RESUMEN
With the use of three-dimensional whole body scanning technology, this study compared the 'traditional' anthropometric model [one-dimensional (1D) measurements] to a 'new' model [1D, two-dimensional (2D), and three-dimensional (3D) measurements] to determine: (1) which model predicted more of the variance in self-reported best 2000-m ergometry rowing performance; and (2) what were the best anthropometric predictors of ergometry performance, for junior rowers competing at the 2007 and 2008 Australian Rowing Championships. Each rower (257 females, 16.3 ± 1.4 years and 243 males, 16.6 ± 1.5 years) completed a performance and demographic questionnaire, had their mass, standing and sitting height physically measured and were landmarked and scanned using the Vitus Smart® 3D whole body scanner. Absolute and proportional anthropometric measurements were extracted from the scan files. Partial least squares regression analysis, with anthropometric measurements and age as predictor variables and self-reported best 2000-m ergometer time as the response variable, was used to first compare the two models and then to determine the best performance predictors. The variance explained by each model was similar for both male [76.1% (new) vs. 73.5% (traditional)] and female [72.3% (new) vs. 68.6% (traditional)] rowers. Overall, absolute rather than proportional measurements, and 2D and 3D rather than 1D measurements, were the best predictors of rowing ergometry performance, with whole body volume and surface area, standing height, mass and leg length the strongest individual predictors.
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Antropometría/métodos , Rendimiento Atlético , Tamaño Corporal , Ejercicio Físico , Deportes , Adolescente , Ergometría , Femenino , Humanos , Análisis de los Mínimos Cuadrados , Masculino , Reproducibilidad de los Resultados , Navíos , Encuestas y CuestionariosRESUMEN
The purpose of this study was to compare the effects of two practical precooling techniques (skin cooling vs. skin + core cooling) on cycling time trial performance in warm conditions. Six trained cyclists completed one maximal graded exercise test (VO2(peak) 71.4 +/- 3.2 ml x kg(-1) x min(-1)) and four approximately 40 min laboratory cycling time trials in a heat chamber (34.3 degrees C +/- 1.1 degrees C; 41.2% +/- 3.0% rh) using a fixed-power/variable-power format. Cyclists prepared for the time trial using three techniques administered in a randomised order prior to the warm-up: (1) no cooling (control), (2) cooling jacket for 40 min (jacket) or (3) 30-min water immersion followed by a cooling jacket application for 40 min (combined). Rectal temperature prior to the time trial was 37.8 degrees C +/- 0.1 degrees C in control, similar in jacket (37.8 degrees C +/- 0.3 degrees C) and lower in combined (37.1 degrees C +/- 0.2 degrees C, P < 0.01). Compared with the control trial, time trial performance was not different for jacket precooling (-16 +/- 36 s, -0.7%; P = 0.35) but was faster for combined precooling (-42 +/- 25 s, - .8%; P = 0.009). In conclusion, a practical combined precooling strategy that involves immersion in cool water followed by the use of a cooling jacket can produce decrease in rectal temperature that persist throughout a warm-up and improve laboratory cycling time trial performance in warm conditions.
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Temperatura Corporal , Ejercicio Físico/fisiología , Adulto , Temperatura Corporal/fisiología , Regulación de la Temperatura Corporal/fisiología , Frío , Estudios Cruzados , Frecuencia Cardíaca , Humanos , Inmersión , Masculino , Resistencia Física/fisiología , Análisis y Desempeño de TareasRESUMEN
PURPOSE: The aim of the present study was to compare the effectiveness of different nutritional recovery strategies between weigh-in and racing on 2000-m rowing ergometer performance among oarsmen undertaking short-term weight loss before competition. METHODS: Competitive rowers (N = 12) completed four ergometer trials, each separated by 48 h. No weight restrictions were imposed for the first trial (TR1). Thereafter, athletes were required to reduce their body mass by 5.2% in the 24 h before trial 2 (TR2), again reaching this body mass before the final two trials (TR3 and TR4). Athletes were provided with one of three nutritional recovery strategies in the 2 h between weigh-in and racing in a counterbalanced fashion according to a Latin square design: fluid (2.8 kJ.kg(-1), 0.0 g.kg(-1) carbohydrate, 0.6 mg.kg(-1) sodium, 28.5 mL.kg(-1) fluid; FLU), carbohydrate/sodium (45.3 kJ.kg(-1), 2.2 g.kg(-1) carbohydrate, 32.9 mg.kg(-1) sodium, 7.2 mL.kg(-1) fluid; CHO), and a combination of water and carbohydrate/sodium (44.8 kJ.kg(-1), 2.3 g.kg(-1) carbohydrate, 33 mg.kg(-1) sodium, 28.5 mL.kg(-1) fluid; COM). RESULTS: Performance was slower for CHO compared with both COM (mean difference, 4.13; 95% CI, 1.37-6.88 s; P = 0.003) and FLU (2.88; 95% CI, 0.13-5.63 s; P = 0.039). However, FLU was not significantly slower than COM (1.24; 95% CI, -1.41 to 3.90 s; P = 0.474). CONCLUSIONS: The present investigation has shown that although carbohydrate and sodium intake may be important in the recovery period between weigh-in and 2000-m rowing ergometer performance, fluid intake has a greater influence on performance among lightweight male rowers who undertake short-term weight loss to achieve specified body-mass limits.
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Ingestión de Energía , Prueba de Esfuerzo , Análisis y Desempeño de Tareas , Adolescente , Adulto , Australia , Fenómenos Biomecánicos , Peso Corporal , Ergometría , Humanos , Masculino , NavíosRESUMEN
PURPOSE: The present study was conducted to examine the impact of acute weight loss on repeat 2000-m rowing ergometer performance during a simulated multiday regatta, and to compare two different body mass management strategies between races. METHODS: Competitive rowers (N = 16) were assigned to either a control (CON), partial recovery (REC(partial)), or complete recovery (REC(complete)) group. Volunteers completed four trials, each separated by 48 h. No weight restrictions were imposed for the first trial. Thereafter, athletes in REC(partial) and REC(complete) were required to reduce their body mass by 4% in the 24 h before trial 2, again reaching this body mass before the final two trials. No weight restrictions were imposed on CON. Aggressive nutritional recovery strategies were used in the 2 h following weigh-in for all athletes. These strategies were maintained for the 12-16 h following racing for REC(complete) with the aim of restoring at least three quarters of the original 4% body mass loss. Postrace recovery strategies were less aggressive in REC(partial); volunteers were encouraged to restore no more than half of their initial 4% body mass loss. RESULTS: Acute weight loss increased time to complete the first "at-weight" performance trial by a small margin (mean 3.0, 95% CI -0.3 to 6.3 s, P = 0.07) when compared with the CON response. This effect decreased when sustained for several days. Aggressive postrace recovery strategies tended to eliminate the effect of acute weight loss on subsequent performance. CONCLUSION: Acute weight loss resulted in a small performance compromise that was reduced or eliminated when repeated over several days. Athletes should be encouraged to maximize recovery in the 12-16 h following racing when attempting to optimize subsequent performance.
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Ejercicio Físico , Deportes , Análisis y Desempeño de Tareas , Pérdida de Peso/fisiología , Adolescente , Adulto , Territorio de la Capital Australiana , Tamaño Corporal , Fluidoterapia , Humanos , MasculinoRESUMEN
AIM: The aim of this study was to examine the relationship between ventilatory adaptation and performance during altitude training at 2700â m. METHODS: Seven elite cyclists (age: 21.2 ± 1.1â yr, body mass: 69.9 ± 5.6â kg, height 176.3 ± 4.9â cm) participated in this study. A hypoxic ventilatory response (HVR) test and a submaximal exercise test were performed at sea level prior to the training camp and again after 15 d at altitude (ALT15). Ventilation (VE), end-tidal carbon-dioxide partial pressure (PETCO2) and oxyhaemoglobin saturation via pulse oximetry (SpO2) were measured at rest and during submaximal cycling at 250â W. A hill climb (HC) performance test was conducted at sea level and after 14 d at altitude (ALT14) using a road of similar length (5.5-6â km) and gradient (4.8-5.3%). Power output was measured using SRM cranks. Average HC power at ALT14 was normalised to sea level power (HC%). Multiple regression was used to identify significant predictors of performance at altitude. RESULTS: At ALT15, there was a significant increase in resting VE (10.3 ± 1.9 vs. 12.2 ± 2.4â L·min(-1)) and HVR (0.34 ± 0.24 vs. 0.71 ± 0.49â L·min(-1)·%(-1)), while PETCO2 (38.4 ± 2.3 vs. 32.1 ± 3.3â mmHg) and SpO2 (97.9 ± 0.7 vs. 94.0 ± 1.7%) were reduced (P < .05). Multiple regression revealed ΔHVR and exercise VE at altitude as significant predictors of HC% (adjusted r(2) = 0.913; P = 0.003). CONCLUSIONS: Ventilatory acclimatisation occurred during a 2 wk altitude training camp in elite cyclists and a higher HVR was associated with better performance at altitude, relative to sea level. These results suggest that ventilatory acclimatisation is beneficial for cycling performance at altitude.
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Aclimatación/fisiología , Atletas , Ciclismo/fisiología , Consumo de Oxígeno/fisiología , Resistencia Física/fisiología , Respiración , Adulto , Altitud , Estudios de Cohortes , Humanos , Hipoxia/fisiopatología , Masculino , Adulto JovenRESUMEN
PURPOSE: Although the body-mass management strategies of athletes in high-participation weight-category sports such as wrestling have been thoroughly investigated, little is known about such practices among lightweight rowers. This study examined the body-mass management practices of lightweight rowers before competition and compared these with current guidelines of the International Federation of Rowing Association (FISA). Quantification of nutrient intake in the 1-2 h between weigh-in and racing was also sought. METHODS: Lightweight rowers (N = 100) competing in a national regatta completed a questionnaire that assessed body-mass management practices during the 4 wk before and throughout a regatta plus recovery strategies after weigh-in. Biochemical data were collected immediately after weigh-in to validate questionnaire responses. Responses were categorized according to gender and age category (Senior B or younger than 23 yr old, i.e., U23, Senior A or OPEN, i.e., open age limit) for competition. RESULTS: Most athletes (male U23 76.5%, OPEN 92.3%; female U23 84.0%, OPEN 94.1%) decreased their body mass in the weeks before the regatta at rates compliant with FISA guidelines. Gradual dieting, fluid restriction, and increased training load were the most popular methods of body-mass management. Although the importance of recovery after weigh-in was recognized by athletes, nutrient intake and especially sodium (male U23 5.3 +/- 4.9, OPEN 7.7 +/- 5.9; female U23 5.7 +/- 6.8, OPEN 10.2 +/- 5.4 mg x kg(-1)) and fluid intake (male U23 12.1 +/- 7.1, OPEN 13.5 +/- 8.1; female U23 9.4 +/- 7.4, OPEN 14.8 +/- 6.9 mL x kg(-1)) were below current sports nutrition recommendations. CONCLUSION: Few rowers were natural lightweights; the majority reduced their body mass in the weeks before a regatta. Nutritional recovery strategies implemented by lightweight rowers after weigh-in were not consistent with current guidelines.
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Deportes/fisiología , Pérdida de Peso/fisiología , Ácido 3-Hidroxibutírico/sangre , Adulto , Factores de Edad , Australia , Agua Corporal/metabolismo , Peso Corporal/fisiología , Complejo CD3/sangre , Deshidratación/fisiopatología , Dieta Reductora , Conducta de Ingestión de Líquido , Ingestión de Energía/fisiología , Ayuno , Femenino , Humanos , Factor I del Crecimiento Similar a la Insulina/análisis , Masculino , Factores Sexuales , Encuestas y CuestionariosRESUMEN
PURPOSE: The impact of acute weight loss on rowing performance was assessed when generous nutrient intake was provided in 2 h of recovery after making weight. METHODS: Competitive rowers (N = 17) completed four ergometer trials, each separated by 48 h. Two trials were performed after a 4% body mass loss in the previous 24 h (WT) and two were performed after no weight restrictions, that is, unrestricted (UNR). In addition, two trials (1 x WT, 1 x UNR) were in a thermoneutral environment (NEUTRAL, mean 21.1 +/- SD 0.7 degrees C, 29.0 +/- 4.5% RH) and two were in the heat (HOT 32.4, +/- 0.4 degrees C, 60.4 +/- 2.7% RH). Trials were performed in a counterbalanced fashion according to a Latin square design. Aggressive nutritional recovery strategies (WT 2.3 g x kg(-1) carbohydrate, 34 mg x kg(-1) Na, 28.4 mL x kg(-1) fluid; UNR ad libitum) were employed in the 2 h after weigh-in. RESULTS: Both WT (mean 2.1, 95% CI 0.7-3.4 s; P = 0.003) and HOT (4.1, 2.7 - 5.4 s; P < 0.001) compromised 2000-m time-trial performance. Whereas WT resulted in hypohydration, the associated reduction in plasma volume explained only part of the performance compromise observed (0.2 s for every 1% decrement) Moreover, WT did not influence core temperature or indices of cardiovascular function. CONCLUSIONS: Acute weight loss compromised performance, despite generous nutrient intake in recovery, although the effect was small. Performance decrements were further exacerbated when exercise was performed in the heat.
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Ejercicio Físico/fisiología , Pérdida de Peso , Australia , Temperatura Corporal , Peso Corporal , Dieta , Femenino , Frecuencia Cardíaca , Humanos , Ácido Láctico/sangre , Masculino , Volumen Plasmático , AguaRESUMEN
BACKGROUND AND OBJECTIVES: ON- and OFF-model scores derived from blood parameters sensitive to erythropoiesis have been shown to be a useful tool to identify athletes who are currently injecting erythropoietin to enhance performance or those who have recently stopped doing so. We investigated changes in blood parameters and model scores during and after exposure to terrestrial and simulated altitudes. DESIGN AND METHODS: We retrospectively evaluated changes in hematologic data collected from 19 elite cyclists who lived and trained 2690 m above sea level for 26-31 days, from six elite Kenyan runners who lived 2100 m above sea level but descended to compete at sea level competitions, and from 39 well-trained subjects who resided at sea level but slept at a simulated altitude of 2650-3000 m for 20-23 days of either consecutive or intermittent nightly exposure. RESULTS: Upon ascent to a terrestrial altitude, ON- and OFF-model scores increased immediately, mainly because of an increase in hemoglobin concentration. Scores had not returned fully to baseline three weeks after return to sea level, because of the persistence of the raised hemoglobin concentration for the ON and OFF scores and a fall in reticulocyte percentage for OFF scores. Effects were smaller or negligible for simulated altitude. For Kenyan runners, ON- and OFF-model scores decreased within seven days of descent to sea level. INTERPRETATION AND CONCLUSIONS: Our results reinforce the notion that caution should be exercised when interpreting blood results from athletes who have recently been exposed to either terrestrial or simulated altitude, and appropriate allowance should be made for the effect of altitude on blood model scores.
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Altitud , Doping en los Deportes/prevención & control , Eritropoyetina/sangre , Pruebas Hematológicas/normas , Pruebas Hematológicas/tendencias , Aclimatación , Ciclismo , Estudios de Cohortes , Eritropoyesis/fisiología , Hematócrito/normas , Hematócrito/tendencias , Hemoglobinas/metabolismo , Humanos , Masculino , Modelos Biológicos , Valores de Referencia , Recuento de Reticulocitos/normas , Recuento de Reticulocitos/tendencias , Reticulocitos/metabolismo , Estudios Retrospectivos , CarreraRESUMEN
BACKGROUND AND OBJECTIVES: Algorithms that combine scores from multiple blood parameters are demonstrably effective in highlighting recombinant human erythropoietin (rHuEPO) administration, and have been used to deter rHuEPO use by athletes. These models are sensitive to atypical levels of blood parameters encountered during altered states of red cell production. Because hematologic abnormalities can also result in unusual blood profiles, the aim of this study was to document the incidence and magnitude of such abnormalities in an elite athlete population. DESIGN AND METHODS: We screened blood samples obtained from 413 female and 739 male elite athletes from 12 countries for known hematologic abnormalities, and compared the algorithm scores for these athletes with those of their healthy counterparts. We also established the magnitude of blood parameters required for model scores to exceed cut-offs associated with rHuEPO use. RESULTS: We found that 0.7% of male and 2.4% of female athletes were iron deficient either with our without anemia. An additional 1.4% of males and 1.0% of females had hemoglobinopathies. On average these athletes' model scores were at or below the score of their healthy counterparts. The greatest influence on our models was hemoglobin concentration. Values of other parameters must exceed normal ranges by a substantial margin in order for model scores to approach levels associated with rHuEPO use. INTERPRETATION AND CONCLUSIONS: The hematologic disorders we encountered in elite athletes were not associated with model scores that exceeded the nominal cut-offs that we have previously recommended to delineate rHuEPO use. We did not find any abnormalities among elite endurance athletes that were associated with high model scores.
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Eritropoyetina/análisis , Enfermedades Hematológicas/epidemiología , Enfermedades Hematológicas/fisiopatología , Modelos Biológicos , Adolescente , Anemia/sangre , Anemia/epidemiología , Anemia/metabolismo , Anemia/fisiopatología , Anemia Ferropénica/sangre , Anemia Ferropénica/epidemiología , Anemia Ferropénica/metabolismo , Anemia Ferropénica/fisiopatología , Doping en los Deportes/prevención & control , Doping en los Deportes/estadística & datos numéricos , Índices de Eritrocitos/efectos de los fármacos , Eritropoyesis/efectos de los fármacos , Eritropoyesis/fisiología , Eritropoyetina/administración & dosificación , Femenino , Enfermedades Hematológicas/sangre , Enfermedades Hematológicas/metabolismo , Pruebas Hematológicas/métodos , Pruebas Hematológicas/estadística & datos numéricos , Hemoglobinopatías/sangre , Hemoglobinopatías/epidemiología , Hemoglobinopatías/metabolismo , Hemoglobinopatías/fisiopatología , Hemoglobinas/metabolismo , Humanos , Masculino , Proteínas Recombinantes , Recuento de Reticulocitos/estadística & datos numéricos , Sensibilidad y Especificidad , Caracteres Sexuales , Distribución por Sexo , Deportes/fisiología , Deportes/estadística & datos numéricosRESUMEN
This study was designed to test the hypothesis that intermittent normobaric hypoxia at rest is a sufficient stimulus to elicit changes in physiological measures associated with improved performance in highly trained distance runners. Fourteen national-class distance runners completed a 4-wk regimen (5:5-min hypoxia-to-normoxia ratio for 70 min, 5 times/wk) of intermittent normobaric hypoxia (Hyp) or placebo control (Norm) at rest. The experimental group was exposed to a graded decline in fraction of inspired O2: 0.12 (week 1), 0.11 (week 2), and 0.10 (weeks 3 and 4). The placebo control group was exposed to the same temporal regimen but breathed fraction of inspired O2 of 0.209 for the entire 4 wk. Subjects were matched for training history, gender, and baseline measures of maximal O2 uptake and 3,000-m time-trial performance in a randomized, balanced, double-blind design. These parameters, along with submaximal treadmill performance (economy, heart rate, lactate, and ventilation), were measured in duplicate before, as well as 1 and 3 wk after, the intervention. Hematologic indexes, including serum concentrations of erythropoietin and soluble transferrin receptor and reticulocyte parameters (flow cytometry), were measured twice before the intervention, on days 1, 5, 10, and 19 of the intervention, and 10 and 25 days after the intervention. There were no significant differences in maximal O2 uptake, 3,000-m time-trial performance, erythropoietin, soluble transferrin receptor, or reticulocyte parameters between groups at any time. Four weeks of a 5:5-min normobaric hypoxia exposure at rest for 70 min, 5 days/wk, is not a sufficient stimulus to elicit improved performance or change the normal level of erythropoiesis in highly trained runners.
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Altitud , Eritropoyesis , Hipoxia/fisiopatología , Educación y Entrenamiento Físico , Carrera , Análisis y Desempeño de Tareas , Adulto , Biomarcadores/sangre , Método Doble Ciego , Eritropoyetina/sangre , Femenino , Humanos , Hipoxia/sangre , Masculino , Receptores de Transferrina/sangre , Receptores de Transferrina/química , Recuento de Reticulocitos , SolubilidadRESUMEN
We examined the initial effect of sleeping at a simulated moderate altitude of 2,650 m on the frequency of apneas and hypopneas, as well as on the heart rate and blood oxygen saturation from pulse oximetry (SpO2) during rapid eye movement (REM) and non-rapid eye movement (NREM) sleep of 17 trained cyclists. Pulse oximetry revealed that sleeping at simulated altitude significantly increased heart rate (3 +/- 1 beats/min; means +/- SE) and decreased SpO2 (-6 +/- 1%) compared with baseline data collected near sea level. In response to simulated altitude, 15 of the 17 subjects increased the combined frequency of apneas plus hypopneas from baseline levels. On exposure to simulated altitude, the increase in apnea was significant from baseline for both sleep states (2.0 +/- 1.3 events/h for REM, 9.9 +/- 6.2 events/h for NREM), but the difference between the two states was not significantly different. Hypopnea frequency was significantly elevated from baseline to simulated altitude exposure in both sleep states, and under hypoxic conditions it was greater in REM than in NREM sleep (7.9 +/- 1.8 vs. 4.2 +/- 1.3 events/h, respectively). Periodic breathing episodes during sleep were identified in four subjects, making this the first study to show periodic breathing in healthy adults at a level of hypoxia equivalent to 2,650-m altitude. These results indicate that simulated moderate hypoxia of a level typically chosen by coaches and elite athletes for simulated altitude programs can cause substantial respiratory events during sleep.
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Hipoxia/fisiopatología , Periodicidad , Respiración , Síndromes de la Apnea del Sueño/fisiopatología , Sueño , Adulto , Altitud , Apnea/fisiopatología , Cámaras de Exposición Atmosférica , Femenino , Frecuencia Cardíaca/fisiología , Humanos , Hipoxia/complicaciones , Masculino , Oximetría , Oxígeno/sangre , Aptitud Física , Polisomnografía , Sueño/fisiología , Síndromes de la Apnea del Sueño/etiología , Fases del SueñoRESUMEN
This study determined whether "living high-training low" (LHTL)-simulated altitude exposure increased the hypoxic ventilatory response (HVR) in well-trained endurance athletes. Thirty-three cyclists/triathletes were divided into three groups: 20 consecutive nights of hypoxic exposure (LHTLc, n = 12), 20 nights of intermittent hypoxic exposure (four 5-night blocks of hypoxia, each interspersed with 2 nights of normoxia, LHTLi, n = 10), or control (Con, n = 11). LHTLc and LHTLi slept 8-10 h/day overnight in normobaric hypoxia (approximately 2,650 m); Con slept under ambient conditions (600 m). Resting, isocapnic HVR (DeltaVE/DeltaSp(O(2)), where VE is minute ventilation and Sp(O(2)) is blood O(2) saturation) was measured in normoxia before hypoxia (Pre), after 1, 3, 10, and 15 nights of exposure (N1, N3, N10, and N15, respectively), and 2 nights after the exposure night 20 (Post). Before each HVR test, end-tidal PCO(2) (PET(CO(2))) and VE were measured during room air breathing at rest. HVR (l. min(-1). %(-1)) was higher (P < 0.05) in LHTLc than in Con at N1 (0.56 +/- 0.32 vs. 0.28 +/- 0.16), N3 (0.69 +/- 0.30 vs. 0.36 +/- 0.24), N10 (0.79 +/- 0.36 vs. 0.34 +/- 0.14), N15 (1.00 +/- 0.38 vs. 0.36 +/- 0.23), and Post (0.79 +/- 0.37 vs. 0.36 +/- 0.26). HVR at N15 was higher (P < 0.05) in LHTLi (0.67 +/- 0.33) than in Con and in LHTLc than in LHTLi. PET(CO(2)) was depressed in LHTLc and LHTLi compared with Con at all points after hypoxia (P < 0.05). No significant differences were observed for VE at any point. We conclude that LHTL increases HVR in endurance athletes in a time-dependent manner and decreases PET(CO(2)) in normoxia, without change in VE. Thus endurance athletes sleeping in mild hypoxia may experience changes to the respiratory control system.
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Aclimatación , Altitud , Hipoxia/fisiopatología , Educación y Entrenamiento Físico , Resistencia Física , Respiración , Ciclismo , Dióxido de Carbono , Humanos , Presión Parcial , Descanso , Volumen de Ventilación PulmonarRESUMEN
We determined the effect of 20 nights of live high, train low (LHTL) hypoxic exposure on lactate kinetics, monocarboxylate lactate transporter proteins (MCT1 and MCT4), and muscle in vitro buffering capacity (betam) in 29 well-trained cyclists and triathletes. Subjects were divided into one of three groups: 20 consecutive nights of hypoxic exposure (LHTLc), 20 nights of intermittent hypoxic exposure [four 5-night blocks of hypoxia, each interspersed with 2 nights of normoxia (LHTLi)], or control (Con). Rates of lactate appearance (Ra), disappearance (Rd), and oxidation (Rox) were determined from a primed, continuous infusion of l-[U-14C]lactic acid tracer during 90 min of steady-state exercise [60 min at 65% peak O2 uptake (VO(2 peak)) followed by 30 min at 85% VO(2 peak)]. A resting muscle biopsy was taken before and after 20 nights of LHTL for the determination of betam and MCT1 and MCT4 protein abundance. Ra during the first 60 min of exercise was not different between groups. During the last 25 min of exercise at 85% VO(2 peak), Ra was higher compared with exercise at 65% of VO(2 peak) and was decreased in LHTLc (P < 0.05) compared with the other groups. Rd followed a similar pattern to Ra. Although Rox was significantly increased during exercise at 85% compared with 65% of VO(2 peak), there were no differences between the three groups or across trials. There was no effect of hypoxic exposure on betam or MCT1 and MCT4 protein abundance. We conclude that 20 consecutive nights of hypoxia exposure decreased whole body Ra during intense exercise in well-trained athletes. However, muscle markers of lactate metabolism and pH regulation were unchanged by the LHTL intervention.
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Hipoxia/metabolismo , Hipoxia/fisiopatología , Ácido Láctico/sangre , Músculo Esquelético/metabolismo , Esfuerzo Físico/fisiología , Equilibrio Ácido-Base/fisiología , Adulto , Glucemia , Ácidos Grasos no Esterificados/sangre , Ferritinas/sangre , Hematócrito , Hemoglobinas , Humanos , Masculino , Transportadores de Ácidos Monocarboxílicos/metabolismo , Proteínas Musculares/metabolismo , Oxidación-Reducción , Consumo de Oxígeno/fisiología , Simportadores/metabolismoRESUMEN
The direct effects of cycling on movement and muscle recruitment patterns (neuromuscular control) during running are unknown but critical to success in triathlon. We outline and test a new protocol for investigating the direct influence of cycling on neuromuscular control during running. Leg movement (three-dimensional kinematics) and muscle recruitment (surface electromyography, EMG) were compared between a control run (no prior exercise) and a 30-min transition run that was preceded by 20 min of cycling. We conducted three experiments investigating: (a) the repeatability (between-day reliability) of the protocol; (b) the ability of the protocol to investigate, in highly trained national or international triathletes, the direct influence of cycling on neuromuscular control during running independent of neuromuscular fatigue; and (c) the ability of the protocol to provide a control, or baseline, measure of neuromuscular control (determined using a measure of stability) without causing fatigue. Kinematic and EMG measures of neuromuscular control during running showed moderate to high repeatability: mean coefficients of multiple correlation for repeatability of EMG and kinematics were 0.816 +/- 0.014 and 0.911 +/- 0.031, respectively. The protocol provided a robust baseline measure of neuromuscular control during running without causing neuromuscular fatigue (coefficients of multiple correlation for stability of EMG and kinematics were 0.827 +/- 0.023 and 0.862 +/- 0.054), while EMG and force data provided no evidence of fatigue. The protocol outlined here is repeatable and can be used to measure any direct influence of cycling on neuromuscular control during running.
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Ciclismo/fisiología , Pierna/fisiología , Movimiento/fisiología , Músculo Esquelético/fisiología , Carrera/fisiología , Adulto , Fenómenos Biomecánicos , Estudios de Cohortes , Electromiografía , Femenino , Humanos , Masculino , Contracción Muscular/fisiología , Fatiga Muscular/fisiología , Resistencia Física/fisiologíaRESUMEN
We quantified the effect of an extended live high-train low (LHTL) simulated altitude exposure followed by a series of training camps at natural moderate altitude on competitive performance in seven elite middle-distance runners (Vo2max 71.4 +/- 3.4 mL.min-1.kg-1, mean +/- SD). Runners spent 44 +/- 7 nights (mean +/- SD) at a simulated altitude of 2846 +/- 32 m, and a further 4 7- to 10-d training at natural moderate altitude (1700-2200 m) before racing. The combination of simulated LHTL and natural altitude training improved competitive performance by 1.9% (90% confidence limits, 1.3-2.5%). Middle-distance runners can confidently use a combination of simulated and natural altitude to stimulate adaptations responsible for improving performance.
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Altitud , Tolerancia al Ejercicio/fisiología , Hipoxia , Carrera/fisiología , Aclimatación , Adulto , Conducta Competitiva , Exposición a Riesgos Ambientales , Femenino , Humanos , Masculino , Consumo de Oxígeno , Adulto JovenRESUMEN
To strengthen the depth of lightweight rowing talent, we sought to identify experienced heavyweight rowers who possessed physique traits that predisposed them to excellence as a lightweight. Identified athletes (n = 3) were monitored over 16 wk. Variables measured included performance, anthropometric indices, and selected biochemical and metabolic parameters. All athletes decreased their body mass (range 2.0 to 8.0 kg), with muscle mass accounting for a large proportion of this (31.7 to 84.6%). Two athletes were able to maintain their performance despite reductions in body mass. However, performance was compromised for the athlete who experienced the greatest weight loss. In summary, smaller heavyweight rowers can successfully make the transition into the lightweight category, being nationally competitive in their first season as a lightweight.
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Deportes/estadística & datos numéricos , Pérdida de Peso/fisiología , Adolescente , Adulto , Antropometría/métodos , Australia , Metabolismo Basal/fisiología , Biomarcadores/sangre , Biomarcadores/orina , Composición Corporal/fisiología , Índice de Masa Corporal , Registros de Dieta , Ergometría/métodos , Humanos , Masculino , Resistencia Física/fisiología , Factores de TiempoRESUMEN
This study tested the hypothesis that live high, train low (LHTL) would increase submaximal exercise ventilation (V(E)) in normoxia, and the increase would be related to enhanced hypoxic ventilatory response (HVR). Thirty-three cyclists/triathletes were divided into three groups: 20 consecutive nights of hypoxia (LHTLc, n = 12), 20 nights of intermittent hypoxia (4x5-night 'blocks' of hypoxia interspersed by two nights of normoxia, LHTLi, n = 10), or control (CON, n = 11). LHTLc and LHTLi slept 8-10 h per night in normobaric hypoxia (2,650 m), and CON slept under ambient conditions (600 m). Resting, isocapnic HVR (DeltaV(E)/Deltablood oxygen saturation) was measured in normoxia before (PRE) and after 15 nights (N15) hypoxia. Submaximal cycle ergometry was conducted PRE and after 4, 10, and 19 nights of hypoxia (N4, N10, and N19 respectively). Mean submaximal exercise V(E) was increased (P < 0.05) from PRE to N4 in LHTLc [74.4 (5.1) vs 80.0 (8.4) l min(-1); mean (SD)] and in LHTLi [69.0 (7.5) vs 76.9 (7.3) l min(-1)] and remained elevated in both groups thereafter, with no changes observed in CON at any time. Prior to LHTL, submaximal V(E) was not correlated with HVR, but this relationship was significant at N4 (r = 0.49, P = 0.03) and N19 (r = 0.77, P < 0.0001). Additionally, the increases in submaximal V(E) and HVR from PRE to N15-N19 were correlated (r = 0.51, P = 0.02) for the pooled data of LHTLc and LHTLi. These results suggest that enhanced hypoxic chemosensitivity contributes to increased exercise V(E) in normoxia following LHTL.
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Altitud , Consumo de Oxígeno/fisiología , Oxígeno/metabolismo , Resistencia Física/fisiología , Esfuerzo Físico/fisiología , Ventilación Pulmonar/fisiología , Aclimatación/fisiología , Adulto , Humanos , MasculinoRESUMEN
At high altitudes, the clinically defined respiratory disturbance index (RDI) and high hypoxic ventilatory response (HVR) have been associated with diminished sleep quality. Increased RDI has also been observed in some athletes sleeping at simulated moderate altitude. In this study, we investigated relationships between the HVR of 14 trained male endurance cyclists with variable RDI and sleep quality responses to simulated moderate altitude. Blood oxygen saturation (SpO2%), heart rate, RDI, arousal rate, awakenings, sleep efficiency, rapid eye movement (REM) sleep, non-REM sleep stages 1, 2 and slow wave sleep as percentages of total sleep time (%TST) were measured for two nights at normoxia of 600 m and one night at a simulated altitude of 2,650 m. HVR and RDI were not significantly correlated with sleep stage, arousal rate or awakening response to nocturnal simulated altitude. SpO2 was inversely correlated with total RDI (r = -0.69, P = 0.004) at simulated altitude and with the change in arousal rate from normoxia (r = -0.65, P = 0.02). REM sleep response to simulated altitude correlated with the change, relative to normoxia, in arousal (r = -0.63, P = 0.04) and heart rate (r = -0.61, P = 0.04). When stratified, those athletes at altitude with RDI >20 h(-1) (n = 4) and those with <10 h(-1) (n = 10) exhibited no difference in HVR but the former had larger falls in SpO2 (P = 0.05) and more arousals (P = 0.03). Neither RDI (without stratification) nor HVR were sufficiently sensitive to explain any deterioration in REM sleep or arousal increase. However, the stratified RDI provides a basis for determining potential sleep disturbance in athletes at simulated moderate altitude.
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Mal de Altura/fisiopatología , Altitud , Disomnias/diagnóstico , Disomnias/fisiopatología , Polisomnografía/métodos , Pruebas de Función Respiratoria/métodos , Síndromes de la Apnea del Sueño/diagnóstico , Síndromes de la Apnea del Sueño/fisiopatología , Adulto , Mal de Altura/complicaciones , Disomnias/complicaciones , Disomnias/etiología , Humanos , Masculino , Ventilación Pulmonar , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Índice de Severidad de la Enfermedad , Síndromes de la Apnea del Sueño/etiologíaRESUMEN
The aim of this study was to characterise the effect of prolonged low doses of recombinant erythropoietin (r-HuEPO) on the responses to submaximal and maximal exercise. Volunteer recreational athletes ( n=21) were divided into three groups: r-HuEPO+intravenous iron (EPO+IV, n=7), r-HuEPO+oral iron (EPO+OR, n=9) and placebo ( n=5). During the 12 week study, r-HuEPO or saline injections were given three times a week for the first 8 weeks and for the final 4 weeks the subjects were monitored but no injections were administered. The r-HuEPO doses were 50 IU x kg(-1) body mass for 3 weeks and 20 IU x kg(-1) body mass for the next 5 weeks. An exercise test comprising three submaximal intensities and then increments to elicit maximal aerobic power (VO2max ) was conducted during weeks 0, 4, 8 and 12. During week 0, the mean intensity of the submaximal stages was 60%, 72% and 81%. Blood taken at rest was analysed twice a week for haematocrit (Hct). The relative increases in at weeks 4, 8 and 12 were 7.7%, 9.7% and 4.5%, respectively, for the EPO+IV group; 6.0%, 4.7% and 3.1% for the EPO+OR group; and -0.5%, -0.1% and -1.0% for the placebo group, where the improvements at week 12 for the EPO+IV and EPO+OR groups remained significantly above week 0 values. The Hct was significantly elevated by 0.06 and 0.07 units at week 3 in the EPO+IV and EPO+OR groups, respectively, and was stable during the 5 weeks of low-dose r-HuEPO. After 8 weeks of r-HuEPO use, plasma lactate concentration tended to be lower at exercise intensities ranging from 60% to 100%. This study confirmed the ability of low doses of r-HuEPO to maintain Hct and at elevated levels.