Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 19.487
Filtrar
1.
Zhonghua Xin Xue Guan Bing Za Zhi ; 48(2): 100-103, 2020 Feb 24.
Artículo en Chino | MEDLINE | ID: mdl-32135608

Asunto(s)
Carrera , Corazón , Humanos
2.
J Sports Sci ; 38(5): 518-527, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31900052

RESUMEN

The purpose of this study was to investigate the effects of slope on three-dimensional running kinematics at high speed. Thirteen male sprinters ran at high speed (7.5 m/s) on a motorised treadmill in each a level and a 5.0% slope condition. Three-dimensional motion analysis was conducted to compare centre of mass (CoM) energetics, pelvis segment and lower limb joints kinematics. We found that contact time was not affected by the slope, whereas flight time and step length were significantly shorter in uphill compared to level running. Uphill running reduced negative CoM work and increased positive CoM work compared to level running. Ankle, knee and hip joints were more flexed at initial ground contact, but only the knee was more extended at the end of stance in uphill compared to level running. Additionally, the hip joint was more abducted, and the free leg side of the pelvis was more elevated at the end of stance in uphill running. Our results demonstrate that joint motion must be developed from a more flexed/adducted position at initial contact through a greater range of motion compared to level running in order to meet the greater positive CoM work requirements in uphill running at high speed.


Asunto(s)
Articulación del Tobillo/fisiología , Articulación de la Cadera/fisiología , Articulación de la Rodilla/fisiología , Carrera/fisiología , Fenómenos Biomecánicos/fisiología , Prueba de Esfuerzo , Marcadores Fiduciales , Marcha , Humanos , Imagen Tridimensional , Masculino , Movimiento/fisiología , Rango del Movimiento Articular/fisiología , Adulto Joven
3.
J Sports Sci ; 38(5): 542-551, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31924128

RESUMEN

Males and females demonstrate unique running mechanics that may contribute to sex-related differences in common running related injuries. Understanding differences in muscle forces during running may inform intervention approaches, such as gait retraining addressing muscle force distribution. The purpose of this study was to compare muscle force characteristics and inter-trial variability between males and females during running. Twenty female and 14 male collegiate cross-country runners were examined. Three-dimensional kinetic and kinematic data were collected during overground running and used to estimate muscle forces via musculoskeletal modelling. Principle components analysis was used to capture the primary sources of variance from the muscle force waveforms. The magnitude of the forces for the hamstrings, gastrocnemius, and soleus muscles were higher across the majority of stance in male runners regardless of footstrike pattern. Males also demonstrated greater inter-trial variability in the timing of the peak gluteus maximus force and the magnitude of local peaks in the gastrocnemius force waveform. Male and female collegiate cross-country runners appear to employ unique lower extremity muscle force characteristics during overground running.


Asunto(s)
Músculo Esquelético/fisiología , Carrera/fisiología , Adolescente , Fenómenos Biomecánicos/fisiología , Femenino , Marcha/fisiología , Músculos Isquiotibiales/fisiología , Humanos , Extremidad Inferior/fisiología , Masculino , Análisis Multivariante , Músculo Cuádriceps/fisiología , Factores Sexuales , Adulto Joven
4.
Adv Exp Med Biol ; 1232: 245-251, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893417

RESUMEN

Skeletal muscle metabolic function is known to respond positively to endurance exercise interventions, such as marathon training. Studies investigating skeletal muscle have typically used muscle biopsy samples or magnetic resonance spectroscopy (MRS) to interrogate metabolic function. We aimed to non-invasively detect exercise-training-induced improvements in muscle function using broadband near-infrared spectroscopy (NIRS). We used NIRS to determine concentration changes in oxygenated haemoglobin (HbO2) and the oxidation state of cytochrome-c-oxidase (oxCCO) in gastrocnemius during arterial occlusion in 14 volunteers. We also used a cardio-pulmonary exercise test (CPET) to assess peak total body oxygen uptake (peakVO2; a measure of fitness). Measurements were made at baseline (BL) which was prior to a period of at least 16 weeks of training for the 2017 London Marathon, and then within 3 weeks after completion of the marathon, follow-up (FU). We observed an increase in locally measured muscle oxygen consumption and rate of oxCCO concentration change, but not in cardio-respiratory fitness measured as whole-body peak oxygen consumption (peakVO2).


