RESUMEN
There are many important sport events that are organized in environments with a very hot ambient temperature (Summer Olympics, FIFA World Cup, Tour de France, etc.) and in hot locations (e.g., Qatar). Additionally, in the context of global warming and heat wave periods, athletes are often subjected to hot ambient temperatures. It is known that exercising in the heat induces disturbances that may provoke premature fatigue and negatively affects overall performance in both endurance and high intensity exercises. Deterioration in several cognitive functions may also occur, and individuals may be at risk for heat illnesses. To train, perform, work and recover and in a safe and effective way, cooling strategies have been proposed and have been routinely applied before, during and after exercise. However, there is a limited understanding of the influences of per-cooling on performance, and it is the subject of the present review. This work examines the influences of per-cooling of different areas of the body on performance in terms of intense short-term exercises ("anaerobic" exercises), endurance exercises ("aerobic" exercises), and cognitive functioning and provides detailed strategies that can be applied when individuals train and/or perform in high ambient temperatures.
Asunto(s)
Rendimiento Atlético , Regulación de la Temperatura Corporal , Cognición/fisiología , Ejercicio Físico/fisiología , Calor , HumanosRESUMEN
The arteriovenous anastomoses (AVAs) in the distal parts of the extremities play a significant role in the heat exchange with the environment. The aim of the study was to examine the thermal responses to whole-body cooling in air, and especially the behaviour of finger skin temperature (T(f) , rich in AVAs). Eight young men sat in minimal clothing at 32°C air temperature (T(a) ), which was then lowered gradually to 13°C in 100 min. In the beginning of cooling, T(f) was high and fluctuating, and then suddenly exhibited a rapid fall, while temperatures in other skin sites fell fairly linearly along decreasing T(a) to the end of cooling. During the period from start to the rapid fall in T(f) , rectal temperature decreased from 37·4°C (SD 0.2) to 37·2°C (0·2), mean skin temperature (T(sk) ) from 34·6°C (0·5) to 31·2°C (2·0) and whole-body thermal sensation from 'slightly warm/warm' to 'slightly cool/cold'. The start of the steep fall in T(f) varied considerably between individuals in terms of time (2-75 min), T(a) (16·7 - 32·0°C) and T(sk) (28·8 - 34·7°C). On the other hand, the range of T(f) at that point was narrower (32·1 - 35·8°C). The findings stress the importance of taking into account the distal skin temperatures in thermoregulatory studies in addition to the ordinarily used more proximal and central skin sites. Also, it might be advisable to start such experiments with relatively high and fluctuating T(f) to guarantee that the thermal state of the subject is well defined.
Asunto(s)
Anastomosis Arteriovenosa/fisiología , Regulación de la Temperatura Corporal , Dedos/irrigación sanguínea , Hipotermia Inducida , Temperatura Cutánea , Adulto , Humanos , Modelos Lineales , Masculino , Flujo Sanguíneo Regional , Sensación Térmica , Factores de Tiempo , Vasoconstricción , Adulto JovenRESUMEN
Heart rate (HR) as an estimator of oxygen consumption (VO(2) ) usually requires HR to be individually calibrated in a separate test. This study examined the validity of a new HR - and HR variability-based method (Firstbeat PRO heartbeat analysis software) in the estimation of VO(2) in real-life tasks. The method takes into account the respiration rate determined from HR variability and the differences in the on/off dynamics of HR and VO(2) , and no calibration tests are needed. Ten men and nine women performed 25 tasks representing different types of daily activities. Portable devices were used to measure R-to-R intervals (ECG), VO(2) and respiration rate. In pooled regression analysis, the estimated VO(2) accounted for 87% of the variability in the actual VO(2) , SEE 3·5 ml min(-1) kg(-1) (1 MET). At group level, the method underestimated slightly the measured VO(2) (mean difference - 1·5 ml min(-1) kg(-1) or - 0·4 METs). Some of the values at low exercise intensities were markedly underestimated, but the agreement was better during light and heavy activities. The limits of agreement for the data were from -8·4 to 5·4 ml min(-1) kg(-1) or from -2·4 to 1·5 METs. At individual level, the average deviations of the predicted VO(2) ranged from -1·0 to 0·6 METs and R(2) from 0·77 to 0·94, respectively. The present data indicate that the prediction method may be considered sufficiently accurate to determine the average VO(2) in field use, but it does not allow precise estimation of VO(2) .
