the menstrual cycle and with hormonal contraceptive use, which could have implications for iron status in female athletes. SUMMARY: Exercise can affect iron regulatory hormone activity, which subsequently impairs iron absorption, potentially contributing to the high rates of iron deficiency seen in athletes. Future research should continue to examine strategies to optimize iron absorption, with consideration to the timing, mode and intensity of exercise, the time of day, and in females, the menstrual cycle/menstrual status.
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Deficiências de Ferro , Ferro , Humanos , Feminino , Atletas , Exercício Físico/fisiologia , Estado Nutricional , HepcidinasRESUMO
PURPOSE: A cyclist's rate of force/torque development (RFD/RTD) and peak force/torque can be measured during single-joint or whole-body isometric tests, or during cycling. However, there is limited understanding of the relationship between these measures, and of the mechanisms that contribute to each measure. Therefore, we examined the: (i) relationship between quadriceps central and peripheral neuromuscular function with RFD/RTD in isometric knee extension, isometric mid-thigh pull (IMTP), and sprint cycling; and (ii) relationship among RFD/RTD and peak force/torque between protocols. METHODS: Eighteen trained cyclists completed two familiarisation and two experimental sessions. Each session involved an isometric knee extension, IMTP, and sprint cycling protocol, where peak force/torque, average and peak RFD/RTD, and early (0-100 ms) and late (0-200 ms) RFD/RTD were measured. Additionally, measures of quadriceps central and peripheral neuromuscular function were assessed during the knee extension. RESULTS: Strong relationships were observed between quadriceps early EMG activity (EMG50/M) and knee extension RTD (r or ρ = 0.51-0.65) and IMTP late RFD (r = 0.51), and between cycling early or late RTD and peak twitch torque (r or ρ = 0.70-0.75). Strong-to-very strong relationships were observed between knee extension, IMTP, and sprint cycling for peak force/torque, early and late RFD/RTD, and peak RFD/RTD (r or ρ = 0.59-0.80). CONCLUSION: In trained cyclists, knee extension RTD or IMTP late RFD are related to measures of quadriceps central neuromuscular function, while cycling RTD is related to measures of quadriceps peripheral neuromuscular function. Further, the strong associations among force/torque measures between tasks indicate a level of transferability across tasks.
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Contração Isométrica , Força Muscular , Humanos , Torque , Músculo Quadríceps , Articulação do JoelhoRESUMO
A high prevalence of iron deficiency exists in athlete populations. Various mechanisms, including increased losses through sweat, haemolysis, haematuria, and gastrointestinal micro-ischemia; inadequate dietary intake; and transient exercise-induced increases in the regulatory hormone, hepcidin, contribute to the increased prevalence in athletes. Indeed, hepcidin has been shown to peak around 3-6 hours post-exercise, limiting iron absorption from the gut. As the practitioner's ability to control losses is limited, the key to treatment of iron deficiency in athletes is optimal timing of dietary and oral iron supplementation around these periods of reduced gut absorption. While timing and dosing schedule strategies might be sufficient to treat iron deficiency non-anaemia, the significant lag to impact iron status is relatively long. Therefore, in iron deficiency anaemia, the use of parenteral iron has the benefit of rapid repletion of iron stores and normalisation of haemoglobin status, while bypassing the action of hepcidin at the gut. Furthermore, newer intravenous formulations can be administered as a single total dose over 15-60 min and have a similar safety profile to oral treatment. This review discusses the existing evidence for parenteral iron use in athletes and the unique context for consideration when choosing the parenteral route in this population.