Asunto(s)
Músculo Esquelético , Consumo de Oxígeno , Carrera , Espectroscopía Infrarroja Corta , Adulto , Complejo IV de Transporte de Electrones/metabolismo , Femenino , Humanos , Masculino , Músculo Esquelético/metabolismo , Oxihemoglobinas/metabolismo
5.
Mymensingh Med J ; 29(1): 169-176, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31915354

RESUMEN

This cross sectional analytical type of study was conducted at department of Anatomy, Dhaka Medical College, Dhaka, Bangladesh from July 2015 to June 2016 on 50 adult Bangladeshi male sprinters (Group A) and 50 adult Bangladeshi male cricket batsman (Group B). Sample collection was done by convenient purposive sampling technique. History of any injury of hand during playing was excluded to construct standard measurement. Hand breadth was measured with the help of slide calipers. Hand grip strength Dynamometer was used to measure the hand grip strength. Paired Student's 't' test, unpaired student's 't' test and Pearson's correlation coefficient test were done for statistical analysis of the result. The aim of the present study was to determine hand breadth and average hand grip strength of Bangladeshi male cricket batsman to find out correlation between them that may be used as a baseline for other professions as well for future research in our country. The mean right and left hand grip strength was significantly higher in the cricket batsman than in the sprinters. The mean right and left hand breadth was found to be significantly higher in the cricket batsman than in the sprinters. Right and left hand grip strength showed significant positive correlation with hand breadth in both hand. The study findings suggest that regular physical exercise and training increase hand grip strength.


Asunto(s)
Fuerza de la Mano , Mano/anatomía & histología , Adulto , Animales , Antropometría , Grupo de Ascendencia Continental Asiática , Atletas , Bangladesh , Estudios Transversales , Grupos Étnicos , Humanos , Masculino , Dinamómetro de Fuerza Muscular , Carrera
7.
Int J Sports Med ; 41(3): 161-167, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31902130

RESUMEN

Aerobic performance is negatively impacted by tropical climate due to impairment of thermoregulatory mechanisms. We tested the hypothesis that a torso application of a 4% menthol solution would have the same effect on a best performance 10-km run as an external use of cold water. Thirteen trained male athletes completed four outdoor 10-km runs (T=29.0±1.3°C, relative humidity 59.0±13.6%) wearing a tee-shirt soaked every 2-km either in a cold (~6°C) or warm/ambient (~28°C) solution, consisting in water or in a 4% menthol solution, (CTL, MENT-Amb, CLD and MENT-CLD). Run performances were improved from 4.8 to 6.1% in CLD (51.4±5.5 min), MENT-Amb (52.2±5.9 min) and MENT-CLD (51.4±5.1 min) conditions (vs. CTL, 55.4±8.4 min, P<0.05), without differences between these three conditions, whereas heart rate (177±13bpm), body temperature (38.7±0.6°C) and drink ingestion (356±170 g) were not modified. Thermal sensation after running was lower in MENT-CLD (vs. CTL, P<0.01) and thermal acceptability was higher in CLD and MENT-Amb (vs. CTL, P<0.05), but thermal comfort, feeling scale and rate of perceived exertion remained unchanged. The use of menthol on skin enhances aerobic performance in a tropical climate, and no differences in performance were observed between menthol and traditional percooling strategies. However, combining both menthol and traditional percooling brought no further improvements.


Asunto(s)
Rendimiento Atlético/fisiología , Regulación de la Temperatura Corporal/efectos de los fármacos , Humedad , Mentol/administración & dosificación , Carrera/fisiología , Clima Tropical , Administración Cutánea , Adulto , Ingestión de Líquidos , Marcha/fisiología , Frecuencia Cardíaca/fisiología , Humanos , Masculino , Percepción/fisiología , Esfuerzo Físico/fisiología , Pérdida de Peso/fisiología , Adulto Joven
8.
Scand J Immunol ; 91(2): e12834, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31680301

