摘要:

Pedometers are simple and inexpensive body-worn motion sensors that are readily being used by researchers and practitioners to assess and motivate physical activity behaviours. Pedometer-determined physical activity indices are needed to guide their efforts. Therefore, the purpose of this article is to review the rationale and evidence for general pedometer-based indices for research and practice purposes. Specifically, we evaluate popular recommendations for steps/day and attempt to translate existing physical activity guidelines into steps/day equivalents. Also, we appraise the fragmented evidence currently available from associations derived from cross-sectional studies and a limited number of interventions that have documented improvements (primarily in body composition and/or blood pressure) with increased steps/day.A value of 10 000 steps/day is gaining popularity with the media and in practice and can be traced to Japanese walking clubs and a business slogan 30+ years ago. 10 000 steps/day appears to be a reasonable estimate of daily activity for apparently healthy adults and studies are emerging documenting the health benefits of attaining similar levels. Preliminary evidence suggests that a goal of 10 000 steps/day may not be sustainable for some groups, including older adults and those living with chronic diseases. Another concern about using 10 000 steps/day as a universal step goal is that it is probably too low for children, an important target population in the war against obesity.Other approaches to pedometer-determined physical activity recommendations that are showing promise of health benefit and individual sustainability have been based on incremental improvements relative to baseline values. Based on currently available evidence, we propose the following preliminary indices be used to classify pedometer-determined physical activity in healthy adults:<5000 steps/day may be used as a ‘sedentary lifestyle index’;5000–7499 steps/day is typical of daily activity excluding sports/exercise and might be considered ‘low active’;7500–9999 likely includes some volitional activities (and/or elevated occupational activity demands) and might be considered ‘somewhat active’; and≥10 000 steps/day indicates the point that should be used to classify individuals as ‘active’.Individuals who take >12 500 steps/day are likely to be classified as ‘highly active’.

ISSN:0112-1642    

出版商:ADIS    

年代:2004

数据来源: ADIS

摘要:

In 1980, 1700 people died during a prolonged heat wave in a region under-prepared for heat illness prevention. Dramatically underreported, heat-related pathology contributes to significant morbidity as well as occasional mortality in athletic, elderly, paediatric and disabled populations. Among US high school athletes, heat illness is the third leading cause of death.Significant risk factors for heat illness include dehydration, hot and humid climate, obesity, low physical fitness, lack of acclimatisation, previous history of heat stroke, sleep deprivation, medications (especially diuretics or antidepressants), sweat gland dysfunction, and upper respiratory or gastrointestinal illness. Many of these risk factors can be addressed with education and awareness of patients at risk. Dehydration, with fluid loss occasionally as high as 6–10% of bodyweight, appears to be one of the most common risk factors for heat illness in patients exercising in the heat. Core body temperature has been shown to rise an additional 0.15–0.2°C for every 1% of bodyweight lost to dehydration during exercise.Identifying athletes at risk, limiting environmental exposure, and monitoring closely for signs and symptoms are all important components of preventing heat illness. However, monitoring hydration status and early intervention may be the most important factors in preventing severe heat illness.

ISSN:0112-1642    

出版商:ADIS    

年代:2004

数据来源: ADIS

摘要:

Baseball has one of the highest impact injury rates of all sports. These injuries are primarily attributed to impact by a ball after it has been hit, pitched or thrown. This paper will review the incidence and causal factors for impact injuries in baseball. Attention is given to the design and material properties of bats, in light of evidence suggesting balls hit into the infield from metal bats can reach velocities potentially lethal to defensive players. The distribution of bat mass along the long axis of the implement appears a major factor in the greater performance potential of metal bats over wooden bats of equal length and mass. The dynamic behaviour of baseballs has also been implicated in the severity of head and chest injuries experienced by players. Balls of greatly reduced stiffness have been introduced for junior play, but debate still remains over their performance and impact characteristics. The behaviour of the ball during high-speed impact with the bat has been the subject of relatively limited research, and the effect of manipulating baseball material properties to decrease batted-ball velocity is unclear. The value of batting helmets is evident in the observed reduction of head injuries in baseball, but the use of protective vests to decrease the incidence and severity of cardio-thoracic trauma appears to be contraindicated.

ISSN:0112-1642    

出版商:ADIS    

年代:2004

数据来源: ADIS

摘要:

The role of exercise training in the prevention and treatment of type 2 diabetes mellitus has been studied extensively over the past two decades. Although the primary treatment aim for patients with type 2 diabetes is metabolic control, the morbidity and mortality associated with the disease is more a function of cardiovascular disease. As exercise is associated with favourable reductions in the risk for cardiovascular disease in other high-risk populations, here we explore the role of exercise in the treatment of cardiovascular maladaptations associated with type 2 diabetes.The cardiovascular adaptation to type 2 diabetes is characterised by hypertrophy, stiffening and loss of functional reserve. Clinically, the cardiovascular adaptations to the diabetic state are associated with an increased risk for cardiovascular disease. Functionally, these adaptations have been shown to contribute to a reduced exercise capacity, which may explain the reduced cardiovascular fitness observed in this population.Exercise training is associated with improved exercise capacity in various populations, including type 2 diabetes. Several structural and functional adaptations within the cardiovascular system following exercise training could explain these findings, such as reductions in ventricular and vascular structural hypertrophy and compliance coupled with increased functional reserve. Although these cardiovascular adaptations to aerobic exercise training have been well documented in older populations with similar decrements in cardiovascular fitness and function, they have yet to be examined in patients with type 2 diabetes. For this reason, we contend that exercise training may be an excellent therapeutic adjunct in the treatment of diabetic cardiovascular disease.

ISSN:0112-1642    

出版商:ADIS    

年代:2004

数据来源: ADIS

摘要:

Exercise-induced muscle damage is a well documented phenomenon particularly resulting from eccentric exercise. When eccentric exercise is unaccustomed or is performed with an increased intensity or duration, the symptoms associated with muscle damage are a common outcome and are particularly associated with participation in athletic activity. Muscle damage results in an immediate and prolonged reduction in muscle function, most notably a reduction in force-generating capacity, which has been quantified in human studies through isometric and dynamic isokinetic testing modalities. Investigations of the torque-angular velocity relationship have failed to reveal a consistent pattern of change, with inconsistent reports of functional change being dependent on the muscle action and/or angular velocity of movement. The consequences of damage on dynamic, multi-joint, sport-specific movements would appear more pertinent with regard to athletic performance, but this aspect of muscle function has been studied less often. Reductions in the ability to generate power output during single-joint movements as well as during cycling and vertical jump movements have been documented. In addition, muscle damage has been observed to increase the physiological demand of endurance exercise and to increase thermal strain during exercise in the heat. The aims of this review are to summarise the functional decrements associated with exercise-induced muscle damage, relate these decrements to theoretical views regarding underlying mechanisms (i.e. sarcomere disruption, impaired excitation-contraction coupling, preferential fibre type damage, and impaired muscle metabolism), and finally to discuss the potential impact of muscle damage on athletic performance.

ISSN:0112-1642    

出版商:ADIS    

年代:2004

数据来源: ADIS