摘要:

Atherosclerosis and inflammatory arterial diseases are rare in young people. Since the early 1980s, an increasing incidence of iliac arterial stenosis in competition cyclists has been reported. Histological findings in these individuals are specific, with fibrosis of the intimal wall on histology and no atherosclerotic or inflammatory lesions. Clinical consequences of this arterial endofibrosis are usually described as an exercise-related subjective sensation of swollen thigh in one or both (15%) legs, with normal clinical and Doppler investigations at rest. Following maximal exercise, ankle-to-brachial systolic pressure index is lower than 0.5 in 85% of individuals with disease and is used as a key argument for diagnosis before deciding upon arteriography. Surgery (recalibrated saphenous grafts or angioplasty-endofibrosectomy) seems to be efficient to allow an early return to competition, but its long term results are still to be evaluated. The physiopathology of this disease and its possible relationship with atherosclerosis are unknown.

ISSN:0112-1642    

出版商:ADIS    

年代:1997

数据来源: ADIS

摘要:

Cycle ergometry studies originated in the early 1900s but it was not until the early 1970s that the first studies of children and anaerobic performance were established. Since that time, research into the anaerobic performance of children and adolescents has proliferated, mainly due to attempts by investigators to overcome methodological problems. Besides the increase in studies using the most popular anaerobic test, the friction-braked Wingate, other tests such as the forcevelocity and isokinetic cycle ergometers are becoming more common. No matter how the data are standardised, there is unequivocal agreement that children's and adolescents' anaerobic power scores are lower than those of adults. Qualitative muscular differences are often cited for this disparity rather than differences in the quantity of muscle, but conclusive research is lacking in this area. Despite the ethical considerations involved in studies with children, cycle ergometry has aided researchers to assess external short term power output, mean power and fatigue.

ISSN:0112-1642    

出版商:ADIS    

年代:1997

数据来源: ADIS

摘要:

The cardiovascular system of children responds to exercise differently than does that of an adult, although the mechanisms behind the differences are unclear. During dynamic exercise, it has been reported that heart rate (HR) response to the initiation of exercise is both faster and slower in children than adults. Furthermore, HR recovery has been reported to be faster in children. During submaximal steady state exercise, HR and total peripheral resistance are higher, while stroke volume [SV (ml)] and cardiac output [&OV0422; (L/min)] are lower in children at a given rate of work. At maximal exercise intensities HR is higher while SV and &OV0422; are lower in children than adults.Differences in cardiovascular responses to dynamic exercise between young boys and girls have also been reported. The majority of studies report that HR is lower and SV is higher in boys than girls at a given rate of work, although data to the contrary have been reported. These differences seem to be related to larger hearts in the boys. Further, the majority of the studies report that &OV0422; is similar in young boys and girls at a given rate of work. Few studies have reported differences between boys and girls at maximal intensities of exercise, and the results of those studies are inconsistent.Less is known about cardiovascular responses of children to static exercise compared with adults. A number of studies have reported that HR response to handgrip exercise is greater in children than adults, while others have reported no difference in this response. Even fewer studies have compared boys and girls in their cardiovascular response to static exercise and the results of these studies are also inconsistent.During prolonged exercise both children and adults exhibit cardiovascular drift (gradual increase in HR and decrease in SV). The direction and degree to which these changes differ between children and adults is unclear, with both greater and lesser responses being reported in children. Few studies have investigated differences in cardiovascular response to prolonged exercise between boys and girls. Those that have, report no difference between young boys and girls.

ISSN:0112-1642    

出版商:ADIS    

年代:1997

数据来源: ADIS

摘要:

Understanding the progression of physical activity behaviour from childhood to adulthood requires a valid, reliable and practical method of assessing activity levels which is appropriate for use in large groups. The measurement of physical activity in large scale research projects requires a method which is low in cost, agreeable to the study volunteer and accurate. Self-report can be used to determine adult activity patterns, but children lack the cognitive ability to recall details about their activity patterns. Heart rate telemetry has been used to estimate daily activity in children as a sole criterion and to validate commercial accelerometers. However, heart rate is an indirect estimate of physical activity which makes assumptions based on the linear relationship between heart rate and oxygen uptake. It is sensitive to emotional stress and body position, and takes longer to reach resting levels after physical exertion compared with oxygen uptake. It also lags behind movement, particularly as children's physical activity is spasmodic or intermittent in nature. One alternative is the pedometer. Many early studies reported that the pedometer is inaccurate and unreliable in measuring distance or counting steps. While reasonably accurate at mid range speeds, the accuracy of the pedometer decreases in very slow walking or very fast walking or running. However, more recent studies have examined the efficacy of using pedometers to assess daily or weekly activity patterns as a whole, and these have produced more promising results. In this regard, the pedometer has a number of advantages. It is very cheap, objective and does not interfere with daily activities and is therefore appropriate for use in population studies. Commercial accelerometers with a time-sampling mechanism offer further potential and could be used to provide a picture of the pattern of children's activity. As it has been observed that prolonged activity periods are not typically associated with childhood behaviour patterns, the use of a threshold value for ‘aerobic’ training stimulus is not appropriate as a cut-off value for physical activity. Instead, there is evidence to suggest that the total activity data measured by pedometers over limited periods of time may be more appropriate to assess how active children are.

ISSN:0112-1642    

出版商:ADIS    

年代:1997

数据来源: ADIS

摘要:

As a major weight-bearing joint, normal hip function is fundamental to successful sporting participation. Not only is it important in running-, jumping- and kicking-based activities, it also contributes to the generation and transference of forces in upper limb-dominated activities. Injuries to the hip do not account for a large proportion of the sports physician's workload, but may result in significant morbidity. The wide variety of acute, subacute and chronic injuries, affecting both the joint and surrounding soft tissues, can prove a diagnostic dilemma. The predisposition and the types of injuries around the hip vary with the age of the athlete. The young child rarely sustains a significant injury but one should be aware of orthopaedic conditions common in this age group that may manifest themselves through exercise. The immature skeleton of the adolescent is relatively injury prone and the demands of sport often exceed the capacity of the growing musculoskeletal system. In adults and older athletes, a further spectrum of injury exists, along with the effects of aging tissues and the concerns of degenerative joint disease. Rational treatment is based on a clear diagnosis developed through sound knowledge and a thorough history and examination. For the sports physician, treatments are typically early physical therapy and structured, progressive rehabilitation programmes which are individualised to the needs of the athlete. The spectrum of hip injuries is reviewed with current recommended diagnoses and management.

ISSN:0112-1642    

出版商:ADIS    

年代:1997

数据来源: ADIS