RESUMEN

This review analyses the influence of acute running and cycling exercise on T lymphocyte apoptosis. We included randomized controlled trials (RCTs) and non-randomized case-control studies (NRCTs) measuring apoptosis by flow cytometry. Cochrane Library, Scopus, PubMed and Ovid were searched for running and cycling intervention studies. Risk of bias was assessed by Cochrane Collaboration's tools. We included five NRCTs and one RCT with a total of 93 participants. The RCT found a higher percentage of apoptotic T helper cells identified by upregulation of Annexin V, caspase-3 and caspase-9 under hypoxic conditions, and only one NRCT reported a higher percentage of highly differentiated apoptotic T cells immediately after exercise. Three hours after exercise, the same NRCT showed an increase in several T cell subsets such as T helper, cytotoxic T, low differentiated and regulatory T cells. The interventions were very heterogeneous by exercise protocol and external conditions. High risk of bias in NRCTs restricts accuracy of the included studies. Imprecision due to the small sample size limits further evidence. In the future, scientists should include apoptotic measures into their research design, plan RCTs, measure apoptosis at different time points post-exercise and increase sample size.


Asunto(s)
Ejercicio/fisiología , Carrera/fisiología , Subgrupos de Linfocitos T/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Animales , Apoptosis , Sesgo , Humanos , Ensayos Clínicos Controlados Aleatorios como Asunto
10.
J Sports Sci ; 38(2): 214-230, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31795815

RESUMEN

Injuries and lack of motivation are common reasons for discontinuation of running. Real-time feedback from wearables can reduce discontinuation by reducing injury risk and improving performance and motivation. There are however several limitations and challenges with current real-time feedback approaches. We discuss these limitations and challenges and provide a framework to optimise real-time feedback for reducing injury risk and improving performance and motivation. We first discuss the reasons why individuals run and propose that feedback targeted to these reasons can improve motivation and compliance. Secondly, we review the association of running technique and running workload with injuries and performance and we elaborate how real-time feedback on running technique and workload can be applied to reduce injury risk and improve performance and motivation. We also review different feedback modalities and motor learning feedback strategies and their application to real-time feedback. Briefly, the most effective feedback modality and frequency differ between variables and individuals, but a combination of modalities and mixture of real-time and delayed feedback is most effective. Moreover, feedback promoting perceived competence, autonomy and an external focus can improve motivation, learning and performance. Although the focus is on wearables, the challenges and practical applications are also relevant for laboratory-based gait retraining.


Asunto(s)
Rendimiento Atlético/fisiología , Rendimiento Atlético/psicología , Retroalimentación , Monitores de Ejercicio , Motivación , Carrera/fisiología , Carrera/psicología , Traumatismos en Atletas/prevención & control , Fenómenos Biomecánicos , Marcha/fisiología , Humanos , Percepción , Carrera/lesiones
11.
J Sports Sci ; 38(3): 336-342, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31795818

RESUMEN

A decrease in speed when sprinting on the bend compared with the straight has been attributed to kinetic, kinematic and spatiotemporal modifications. Although maximal speed is dependent on an athlete's ability to accelerate, there is limited research investigating the acceleration phase of bend sprinting. This study used a lower limb and trunk marker set with 15 optoelectronic cameras to examine kinematic and spatiotemporal variables of the lower limb during sprinting on the bend and straight. Nine sprinters completed up to six 30 m maximal effort trials in bend (radius 36.5 m, lane one) and straight conditions. An increase in body lateral lean at touchdown resulted in a number of asymmetric kinematic modifications. Whilst the left limb demonstrated a greater peak hip adduction, peak hip internal rotation and peak ankle eversion on the bend compared with the straight, the right limb was characterised by an increase in peak hip abduction. These results demonstrate that kinematic modifications start early in the race and likely accumulate, resulting in greater modifications at maximal speed. It is recommended that strength and conditioning programmes target the hip, ankle and foot in the non-sagittal planes. In addition, sprint training should prioritise specificity by occurring on the bend.


Asunto(s)
Extremidad Inferior/fisiología , Carrera/fisiología , Atletismo/fisiología , Aceleración , Tobillo/fisiología , Fenómenos Biomecánicos , Pie/fisiología , Cadera/fisiología , Humanos , Rodilla/fisiología , Postura/fisiología , Rotación , Estudios de Tiempo y Movimiento , Adulto Joven
12.
J Sports Sci ; 38(3): 343-350, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31809646

RESUMEN

Resolving intra-stride accelerations from training and game data routinely collected by athlete tracking devices is rarely attempted, even though these data can provide important insights into the physical condition of athletes. This study describes in detail a novel analysis tool which uses accelerometer-based measures of step variability to assess longitudinal consistency of stride technique. The performance of the analysis tool was examined by combining results from the analysis of data collected over the course of an Australian Football League season with instances of missed or modified training. Results demonstrated increased gait-related trunk acceleration variability when training was modified due to load or accumulated game and training activity (p = 0.02) and reduced trunk acceleration variability in the week following a training modification due to any injury described as "ankle", "heel", or any other description that would loosely refer to a joint or bone in the leg (p = 0.01). These results support the findings of recent research which used a slightly modified version of the same analysis tool to demonstrate an increase in gait-related trunk acceleration variability with the increased acute physical load.


