Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 19 de 19
Filtrar
1.
J Strength Cond Res ; 36(3): 838-844, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32108719

RESUMO

ABSTRACT: Palmer, JA, Landers, G, Buttfield, A, and Polglaze, T. Physical demands of elite women's Ultimate Frisbee between halves and across matches in an international tournament. J Strength Cond Res 36(3): 838-844, 2022-To quantify the physical match demands of elite women's Ultimate Frisbee across a tournament, elite female Ultimate players (N = 9) from the Australian Under 24 Women's team wore global positioning system units in all 12 matches of the 2018 Under 24 World Championship competition. Temporal, displacement, and energetic parameters were obtained. Distribution of activity above and below a generic speed threshold (12.42 km·h-1) and its equivalent metabolic power value (16.02 W·kg-1) were determined. Players spent 12:44 ± 6:41 min:s on the field, covered 1,559 ± 741 m and expended 8.95 ± 4.21 kJ·kg-1 during a match. The mean stint duration was 2:00 ± 0:48 min:s, mean bench duration was 13:25 ± 7:05 min:s, and work-to-recovery ratio was 0.22 ± 0.11. Players performed 57 ± 27 high-speed runs per match and 45 ± 20 high-accelerations. Mean match speed was 127 ± 18 m·min-1, mean metabolic power was 12.2 ± 1.7 W·kg-1, and mean intermittency index was 1.24 ± 0.04. No differences were found between halves for any parameters. Compared with the first 4 matches, the last 4 matches were shorter and more intense (p < 0.05). At the international level, Ultimate is an intense and highly intermittent sport, characterized by brief playing stints interspersed with long periods of recovery, which allow playing intensity to be maintained throughout a match and elevated in the latter stages of a tournament. The information gained from this research can be used to guide the creation of Ultimate-specific conditioning programs for elite female players.


Assuntos
Desempenho Atlético , Corrida , Austrália , Feminino , Sistemas de Informação Geográfica , Frequência Cardíaca , Humanos
2.
J Sports Sci ; 38(19): 2186-2192, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32543342

RESUMO

PURPOSE: To compare the occurrence and characteristics of repeated-sprint (RS) activity in elite team sport competition when classified according to speed and/or acceleration, and their interaction via metabolic power (Pmet). Methods: Elite male hockey players (N = 16) wore player-tracking devices in six international matches. Sprint efforts were defined using four separate classifications: speed >5.5 m∙s-1, acceleration >1.5 m∙s-2, speed-or-acceleration, and Pmet >25.5 W∙kg-1. RS bouts were defined as ≥3 efforts with mean recovery ≤21 s. For Pmet, RS bouts were also classified using a maximal recovery period ≤21 s. The number of sprint efforts and RS bouts, and the number of efforts, effort durations and recovery periods within RS bouts, were compared across each classification method, and between mean and maximal recovery criteria. Results: More RS bouts were identified via Pmet (8.5 ± 2.8) than either speed and/or acceleration, and comprised more efforts (4.0 ± 0.4) with shorter recovery periods (11.5 ± 1.8 s). Fewer RS bouts (7.3 ± 2.8 vs. 8.5 ± 2.8) were identified with a maximum rather than mean recovery criterion. Conclusions: Definitions of sprint efforts and recovery periods which reflect ATP depletion and replenishment via Pmet suggest that RS activity occurs frequently in team sport competition, and is more demanding than when speed and/or acceleration are used to define RS activity in variable-speed locomotion.


Assuntos
Comportamento Competitivo/fisiologia , Hóquei/fisiologia , Corrida/fisiologia , Aceleração , Adulto , Metabolismo Energético , Sistemas de Informação Geográfica , Hóquei/classificação , Humanos , Masculino , Corrida/classificação , Estudos de Tempo e Movimento , Adulto Jovem
3.
Int J Sports Physiol Perform ; 14(3): 407-411, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30732493

RESUMO

The ability of the "metabolic power" model to assess the demands of team-sport activity has been the subject of some interest-and much controversy-in team-sport research. Because the cost of acceleration depends on the initial speed and the costs of acceleration and deceleration are not "equal and opposite," changes in speed must be accounted for when evaluating variable-speed locomotion. The purpose of this commentary is to address some of the misconceptions regarding "metabolic power," acknowledge its limitations, and highlight some of the benefits that energetic analysis offers over alternative approaches to quantifying the demands of team sports.