Asunto(s)
Frecuencia Cardíaca/fisiología , Oximetría/métodos , Consumo de Oxígeno/fisiología , Oxígeno/metabolismo , Frecuencia Respiratoria/fisiología , Adulto , Algoritmos , Femenino , Humanos , Masculino , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
BACKGROUND: Limited data exist on the associations between muscle performance and work ability measures in working age adults. AIMS: To evaluate how the results of simple muscle performance tests correlate with self-reported work ability and physical functioning in middle-aged men. METHODS: Muscle performance was measured with handgrip, sit-up, arch-up, squatting and lifting tests. The Physical Functioning scale and the Role Limitations due to Physical Health Problems scale of the RAND-36 health questionnaire were used to assess functioning and the Work Ability Index (WAI) questionnaire to assess perceived work ability in a subgroup of 51 subjects. RESULTS: A total of 104 men aged 45-55 years employed in physically active work participated. Muscle performance was weakly associated with WAI and functioning measures, accounting for 10% of the variance at most. Dynamic lifting test results for both arms correlated with WAI scores (right: r = 0.31, left: r = 0.34). Scores of the dynamic lifting test for both arms correlated with the Physical Functioning scores (right: r = 0.23, left: r = 0.28) and with the Role Limitations due to Physical Health Problems scores (right: r = 0.25, left: r = 0.28). Results of the squatting test were associated with the Physical Functioning scores (r = 0.24). CONCLUSIONS: The study failed to provide support for the use of muscle performance tests in work-related fitness evaluations in middle-aged men employed in physical jobs.
Asunto(s)
Fuerza Muscular/fisiología , Aptitud Física , Evaluación de Capacidad de Trabajo , Humanos , Masculino , Persona de Mediana Edad , Análisis de Regresión , Encuestas y Cuestionarios , Análisis y Desempeño de TareasRESUMEN
Cold therapy is used to relieve pain and inflammatory symptoms. Humoral changes may account for the pain alleviation related to the cold exposures. The aim of the present study was to examine the effects of two types of cold therapy, winter swimming in ice-cold water (WS) and whole body cryotherapy (WBC), on the serum levels of the growth hormone, prolactin, thyrotropin and free fractions of thyroid hormones (fT3, fT4). One group of healthy females (n = 6) was exposed to WS (water 0-2 degrees C) for 20 s and another group (n = 6) to WBC (air 110 degrees C) for 2 min, three times a week for 12 weeks. Blood samples used for the hormone measurements were taken on weeks 1, 4 and 12 before and 35 min after the cold exposures and on the days of the respective weeks, when the cold exposures were not performed. During the WS treatments, serum thyrotropin increased significantly at 35 min on weeks 1 (p < 0.01) and 4 (p < 0.05), but the responses were within the health-related reference interval. During the WS, the serum prolactin measured at 35 min on week 12 was lower than during the control treatment, and no changes in fT3 or fT4 were observed. During the WBC, no changes in the serum levels of the studied hormones were observed during the 12 weeks. In conclusion, repeated WS and WBC treatments for healthy females do not lead to disorders related to altered secretions of the growth hormone, prolactin, thyrotropin, or thyroid hormones.
Asunto(s)
Frío , Hormona del Crecimiento/sangre , Prolactina/sangre , Hormonas Tiroideas/sangre , Tirotropina/sangre , Adaptación Fisiológica , Temperatura Corporal , Crioterapia , Femenino , Humanos , Sensación TérmicaRESUMEN
The Work ability of ageing work force is a matter of major concern in many countries. The aim of this study was to examine the relationship between perceived work ability and health-related quality of life (HRQoL), and to investigate their associations with age, physical activity and physical fitness in middle-aged men working in blue-collar occupations. The study population consisted of 196 middle-aged (aged 40-60 years) men (construction and industrial work) attending occupationally orientated early medical rehabilitation. They were mostly healthy having only symptoms of musculoskeletal or psychological strain. Perceived work ability was assessed with the work ability index (WAI) and HRQoL with the Rand, 36-item health survey (Rand-36). Information on physical activity was obtained with a structured questionnaire. Cardiorespiratory fitness was estimated with a submaximal exercise test on a cycle-ergometer. The WAI was significantly (p<0.001) associated with the total score of Rand-36, and with all its domains. Age, physical activity and cardiorespiratory fitness were neither associated with the WAI, nor did physical activity predict any of the dimensions of Rand-36. Cardiorespiratory fitness was associated with the physical functioning dimension of the Rand-36 whilst age was positively associated with the dimensions of the energy, emotional well being and social functioning of the Rand-36. The present study on middle-aged men showed a close relationship between perceived work ability and the HRQoL. It is suggested that the promotion of work ability may have beneficial effects on quality of life.