Asunto(s)
Acelerometría/instrumentación , Monitores de Ejercicio , Análisis de la Marcha , Pierna/fisiología , Carrera/fisiología , Fútbol/fisiología , Aceleración , Adulto , Australia , Fenómenos Biomecánicos , Conducta Competitiva/fisiología , Sistemas de Información Geográfica , Humanos , Masculino , Movimiento/fisiología , Acondicionamiento Físico Humano/fisiología , Torso/fisiología , Adulto Joven
13.
Sports Health ; 12(1): 74-79, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31642726

RESUMEN

BACKGROUND: Lower extremity overuse injuries are common among runners, especially first-time marathoners. Hip abductor and quadriceps strengthening is often recommended to reduce running-related injuries. HYPOTHESIS: A 12-week strength training program would decrease the rate of overuse injuries resulting in marathon noncompletion and improve race finishing time. STUDY DESIGN: Randomized trial. LEVEL OF EVIDENCE: Level 2. METHODS: Twelve weeks before the New York City Marathon, first-time marathon runners age 18 years and older were randomized into a strength training group or an observation group. The strength training group was instructed to perform a 10-minute program 3 times weekly using written and video instruction. This program targeted the quadriceps, hip abductor, and core muscle groups. Injuries were self-reported through biweekly surveys, with major injuries being those that resulted in marathon noncompletion and minor injuries being those that impaired training or race performance. RESULTS: A total of 720 runners were enrolled (mean age, 35.9 ± 9.4 years; 69.4% female), of whom 583 runners started the marathon and 579 completed it. The incidence of major injury was 8.9% and minor injury was 48.5%. Fifty two of 64 major injuries were overuse, of which 20 were bone stress injuries. The incidence of overuse injury resulting in marathon noncompletion was 7.1% in the strength training group and 7.3% in the observation group (risk ratio, 0.97; 95% CI, 0.57-1.63; P = 0.90). The mean finishing time was 5 hours 1 ± 60 minutes in the strength training group and 4 hours 58 ± 55 minutes in the observation group (P = 0.35). CONCLUSION: There is a high prevalence of injury among first-time marathon runners, but this self-directed strength training program did not decrease overuse injury incidence resulting in marathon noncompletion. CLINICAL RELEVANCE: Prevention strategies such as strength training need to be developed and evaluated through clinical trials to reduce the high prevalence of overuse injuries in runners, especially for high-risk populations such as first-time marathon runners.


Asunto(s)
Trastornos de Traumas Acumulados/prevención & control , Extremidad Inferior/lesiones , Fuerza Muscular/fisiología , Resistencia Física/fisiología , Entrenamiento de Resistencia , Carrera/lesiones , Adulto , Trastornos de Traumas Acumulados/epidemiología , Trastornos de Traumas Acumulados/fisiopatología , Humanos , Ciudad de Nueva York/epidemiología , Factores de Riesgo , Carrera/fisiología
14.
J Sports Sci ; 38(1): 29-37, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31631783

RESUMEN

This study investigated the role of reactive and eccentric strength in stiffness regulation during maximum velocity sprinting (Vmax) in team sport athletes compared with highly trained sprinters. Thirteen team sport athletes and eleven highly trained sprinters were recruited. Vmax was measured using radar, and stiffness regulation was inferred from modelled vertical and leg spring stiffness. Reactive strength (RSI) was determined from a 0.50 m drop jump, and an eccentric back squat was used to assess maximum isoinertial eccentric force. Trained sprinters attained a higher Vmax than team sport athletes, partly due to a briefer contact time and higher vertical stiffness. Trained sprinters exhibited a moderately higher RSI via the attainment of a briefer and more forceful ground contact phase, while RSI also demonstrated large to very large associations with vertical stiffness and Vmax, respectively. Isoinertial eccentric force was largely correlated with Vmax, but only moderately correlated with vertical stiffness. Reactive and eccentric strength contribute to the ability to regulate leg spring stiffness at Vmax, and subsequently, the attainment of faster sprinting speeds in highly trained sprinters versus team sport athletes. However, stiffness regulation appears to be a task-specific neuromuscular skill, reinforcing the importance of specificity in the development of sprint performance.


