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1.
J Sports Sci ; 39(1): 84-90, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32787678

RESUMEN

This study aimed to compare mechanical variables derived from torque-cadence and power-cadence profiles established from different cycle ergometer modes (isoinertial and isokinetic) and modelling procedures (second- and third-order polynomials), whilst employing a novel method to validate the theoretical maximal power output (Pmax). Nineteen well-trained cyclists (n = 12 males) completed two experimental sessions comprising six, 6-s maximal isoinertial or isokinetic cycling sprints. Maximal pedal strokes were extracted to construct power-cadence relationships using second- and third-order polynomials. A 6-s sprint at the optimal cadence (Fopt) or optimal resistance (Topt) was performed to assess construct validity of Pmax. No differences were found in the mechanical parameters when derived from isokinetic (Pmax = 1311 ± 415, Fopt = 118 ± 12) or isoinertial modes (Pmax = 1320 ± 421, Fopt = 116 ± 19). However, R2 improved (P < 0.02) when derived from isoinertial sprints. Third-order polynomial modelling improved goodness of fit values (Standard Error, adjusted R2), but derived similar mechanical parameters. Finally, peak power output during the optimised sprint did not significantly differ from the theoretical Pmax in both cycling modes, thus providing construct validity. The most accurate P-C profile can be derived from isoinertial cycling sprints, modelled using third-order polynomial equations.


Asunto(s)
Rendimiento Atlético/fisiología , Ciclismo/fisiología , Fenómenos Biomecánicos/fisiología , Esfuerzo Físico/fisiología , Adolescente , Adulto , Análisis de Varianza , Femenino , Humanos , Masculino , Modelos Teóricos , Torque , Adulto Joven
2.
J Strength Cond Res ; 34(12): 3423-3430, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-29189585

RESUMEN

Minahan, CL, Poke, DP, Morrison, J, and Bellinger, PM. Muscle damage and metabolic responses to repeated-sprint running with and without deceleration. J Strength Cond Res 34(12): 3423-3430, 2020-This study aimed to determine whether repeated-sprint running with deceleration aggravates markers of muscle damage or delays the recovery of performance compared with repeated-sprint running without deceleration. Fourteen male team-sport athletes performed 2 randomly ordered testing sessions on a nonmotorized treadmill with one session requiring subjects to decelerate (TMd) within 4 seconds before stopping or immediately step to the side of the treadmill belt at the completion of each sprint (TMa). Peak and mean velocities, speed decrement, blood lactate concentrations, and oxygen uptake were monitored during the repeated-sprint running protocols. Countermovement vertical jump (CMJ) performance, perceived muscle soreness, sit-and-reach flexibility, plasma creatine kinase (CK), lactate dehydrogenase (LDH), and myoglobin (Mb) concentrations were quantified immediately before and after and 45 minutes, 24 and 48 hours after repeated-sprint running protocols. Although muscle damage was indicated by increases in CK, LDH, and Mb (p ≤ 0.05) in both groups, there was no significant effect of condition (TMa vs. TMd) on any of the measured performance or physiological variables (p > 0.05). The present study indicated that the removal of deceleration from repeated-sprint running on a nonmotorized treadmill has no effect on metabolism or performance during or after repeated-sprint running or markers of muscle damage.


Asunto(s)
Desaceleración , Músculo Esquelético/fisiopatología , Carrera/fisiología , Adulto , Atletas , Rendimiento Atlético/fisiología , Biomarcadores , Creatina Quinasa/sangre , Prueba de Esfuerzo , Humanos , L-Lactato Deshidrogenasa/sangre , Ácido Láctico/sangre , Masculino , Mialgia/fisiopatología , Mioglobina/sangre , Consumo de Oxígeno , Adulto Joven
3.
Eur J Appl Physiol ; 118(11): 2417-2427, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-30167957

RESUMEN

PURPOSE: To compare prefrontal cortex oxygenation in recreationally-active women using oral contraceptives (WomenOC; n = 8) to women with a natural menstrual cycle (WomenNC; n = 8) during incremental exercise to exhaustion. METHODS: Participants performed incremental cycling to exhaustion to determine lactate threshold 1 (LT1) and 2 (LT2) and peak oxygen uptake (VO2peak). Prefrontal cortex oxygenation was monitored via near-infrared spectroscopy through concentration changes in oxy-haemoglobin (Δ[HbO2]), deoxy-haemoglobin (Δ[HHb]), total-haemoglobin (Δ[tHb]) and tissue saturation index (TSI). RESULTS: 17ß-oestradiol and progesterone were lower in WomenOC (35 ± 26; 318 ± 127 pmol·L-1, respectively) than WomenNC (261 ± 156; 858 ± 541 pmol·L-1, respectively). There were no differences in full blood examination results or serum nitric oxide (p > 0.05). However, WomenOC presented lower concentrations in ferric-reducing ability of plasma (- 8%; effect size; ES - 0.52 ± 0.61), bilirubin (- 32%; ES - 0.56 ± 0.62) and uric acid (- 17%; ES - 0.53 ± 0.61). Cardiopulmonary parameters were similar between groups during cycling, including VO2peak (p = 0.99). While there was a significant effect of time on all parameters measured by near-infrared spectroscopy during incremental cycling, there was no effect of OC at LT1, LT2 or exhaustion calculated as a change from baseline (TSI; p = 0.096, Δ[HbO2]; p = 0.143, Δ[HHb]; p = 0.085 and Δ[tHb]; p = 0.226). The change in TSI from LT1 to LT2 was significantly different between groups (WomenNC; mean difference + 2.06%, WomenOC; mean difference - 1.73%; p = 0.003). CONCLUSION: Prefrontal tissue oxygenation declined at a lower relative exercise intensity in WomenOC as compared to WomenNC, however, this did not influence VO2peak. The results provide the first evidence for variance in the cerebral oxygenation response to exercise, which may be associated with female sex hormones.