Asunto(s)
Actividad Motora , Aptitud Física , Calidad de Vida , Trabajo , Adulto , Factores de Edad , Humanos , Modelos Lineales , Masculino , Persona de Mediana Edad , Ocupaciones , Encuestas y CuestionariosRESUMEN
Traditionally, the estimation of oxygen consumption (VO2) at work using heart rate (HR) has required the determination of individual HR/VO2 calibration curves in a separate exercise test in a laboratory (VO2-TRAD). Recently, a new neural network-, and heart rate variability-based method has been developed (Firstbeat PRO heartbeat analysis software) for the estimation of VO2 without individual calibration (VO2-HRV). In the present study, the VO2-values by the VO2-HRV were compared with the values by VO2-TRAD in 22 postal workers. Within individuals the correlation between the two methods was high (range 0.80-0.99). The VO2-TRAD gave higher values of VO2 compared to VO2-HRV (19%) especially during low physical activity work when non-metabolic factors may increase HR. When assessed in different HR categories, the smallest difference (11%), and highest correlations (range 0.83-0.99) in VO2 between the methods were observed at higher HR levels. The results indicate that the VO2-HRV is a potentially useful method to estimate VO2 in the field without laboratory calibration.
Asunto(s)
Frecuencia Cardíaca/fisiología , Consumo de Oxígeno/fisiología , Servicios Postales , Adulto , Metabolismo Energético , Femenino , Finlandia , Humanos , Masculino , Persona de Mediana EdadRESUMEN
OBJECTIVES: In Finland, testing cardiorespiratory fitness (VO2max) is popular in health promotion programs and work ability evaluations. The most common instruments used for this purpose are the submaximal cycle ergometer test, and the 2-km walking test. However, limited data exist on the associations between VO2max and wellbeing in working age adults. The aim of the study was to evaluate how the measured (cycle ergometer) and the estimated (walking test) VO2max and walking performance are associated with health-related quality of life and work ability. MATERIALS AND METHODS: The subjects were 104 middle-aged men workers (45-55 years old), mostly from the construction and manufacturing industries. VO2max was directly measured by a maximal exercise test on a cycle ergometer. The 2-km walking test parameters were the walking time, predicted VO2max, and fitness index. Health-related quality of life was assessed with the RAND-36 questionnaire which was further divided into physical dimensions (P-RAND-36) and mental dimensions (M-RAND-36). Perceived work ability was assessed with the work ability index (WAI) in a subgroup of 51 subjects. RESULTS: The 2-km walking test parameters significantly predicted the score on P-RAND-36 (r2=0.18, p=0.001), and correlated significantly with WAI. The directly measured VO2max was not associated with P-RAND-36, M-RAND-36 or WAI. CONCLUSIONS: The inexpensive 2-km walking test may be more useful when evaluating the quality of life and work ability, compared to the more expensive direct measurement of one's cardiorespiratory fitness in a laboratory.
Asunto(s)
Aptitud Física/fisiología , Calidad de Vida , Análisis y Desempeño de Tareas , Caminata , Finlandia , Humanos , Masculino , Persona de Mediana Edad , Consumo de Oxígeno/fisiología , Encuestas y CuestionariosRESUMEN
The influence of an upper-limb interval-training program after total hip arthroplasty (THA) in elderly patients was studied during a 1 yr follow-up on health status and walking ability. After surgery, 14 patients were randomly assigned to the control group that started a 6 wk general rehabilitation program or the training group that combined it with an interval exercise program on an arm ergometer. A Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index was completed 1 mo before and 2 mo and 1 yr after surgery. A 6 min walking test was performed at 2 mo and 1 yr after surgery. The training group covered a significantly longer distance than the control group in the 6 min walk test and obtained significantly lower WOMAC scores both at 2 mo and 1 yr after surgery. However, both groups significantly improved in WOMAC and in their performance during the survey. Endurance-type upper-body aerobic training in a rehabilitation program might be important after THA.
Asunto(s)
Brazo , Artroplastia de Reemplazo de Cadera/rehabilitación , Terapia por Ejercicio , Estado de Salud , Caminata , Anciano , Femenino , Estudios de Seguimiento , Humanos , Masculino , Proyectos Piloto , Factores de TiempoRESUMEN
The aim of the study was to compare heat strain among different age groups of men in protective clothing during short-term physical work. Eight young (20-29 years), 6 middle-aged (41-55 years), and 6 older (58-65 years) men exercised for 30 min on a cycle ergometer (40% V(O2 max)) in 2 hot environments with a similar WBGT (ca. 26 degrees C): once with minimal clothing without infrared radiation (E1), and once with aluminized protective clothing under infrared radiation (E2). All subjects had sedentary jobs, but only the older subjects were physically active in their leisure-time. Body temperatures, heart rate, sweat rate, and subjective feelings were determined during the tests. Higher thermal strain was observed in E2 than in E1. No age-related differences in thermal strain were observed in either experiment indicating that active older men can tolerate short work periods with protective clothing in the heat as well as younger sedentary men.