Asunto(s)
Rendimiento Atlético/fisiología , Extremidad Inferior/fisiología , Fuerza Muscular/fisiología , Músculo Esquelético/fisiología , Acondicionamiento Físico Humano , Carrera/fisiología , Aceleración , Adulto , Fenómenos Biomecánicos , Estudios Transversales , Femenino , Humanos , Masculino , Adulto Joven
15.
J Sports Sci ; 38(1): 53-61, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31623521

RESUMEN

This study aimed 1) to examine the validity of inertial measurement unit (IMU)-based hip flexion strength test, and 2) to investigate the hip flexion strength test as an indicator of sprint performance. Eight males performed five repeated hip flexion-extension, while leg motion was recorded using an IMU and a motion capture system (Mocap). As the second experiment, 24 male athletes performed the IMU-based hip flexion strength test and sprinted 50 m, during which step-to-step ground reaction force (GRF) was recorded. The strength test variables were calculated using IMU and Mocap data including angular impulse, mean moment, and positive and negative work and power. Using GRF data, step-to-step spatiotemporal variables were obtained. The results showed high intra-class correlation coefficient and correlation coefficient (both >0.909) between IMU and Mocap for angular impulse, mean moment, positive work and power. The hip flexion mean moment showed significant correlation with running speed from the 5th-8th step section onwards. The angular impulse, mean moment, positive work and power are recommended to be used for the IMU-based hip flexion strength test variables in terms of accuracy and validity. Moreover, the proposed IMU-based hip flexion strength test can be an indicator for better sprinting performance.


Asunto(s)
Rendimiento Atlético/fisiología , Prueba de Esfuerzo/métodos , Cadera/fisiología , Fuerza Muscular/fisiología , Carrera/fisiología , Aceleración , Adulto , Fenómenos Biomecánicos , Humanos , Masculino , Reproducibilidad de los Resultados , Estudios de Tiempo y Movimiento , Adulto Joven
16.
J Sports Sci ; 38(1): 6-12, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31603027

RESUMEN

This study aimed to examine the characteristics of electromyography (EMG) and kinematics of the supporting leg affecting energy cost while running at incline, level, and decline slopes. Twelve male Japanese middle- and long-distance runners volunteered for this study. The subjects were asked to run at 13.5 km·h-1 on a treadmill under three slope conditions. Sagittal plane kinematics and the EMG of the lower limb muscles, respiratory gases were recorded. Energy cost differed significantly between slopes, being the lowest in decline slope and the greatest in incline slope. Integrated EMG (iEMG) of leg extensor muscles was greater in the incline slope than in the decline slope, and iEMG of the gastrocnemius and soleus muscles correlated positively with energy cost. The knee and ankle joint kinematics were associated with energy cost during running. In incline slope, the knee and ankle joints were more extended (plantarflexed) to lift the body. These movements may disturb the coordination between the ankle and knee joints. The gastrocnemius muscle would do greater mechanical work to plantarflex the ankle joint rather than transfer mechanical energy as well as greater mechanical work of mono-articular muscles. These muscular activities would increase energy cost.


Asunto(s)
Metabolismo Energético/fisiología , Extremidad Inferior/fisiología , Carrera/fisiología , Articulación del Tobillo/fisiología , Fenómenos Biomecánicos , Electromiografía , Prueba de Esfuerzo/métodos , Articulación de la Cadera/fisiología , Humanos , Articulación de la Rodilla/fisiología , Masculino , Movimiento/fisiología , Músculo Esquelético/fisiología , Intercambio Gaseoso Pulmonar/fisiología , Adulto Joven
18.
J Sports Sci ; 38(4): 383-389, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31818198