Assuntos
Metabolismo Energético , Esportes/fisiologia , Aceleração , Desempenho Atlético/fisiologia , Fenômenos Biomecânicos , Desaceleração , Humanos , Locomoção/fisiologia , Corrida/fisiologia , Terminologia como Assunto
4.
Int J Sports Physiol Perform ; 13(8): 1005-1010, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-29466098

RESUMO

PURPOSE: To compare data from conventional global positioning system (GPS-) and new global navigation satellite system (GNSS-) enabled tracking devices and to examine the interunit reliability of GNSS devices. METHODS: Interdevice differences between 10-Hz GPS and GNSS devices were examined during laps (n = 40) of a simulated game circuit and during elite hockey matches (n = 21); GNSS interunit reliability was also examined during laps of the simulated game circuit. Differences in distance values and measures in 3 velocity categories (low <3 m·s-1; moderate 3-5 m·s-1; and high >5 m·s-1) and acceleration/deceleration counts (>1.46 and <-1.46 m·s-2) were examined using 1-way analysis of variance. Interunit GNSS reliability was examined using the coefficient of variation (CV) and intraclass correlation coefficient. RESULTS: Interdevice differences (P < .05) were found for measures of peak deceleration, low-speed distance, percentage of total distance at low speed, and deceleration count during the simulated game circuit and for all measures except total distance and low-speed distance during hockey matches. Interunit (GNSS) differences (P < .05) were not found. The coefficient of variation was below 5% for total distance, average and peak speeds and distance and percentage of total distance of low-speed running. The GNSS devices had a lower horizontal dilution of precision score than GPS devices in all conditions. CONCLUSIONS: These findings suggest that GNSS devices may be more sensitive than GPS devices in quantifying the physical demands of team-sport movements, but further study into the accuracy of GNSS devices is required.


Assuntos
Sistemas de Informação Geográfica/instrumentação , Movimento , Aceleração , Desaceleração , Feminino , Hóquei , Humanos , Masculino , Reprodutibilidade dos Testes
5.
Med Sci Sports Exerc ; 50(7): 1487-1494, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29432324

RESUMO

PURPOSE: This study aimed to assess the efficacy of critical metabolic power derived from variable-speed movement for classifying intensity in team sport activity. METHODS: Elite male hockey players (n = 12) completed a series of time trials (100 yards, 400 yards, 1500 yards) and a 3-min all-out test to derive both critical speed (CS) and critical power (CP). Heart rate (HR), blood lactate, and rating of perceived exertion were measured during each protocol. Participants (n = 10) then played two competitive hockey matches. Time spent greater than 85% of maximum HR was compared with time spent above CS (from the time trials) and CP (from the 3-min test). RESULTS: Between protocols, there was a moderate and nonsignificant association for CS (r = 0.359, P = 0.252) and a very large association for CP (r = 0.754, P = 0.005); the association was very large for peak HR (r = 0.866, P < 0.001), large for blood lactate (r = 0.506, P = 0.093), and moderate for rating of perceived exertion (rho = 0.441, P = 0.152). Time trials produced higher CS (4.3 vs 2.0 m·s, P < 0.001) and CP (18.3 vs 10.5 W·kg, P < 0.001) values than did the 3-min test. In matches, there was a very large association between time spent above 85% of maximum HR and time spent above both CS (r = 0.719, P < 0.001) and CP (r = 0.867, P < 0.001). This relationship was stronger for CP compared with CS (Z = 3.29, P = 0.0007). CONCLUSIONS: Speed is not an appropriate parameter for the classification of team sport activity comprising continual changes in speed and direction; however, critical metabolic power derived from variable-speed activity seems useful for this purpose.