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This investigation explored differences in the pre-tournament preparation period relative to the movement demands of the Tokyo 2020 Olympic Games for the Australian male field-hockey team. Movement data was collected over 7 months prior to and during the 13-day Olympic tournament. Duration, distance (total; >80% individual peak velocity; >5 m.s-1), high-speed decelerations (>3.5 m.s-2), and total accelerations and decelerations (>2.5 m.s-2) were measured during each running-based session. A 13-day moving sum was calculated for each variable and compared to a player-specific "worst-case scenario" (WCS) for intra-tournament total movement demands. Summed 13-day movement demands exceeded the WCS for 6-58% of the preparation period across variables, for the entire squad. During the tournament, midfielders covered significantly greater sprint distance than Defenders (+84%,p = 0.020), with no other positional differences found. Greater variation in tournament movement demands was observed between players for accelerations, decelerations, and high-speed distance (CV = 19-46%) compared to duration and distance (CV = 4-9%). In conclusion, physical preparation exposed athletes to movement demands which surpassed WCS. Additionally, gross measures of training volume (duration and distance) are more generalisable to a squad; however, additional metrics such as sprint distance and high-speed decelerations are needed to better define positional and individual movement demands, and therefore, should be monitored by practitioners.
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Desempenho Atlético , Hóquei , Humanos , Masculino , Tóquio , Austrália , Aceleração , Sistemas de Informação GeográficaRESUMO
ABSTRACT: Watts, SP, Binnie, MJ, Goods, PSR, Hewlett, J, Fahey-Gilmour, J, and Peeling, P. Demarcation of intensity from 3 to 5 zones aids in understanding physiological performance progression in highly trained under-23 rowing athletes. J Strength Cond Res 37(11): e593-e600, 2023-The purpose of this investigation was to compare 2 training intensity distribution models (3 and 5 zone) in 15 highly trained rowing athletes ( n = 8 male; n = 7 female; 19.4 ± 1.1 years) to determine the impact on primary (2,000-m single-scull race) and secondary (2,000-m ergometer time trial, peak oxygen consumption [VÌO 2 peak], lactate threshold 2 [LT2 power]) performance variables. Performance was assessed before and after 4 months training, which was monitored through a smart watch (Garmin Ltd, Olathe, KS) and chest-strap heart rate (HR) monitor (Wahoo Fitness, Atlanta, GA). Two training intensity distribution models were quantified and compared: a 3-zone model (Z1: between 50% VÌO 2 peak and lactate threshold 1 (LT1); Z2: between LT1 and 95% LT2; Z3: >95% LT2) and a 5-zone model (T1-T5), where Z1 and Z3 were split into 2 additional zones. There was significant improvement in LT2 power for both male (4.08% ± 1.83, p < 0.01) and female (3.52% ± 3.38, p = 0.02) athletes, with male athletes also demonstrating significant improvement in 2,000-m ergometer time trial (2.3% ± 1.92, p = 0.01). Changes in VÌO 2 peak significantly correlated with high-quality aerobic training (percent time in T2 zone; r = 0.602, p = 0.02), whereas changes in LT2 power significantly correlated with "threshold" training (percent time in T4 zone; r = 0.529, p = 0.04). These correlations were not evident when examining intensity distribution through the 3-zone model. Accordingly, a 5-zone intensity model may aid in understanding the progression of secondary performance metrics in rowing athletes; however, primary (on-water) performance remains complex to quantify.
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Consumo de Oxigênio , Esportes Aquáticos , Humanos , Masculino , Feminino , Consumo de Oxigênio/fisiologia , Ergometria , Atletas , Ácido LácticoRESUMO
Understanding on-court movement in tennis allows for enhanced preparation strategies to improve player readiness and performance. Here, we explore expert physical preparation coaches' perceptions of elite training strategies for preparation and performance in tennis, with special reference to lower limb activity. Thirteen world renowned tennis strength and conditioning coaches were interviewed in a semi-structured method that explored four key topic areas of physical preparation for tennis: i) the physical demands; ii) load monitoring practice; iii) the direction of ground reaction forces application during match-play; and iv) the application of strength and conditioning for tennis. Three higher-order themes emerged from these discussions: i) off-court training for tennis should be specific to the demands of the sport, ii) the mechanical understanding of tennis lags our physiological approach, and iii) our understanding of the lower limb's contribution to tennis performance is limited. These findings provide valuable insights into the importance of improving our knowledge relevant to the mechanical demands of tennis movement, whilst highlighting important practical considerations from leading tennis conditioning experts.