Asunto(s)
Anticonceptivos Hormonales Orales/uso terapéutico , Estradiol/sangre , Consumo de Oxígeno/efectos de los fármacos , Oxígeno/sangre , Corteza Prefrontal/efectos de los fármacos , Progesterona/sangre , Adolescente , Adulto , Anticonceptivos Hormonales Orales/administración & dosificación , Femenino , Humanos , Consumo de Oxígeno/fisiología , Oxihemoglobinas/metabolismo , Corteza Prefrontal/irrigación sanguínea , Corteza Prefrontal/metabolismo , Espectroscopía Infrarroja Corta , Adulto Joven
4.
J Sports Sci ; 36(4): 378-383, 2018 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-28357897

RESUMEN

This study determined the effect of 8 wk of mindfulness training (MT) on salivary cortisol (sCort) and rate of salivary Immunoglobulin-A (sIgA) secretion in wheelchair-basketball players during a competition period. The mindful group completed 8 weeks of MT in addition to training and competition. sCort and rate of sIgA secretion were measured at baseline, at 2-week intervals, the end and 2 weeks following the intervention. A significant time and group interaction was observed for sCort (F = 3.297, P = 0.040, ES = 0.191); sCort increased in the control group from MT-BL to MT-2wk (P = 0.001) and remained significantly elevated at MT-4wk (P = 0.013) and MT-6wk (P = 0.002). sCort decreased from MT-6wk to MT-8wk (P < 0.001) and concentrations were not different at MT-8wk and Post-2wk to MT-BL (P > 0.05). Mindful group sCort increased from MT-BL to MT-2wk (P = 0.042) but decreased to concentrations no different to MT-BL for the rest of the intervention period (P > 0.05). There were no group differences in rate of sIgA secretion during the intervention (P = 0.810). It was concluded that 8 weeks of MT attenuated the increase in sCort associated with the competition period.


Asunto(s)
Baloncesto/fisiología , Baloncesto/psicología , Conducta Competitiva/fisiología , Atención Plena , Estrés Psicológico/prevención & control , Silla de Ruedas , Adulto , Femenino , Humanos , Hidrocortisona/metabolismo , Inmunoglobulina A Secretora/metabolismo , Masculino , Aplicaciones Móviles , Saliva/metabolismo , Tasa de Secreción , Teléfono Inteligente
5.
J Sports Sci ; 34(17): 1669-74, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-26756946

RESUMEN

The purpose of this study was to investigate the intra- and inter-day reliability of cognitive performance using a computer-based test battery in team-sport athletes. Eighteen elite male rugby union players (age: 19 ± 0.5 years) performed three experimental trials (T1, T2 and T3) of the test battery: T1 and T2 on the same day and T3, on the following day, 24 h later. The test battery comprised of four cognitive tests assessing the cognitive domains of executive function (Groton Maze Learning Task), psychomotor function (Detection Task), vigilance (Identification Task), visual learning and memory (One Card Learning Task). The intraclass correlation coefficients (ICCs) for the Detection Task, the Identification Task and the One Card Learning Task performance variables ranged from 0.75 to 0.92 when comparing T1 to T2 to assess intraday reliability, and 0.76 to 0.83 when comparing T1 and T3 to assess inter-day reliability. The ICCs for the Groton Maze Learning Task intra- and inter-day reliability were 0.67 and 0.57, respectively. We concluded that the Detection Task, the Identification Task and the One Card Learning Task are reliable measures of psychomotor function, vigilance, visual learning and memory in rugby union players. The reliability of the Groton Maze Learning Task is questionable (mean coefficient of variation (CV) = 19.4%) and, therefore, results should be interpreted with caution.