Asunto(s)
Factores de Edad , Ejercicio Físico , Trastornos de Estrés por Calor , Ropa de Protección , Protección Radiológica , Adulto , Anciano , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Whole-body cryotherapy (WBC; -110 degrees C) and winter swimming (WS) in ice-cold water are severe ambient cold exposures, which are voluntarily practiced by humans in minimal clothing. The purpose was to examine thermal sensation and thermal comfort associated with WBC and WS. Twenty women similar in body mass index, age, physical activity, and use of hormonal contraception were pairwise randomized either to the WBC group or the WS group. The duration of each WBC exposure was 2 min, which was repeated three times per week for 3 months (13 weeks). Similar exposure frequency was used for the WS group, but each exposure lasted 20 s in outdoor conditions. Thermal sensation and comfort were asked with standard scales. After WBC, 65% of the thermal sensation votes were 'neutral' or 'slightly cool.' After WS, 81% of the thermal sensation votes were 'warm,' 'neutral,' or 'slightly cool.' Majority of comfort votes immediately after exposures in WBC group (98%) and in the WS group (93%) were 'comfortable' or 'slightly uncomfortable.' Thermal sensation and comfort became habituated in both groups at an early stage of trials, but the changes were less conclusive in WS group due to variable conditions outdoors. In the WBC group, cold sensation was less intense already after the second exposure. In conclusion, repeated exposures to WBC and WS in healthy women were mostly well tolerated and comfortable. The results indicate that during repeated severe whole-body cold stress of short duration, thermal sensation and comfort become habituated during the first exposures.
Asunto(s)
Frío/efectos adversos , Crioterapia/efectos adversos , Natación/fisiología , Natación/psicología , Sensación Térmica/fisiología , Adulto , Índice de Masa Corporal , Femenino , Humanos , Persona de Mediana Edad , Estaciones del Año , Estrés Fisiológico/fisiopatología , Temperatura , Factores de Tiempo , AguaRESUMEN
The aim of the study was to examine the effects of wearing an ice-vest (ca 1 kg) on physiological and subjective responses in fire fighters. The experiments were carried out on a treadmill in a hot-dry environment. The physical cooling effect of the ice-vest was measured with a thermal manikin. The ice-vest effectively reduced skin temperatures under the vest. On average, heart rate was 10 beats/min lower, the amount of sweating was reduced by 13%, and subjective sensations of effort and warmth were lower during work with the ice-vest compared to work without it. Thermal manikin tests indicated that the useful energy available from the vest for body cooling was rather high (58%). In conclusion, the ice-vest reduces physiological and subjective strain responses during heavy work in the heat, and may promote efficient work time by 10%.
Asunto(s)
Regulación de la Temperatura Corporal/fisiología , Agotamiento por Calor/prevención & control , Hemodinámica/fisiología , Hielo , Ropa de Protección , Adaptación Fisiológica , Adulto , Prueba de Esfuerzo , Incendios , Frecuencia Cardíaca/fisiología , Trastornos de Estrés por Calor/prevención & control , Humanos , Masculino , Maniquíes , Probabilidad , Medición de Riesgo , Muestreo , Sudoración/fisiología , Suecia , Factores de TiempoRESUMEN
OBJECTIVE: To evaluate the influence of an interval training program for the upper limbs on cardiorespiratory fitness and walking ability in elderly patients after total hip joint arthroplasty. DESIGN: A randomized controlled trial. After surgery, control and training groups started general rehabilitation. Training group combined it with an arm-interval exercise program (3 sessions of 30 minutes per week, for 6 weeks). SUBJECTS: Patients were assigned randomly to control (n = 7) and training groups (n = 7). METHODS: Incremental exercise tests were carried out until exhaustion on an arm crank ergometer 1 month before and 2 months after surgery. A 6-minute walk test was also performed 2 months after surgery. RESULTS: VO2 peak increased significantly in the training group (p = 0.0424) and did not change in the control group. The difference in VO2 peak change between the groups was significant (p = 0.0362, +19.2% in the training group and -3.5% in the control group). In the walking test the training group covered a significantly longer distance than did the control group (p = 0.0055, 396.4 metres and 268.1 metres, respectively). CONCLUSION: These results stress the importance of physical training in a rehabilitation program after total hip joint arthroplasty and this should be considered for improving the current practices in rehabilitation.