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Esportes , Tênis , Humanos , Monitores de Aptidão Física , Conhecimento , Extremidade InferiorRESUMO
This investigation assessed the psycho-physiological and performance effects of hot water immersion (HWI) implemented either before or after a repeated-sprint training in hypoxia (RSH) session conducted in the heat. Ten participants completed three RSH trials (3 × 10 × 5-s sprints), conducted at 40°C and simulated altitude of 3000 m. A 30-min monitoring period preceded and followed all exercise sessions. In PRE, the pre-exercise period was HWI, and the post-exercise period was seated rest in temperate conditions. This combination was reversed in POST. In CON, participants were seated in temperate conditions for both periods. Compared to CON, PRE elicited a reduction in power output during each repeated-sprint set (14.8-16.2%, all p < 0.001), and a significantly higher core temperature (Tc) during the pre-exercise period and throughout the exercise session (p < 0.001 and p = 0.025, respectively). In POST, power output and Tc until the end of exercise were similar to CON, with Tc higher at the conclusion of the post-exercise period (p < 0.001). Time across the entire protocol spent ≥38.5°C Tc was significantly longer in PRE (48.1 ± 22.5 min) than POST (31.0 ± 11.3 min, p = 0.05) and CON (15.8 ± 16.3 min, p < 0.001). Employing HWI following RSH conducted in the heat provides effective outcomes regarding physiological strain and cycling performance when compared to pre-exercise or no HWI.
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Temperatura Alta , Imersão , Humanos , Exercício Físico/fisiologia , Água , HipóxiaRESUMO
Iron deficiency is a common health issue in active and athlete populations. Accordingly, research into iron status, regulation, absorption, and iron deficiency treatment strategies is increasing at a rapid rate. However, despite the increase in the quantity of research, various methodological issues need to be addressed as we progress our knowledge in this area. The purpose of this review is to highlight specific considerations for conducting iron-related research in active and athlete populations. First, we discuss the methodological importance of assessment and interpretation of iron status, with reference to blood collection protocols, participant screening procedures, and biomarker selection. Next, we consider numerous variables that should be accounted for in the design of iron-related research studies, such as the iron regulatory hormone hepcidin and its interaction with exercise, in addition to an examination of female physiology and its impact on iron metabolism. Subsequently, we explore dietary iron and nutrient interactions that impact iron regulation and absorption, with recommendations made for optimal methodological control. Consideration is then given to key features of long-term study designs, such as the monitoring of training load, oral iron supplementation, dietary analysis, and general lifestyle factors. Finally, we conclude our recommendations with an exploration of stable iron isotope tracers as a methodology to measure iron absorption. Ultimately, it is our intention that this review can be used as a guide to improve study design, biomarker analysis, and reporting of findings, to maximize the quality of future research outputs in iron-related research focused on active and athlete populations.
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Anemia Ferropriva , Deficiências de Ferro , Esportes , Biomarcadores , Feminino , Hepcidinas , Humanos , Ferro , Ferro da DietaRESUMO
BACKGROUND: Nitrate supplements can improve vascular and muscle function. Whether higher habitual dietary nitrate is associated with better muscle function remains underexplored. OBJECTIVE: The aim was to examine whether habitual dietary nitrate intake is associated with better muscle function in a prospective cohort of men and women, and whether the relation was dependent on levels of physical activity. METHODS: The sample (n = 3759) was drawn from the Australian Diabetes, Obesity, and Lifestyle Study (AusDiab) (56% female; mean ± SD baseline age: 48.6 ± 11.1 y). Habitual dietary intake was assessed over 12 y by obtaining an average [of at least 2 time points, e.g., baseline (2000/2001) and 2004/2005 and/or 2011/2012] from a food-frequency questionnaire. Nitrate intake was calculated from a validated nitrate database and other published literature. Muscle function was quantified by knee extension strength (KES) and the 8-ft-timed-up-and-go (8ft-TUG) test performed in 2011/2012. Physical activity was assessed by questionnaire. Generalized linear models and logistic regression were used to analyze the data. RESULTS: Median (IQR) total nitrate intake was 65 (52-83) mg/d, with â¼81% derived from vegetables. Individuals in the highest tertile of nitrate intake (median intake: 91 mg/d) had 2.6 kg stronger KES (11%) and 0.24 s faster 8ft-TUG (4%) compared with individuals in the lowest tertile of nitrate intake (median intake: 47 mg/d; both P < 0.05). Similarly, individuals in the highest tertile of nitrate intake had lower odds for weak KES (adjusted OR: 0.69; 95% CI: 0.47, 0.73) and slow 8ft-TUG (adjusted OR: 0.63; 95% CI: 0.50, 0.78) compared with those in the lowest tertile. Physical activity did not influence the relationship between nitrate intake and muscle function (KES; P-interaction = 0.86; 8ft-TUG; P-interaction = 0.99). CONCLUSIONS: Higher habitual dietary nitrate intake, predominantly from vegetables, could be an effective way to promote lower-limb muscle strength and physical function in men and women.
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Força da Mão , Músculo Esquelético/efeitos dos fármacos , Nitratos/administração & dosagem , Adulto , Dieta , Suplementos Nutricionais , Exercício Físico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/fisiologia , Inquéritos e QuestionáriosRESUMO
This study compared warm-up strategies employed by sub-elite and world-class elite sprint kayak athletes, evaluating their impact on subsequent race performance. Forty-seven (n = 33 male, n = 14 female) athletes competing at a National Sprint Kayak Championships had Global Navigation Satellite System devices fitted to their kayak to measure speed, distance and stroke rate during the on-water warm-up before racing (OWWU), and during racing. The OWWU total duration, average/peak speeds and stroke rates, and the time spent in speed-zones classified based upon athletes' relative race-pace (low-to-moderate, moderate-to-high, and race-specific) were compared between events, sexes, and athlete standard. The relationship of these variables to subsequent race performance, expressed as a percentage of the best time-to-completion for each event (%racebest), was also examined. Women spent greater OWWU time at moderate-to-high and race-specific speeds compared to men prior to 200-m and 500-m races (P ≤.001). Sub-elite men reported greater total OWWU duration for 200-m and 500-m (P ≤.025), but not for 1000-m races (P >.05) compared to elite men. Finally, %racebest had large inverse correlations to OWWU peak speed for men's 200-m (r = -.53), and average stroke rate for women's 500-m races (r = -.50). This study provides valuable insight for competition warm-up routines based upon data from an elite athlete population.
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Atletas , Desempenho Atlético , Exercício de Aquecimento , Esportes Aquáticos , Austrália , Estudos Transversais , Feminino , Sistemas de Informação Geográfica , Humanos , Umidade , Masculino , Fatores Sexuais , Temperatura , Fatores de Tempo , Esportes Aquáticos/estatística & dados numéricos , Adulto JovemRESUMO
This study determined the impact of heat stress on postexercise inflammation and hepcidin levels. Twelve moderately trained males completed three, 60-min treadmill running sessions under different conditions: (a) COOL, 18 °C with speed maintained at 80% maximum heart rate; (b) HOTHR, 35 °C with speed maintained at 80% maximum heart rate; and (c) HOTPACE, 35 °C completed at the average running speed from the COOL trial. Venous blood samples were collected pre-, post-, and 3-hr postexercise and analyzed for serum ferritin, interleukin-6 (IL-6), and hepcidin concentrations. Average HR was highest during HOTPACE compared with HOTHR and COOL (p < .001). Running speed was slowest in HOTHR compared with COOL and HOTPACE (p < .001). The postexercise increase in IL-6 was greatest during HOTPACE (295%; p = .003). No differences in the IL-6 response immediately postexercise between COOL (115%) and HOTHR (116%) were evident (p = .992). No differences in hepcidin concentrations between the three trials were evident at 3 hr postexercise (p = .407). Findings from this study suggest the IL-6 response to exercise is greatest in hot compared with cool conditions when the absolute running speed was matched. No differences in IL-6 between hot and cool conditions were evident when HR was matched, suggesting the increased physiological strain induced from training at higher intensities in hot environments, rather than the heat per se, is likely responsible for this elevated response. Environmental temperature had no impact on hepcidin levels, indicating that exercising in hot conditions is unlikely to further impact transient alterations in iron regulation, beyond that expected in temperate conditions.
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Transtornos de Estresse por Calor , Ferro , Exercício Físico , Resposta ao Choque Térmico , Temperatura Alta , Humanos , Inflamação , MasculinoRESUMO
This study implemented a 2-week high carbohydrate (CHO) diet intended to maximize CHO oxidation rates and examined the iron-regulatory response to a 26-km race walking effort. Twenty international-level, male race walkers were assigned to either a novel high CHO diet (MAX = 10 g/kg body mass CHO daily) inclusive of gut-training strategies, or a moderate CHO control diet (CON = 6 g/kg body mass CHO daily) for a 2-week training period. The athletes completed a 26-km race walking test protocol before and after the dietary intervention. Venous blood samples were collected pre-, post-, and 3 hr postexercise and measured for serum ferritin, interleukin-6, and hepcidin-25 concentrations. Similar decreases in serum ferritin (17-23%) occurred postintervention in MAX and CON. At the baseline, CON had a greater postexercise increase in interleukin-6 levels after 26 km of walking (20.1-fold, 95% CI [9.2, 35.7]) compared with MAX (10.2-fold, 95% CI [3.7, 18.7]). A similar finding was evident for hepcidin levels 3 hr postexercise (CON = 10.8-fold, 95% CI [4.8, 21.2]; MAX = 8.8-fold, 95% CI [3.9, 16.4]). Postintervention, there were no substantial differences in the interleukin-6 response (CON = 13.6-fold, 95% CI [9.2, 20.5]; MAX = 11.2-fold, 95% CI [6.5, 21.3]) or hepcidin levels (CON = 7.1-fold, 95% CI [2.1, 15.4]; MAX = 6.3-fold, 95% CI [1.8, 14.6]) between the dietary groups. Higher resting serum ferritin (p = .004) and hotter trial ambient temperatures (p = .014) were associated with greater hepcidin levels 3 hr postexercise. Very high CHO diets employed by endurance athletes to increase CHO oxidation have little impact on iron regulation in elite athletes. It appears that variations in serum ferritin concentration and ambient temperature, rather than dietary CHO, are associated with increased hepcidin concentrations 3 hr postexercise.
Assuntos
Carboidratos da Dieta/administração & dosagem , Ferro/sangue , Resistência Física/fisiologia , Esportes/fisiologia , Caminhada/fisiologia , Adulto , Carboidratos da Dieta/metabolismo , Ferritinas/sangue , Hepcidinas/sangue , Humanos , Interleucina-6/sangue , Masculino , Oxirredução , Condicionamento Físico Humano/fisiologia , TemperaturaRESUMO
ABSTRACT: Jones, MJ, Dawson, B, Eastwood, PR, Halson, SL, Miller, J, Murray, K, Dunican, IC, Landers, GJ, and Peeling, P. Influence of electronic devices on sleep and cognitive performance during athlete training camps. J Strength Cond Res 35(6): 1620-1627, 2021-This study investigated the effects of removing athletes' electronic devices in the evening on sleep and performance during training camps. Water polo athletes (n = 26) attending a 7-night training camp (study 1) and triathletes (n = 23) attending a 4-night training camp (study 2) were randomly allocated to a no-device group (no electronic devices could be used after dinner or overnight; ND) or control group (unrestricted electronic device use; CON). Sleep was monitored through wrist actigraphy. The ND group completed a questionnaire measuring anxiety related to being unable to use electronic devices ("nomophobia"). Triathletes also completed a psychomotor vigilance test (PVT) at the start and end of camp. Water polo ND athletes went to bed earlier and spent longer time in bed than CON on the first night, but not on other nights. In triathletes, sleep quantity was not different between groups on any night. No statistically significant differences were observed for changes in nomophobia from the first to the last night of camp. No differences in PVT performance were observed between ND and CON triathletes. In conclusion, removal of evening electronic devices does not improve sleep quantity or cognitive performance in athletes during short-duration (4-7 nights) training camps.