Assuntos
Desempenho Atlético/fisiologia , Hóquei/fisiologia , Esforço Físico , Adulto , Teste de Esforço , Frequência Cardíaca , Humanos , Ácido Láctico/sangue , Masculino , Movimento , Adulto Jovem
6.
PLoS One ; 13(2): e0192708, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29420620

RESUMO

This study aimed to investigate the validity and reliability of global (GPS) and local (LPS) positioning systems for measuring distances covered and sprint mechanical properties in team sports. Here, we evaluated two recently released 18 Hz GPS and 20 Hz LPS technologies together with one established 10 Hz GPS technology. Six male athletes (age: 27±2 years; VO2max: 48.8±4.7 ml/min/kg) performed outdoors on 10 trials of a team sport-specific circuit that was equipped with double-light timing gates. The circuit included various walking, jogging, and sprinting sections that were performed either in straight-lines or with changes of direction. During the circuit, athletes wore two devices of each positioning system. From the reported and filtered velocity data, the distances covered and sprint mechanical properties (i.e., the theoretical maximal horizontal velocity, force, and power output) were computed. The sprint mechanical properties were modeled via an inverse dynamic approach applied to the center of mass. The validity was determined by comparing the measured and criterion data via the typical error of estimate (TEE), whereas the reliability was examined by comparing the two devices of each technology (i.e., the between-device reliability) via the coefficient of variation (CV). Outliers due to measurement errors were statistically identified and excluded from validity and reliability analyses. The 18 Hz GPS showed better validity and reliability for determining the distances covered (TEE: 1.6-8.0%; CV: 1.1-5.1%) and sprint mechanical properties (TEE: 4.5-14.3%; CV: 3.1-7.5%) than the 10 Hz GPS (TEE: 3.0-12.9%; CV: 2.5-13.0% and TEE: 4.1-23.1%; CV: 3.3-20.0%). However, the 20 Hz LPS demonstrated superior validity and reliability overall (TEE: 1.0-6.0%; CV: 0.7-5.0% and TEE: 2.1-9.2%; CV: 1.6-7.3%). For the 10 Hz GPS, 18 Hz GPS, and 20 Hz LPS, the relative loss of data sets due to measurement errors was 10.0%, 20.0%, and 15.8%, respectively. This study shows that 18 Hz GPS has enhanced validity and reliability for determining movement patterns in team sports compared to 10 Hz GPS, whereas 20 Hz LPS had superior validity and reliability overall. However, compared to 10 Hz GPS, 18 Hz GPS and 20 Hz LPS technologies had more outliers due to measurement errors, which limits their practical applications at this time.


Assuntos
Comportamento Cooperativo , Sistemas de Informação Geográfica , Processos Grupais , Corrida , Esportes , Adulto , Humanos , Masculino , Reprodutibilidade dos Testes
7.
J Sports Sci ; 36(2): 140-148, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28282747

RESUMO

The purpose of this study was to ascertain the typical metabolic power characteristics of elite men's hockey, and whether changes occur within matches and throughout an international tournament. National team players (n = 16), divided into 3 positional groups (strikers, midfielders, defenders), wore Global Positioning System devices in 6 matches. Energetic (metabolic power, energy expenditure) and displacement (distance, speed, acceleration) variables were determined, and intensity was classified utilising speed, acceleration and metabolic power thresholds. Midfielder's average metabolic power (11.8 ± 1.0 W · kg-1) was similar to strikers (11.1 ± 1.3 W · kg-1) and higher than defenders (10.8 ± 1.2 W · kg-1, P = 0.001). Strikers (29.71 ± 3.39 kJ · kg-1) expended less energy than midfielders (32.18 ± 2.67 kJ · kg-1, P = 0.014) and defenders (33.23 ± 3.96 kJ · kg-1, P < 0.001). Energetic variables did not change between halves or across matches. Across all positions, over 45% of energy expenditure was at high intensity (>20 W · kg-1). International hockey matches are intense and highly intermittent; however, intensity is maintained throughout matches and over a tournament. In isolation, displacement measures underestimate the amount of high-intensity activity, whereas the integration of instantaneous speed and acceleration provides a more comprehensive assessment of the demands for variable-speed activity typically occurring in hockey matches.