RESUMEN

The purpose of this study is to establish evidence of validity for wearable activity monitors providing real-time cadence against a criterion measure. Thirty-six healthy adults, aged 18-65 years, participated in the study. Four activity monitors including 2 watch-based monitors and 2 cadence sensors attaching to shoelaces were tested. Each participant completed the study protocol consisting of 2 distinct components: (1) treadmill protocol and (2) overground protocol. Lin's concordance correlation and mean absolute percentage error (MAPE) were calculated for the comparisons between the criterion and measures of the monitors. Bland-Altman analysis was performed to determine the mean bias and 95% limits of agreement. All activity monitors showed high correlations with the criterion measures (p < .01). Lower correlations were observed at slow walking speeds in the watch-based monitors. In contrast, consistent and strong correlations were found with both cadence sensors regardless of walking speeds (p < .01). Similar patterns were observed in the MAPE scores. Greater than 90% of the participants were able to maintain prescribed walking intensity using real-time cadence. The results suggest that the wearable activity monitors are an acceptable measure of real-time cadence and provide the potential to improve intensity-based prescription of physical activity using the monitors.


Asunto(s)
Monitores de Ejercicio , Velocidad al Caminar/fisiología , Adolescente , Adulto , Anciano , Humanos , Persona de Mediana Edad , Reproducibilidad de los Resultados , Carrera/fisiología , Adulto Joven
19.
J Sports Sci ; 38(2): 187-191, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31783721

RESUMEN

The popularity of pre-workout supplements is rising amongst professional athletes and fitness enthusiasts. Despite increased usage, the safety profile of pre-workout supplements is likely to be not well understood. Additionally, many different brands use various undisclosed proprietary blends of active ingredients creating safety regulation difficulties. This lack of oversight could prove unsafe for certain patients. This patient MK is a 33-year-old healthy housewife who presented with central chest tightness, pre-syncope and mild dyspnoea to the emergency department via ambulance. The presentation was in the context of recent strenuous exercise and ingestion of a pre-workout supplement (Alpha Lean-7). Most striking in her presentation was a troponin rise of 50 ng/L, while not very high it is unusual given her lack of cardiac risk factors. She had a 3-day uneventful admission with a downtrending troponin prior to discharge. This case highlights the possible dangers of pharmacologically active ingredients in pre-workout supplements.


Asunto(s)
Suplementos Dietéticos/efectos adversos , Isquemia Miocárdica/etiología , Carrera/fisiología , Adulto , Cafeína/efectos adversos , Estimulantes del Sistema Nervioso Central/efectos adversos , Disnea/etiología , Servicio de Urgencia en Hospital , Femenino , Productos de Degradación de Fibrina-Fibrinógeno/metabolismo , Humanos , Isquemia Miocárdica/sangre , Síncope/etiología , Troponina/sangre
20.
J Sports Sci ; 38(4): 366-374, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31835963

RESUMEN

Ultra-endurance athletes accumulate an energy deficit throughout their events and those competing in self-sufficient multi-stage races are particularly vulnerable due to load carriage considerations. Whilst urinary ketones have previously been noted in ultra-endurance exercise and attributed to insufficient carbohydrate (CHO) availability, not all studies have reported concomitant CHO intake. Our aim was to determine changes in blood glucose and ß-hydroxybutyrate concentrations over five days (240 km) of a self-sufficient multi-stage ultramarathon in combination with quantification of energy and macronutrient intakes, estimated energy expenditure and evaluation of energy balance. Thirteen runners (8 male, 5 female, mean age 40 ± 8 years) participated in the study. Glucose and ß-hydroxybutyrate were measured every day immediately post-running, and food diaries completed daily. CHO intakes of 301 ± 106 g·day-1 (4.3 ± 1.8 g·kg-1·day-1) were not sufficient to avoid ketosis (5-day mean ß-hydroxybutyrate: 1.1 ± 0.6 mmol.L-1). Furthermore, ketosis was not attenuated even when CHO intake was high (9 g·kg-1·day-1). This suggests that competing in a state of ketosis may be inevitable during multi-stage events where load reduction is prioritised over energy provisions. Attenuating negative impacts associated with such a metabolic shift in athletes unaccustomed to CHO and energy restriction requires further exploration.


Asunto(s)
Ácido 3-Hidroxibutírico/sangre , Glucemia/metabolismo , Carbohidratos de la Dieta/administración & dosificación , Ingestión de Energía , Cetosis/fisiopatología , Resistencia Física/fisiología , Carrera/fisiología , Adulto , Registros de Dieta , Metabolismo Energético/fisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Soporte de Peso
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA