RESUMO
AIMS: This work explored the effects of irisin on metabolism, gene expression and mitochondrial content in cultured myocytes. METHODS: C2C12 myocytes were treated with various concentrations of irisin for various durations. Glycolysis and oxidative metabolism were quantified by measurement of extracellular acidification and oxygen consumption, respectively. Metabolic gene expression was measured by quantitative real-time polymerase chain reaction (qRT-PCR) and mitochondrial content was assessed by flow cytometry and confocal microscopy. RESULTS: Cells treated with irisin exhibited significantly increased oxidative metabolism. Irisin treatment also significantly increased mitochondrial uncoupling at various doses and durations. Lastly, treatment with irisin also significantly elevated metabolic gene expression including peroxisome proliferator-activated receptor γ coactivator-1 alpha (PGC-1α), nuclear respiratory factor 1 (NRF1), mitochondrial transcription factor A (TFAM), irisin, glucose transporter 4 (GLUT4) and mitochondrial uncoupling protein 3 (UCP3) leading to increased mitochondrial biogenesis. CONCLUSIONS: Our observations are the first to document increased metabolism in myocytes through irisin-mediated induction of mitochondrial biogenesis and uncoupling with corresponding gene expression. These observations support the need for further investigation into the therapeutic and pharmacological effects of irisin, as well as development of irisin-based therapy.
Assuntos
Fibronectinas/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Glicólise/efeitos dos fármacos , Mitocôndrias Musculares/efeitos dos fármacos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Proteínas Musculares/metabolismo , Fosforilação Oxidativa/efeitos dos fármacos , Animais , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Proteínas de Ligação a DNA/agonistas , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Fibronectinas/agonistas , Fibronectinas/genética , Fibronectinas/metabolismo , Proteínas de Grupo de Alta Mobilidade/agonistas , Proteínas de Grupo de Alta Mobilidade/genética , Proteínas de Grupo de Alta Mobilidade/metabolismo , Humanos , Cinética , Camundongos , Mitocôndrias Musculares/metabolismo , Renovação Mitocondrial/efeitos dos fármacos , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/metabolismo , Proteínas Musculares/agonistas , Proteínas Musculares/genética , Fator 1 Nuclear Respiratório/agonistas , Fator 1 Nuclear Respiratório/genética , Fator 1 Nuclear Respiratório/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Proteínas Recombinantes/farmacologia , Fatores de Transcrição/agonistas , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
New approaches to inducing altitude acclimation in a relatively short timeframe are needed, as it is not practical for many soldiers and athletes to gain access to specialized training facilities. Acclimation to one environmental stressor could enhance adaptation to various other stressors in animals and humans. This phenomenon has been described as cross-tolerance and involves the activation of common protective pathways. The purpose of this review is to discuss possible mechanisms involved in the cross-tolerance between heat and hypoxia. Future data could potentially support the use of a cross-tolerance model as a means for military personnel to prepare for deployment to high-altitude environments, as well as for athletes competing at high altitude.
Assuntos
Aclimatação/fisiologia , Altitude , Temperatura Alta , Animais , Fenômenos Fisiológicos Cardiovasculares , Humanos , Fator 1 Induzível por Hipóxia/fisiologia , Volume PlasmáticoRESUMO
Reports of VO2 response differences between normoxia and hypoxia during incremental exercise do not agree. In this study VO2 and VE were obtained from 15-s averages at identical work rates during continuous incremental cycle exercise in 8 subjects under ambient pressure (633 mmHg ≈1,600 m) and during duplicate tests in acute hypobaric hypoxia (455 mmHg ≈4,350 m), ranging from 49 to 100% of VO2 peak in hypoxia and 42-87% of VO2 peak in normoxia. The average VO2 was 96 mL/min (619 mL) lower at 455 mmHg (n.s. P = 0.15) during ramp exercises. Individual response points were better described by polynomial than linear equations (mL/min/W). The VE was greater in hypoxia, with marked individual variation in the differences which correlated significantly and directly with the VO2 difference between 455 mmHg and 633 mmHg (P = 0.002), likely related to work of breathing (Wb). The greater VE at 455 mmHg resulted from a greater breathing frequency. When a subject's hypoxic ventilatory response is high, the extra work of breathing reduces mechanical efficiency (E). Mean ∆E calculated from individual linear slopes was 27.7 and 30.3% at 633 and 455 mmHg, respectively (n.s.). Gross efficiency (GE) calculated from mean VO2 and work rate and correcting for Wb from a VE-VO2 relationship reported previously, gave corresponding values of 20.6 and 21.8 (P = 0.05). Individual variation in VE among individuals overshadows average trends, as also apparent from other reports comparing hypoxia and normoxia during progressive exercise and must be considered in such studies.
Assuntos
Teste de Esforço , Hipóxia , Exercício Físico , Humanos , Oxigênio , Consumo de OxigênioRESUMO
Autophagy is a lysosome degradation pathway through which damaged organelles and macromolecules are degraded within the cell. A decrease in activity of the autophagic process has been linked to several age-associated pathologies, including triglyceride accumulation, mitochondrial dysfunction, muscle degeneration, and cardiac malfunction. Here, we examined the differences in the autophagic response using autophagy-inducer rapamycin (Rapa) in peripheral blood mononuclear cells (PBMCs) from young (21.8 ± 1.9 years) and old (64.0 ± 3.7 years) individuals. Furthermore, we tested the interplay between the heat shock response and autophagy systems. Our results showed a significant increase in LC3-II protein expression in response to Rapa treatment in young but not in old individuals. This was associated with a decreased response in MAP1LC3B mRNA levels, but not SQSTM1/p62. Furthermore, HSPA1A mRNA was upregulated only in young individuals, despite no differences in HSP70 protein expression. The combined findings suggest a suppressed autophagic response following Rapa treatment in older individuals.
Assuntos
Envelhecimento/fisiologia , Autofagia/fisiologia , Proteínas de Choque Térmico HSP70/metabolismo , Leucócitos Mononucleares/fisiologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
This study compared the ventilation response to an incremental ergometer exercise at two altitudes: 633 mmHg (resident altitude = 1,600 m) and following acute decompression to 455 mmHg (≈4,350 m altitude) in eight male cyclists and runners. At 455 mmHg, the VESTPD at RER <1.0 was significantly lower and the VEBTPS was higher because of higher breathing frequency; at VO2max, both VESTPD and VEBTPS were not significantly different. As percent of VO2max, the VEBTPS was nearly identical and VESTPD was 30% lower throughout the exercise at 455 mmHg. The lower VESTPD at lower pressure differs from two classical studies of acclimatized subjects (Silver Hut and OEII), where VESTPD at submaximal workloads was maintained or increased above that at sea level. The lower VESTPD at 455 mmHg in unacclimatized subjects at submaximal workloads results from acute respiratory alkalosis due to the initial fall in HbO2 (≈0.17 pHa units), reduction in PACO2 (≈5 mmHg) and higher PAO2 throughout the exercise, which are partially pre-established during acclimatization. Regression equations from these studies predict VESTPD from VO2 and PB in unacclimatized and acclimatized subjects. The attainment of ventilatory acclimatization to altitude can be estimated from the measured vs. predicted difference in VESTPD at low workloads after arrival at altitude.
Assuntos
Aclimatação/fisiologia , Altitude , Pressão Atmosférica , Hipóxia/fisiopatologia , Ventilação Pulmonar/fisiologia , Adulto , Alcalose Respiratória/fisiopatologia , Biomarcadores , Exercício Físico/fisiologia , Resposta ao Choque Térmico/fisiologia , Humanos , Masculino , Pressões Respiratórias Máximas , Mecânica Respiratória/fisiologia , Adulto JovemRESUMO
BACKGROUND/OBJECTIVES: Traditional tetrapolar bioimpedance spectroscopy (BIS) is performed with the participant supine for 10 min. New vertical analyzers are penetrating clinical, home and fitness markets, but have body water values that differ from supine reference measures. The minimum time standing prior to assessment does not appear in the literature. We investigated the time course of body water shifts in healthy adults undergoing 30-min assessments in supine and vertical positions. SUBJECTS/METHODS: While seated, participants were prepped for standard tetrapolar electrode placement. Starting position was counterbalanced and body water measurements were taken every 5 min for 30 min in both positions. Participants sat for 2 min prior to switching positions. Of the 64 participants, three were unable to stand for 30 min; their data were excluded. Body size differences were minimized via computation of relative (%) change between time intervals for total body water (TBW), extracellular water (ECW) and intracellular water (ICW). RESULTS: ECW and ICW shifted in opposite directions while participants were supine; as ECW decreased at each time point, ICW increased (P<0.0125). Likewise, when participants stood, ECW increased incrementally (P<0.0125), but the decreases in ICW were not significant. At each time interval, the changes in supine ECW and ICW differed from the standing values (P<0.05). No postural or time differences were found for %change TBW. CONCLUSIONS: For TBW, 5 min appears sufficient for fluid stabilization in either position. Supine ECW and ICW stabilization require more than 30 min as does standing ECW.
Assuntos
Água Corporal , Líquido Extracelular/fisiologia , Líquido Intracelular/fisiologia , Postura/fisiologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Decúbito Dorsal/fisiologia , Fatores de TempoRESUMO
The purpose of this investigation was to determine the effects of transdermal estradiol (E2) replacement on substrate utilization during exercise. Amenorrheic females (N = 6) performed three exercise trials following 72 h of placebo (C 72) and 72 and 144 h of medicated transdermal estradiol (E2) treatment (E2 72 and E2 144). Exercise involved 90 min of treadmill running at 65% VO2max followed by timed exercise to exhaustion at 85% VO2max. Resting blood samples were obtained for glucose, insulin, free fatty acids (FFA), and E2. Exercise blood samples were obtained for E2, lactate, epinephrine, and norepinephrine. Rates of appearance and disposal were calculated for glucose and glycerol using a primed, continuous infusion of [6,6-2H] glucose and [2H5] glycerol. Medicated transdermal placement increased E2 significantly at rest, before exercise (35.03 +/- 12.3, 69.5 +/- 20.1, and 73.1 +/- 31.6 pg.mL-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Resting FFA increased significantly following E2 treatment (0.28 +/- 0.16, 0.41 +/- 0.27, and 0.40 +/- 0.21 mmol.L-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Glucose Ra was significantly decreased during exercise as a result of E2 replacement (21.9 +/- 7.7, 18.9 +/- 6.2, and 18.9 +/- 5.6 mumol.kg-1.min-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Average glucose Rd also decreased during exercise as a result of E2 replacement (21.3 +/- 7.8, 18.5 +/- 6.4, and 18.6 +/- 5.8 mumol.kg-1.min-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). However, the estimated relative contribution of plasma glucose and muscle glycogen to total carbohydrate oxidation was similar among the trials. Epinephrine values were significantly lower late in exercise during the E2 72 and E2 144 trials, compared with the C 72 trial (P < 0.05). These results indicate that elevated E2 levels can alter glucose metabolism at rest and during moderate intensity exercise as a result of decreased gluconeogenesis, epinephrine secretion, and/or glucose transport.
Assuntos
Amenorreia/fisiopatologia , Estradiol/farmacologia , Exercício Físico/fisiologia , Glucose/metabolismo , Administração Cutânea , Adulto , Metabolismo Energético , Terapia de Reposição de Estrogênios , Feminino , Glicerol/metabolismo , Humanos , Esportes/fisiologiaRESUMO
BACKGROUND: The amount of limb-length discrepancy necessary to adversely affect gait parameters in older adults is unknown, with information being largely anecdotal. This investigation was conducted to determine the effects of limb-length discrepancy on gait economy and lower-extremity muscle activity in older adults. METHODS: Forty-four men and women ranging in age from fifty-five to eighty-six years with no evidence of limb-length discrepancy of >1 cm participated in the study. Subjects walked on a treadmill at a self-selected normal walking pace with artificial limb-length discrepancies of 0, 2, 3, and 4 cm applied in a randomly selected order. Indirect calorimetry was used to measure oxygen consumption and minute ventilation. Electromyography was used to measure muscle activity of the right and left quadriceps femoris, plantar flexors, gluteus maximus, and gluteus medius. Heart rate, the rating of perceived exertion, and frequency of gait compensation patterns were also measured. RESULTS: There was a significant increase in oxygen consumption and the rating of perceived exertion with 2, 3, and 4-cm artificial limb-length discrepancies; a significant increase in heart rate, minute ventilation, and quadriceps activity in the longer limb with 3 and 4-cm artificial limb-length discrepancies; and a significant increase in plantar flexor activity in the shorter limb with a 4-cm artificial limb-length discrepancy compared with the same parameters with no artificial limb-length discrepancy. CONCLUSIONS: Both oxygen consumption and the rating of perceived exertion were greater with a 2-cm artificial limb-length discrepancy than they were with no artificial limb-length discrepancy. There appears to be a breakpoint between 2 and 3 cm of artificial limb-length discrepancy in older adults with regard to the effects on most other physiological parameters. A 3-cm artificial limb-length discrepancy is likely to induce significant quadriceps fatigue in the longer limb. Elderly patients with substantial pulmonary, cardiac, or neuromuscular disease may have difficulty walking with a limb-length discrepancy as small as 2 cm.
Assuntos
Marcha , Desigualdade de Membros Inferiores/fisiopatologia , Perna (Membro) , Músculo Esquelético/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Eletromiografia , Feminino , Frequência Cardíaca , Humanos , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio , Percepção , Esforço Físico , Ventilação PulmonarRESUMO
The rate of ventilation and route of breathing (i.e., nasal versus oronasal) are potential determinants of pollutant doses to target sites in the lung. However, the lack of accurate methods for ambulatory measurement of ventilation has hindered estimation of exposure and dose in freely ranging individuals, complicating the interpretation of the relationships among exposure, dose, and response in epidemiological studies. The goal of this project was to develop and validate a method of monitoring ventilation for large-scale epidemiologic investigations. We estimated ventilation for individual subjects from ambulatory heart rate monitoring, using the relationship between ventilation and heart rate that had been obtained during exercise testing. Fifty-eight subjects participated in the study, which included healthy adults and children, and subjects with lung and heart disease. Subjects performed cycle exercise and tasks involving lifting and vacuuming. Work loads of progressive and variable order were used in the testing. Conventional methods were used to measure heart rate and total ventilation, and a sampling mask was developed to measure the partitioning of breathing between oral and nasal routes. The minute ventilation-heart rate relation was evaluated under steady-state and varying work loads. In a second phase, subjects wore wristwatch monitors that recorded their heart rates, minute by minute, throughout the day. Subjects recorded activities, locations, and levels of exertion. Two 16-hour monitoring periods were obtained from each subject. The laboratory findings documented considerable intersubject variability in the minute ventilation-heart rate relation with a two- to five-fold range in the coefficients describing the change in ventilation relative to heart rate. This variation implies that individual testing is required to derive accurate predictive equations. Minute ventilation-heart rate regressions for the maximal progressive exercise test and for the test with a nonprogressive submaximal work load sequence were comparable, indicating that varying the sequence of work loads does not substantially affect the minute ventilation-to-heart rate ratio. During upper body work (e.g., lifting), the minute ventilation-to-heart rate ratio was one-third greater than during lower body exercise. Diverse patterns of partitioning breathing between oral and nasal routes were observed with increasing oral ventilation in most subjects as work load increased. In the field, heart rate and activity patterns were monitored successfully in adults and children with low rates of instrument failure and noncompliance.(ABSTRACT TRUNCATED AT 400 WORDS)
Assuntos
Exercício Físico/fisiologia , Frequência Cardíaca , Ventilação Pulmonar/fisiologia , Testes de Função Respiratória/métodos , Adolescente , Adulto , Idoso , Criança , Teste de Esforço , Feminino , Humanos , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Valores de Referência , Respiração/fisiologia , Volume de Ventilação PulmonarRESUMO
Sources of variability in nasal airway resistance measured by posterior rhinomanometry were studied in 5 subjects tested on 5 different days and 56 subjects tested on 2 different days. On each day, a questionnaire on upper airway health and nasal symptoms was completed. The mean individual difference in nasal airway resistance between the 2 test days in the group of 56 subjects was 5.3% (SD 52.7%). Between-subject variability accounted for 74.9% and 72.5% of the total variability in the group of 5 and the group of 56 subjects, respectively. For the 5 subjects, by accounting for a change in upper airway symptoms or upper respiratory tract infection that occurred over the 5 test days, there was a significant decrease in the between-subject variability. The difference in sources of variation due to a change in upper airway symptoms was not seen in the group of 56 subjects. We conclude that the largest source of variability in nasal airway resistance is due to between-subject differences.
Assuntos
Resistência das Vias Respiratórias/fisiologia , Obstrução Nasal/diagnóstico , Adulto , Análise de Variância , Feminino , Humanos , Masculino , Manometria/métodos , Obstrução Nasal/epidemiologia , Reprodutibilidade dos Testes , Testes de Função Respiratória/métodos , Testes de Função Respiratória/estatística & dados numéricos , Fatores de TempoRESUMO
OBJECTIVE: The purpose of the study was to evaluate the cross-training response between running and cycling in untrained females. EXPERIMENTAL DESIGN: The following study involved a pretest, post-test, 3 x 3 factorial design. SETTING: Training (4 days-week-1, 10 weeks, 70-80% heart rate reserve) occurred at the Center for Exercise and Applied Human Physiology. Exercise testing occurred at the Veterans Hospital, Exercise Laboratory. PATIENTS AND PARTICIPANTS: Subjects included healthy, untrained females aged 18-25 years, (N = 18). INTERVENTION: Subjects were assigned to one of three (n = 6) training groups (run = R, cycle = C, both run and cycle = RC) matched on pre-training CE VO2max results. MEASURES: Graded treadmill run (TR) and cycle ergometer (CE) tests were performed on each subject to determine a mode specific VO2max and the lactate threshold (LT). Graded arm ergometer (AE) was performed to determine VO2max and heart rate and blood lactate at 20 and 40 Watts (W). Testing occurred prior to (0T), after 5 (5T) and after 10 weeks of training (10T). Body fat testing (hydrodensitometry at residual lung volume) was performed at 0T and 10T. RESULTS: TR and CE VO2max as well as TR and CE VO2 at the LT improved throughout the 10 weeks, regardless of training group. Although there were no changes in VO2max or blood lactate levels during AE, submaximal heart rates were significantly reduced over the 10 weeks, regardless of training group. CONCLUSIONS: These results indicate that the aerobic benefits of either run, cycle or combined run and cycle training are similar in untrained females. The LT and AE heart rate data demonstrate that improvements in VOmax due to ten weeks of training are a result of pronounced peripheral and moderate central adaptations.
Assuntos
Ciclismo/fisiologia , Corrida/fisiologia , Tecido Adiposo/anatomia & histologia , Adolescente , Adulto , Aerobiose , Limiar Anaeróbio , Análise de Variância , Composição Corporal , Comportamento Cooperativo , Estudos de Avaliação como Assunto , Teste de Esforço , Feminino , Seguimentos , Frequência Cardíaca , Humanos , Lactatos/sangue , Consumo de Oxigênio , Educação Física e Treinamento , Resistência Física/fisiologiaRESUMO
Estimation of pulmonary exposure and dose in air pollution epidemiology has been impaired by the lack of methods for directly measuring ventilation in ambulatory subjects. Heart-rate monitoring offers an approach to estimate ventilation by using ventilation-on-heart-rate (VE-HR) regressions established during exercise testing to estimate ventilation in the field. Conventional methods and protocols for testing were used to evaluate the relationship between VE and HR during three tasks: (1) exercising on a cycle ergometer, (2) lifting, and (3) vacuuming. The relationship between VE and HR was curvilinear and was best fit with linear regression models, using a natural log transformation of VE. Considerable interindividual variability in slopes and intercepts was observed across all types of exercise tests. The variability about the fitted regression lines for individual subjects was minimal; for example, individual R2 values for the maximum exercise test on 15 men ranged from 0.90 to 0.99 (mean = 0.97). The regression slopes established during upper-body exercise were greater by approximately 30%, relative to those derived in lower-body exercise (paired t test, p < .001). However, VE-HR regression slopes derived from tests in which progressively increasing workloads were used were comparable to those obtained during variable and nonprogressive protocols. These findings indicate that predictive accuracy is maximized by deriving VE-HR regressions for individual subjects and for both lower- and upper-body activities.
Assuntos
Poluentes Atmosféricos/efeitos adversos , Exposição Ambiental , Monitoramento Ambiental/métodos , Frequência Cardíaca , Medidas de Volume Pulmonar , Modelos Biológicos , Modelos Estatísticos , Adolescente , Adulto , Idoso , Asma/fisiopatologia , Criança , Protocolos Clínicos , Doença das Coronárias/fisiopatologia , Métodos Epidemiológicos , Monitoramento Epidemiológico , Teste de Esforço , Feminino , Humanos , Modelos Lineares , Pneumopatias Obstrutivas/fisiopatologia , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica/métodos , Consumo de Oxigênio , Esforço Físico , Valor Preditivo dos TestesRESUMO
The route of breathing, oral or nasal, is a determinant of the doses of inhaled pollutants delivered to target sites in the upper and lower respiratory tracts. We measured partitioning of ventilation, using a divided oronasal mask during a submaximal exercise test, in 37 male and female subjects who ranged in age from 7 to 72 y. The following four patterns of breathing were evident during exercise: (1) nasal only (13.5%), nasal shifting to oronasal (40.5%), oronasal only (40.5%), and oral only (5.4%). Children (i.e., 7-16 y of age) displayed more variability than adults with respect to their patterns of ventilation with exercise. Young adults (i.e., 17-30 y of age) who initially breathed nasally with exercise switched to oral ventilation at a lower percentage of the previously measured maximum ventilation (10.8%) than older subjects (31.8%). The partitioning of ventilation between the nasal and oral routes follows complex patterns that cannot be predicted readily by the age, gender, or nasal airway resistance of the subject.
Assuntos
Envelhecimento/fisiologia , Respiração Bucal/fisiopatologia , Nariz/fisiologia , Respiração/fisiologia , Adolescente , Adulto , Idoso , Resistência das Vias Respiratórias , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Respiração com Pressão Positiva/instrumentação , Testes de Função Respiratória/métodos , Testes de Função Respiratória/estatística & dados numéricosRESUMO
The purpose of this study was to profile the effect of active versus passive recovery on acid-base kinetics during multiple bouts of intense exercise. Ten males completed two exercise trials. The trials consisted of three exercise bouts to exhaustion with either a 12 min active (20% workload max) or passive recovery between bouts. Blood pH was lower in the passive (p) recovery compared to active (a) throughout the second and third recovery periods [second recovery: 7.18 +/- 0.08 to 7.24 +/- 0.09 (p), 7.23 +/- 0.07 to 7.32 +/- 0.07 (a), P < 0.05; third recovery: 7.17 +/- 0.08 to 7.22 +/- 0.09 (p), 7.23 +/- 0.08 to 7.32 +/- 0.08 (a), P < 0.05]. Exercise performance times did not differ between recovery conditions (P = 0.28). No difference was found between conditions for recovery kinetics (slope and half-time to recovery). Subsequent performance during multiple bouts of intense exercise to exhaustion may not be influenced by blood acidosis or mode of recovery.
Assuntos
Equilíbrio Ácido-Base/fisiologia , Metabolismo Energético/fisiologia , Exercício Físico/fisiologia , Descanso/fisiologia , Adulto , Análise de Variância , Bicarbonatos/sangue , Teste de Esforço/métodos , Humanos , Concentração de Íons de Hidrogênio , Ácido Láctico/sangue , Masculino , Consumo de Oxigênio/fisiologia , Fatores de TempoRESUMO
OBJECTIVE: To identify the physiological and anthropometric determinants of sport climbing performance. METHODS: Forty four climbers (24 men, 20 women) of various skill levels (self reported rating 5.6-5.13c on the Yosemite decimal scale) and years of experience (0.10-44 years) served as subjects. They climbed two routes on separate days to assess climbing performance. The routes (11 and 30 m in distance) were set on two artificial climbing walls and were designed to become progressively more difficult from start to finish. Performance was scored according to the system used in sport climbing competitions where each successive handhold increases by one in point value. Results from each route were combined for a total climbing performance score. Measured variables for each subject included anthropometric (height, weight, leg length, arm span, % body fat), demographic (self reported climbing rating, years of climbing experience, weekly hours of training), and physiological (knee and shoulder extension, knee flexion, grip, and finger pincer strength, bent arm hang, grip endurance, hip and shoulder flexibility, and upper and lower body anaerobic power). These variables were combined into components using a principal components analysis procedure. These components were then used in a simultaneous multiple regression procedure to determine which components best explain the variance in sport rock climbing performance. RESULTS: The principal components analysis procedure extracted three components. These were labelled training, anthropometric, and flexibility on the basis of the measured variables that were the most influential in forming each component. The results of the multiple regression procedure indicated that the training component uniquely explained 58.9% of the total variance in climbing performance. The anthropometric and flexibility components explained 0.3% and 1.8% of the total variance in climbing performance respectively. CONCLUSIONS: The variance in climbing performance can be explained by a component consisting of trainable variables. More importantly, the findings do not support the belief that a climber must necessarily possess specific anthropometric characteristics to excel in sport rock climbing.
Assuntos
Antropometria , Montanhismo/fisiologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/fisiologia , Educação Física e Treinamento , Resistência Física/fisiologia , Esforço Físico/fisiologia , Amplitude de Movimento Articular , Análise de Regressão , Inquéritos e QuestionáriosRESUMO
OBJECTIVES: To report the physiological responses of indoor rock climbing. METHODS: Fourteen experienced climbers (nine men, five women) performed three climbing trials on an indoor climbing wall. Subjects performed three trials of increasing difficulty: (a) an easy 90 degrees vertical wall, (b) a moderately difficult negatively angled wall (106 degrees), and (c) a difficult horizontal overhang (151 degrees). At least 15 minutes separated each trial. Expired air was collected in a Douglas bag after four minutes of climbing and heart rate (HR) was recorded continuously using a telemetry unit. Arterialised blood samples were obtained from a hyperaemised ear lobe at rest and one or two minutes after each trial for measurement of blood lactate. RESULTS: Significant differences were found between trials for HR, lactate, oxygen consumption (VO2), and energy expenditure, but not for respiratory exchange ratio. Analysis of the HR and VO2 responses indicated that rock climbing does not elicit the traditional linear HR-VO2 relationship characteristic of treadmill and cycle ergometry exercise. During the three trials, HR increased to 74-85% of predicted maximal values and energy expenditure was similar to that reported for running at a moderate pace (8-11 minutes per mile). CONCLUSIONS: These data indicate that indoor rock climbing is a good activity to increase cardiorespiratory fitness and muscular endurance. In addition, the traditional HR-VO2 relationship should not be used in the analysis of this sport, or for prescribing exercise intensity for climbing.
Assuntos
Metabolismo Energético/fisiologia , Esportes/fisiologia , Adulto , Dióxido de Carbono/análise , Dióxido de Carbono/sangue , Orelha Externa/irrigação sanguínea , Ambiente Controlado , Teste de Esforço , Feminino , Previsões , Frequência Cardíaca/fisiologia , Humanos , Hiperemia/sangue , Lactatos/sangue , Pulmão/fisiologia , Masculino , Oxigênio/análise , Oxigênio/sangue , Consumo de Oxigênio/fisiologia , Resistência Física/fisiologia , Aptidão Física/fisiologia , Troca Gasosa Pulmonar/fisiologia , Respiração/fisiologia , Descanso/fisiologia , Corrida/fisiologia , Espirometria , TelemetriaRESUMO
This study was conducted to compare blood glucose and glucoregulatory hormone responses to the ingestion of solid and liquid carbohydrate (CHO) during prolonged cycling, followed by 30 min of isokinetic cycling. Eight male cyclists randomly completed three cycling trials (LC = liquid CHO, SCE = solid CHO with water equal to LC, SCA = solid CHO + ad libitum water). Each subject cycled for 120 min at 65% of VO2max with CHO ingestion (0.6 g CHO/ kg/hr) at 0, 30, 60, 90, and 120 min. Subjects then completed a 30-min maximal isokinetic ride at 90 rpm. There was no significant (p < .05) difference between the trials for plasma glucose, insulin, glucagon, glycerol, lactate, RER, HR, VO2, RPE, and total work performed during the isokinetic ride. However, serum glucose was significantly lower in the SCE and SCA trials compared to LC at 80 min. The ingestion of a solid food containing CHO, protein, and fat with added water produced similar blood glucose, metabolic, glucoregulatory hormone, and exercise performance responses to those seen with the ingestion of liquid CHO.