Assuntos
Desempenho Atlético/fisiologia , Comportamento Competitivo/fisiologia , Metabolismo Energético , Hóquei/fisiologia , Aceleração , Adulto , Sistemas de Informação Geográfica , Humanos , Masculino , Corrida/fisiologia , Estudos de Tempo e Movimento
8.
J Hum Kinet ; 58: 233-245, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28828094

RESUMO

This study aimed to determine the within-subject variability of GPS-derived metabolic power data in elite soccer players across several pre-season matches and compare the variability of high metabolic power, velocity, acceleration and deceleration running. Additionally, differences in metabolic power data among playing positions and relationships with various physical abilities were also investigated. Metabolic power data from 12 outfield starting players competing in the German Bundesliga were collected during five pre-season matches using GPS-technology (10 Hz). The players were also tested for speed, agility, power and intermittent endurance. Variability of global metabolic power data such as energy expenditure (CV = 2.2-7.0%) was lower than that for high-intensity including time ≥20 W·kg-1 (CV = 14.0-26.2%). Variability of high metabolic power (≥20 W·kg-1; CV = 14.1 ± 3.5%) was comparable to that of high velocity (≥15.5 km·h-1; CV = 17.0 ± 6.2%), acceleration (≥3 m·s-2; CV = 11.1 ± 5.1%) and deceleration running (≤-3 m·s-2; CV = 11.9 ± 4.5%) (p > 0.05, ES < 0.2). Defenders had a largely higher overall energy expenditure than midfielders and attackers (p < 0.01, ES > 0.6). Overall energy expenditure and cost were largely to very largely correlated with 5 m speed and 22 m agility sprint time and counter movement jump height (r = -0.70-0.69, p < 0.05). The detected variability indicates that global GPS-derived metabolic power data in elite soccer players from a single preseason match should be preferably used for practical applications. Contrary, high-intensity indicators should be interpreted cautiously and repeated match observations are recommended to establish meaningful high-intensity profiles of the players. Differences among playing positions and relationships with explosive physical abilities indicate that metabolic power analyses can provide new insights into the mechanics and energetics of soccer.

9.
Sports Med ; 46(5): 657-70, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26643522

RESUMO

Over recent decades, the use of player tracking technology to monitor physical work output has become established practice in many team sports. Early tracking systems were manual in nature, relying on subjective assessments and arbitrary classifications of movement intensity. Poor spatial and temporal resolution meant that only gross displacement measures could be used to infer energy demands. However, the advent and evolution of automated systems, with higher sampling rates and improved accuracy, have enabled data collection to occur on a mass scale, and served as a catalyst for extensive research into the demands of team sport activity, including comparisons between different groups of athletes, and the effects of various interventions on performance. The inherent assumption with this research is that, based on steady-state models where energy cost is independent of speed, total distance and average speed are indicative of the amount and rate of work done, respectively. This assumption could be justified if the activity was performed at a constant speed in a straight line. However, team sport movement involves continual changes in both speed and direction, both of which increase energy cost. Accordingly, new models have emerged that incorporate both speed and acceleration to determine metabolic power. This provides a more complete measure of energy expenditure in intermittent activity, and is potentially more suitable than displacement variables for research into the demands of team sports.


Assuntos
Desempenho Atlético/fisiologia , Metabolismo Energético , Estudos de Tempo e Movimento , Aceleração , Comportamento Competitivo/fisiologia , Sistemas de Informação Geográfica , Humanos , Movimento
10.
Int J Sports Physiol Perform ; 10(4): 446-51, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25364940

RESUMO

PURPOSE: To determine the relationship between distance covered and player load (PL: sum of accelerations in all 3 planes of movement) in hockey training and competition. METHODS: Elite male hockey players (N=24) wore player-tracking devices in 7 international matches and 7 training sessions. Players were arranged in 4 positional groups (strikers, attacking midfielders, defensive midfielders, defenders) in competition but had generic roles in training. Relationships between distance and PL were assessed in both absolute (m, AU) and relative (m/min, AU/min) terms and were compared between matches and training and between positions within matches, using the Fisher Z test. RESULTS: In competition, the absolute distance-PL relationship was very large overall (r=.868), with no differences between positions. The relative distance-PL relationship was moderate overall (r=.486) and weaker in strikers than in defensive midfielders (Z=1.785, P=.037) and defenders (Z=1.690, P=.045). In training, the absolute distance-PL relationship was very large (r=.742), and large (r=.633) in relative terms. The relationship was stronger in competition than training for absolute values (Z=2.824, P=.005) but not different for relative values. CONCLUSIONS: The strong relationship between these variables suggests that PL in hockey is mostly accumulated through running and other locomotor actions, such that PL is not effective in quantifying other activities (evasion, low stance) that contribute to physiological demands, particularly in training.


Assuntos
Hóquei/fisiologia , Educação Física e Treinamento/métodos , Esforço Físico , Aceleração , Adulto , Desempenho Atlético , Sistemas de Informação Geográfica , Humanos , Masculino , Corrida/fisiologia , Estudos de Tempo e Movimento
11.
J Strength Cond Res ; 29(1): 126-36, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25264672

RESUMO

Despite lacrosse being one of the fastest growing team sports in the world, there is a paucity of information detailing the activity profile of high-level players. Microtechnology systems (global positioning systems and accelerometers) provide the opportunity to obtain detailed information on the activity profile in lacrosse. Therefore, this study aimed to analyze the activity profile of lacrosse match-play using microtechnology. Activity profile variables assessed relative to minutes of playing time included relative distance (meter per minute), distance spent standing (0-0.1 m·min), walking (0.2-1.7 m·min), jogging (1.8-3.2 m·min), running (3.3-5.6 m·min), sprinting (≥5.7 m·min), number of high, moderate, low accelerations and decelerations, and player load (PL per minute), calculated as the square root of the sum of the squared instantaneous rate of change in acceleration in 3 vectors (medio-lateral, anterior-posterior, and vertical). Activity was recorded from 14 lacrosse players over 4 matches during a national tournament. Players were separated into positions of attack, midfield, or defense. Differences (effect size [ES] ± 90% confidence interval) between positions and periods of play were considered likely positive when there was ≥75% likelihood of the difference exceeding an ES threshold of 0.2. Midfielders had likely covered higher (mean ± SD) meters per minute (100 ± 11) compared with attackers (87 ± 14; ES = 0.89 ± 1.04) and defenders (79 ± 14; ES = 1.54 ± 0.94) and more moderate and high accelerations and decelerations. Almost all variables across positions were reduced in quarter 4 compared with quarter 1. Coaches should accommodate for positional differences when preparing lacrosse players for competition.


Assuntos
Desempenho Atlético/fisiologia , Esportes com Raquete/fisiologia , Aceleração , Desaceleração , Sistemas de Informação Geográfica , Humanos , Corrida Moderada , Masculino , Microtecnologia , Corrida , Caminhada
12.
Br J Sports Med ; 47 Suppl 1: i70-3, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24282211

RESUMO

OBJECTIVES: Water polo requires high aerobic power to meet the demands of match play. Live high:train low (LHTL) may enhance aerobic capacity at sea level. Before the Olympics, the Australian women's water polo team utilised LHTL in an attempt to enhance aerobic fitness. METHODS: Over 6 months, 11 players completed three normobaric LHTL exposures (block 1:11 days at 3000 m; block 2+3:9 days at 2500 m, 11 days normoxia, 10 days at 2800 m). Haemoglobin mass (Hbmass) was measured through carbon monoxide-rebreathing. Before each block, the relationship between Hbmass and water polo-specific aerobic fitness was investigated using the Multistage Shuttle Swim Test (MSST). Effect size statistics were adopted with likely, highly likely and almost certainly results being >75%, >95%, >99%, respectively. A Pearson product moment correlation was used to characterise the association between pooled data of Hbmass and MSST. RESULTS: Hbmass (mean ± SD, pre 721 ± 66 g) likely increased after block 1 and almost certainly after block 2+3 (% change; 90% confidence limits: block 1: 3.7%; 1.3-6.2%, block 2+3: 4.5%; 3.8-5.1%) and the net effect was almost certainly higher after block 2+3 than before block 1 (pre) by 8.5%; 7.3-9.7%. There was a very large correlation between Hbmass (g/kg) and MSST score (r=0.73). CONCLUSIONS: LHTL exposures of <2 weeks induced approximately 4% increase in Hbmass of water polo players. Extra Hbmass may increase aerobic power, but since match performance is nuanced by many factors it is impossible to ascertain whether the increased Hbmass contributed to Australia's Bronze medal.