Asunto(s)
Cognición , Fútbol Americano/psicología , Pruebas Neuropsicológicas , Atención , Computadores , Función Ejecutiva , Humanos , Masculino , Recuerdo Mental , Reproducibilidad de los Resultados , Análisis y Desempeño de Tareas , Adulto Joven
6.
Int J Sports Physiol Perform ; 18(12): 1442-1448, 2023 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-37857382

RESUMEN

PURPOSE: To examine the association between muscle fiber typology and match running performance in professional Australian football (AF) athletes. METHODS: An observational time-motion analysis was performed on 23 professional AF athletes during 224 games throughout the 2020 competitive season. Athletes were categorized by position as hybrid, small, or tall. Athlete running performance was measured using Global Navigation Satellite System devices. Mean total match running performance and maximal mean intensity values were calculated for moving mean durations between 1 and 10 minutes for speed (in meters per minute), high-speed-running distance (HSR, >4.17 m·s-1), and acceleration (in meters per second squared), while intercept and slopes were calculated using power law. Carnosine content was quantified by proton magnetic resonance spectroscopy in the gastrocnemius and soleus and expressed as a carnosine aggregate z score (CAZ score) to estimate muscle fiber typology. Mixed linear models were used to determine the association between CAZ score and running performance. RESULTS: The mean (range) CAZ score was -0.60 (-1.89 to 1.25), indicating that most athletes possessed a greater estimated proportion of type I muscle fibers. A greater estimated proportion of type I fibers (ie, lower CAZ score) was associated with a larger accumulation of HSR (>4.17 m·s-1) and an increased ability to maintain HSR as the peak period duration increased. CONCLUSION: AF athletes with a greater estimated proportion of type I muscle fibers were associated with a greater capacity to accumulate distance running at high speeds, as well as a greater capacity to maintain higher output of HSR running during peak periods as duration increases.


Asunto(s)
Rendimiento Atlético , Carnosina , Carrera , Humanos , Australia , Carrera/fisiología , Fibras Musculares Esqueléticas , Rendimiento Atlético/fisiología , Sistemas de Información Geográfica , Deportes de Equipo
7.
Clin Rehabil ; 25(1): 14-24, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-20713434

RESUMEN

OBJECTIVE: The purpose of this study was to compare adaptations in functional and quality of life measures following endurance- and resistance-exercise training in people with multiple sclerosis. DESIGN: Cross-over design with an eight-week washout period. SETTING: Community health centre. SUBJECTS: Sixteen individuals with multiple sclerosis. INTERVENTION: Subjects completed both an eight-week endurance- and an eight-week resistance-exercise training programme in a randomized order. The exercise training comprised individualized progressive programmes that were completed twice weekly in a supervised group setting. MAIN MEASURES: Grip strength, functional reach, four step square, timed up and go and six-minute walk tests, Multiple Sclerosis Impact and Modified Fatigue Impact Scales, Becks Depression Inventory and the Health Status Questionnaire Short Form-36. RESULTS: Sixteen of 21 (76%) subjects completed the study. Subjects attended 13.2 ± 1.6 endurance- and 15.8 ± 1.9 resistance-exercise training sessions. No adverse events were reported. No significant differences (P < 0.05) in any outcome measures were observed between the two exercise training programmes either at baseline or following the completion of both training programmes. CONCLUSION: Both endurance- and resistance-exercise training were well tolerated and appear to provide similar effects for people with multiple sclerosis, but larger studies are required to confirm these findings.


Asunto(s)
Esclerosis Múltiple/rehabilitación , Resistencia Física/fisiología , Entrenamiento de Fuerza/métodos , Actividades Cotidianas , Anciano , Estudios Cruzados , Depresión/etiología , Fatiga , Femenino , Fuerza de la Mano , Humanos , Masculino , Persona de Mediana Edad , Limitación de la Movilidad , Esclerosis Múltiple/fisiopatología , Esclerosis Múltiple/psicología , Proyectos Piloto , Equilibrio Postural , Calidad de Vida , Perfil de Impacto de Enfermedad
8.
Sports Med ; 51(5): 843-861, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33725341

RESUMEN

Until recently, there has been less demand for and interest in female-specific sport and exercise science data. As a result, the vast majority of high-quality sport and exercise science data have been derived from studies with men as participants, which reduces the application of these data due to the known physiological differences between the sexes, specifically with regard to reproductive endocrinology. Furthermore, a shortage of specialist knowledge on female physiology in the sport science community, coupled with a reluctance to effectively adapt experimental designs to incorporate female-specific considerations, such as the menstrual cycle, hormonal contraceptive use, pregnancy and the menopause, has slowed the pursuit of knowledge in this field of research. In addition, a lack of agreement on the terminology and methodological approaches (i.e., gold-standard techniques) used within this research area has further hindered the ability of researchers to adequately develop evidenced-based guidelines for female exercisers. The purpose of this paper was to highlight the specific considerations needed when employing women (i.e., from athletes to non-athletes) as participants in sport and exercise science-based research. These considerations relate to participant selection criteria and adaptations for experimental design and address the diversity and complexities associated with female reproductive endocrinology across the lifespan. This statement intends to promote an increase in the inclusion of women as participants in studies related to sport and exercise science and an enhanced execution of these studies resulting in more high-quality female-specific data.


Asunto(s)
Deportes , Adaptación Fisiológica , Atletas , Ejercicio Físico , Femenino , Humanos , Masculino , Ciclo Menstrual
9.
Eur J Appl Physiol ; 109(2): 287-95, 2010 May.
Artículo en Inglés | MEDLINE | ID: mdl-20082092

RESUMEN

The purpose of this study was to determine if improved supramaximal exercise performance in trained cyclists following caffeine ingestion was associated with enhanced O(2) uptake (VO2 kinetics), increased anaerobic energy provision (accumulated O(2)-AO(2)-deficit), or a reduction in the accumulation of metabolites (for example, K(+)) associated with muscular fatigue. Six highly trained male cyclists (VO2peak 68 +/- 8 mL kg(-1) min(-1)) performed supramaximal (120% VO2peak) exercise bouts to exhaustion on an electronically braked cycle ergometer, following double-blind and randomized ingestion of caffeine/placebo (5 mg kg(-1)). Time to exhaustion (TE), VO2 kinetics, AO(2) deficit, blood lactate (La(-)), plasma potassium (K(+)), caffeine and paraxanthine concentrations were measured. Caffeine ingestion elicited significant increases in TE (14.8%, p < 0.01) and AO(2) deficit (6.5%, p < 0.05). In contrast, no changes were observed in AO(2) deficit at isotime, VO2 kinetics, blood [La(-)] at exhaustion or peak [K(+)] following caffeine ingestion. However, [K(+)] was significantly reduced (13.4%, p < 0.01) during warm-up cycling immediately prior to the onset of the supramaximal bout for the caffeine trials, compared with placebo. It appears that caffeine ingestion is beneficial to supramaximal cycling performance in highly trained men. The reduced plasma [K(+)] during submaximal warm-up cycling may prolong the time taken to reach critical [K(+)] at exhaustion, thus delaying fatigue. Considering caffeine ingestion did not change VO2 kinetics or isotime AO(2) deficit, increases in absolute AO(2) deficit may be a consequence of prolonged TE, rather than causal.


Asunto(s)
Ciclismo , Cafeína/farmacología , Estimulantes del Sistema Nervioso Central/farmacología , Consumo de Oxígeno/efectos de los fármacos , Resistencia Física/efectos de los fármacos , Adulto , Humanos , Cinética , Ácido Láctico/sangre , Masculino , Potasio/sangre , Intercambio Gaseoso Pulmonar/efectos de los fármacos , Xantinas/sangre , Adulto Joven
10.
Physiol Rep ; 8(7): e14398, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-32281749

RESUMEN

Sex differences in motor performance may arise depending on the mode of contraction being performed. In particular, contractions that are held for long durations, rather than contractions that are interspersed with rest periods, may induce greater levels of fatigue in men compared to women. The purpose of this study was to examine fatigue responses in a cohort of healthy men (n = 7, age [mean] = 21.6 ± [SD] 1.1 year) and women (n = 7, age: 22.0 ± 2.0 year) during sustained isometric and intermittent isometric contractions. Two contraction protocols were matched for intensity (20% MVC) and total contraction time (600-s). Biceps brachii EMG and elbow flexion torque steadiness were examined throughout each protocol, and motor nerve stimulation was used to quantify central and peripheral fatigue. Overall, there were few sex-related differences in the fatigue responses during intermittent contractions. However, men exhibited progressively lower maximal torque generation (39% versus 27% decrease), progressively greater muscle activity (220% versus 144% increase), progressively greater declines in elbow flexion steadiness (354% versus 285% decrease), and progressively greater self-perception of fatigue (Borg scale: 8.8 ± 1.2 versus 6.3 ± 1.1) throughout the sustained contractions. The mechanism underlying fatigue responses had a muscle component, as voluntary activation of the biceps brachii did not differ between sexes, but the amplitude of resting twitches decreased throughout the sustained contractions (m: 32%, w: 10% decrease). As generating large sustained forces causes a progressive increase in intramuscular pressure and mechanical occlusion-which has the effect of enhancing metabolite accumulation and peripheral fatigue-it is likely that the greater maximal strength of men contributed to their exacerbated levels of fatigue.


Asunto(s)
Articulación del Codo/fisiología , Fatiga Muscular/fisiología , Músculo Esquelético/fisiología , Adulto , Estudios Cruzados , Femenino , Humanos , Masculino , Contracción Muscular , Resistencia Física , Factores Sexuales , Adulto Joven
11.
Int J Sports Physiol Perform ; 15(6): 801-807, 2020 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-32053792

RESUMEN

PURPOSE: To determine whether there is an association between external match load and contextual factors on subjective wellness in the days before and after Australian Rules football match play. METHODS: A total of 34 elite male Australian football players completed a subjective wellness questionnaire in the days leading into the match (-3, -2, and -1 d), the day of (match day), and the days after each match (+3, +2, and +1 d). Players subjectively rated each item (mood, energy, stress, leg heaviness, muscle soreness, sleep quality, hours slept, and total wellness [a sum of the total response score]) on a visual analog scale ranging from 1 to 10, with 1 representing the negative end of the continuum. External load during competitive matches was quantified using accelerometer-derived PlayerLoad, and running activity was quantified using global positioning system technology across 2 competitive seasons. The relationships between perceptions of wellness (within-individual z score), external match load, and contextual factors (match result, match location, and between-matches recovery duration) were analyzed using linear mixed models. RESULTS: Mixed-effect linear models revealed trivial effects of match-day wellness z score on subsequent external match load metrics. Match result (win) and PlayerLoad in the anteroposterior vector (au·min-1) were associated with an increased (estimate ± SE: 0.30 ± 0.13 z score) and reduced subjective wellness (-0.15 ± 0.06 z score), respectively. CONCLUSION: The results of this study suggest that prematch perceived wellness does not relate to external match load in elite Australian football players. The between-matches microcycle length appears to be sufficient to restore perceived wellness to values that do not affect the subsequent external match loads.


Asunto(s)
Atletas , Estado de Salud , Percepción , Humanos , Masculino , Adulto Joven , Afecto/fisiología , Australia , Fatiga/fisiopatología , Modelos Lineales , Mialgia/fisiopatología , Mialgia/psicología , Percepción/fisiología , Estudios Retrospectivos , Carrera/fisiología , Carrera/psicología , Sueño/fisiología , Estrés Psicológico , Deportes
12.
Front Sports Act Living ; 2: 608939, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33426520

RESUMEN

The aims were to investigate the externally measured weekly loads, and the distribution intensity relative to the 1-min maximal mean (MM) intensity of matches. Athletes (n = 28) wore 10 Hz GNSS devices during training and matches. For the descriptive analysis, a range of movement variables were collected, including total distance, high-speed distance, very high-speed distance, acceleration, and acceleration load. Using raw GNSS files, 1-min moving averages were calculated for speed (m·min-1) and acceleration (m·s-2), and were multiplied by time, specifying total distance (m), and by body mass to quantify impulse (kN·s-1). The distribution of distance and impulse accumulated at varied intensities relative to MMs was calculated, with percentages ranging from zero to 110%. Drills were categorized as either; warm-ups, skill drills, games (i.e., small-sided games), conditioning and matches. Linear mixed models determined if the distribution of intensity within each threshold (>50%) varied between drill types and matches, and if the distribution within drill types varied across the season. Effects were described using standardized effect sizes (ES) and 90% confidence limits (CL). Compared to matches, a higher proportion of distance was accumulated at 50% of the MM within warm-ups and conditioning (ES range 0.86-1.14). During matches a higher proportion of distance was accumulated at 60% of MM when compared to warms ups, skill drills and conditioning (0.73-1.87). Similarly, greater proportion of distance was accumulated between 70 and 100% MM in matches compared to skill drills and warm-ups (1.05-3.93). For impulse, matches had a higher proportion between 60 and 80% of the MM compared to conditioning drills (0.91-3.23). There were no other substantial differences in the proportion of impulse between matches and drill types. When comparing phases, during competition there was a higher proportion of distance accumulated at 50% MM than general preparation (1.08). A higher proportion of distance was covered at higher intensities within matches compared to drills. The proportion of impulse was higher between 60 and 80% MM within matches compared to conditioning. Practitioners can therefore ensure athletes are not only exposed to the intensities common within competition, but also the volume accumulated is comparable, which may have positive performance outcomes, but is also extremely important in the return to play process.

13.
Health Qual Life Outcomes ; 7: 68, 2009 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-19619337

RESUMEN

BACKGROUND: The purpose of this study was to compare fatigue, depression and quality of life scores in persons with multiple sclerosis who do (Exercisers) and do not (Non-exercisers) regularly participate in physical activity. METHODS: A cross-sectional questionnaire study of 121 patients with MS (age 25-65 yr) living in Queensland, Australia was conducted. Physical activity level, depression, fatigue and quality of life were assessed using the International Physical Activity Questionnaire, Health Status Questionnaire Short Form 36, Becks Depression Inventory and Modified Fatigue Impact Scale. RESULTS: 52 participants performed at least two 30-min exercise sessions x wk-1 (Exercisers) and 69 did not participate in regular physical activity (Non-exercisers). Exercisers reported favourable fatigue, depression and quality of life scores when compared to Non-exercisers. Significant weak correlations were found between both leisure-time and overall reported physical activity levels and some subscales of the quality of life and fatigue questionnaires. Additionally, some quality of life subscale scores indicated that regular physical activity had a greater benefit in subjects with moderate MS. CONCLUSION: Favourable fatigue, depression and quality of life scores were reported by persons with MS who regularly participated in physical activity, when compared to persons with MS who were classified as Non-exercisers.


Asunto(s)
Depresión , Ejercicio Físico/fisiología , Ejercicio Físico/psicología , Fatiga , Esclerosis Múltiple/psicología , Calidad de la Atención de Salud , Adulto , Anciano , Estudios Transversales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Queensland , Encuestas y Cuestionarios
14.
J Strength Cond Res ; 23(5): 1489-95, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19593221

RESUMEN

To validate VO2 and energy expenditure predictions by the Suunto heart rate (HR) system against a first principle gas analysis system, well-trained male (n = 10, age 29.8 +/- 4.3 years, VO2 65.9 +/- 9.7 ml x kg x min) and female (n = 7, 25.6 +/- 3.6 years, 57.0 +/- 4.2 ml x kg x min) runners completed a 2-stage incremental running test to establish submaximal and maximal oxygen uptake values. Metabolic cart values were used as the criterion measure of VO2 and energy expenditure (kJ) and compared with the predicted values from the Suunto software. The 3 levels of software analysis for the Suunto system were basic personal information (BI), BI + measured maximal HR (BIhr), and BIhr + measured VO2 (BIhr + v). Comparisons were analyzed using linear regression to determine the standard error of the estimate (SEE). Eight subjects repeated the trial within 7 days to determine reliability (typical error [TE]). The SEEs for oxygen consumption via BI, BIhr, and BIhr + v were 2.6, 2.8, and 2.6 ml.kg.min, respectively, with corresponding percent coefficient of variation (%CV) of 6.0, 6.5, and 6.0. The bias compared with the criterion VO2 decreased from -6.3 for BI, -2.5 for BIhr, to -0.9% for BIhr + v. The SEE of energy expenditure improved from BI (6.74 kJ) to BIhr (6.56) and BIhr + v (6.14) with corresponding %CV of 13.6, 12.2, and 12.7. The TE values for VO2 were approximately 0.60 ml x kg x min and approximately 2 kJ for energy expenditure. The %CV for VO2 and energy expenditure was approximately 1 to 4%. Although reliable, basic HR-based estimations of VO2 and energy expenditure from the Suunto system underestimated VO2 and energy expenditure by approximately 6 and 13%, respectively. However, estimation can be improved when maximal HR and VO2 values are added to the software analysis.


Asunto(s)
Metabolismo Energético , Frecuencia Cardíaca , Monitoreo Fisiológico/instrumentación , Consumo de Oxígeno , Adulto , Prueba de Esfuerzo , Femenino , Humanos , Modelos Lineales , Masculino , Intercambio Gaseoso Pulmonar , Reproducibilidad de los Resultados , Carrera , Programas Informáticos
15.
J Sports Med Phys Fitness ; 57(12): 1680-1686, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27849116

RESUMEN

BACKGROUND: The purpose of this study was to evaluate the inter-day reliability of the IPRO method for determining resting and postexercise salivary cortisol (sCort) and rate of salivary Immunoglobulin-A (sIgA) secretion. METHODS: Fourteen males (32±11 years) performed two trials (T1 and T2) separated by 7 d, comprising saliva sampling before and 15 min after completion of two, 30-s Wingate Anaerobic Tests separated by 3.5 min (2 x WAnT). sCort increased after the 2 x WAnT in both trials (T1: P<0.001; T2: P<0.001), whereas rate of sIgA secretion decreased in both trials (T1: P=0.002; T2: P=0.002). RESULTS: The intraclass correlation coefficients for resting and postexercise sCort and rate of sIgA secretion ranged from 0.96-0.99. Mean reliability, expressed as the coefficient of variation (%) and the typical error of measurement over the two trials were resting sCort 9.4%, 0.14 ng·mL-1 (9% CI: 0.1-0.2), postexercise sCort 11.9%, 0.44 ng·mL-1 (9% CI: 0.3-0.7), resting rate of sIgA secretion 7.4%, 85.5 µg·mL-1·min-1 (9% CI: 65.2-127.1) and postexercise rate of sIgA secretion 10.5%, 82.9 µg·mL-1·min-1 (9% CI: 63.2-123.1). CONCLUSIONS: The IPRO is a reliable method for determining sCort and rate of sIgA secretion at rest and after sprint-cycling exercise.


Asunto(s)
Ejercicio Físico/fisiología , Hidrocortisona/análisis , Inmunoglobulina A Secretora/análisis , Saliva/química , Adulto , Ciclismo , Humanos , Masculino , Reproducibilidad de los Resultados , Adulto Joven
16.
Med Sci Sports Exerc ; 48(12): 2417-2425, 2016 12.
Artículo en Inglés | MEDLINE | ID: mdl-27434084

RESUMEN

PURPOSE: The present study investigated the effects of ß-alanine supplementation only, and in combination with sprint-interval training (SIT), on training intensity, and energy provision and performance during exhaustive supramaximal-intensity cycling and a 4- and 10-km time trial (TT). METHODS: Fourteen trained cyclists (V˙O2max = 4.5 ± 0.6 L·min) participated in this placebo-controlled, double-blind study. Subjects performed a supramaximal cycling test to exhaustion (equivalent to 120% V˙O2max) and a 4- and 10-km TT and 4 × 1-km sprints at three time points: before and after 28 d of supplementation loading (6.4 g·d) with ß-alanine (n = 7) or a placebo (n = 7), and after a 5-wk supervised, SIT program performed twice weekly (repeated 1-km cycling sprints) while maintaining supplementation with ß-alanine (1.2 g·d) or a placebo. RESULTS: After the loading period, sprints 3 and 4 of the 4 × 1-km sprint intervals were improved with ß-alanine supplementation (4.5% ± 3.4% and 7.0% ± 4.0%; P < 0.05, respectively). After 5 wk of SIT, training intensity increased in both groups but the change was greater with ß-alanine supplementation (9.9% ± 5.0% vs 4.9% ± 5.0%; P = 0.04). ß-alanine supplementation also improved supramaximal cycling time to exhaustion to a greater extent than placebo (14.9% ± 9.2% vs 9.0% ± 6.9%; P = 0.04), whereas 4- and 10-km TT performance improved to a similar magnitude in both groups. After SIT, ß-alanine also increased anaerobic capacity (5.5% ± 4.2%; P = 0.04), whereas V˙O2peak increased similarly in each group (3.1% ± 2.9% vs 3.5% ± 2.9%; P < 0.05). CONCLUSIONS: These findings indicate that ß-alanine supplementation enhances training intensity during SIT and provides additional benefits to exhaustive supramaximal cycling compared with SIT alone.


Asunto(s)
Ciclismo/fisiología , Suplementos Dietéticos , Entrenamiento de Intervalos de Alta Intensidad , Resistencia Física/fisiología , beta-Alanina/administración & dosificación , Adulto , Carnosina/metabolismo , Método Doble Ciego , Prueba de Esfuerzo , Humanos , Masculino , Músculo Esquelético/metabolismo
17.
Eur J Sport Sci ; 16(7): 829-36, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26652037

RESUMEN

The varying results reported in response to ß-alanine supplementation may be related to the duration and nature of the exercise protocol employed. We investigated the effects of ß-alanine supplementation on a wide range of cycling performance tests in order to produce a clear concise set of criteria for its efficacy. Fourteen trained cyclists (Age = 24.8 ± 6.7 years; VO2max = 65.4 ± 10.2 mL·kg·min(-1)) participated in this placebo-controlled, double-blind study. Prior to supplementation, subjects completed two (familiarization and baseline) supramaximal cycling bouts until exhaustion (120% pre-supplementation VO2max) and two 1-, 4- and 10-km cycling time trial (TT). Subjects then supplemented orally for 4 weeks with 6.4 g/d placebo or ß-alanine and repeated the battery of performance tests. Blood lactate was measured pre-exercise, post-exercise and 5  min post-exercise. ß-alanine supplementation elicited significant increases in time to exhaustion (TTE) (17.6 ± 11.5 s; p = 0.013, effect compared with placebo) and was likely to be beneficial to 4-km TT performance time (-7.8 ± 8.1 s; 94% likelihood), despite not being statistically different (p = 0.060). Performance times in the 1- and 10-km TT were not affected by treatment. For the highly trained cyclists in the current study, ß-alanine supplementation significantly extended supramaximal cycling TTE and may have provided a worthwhile improvement to 4-km TT performance. However, 1- and 10-km cycling TT performance appears to be unaffected by ß-alanine supplementation.


Asunto(s)
Rendimiento Atlético , Ciclismo/fisiología , beta-Alanina/farmacología , Adulto , Humanos , Ácido Láctico/sangre , Masculino , Factores de Tiempo , Adulto Joven , beta-Alanina/administración & dosificación
18.
Appl Physiol Nutr Metab ; 41(8): 864-71, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-27467218

RESUMEN

The present study investigated the effects of ß-alanine supplementation on the resultant blood acidosis, lactate accumulation, and energy provision during supramaximal-intensity cycling, as well as the aerobic and anaerobic contribution to power output during a 4000-m cycling time trial (TT). Seventeen trained cyclists (maximal oxygen uptake = 4.47 ± 0.55 L·min(-1)) were administered 6.4 g of ß-alanine (n = 9) or placebo (n = 8) daily for 4 weeks. Participants performed a supramaximal cycling test to exhaustion (equivalent to 120% maximal oxygen uptake) before (PreExh) and after (PostExh) the 4-week supplementation period, as well as an additional postsupplementation supramaximal cycling test identical in duration and power output to PreExh (PostMatch). Anaerobic capacity was quantified and blood pH, lactate, and bicarbonate concentrations were measured pre-, immediately post-, and 5 min postexercise. Subjects also performed a 4000-m cycling TT before and after supplementation while the aerobic and anaerobic contributions to power output were quantified. ß-Alanine supplementation increased time to exhaustion (+12.8 ± 8.2 s; P = 0.041) and anaerobic capacity (+1.1 ± 0.7 kJ; P = 0.048) in PostExh compared with PreExh. Performance time in the 4000-m TT was reduced following ß-alanine supplementation (-6.3 ± 4.6 s; P = 0.034) and the mean anaerobic power output was likely to be greater (+6.2 ± 4.5 W; P = 0.035). ß-Alanine supplementation increased time to exhaustion concomitant with an augmented anaerobic capacity during supramaximal intensity cycling, which was also mirrored by a meaningful increase in the anaerobic contribution to power output during a 4000-m cycling TT, resulting in an enhanced overall performance.


Asunto(s)
Ciclismo , Suplementos Dietéticos , beta-Alanina/administración & dosificación , Adolescente , Adulto , Bicarbonatos/sangre , Índice de Masa Corporal , Fatiga/tratamiento farmacológico , Humanos , Concentración de Iones de Hidrógeno , Ácido Láctico/sangre , Modelos Lineales , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/metabolismo , Consumo de Oxígeno , Resistencia Física , Adulto Joven
19.
Eur J Sport Sci ; 16(1): 88-95, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-25636080

RESUMEN

ß-alanine is a common ingredient in supplements consumed by athletes. Indeed, athletes may believe that the ß-alanine induced paresthesia, experienced shortly after ingestion, is associated with its ergogenic effect despite no scientific mechanism supporting this notion. The present study examined changes in cycling performance under conditions of ß-alanine induced paresthesia. Eight competitive cyclists (VO2max = 61.8 ± 4.2 mL·kg·min(-1)) performed three practices, one baseline and four experimental trials. The experimental trials comprised a 1-km cycling time trial under four conditions with varying information (i.e., athlete informed ß-alanine or placebo) and supplement content (athlete received ß-alanine or placebo) delivered to the cyclist: informed ß-alanine/received ß-alanine, informed placebo/received ß-alanine, informed ß-alanine/received placebo and informed placebo/received placebo. Questionnaires were undertaken exploring the cyclists' experience of the effects of the experimental conditions. A possibly likely increase in mean power was associated with conditions in which ß-alanine was administered (±95% CL: 2.2% ± 4.0%), but these results were inconclusive for performance enhancement (p = 0.32, effect size = 0.18, smallest worthwhile change = 56% beneficial). A possibly harmful effect was observed when cyclists were correctly informed that they had ingested a placebo (-1.0% ± 1.9%). Questionnaire data suggested that ß-alanine ingestion resulted in evident sensory side effects and six cyclists reported placebo effects. Acute ingestion of ß-alanine is not associated with improved 1-km TT performance in competitive cyclists. These findings are in contrast to the athlete's "belief" as cyclists reported improved energy and the ability to sustain a higher power output under conditions of ß-alanine induced paresthesia.


Asunto(s)
Rendimiento Atlético/fisiología , Rendimiento Atlético/psicología , Ciclismo/fisiología , Parestesia/inducido químicamente , beta-Alanina/efectos adversos , Adulto , Atletas , Humanos , Encuestas y Cuestionarios , Adulto Joven
20.
Int J Sports Physiol Perform ; 11(6): 810-815, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-26694539

RESUMEN

This study compared determinants of a 30-s all-out paddling effort (30-s sprint-paddling test) between junior surfboard riders (surfers) of varying ability. Eight competitive (COMP) and 8 recreational (REC) junior male surfers performed a 30-s sprint-paddling test for the determination of peak sprint power and accumulated O2 deficit. Surfers also performed an incremental-paddling test for the determination of the O2 uptake-power output relationship that was subsequently used to calculate the accumulated O2 deficit for the 30-s sprint-paddling test. During the 30-s sprint-paddling test, peak sprint power (404 ± 98 vs 292 ± 56 W, respectively, P = .01) and the accumulated O2 deficit (1.60 ± 0.31 vs 1.14 ± 0.38 L, respectively, P = .02) were greater in COMP than in REC surfers, whereas peak O2 uptake measured during the incremental-paddling test was not different (2.7 ± 0.1 vs 2.5 ± 0.2 L/min, respectively, P = .11). The higher peak sprint power and larger accumulated O2 deficit observed in COMP than in REC surfers during a 30-s sprint paddling test suggest that surfing promotes development of the anaerobic energy systems. Furthermore, peak sprint power determined during 30 s of sprint paddling may be considered a sensitive measure of surfing ability or experience in junior male surfers.


Asunto(s)
Rendimiento Atlético/fisiología , Esfuerzo Físico/fisiología , Deportes/fisiología , Adolescente , Prueba de Esfuerzo , Fatiga/fisiopatología , Frecuencia Cardíaca , Humanos , Lactatos/sangre , Masculino , Consumo de Oxígeno , Entrenamiento de Fuerza , Adulto Joven
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