Assuntos
Altitude , Hemoglobinas/metabolismo , Natação/fisiologia , Desempenho Atlético/fisiologia , Peso Corporal , Teste de Esforço , Feminino , Humanos , Aptidão Física/fisiologia , Adulto Jovem
13.
Eur J Sport Sci ; 13(4): 341-9, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23834538

RESUMO

While the effect of lower body compression garments on performance and physiological responses are well documented, no studies have examined the effect of upper body compression garments (UBCG) on upper-body dominant exercise. This study examined the effects of wearing UBCG on performance and physiological responses during simulated flat-water kayaking. Five male (mean values±s: 21.8±2.8 years; 83.5±9.2 kg; 63.0±5.5 ml·kg(-1)·min(-1)) and two female (mean values±s: 25.0±4.2 years; 71.4±2.7 kg; 51.0±4.8 ml·kg(-1)·min(-1)) elite flat-water kayakers completed a six-step incremental test followed by a four-minute maximal performance test (4minPT) in both UBCG and control (no shirt or sports training bra) conditions in a randomized counter-balanced order. Heart rate and oxygen consumption ([Formula: see text]O2) as well as performance measures (power, distance covered, stroke rate) were recorded during the tests, and blood lactate was measured immediately after each incremental step and three minutes following the 4minPT. Near-infrared spectroscopy-derived measures of blood flow and oxygenation of the flexor carpi radialis were monitored continuously for all tests. No significant differences between the UBCG and control conditions were evident for any performance, cardiorespiratory or oxygenation measure across the incremental step test and 4minPT. It was concluded that wearing UBCG did not provide any significant physiological or performance benefits during simulated flat-water kayaking.


Assuntos
Desempenho Atlético , Vestuário , Bandagens Compressivas , Exercício Físico/fisiologia , Navios , Esportes/fisiologia , Água , Adulto , Braço , Atletas , Teste de Esforço , Feminino , Frequência Cardíaca , Humanos , Ácido Láctico/sangue , Masculino , Músculo Esquelético/fisiologia , Consumo de Oxigênio , Espectroscopia de Luz Próxima ao Infravermelho , Tronco , Adulto Jovem
14.
Int J Sport Nutr Exerc Metab ; 20(3): 198-205, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20601737

RESUMO

This study investigated the effects of sodium bicarbonate (NaHCO3) ingestion on simulated water polo match performance. Twelve elite players from the Australian National Women's Water Polo Squad (age 23.7 +/- 3.0 yr, height 1.73 +/- 0.05 m, body mass 75.7 +/- 8.0 kg) participated in the study. In a randomized cross-over double-blind design, players ingested 0.3 g/kg of NaHCO3 or placebo 90 min before performing a 59-min match-simulation test (MST) that included 56 x 10-m maximal-sprint swims as the performance measure. Capillary blood samples were obtained preingestion, pre- and post-warm-up, and after each quarter of the MST. Preexercise ingestion of NaHCO3 was effective in enhancing extracellular pH from baseline levels of 7.41; +/- 0.01 (M; +/- 90% confidence limits) to 7.49; +/- 0.01 and bicarbonate levels from 24.4; +/- 0.3 to 28.5; +/- 0.5 mmol/L. The percentage difference in mean sprint times between trials showed no substantial effects of NaHCO3 (0.4; +/- 1.0, effect size = 0.09; +/- 0.23; p = .51). These findings are contrary to those of previous NaHCO3 studies on simulated team-sport performance, but this investigation is unique in that it examined highly trained athletes performing sport-specific tasks. In conclusion, water polo players should not expect substantial enhancement in intermittent-sprint performance from NaHCO3 supplementation.


Assuntos
Alcalose/fisiopatologia , Bicarbonato de Sódio/farmacologia , Natação/fisiologia , Alcalose/induzido quimicamente , Desempenho Atlético , Estudos Cross-Over , Método Duplo-Cego , Feminino , Humanos , Concentração de Íons de Hidrogênio , Consumo de Oxigênio/fisiologia , Análise e Desempenho de Tarefas , Adulto Jovem
15.
J Athl Train ; 45(2): 164-9, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20210620

RESUMO

CONTEXT: Cooling jackets are a common method for removing stored heat accumulated during exercise. To date, the efficiency and practicality of different types of cooling jackets have received minimal investigation. OBJECTIVE: To examine whether a cooling jacket containing a phase-change material (PC17) results in more rapid postexercise cooling than a gel cooling jacket and a no-jacket (control) condition. DESIGN: Randomized, counterbalanced design with 3 experimental conditions. SETTING: Participants exercised at 75% V o(2)max workload in a hot climate chamber (temperature = 35.0 +/- 1.4 degrees C, relative humidity = 52 +/- 4%) for 30 minutes, followed by postexercise cooling for 30 minutes in cool laboratory conditions (ambient temperature = 24.9 +/- 1.8 degrees C, relative humidity = 39% +/- 10%). PATIENTS OR OTHER PARTICIPANTS: Twelve physically active men (age = 21.3 +/- 1.1 years, height = 182.7 +/- 7.1 cm, body mass = 76.2 +/- 9.5 kg, sum of 6 skinfolds = 50.5 +/- 6.9 mm, body surface area = 1.98 +/- 0.14 m(2), V o(2)max = 49.0 +/- 7.0 mLxkg(-1)xmin(-1)) participated. INTERVENTION(S): Three experimental conditions, consisting of a PC17 jacket, a gel jacket, and no jacket. MAIN OUTCOME MEASURE(S): Core temperature (T(C)), mean skin temperature (T(Sk)), and T(C) cooling rate ( degrees C/min). RESULTS: Mean peak T(C) postexercise was 38.49 +/- 0.42 degrees C, 38.57 +/- 0.41 degrees C, and 38.55 +/- 0.40 degrees C for the PC17 jacket, gel jacket, and control conditions, respectively. No differences were observed in peak T(C) cooling rates among the PC17 jacket (0.038 +/- 0.007 degrees C/min), gel jacket (0.040 +/- 0.009 degrees C/min), and control (0.034 +/- 0.010 degrees C/min, P > .05) conditions. Between trials, no differences were calculated for mean T(Sk) cooling. CONCLUSIONS: Similar cooling rates for all 3 conditions indicate that there is no benefit associated with wearing the PC17 or gel jacket.


Assuntos
Regulação da Temperatura Corporal/fisiologia , Vestuário , Temperatura Baixa , Exercício Físico/fisiologia , Análise de Variância , Géis , Temperatura Alta , Humanos , Masculino , Consumo de Oxigênio/fisiologia , Temperatura Cutânea/fisiologia , Sudorese/fisiologia , Adulto Jovem
16.
Int J Sports Physiol Perform ; 5(1): 117-20, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20308702

RESUMO

Time-motion studies indicate the importance of repeated high-intensity activities during water polo match play. The purpose of this study was to assess the reliability of an in-water repeated-sprint test, which comprised 6x10-m all-out sprints, departing every 17 s. This protocol was chosen to replicate the regular intense periods of match play.


Assuntos
Contração Muscular/fisiologia , Natação/fisiologia , Análise de Variância , Austrália , Intervalos de Confiança , Feminino , Humanos , Músculo Esquelético/fisiologia , Reprodutibilidade dos Testes , Estatística como Assunto , Fatores de Tempo , Adulto Jovem
17.
J Sports Sci ; 27(10): 1095-104, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19847693

RESUMO

The aim of this study was to quantify the movement patterns of contemporary elite women's water polo match play. Thirty-three player matches (centre, n = 15 and perimeter, n = 18) were analysed using video-based time-motion analysis. Frequency and duration of individual movements and distance swum were assessed. Mean match time and playing time were 69:48 +/- 04.30 min:s and 33:14 +/- 14:40 min:s, respectively. Players performed 330 +/- 158 discrete movements per match, representing a change in movement every 6.2 s. There were 54 +/- 25 high-intensity activities per match, or one every 38.4 s. These findings characterise women's water polo as a high-intensity intermittent sport. Total distance swum per match was 699.3 +/- 296.8 m. Positional differences showed a predominance of wrestling in centre players (4:13 vs. 1:53 min:s; P < 0.001) and sprint swimming in perimeter players (2:09 vs. 0:52 min:s; P < 0.001). Players performed 6.7 +/- 3.5 repeated high-intensity activity bouts per match, suggesting that this facet of play is important in water polo. Overall, exercise intensity decreased as a match progressed, suggesting the likelihood of fatigue during the latter stages. These findings provide important information for the planning and monitoring of training in women's water polo.


Assuntos
Desempenho Atlético/fisiologia , Comportamento Competitivo , Natação/fisiologia , Análise de Variância , Feminino , Humanos , Resistência Física/fisiologia , Esforço Físico/fisiologia , Estudos de Tempo e Movimento , Adulto Jovem
18.
J Strength Cond Res ; 23(5): 1530-6, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19620909

RESUMO

The purpose of this study was to investigate the anthropometric and fitness characteristics of elite female water polo players and examine the differences between players of different competition levels (national and international) and playing positions (center and perimeter). Twenty-six female water polo players (National League, n = 12, and National Squad, n = 14) underwent measurements of standard anthropometry (height, body mass, and sum of 7 skinfolds), lower-body muscular power (in-water vertical jump), speed (10-m maximal sprint swim), and aerobic fitness (multistage shuttle swim test). No goalkeepers were involved. The National Squad players were taller (173.7 +/- 5.5 vs. 169.6 +/- 4.4 cm; p < 0.05) and heavier (74.6 +/- 8.0 vs. 65.8 +/- 8.4 kg; p < 0.05) and had better jumping (139.0 +/- 7.0 vs. 129.7 +/- 4.6 cm; p < 0.001), sprinting (5.96 +/- 0.21 vs. 6.26 +/- 0.34 seconds; p < 0.05), and endurance swimming abilities (652 +/- 84 vs. 449 +/- 124 m; p < 0.001) compared with the National League players. Perimeter players had lower-body mass (70.2 +/- 3.8 vs. 82.5 +/- 7.4 kg; p < 0.001) and skinfold levels (88.7 +/- 14.1 vs. 118.6 +/- 22.2 mm; p < 0.01) and better sprinting (5.88 +/- 0.19 vs. 6.10 +/- 0.19 seconds; effect size [ES] = 1.16, p > 0.05) and endurance swimming abilities (678 +/- 65 vs. 606 +/- 102 m; ES = 0.84, p > 0.05) compared with center players. These findings demonstrate that anthropometric and fitness characteristics can discriminate between players of different competition levels and playing positions. These water polo-specific field tests may assist coaches in profiling players and evaluating adaptations to training.


Assuntos
Aptidão Física/fisiologia , Natação/fisiologia , Austrália , Estatura/fisiologia , Índice de Massa Corporal , Peso Corporal/fisiologia , Teste de Esforço , Feminino , Humanos , Força Muscular/fisiologia , Resistência Física/fisiologia , Dobras Cutâneas , Adulto Jovem
19.
Int J Sports Physiol Perform ; 4(2): 206-17, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19567924

RESUMO

PURPOSE: To compare the Multistage Shuttle Swim Test (MSST), Water Polo Intermittent Shuttle Test (WIST) and 5 200 m Incremental Swimming Test (IST) responses in elite female water polo players. METHODS: Fourteen Australian Women's National Water Polo Squad members performed the MSST and WIST, and 13 players from a National Water Polo League club performed the IST, MSST and WIST on separate occasions (no goalkeepers were involved). Peak heart rate, blood lactate and ratings of perceived exertion were obtained for all tests. Expired air was collected following all tests for the National League players. RESULTS: The National Squad players scored significantly better (ie, distance covered) in the MSST and WIST than the National League players (effect sizes=1.60 to 1.79, P<.001). The MSST and WIST scores were significantly correlated (r=.80 to 0.88, P<.001). The MSST scores were significantly correlated with peak oxygen uptake (VO2peak; mL.kg(-1).min(-1)) obtained for all tests (r=.58 to 0.59, P<.05). In contrast, there were no significant correlations between the WIST scores and VO2peakobtained for any of the tests (r=.43 to 0.52, P>.05). Differences in VO2peakfor the IST, MSST and WIST were nonsignificant (P>.05). CONCLUSIONS: The MSST and WIST can discriminate players of different competition standards. The MSST can be used to estimate a player's aerobic fitness and peak heart rate. The WIST appears to better mimic the intermittent activity pattern of the game, but its application to female players, to assess maximal intermittent endurance swimming performance, requires further evaluation.


Assuntos
Desempenho Atlético , Resistência Física , Natação , Análise e Desempenho de Tarefas , Adulto , Feminino , Frequência Cardíaca , Humanos , Ácido Láctico/sangue , Consumo de Oxigênio , Percepção , Esforço Físico , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA