摘要:

The growing years may be the most opportune time in life for exercise to result in large increases in bone density, enough to reduce the risk of fracture late in life. However, it is not known if there is an ‘optimal’ time during growth when the skeleton is most responsive to exercise. Comparing the osteotrophic response to exercise between pre- and peripubertal children is complex because: (i) the development of the skeleton within each stage of puberty is characterised by differing temporal patterns of growth in bone size and mass; (ii) the hormonal regulation of the skeleton is unique to each stage of puberty; and (iii) it is difficult to equate the relative mechanical load placed on the prepubertal compared with the pubertal skeleton. There are sound biological bases for the hypotheses being proposed for both the pre- and peripubertal years being the time when the skeleton is most responsive to exercise; that is, exercise may enhance bone formation in a synergistic fashion in the presence of growth hormone (prepubertal years) or sex steroids (peripubertal years). The paucity of data and the complex methodology make it difficult to draw conclusions as to the most opportune time during growth when exercise may lead to the greatest osteotrophic response. The limited data available support the notion that the prepubertal years may be the most opportune time, due to increases in bone density and periosteal expansion of cortical bone.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS

摘要:

Detraining is the partial or complete loss of training-induced adaptations, in response to an insufficient training stimulus. Detraining characteristics may be different depending on the duration of training cessation or insufficient training. Short term detraining (less than 4 weeks of insufficient training stimulus) is analysed in part I of this review, whereas part II will deal with long term detraining (more than 4 weeks of insufficient training stimulus). Short term cardiorespiratory detraining is characterised in highly trained athletes by a rapid decline in maximal oxygen uptake (V dotO2max) and blood volume. Exercise heart rate increases insufficiently to counterbalance the decreased stroke volume, and maximal cardiac output is thus reduced. Ventilatory efficiency and endurance performance are also impaired. These changes are more moderate in recently trained individuals. From a metabolic viewpoint, short term inactivity implies an increased reliance on carbohydrate metabolism during exercise, as shown by a higher exercise respiratory exchange ratio, and lowered lipase activity, GLUT-4 content, glycogen level and lactate threshold. At the muscle level, capillary density and oxidative enzyme activities are reduced. Training-induced changes in fibre cross-sectional area are reversed, but strength performance declines are limited. Hormonal changes include a reduced insulin sensitivity, a possible increase in testosterone and growth hormone levels in strength athletes, and a reversal of short term training-induced adaptations in fluid-electrolyte regulating hormones.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS

摘要:

Participation in the sport of golf has risen considerably, particularly amongst senior players whose age is categorised as 50 years or more. However, golf presents both potential health benefits and risks for this older group of players. The health risks are compounded by the fact that the musculoskeletal and cardiovascular systems of senior players may not be as efficient at withstanding the strains and stress of this type of repetitive exercise. It was the purpose of this review paper to investigate the age-related health issues facing senior golfers and to discuss appropriate intervention strategies to help minimise these detrimental effects. The literature search identified only a minimal amount of epidemiological information pertaining specifically to the older golfer. A number of case reports were found which described a variety of musculoskeletal and cardiovascular incidents involving senior players. There was evidence from the literature that many of the age-related changes affecting older players' risk profiles were preventable or treatable through exercise. It was the conclusion of the authors of this review that conditioning programmes were highly recommended for all older players irrespective of their level of participation. Not only could the programmes prevent injury, they also had the potential to improve performance. Such programmes should incorporate flexibility, strength, endurance, speed and balance exercises specifically tailored to the demands of golf in order to be effective. Exercise equipment did not need to be elaborate and home-based programmes incorporating bodyweight, weighted clubs or elastic tubing resistance could be utilised. Future research needs to focus more specifically on injury incidence and mechanisms amongst groups of senior golfers whose participation rates vary. Randomised controlled trials are also recommended to investigate the efficacy of specific golf-related exercise regimens in this segment of the older population.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS

摘要:

β-Hydroxy β-methylbutyrate (HMB), a metabolite of the essential amino acid leucine, is one of the latest dietary supplements promoted to enhance gains in strength and lean body mass associated with resistance training. Unlike anabolic hormones that induce muscle hypertrophy by increasing muscle protein synthesis, HMB is claimed to influence strength and lean body mass by acting as an anticatabolic agent, minimising protein breakdown and damage to cells that may occur with intense exercise. Research on HMB has recently tested this hypothesis, under the assumption that it may be the active compound associated with the anticatabolic effects of leucine and its metabolites. While much of the available literature is preliminary in nature and not without methodological concern, there is support for the claims made regarding HMB supplementation, at least in young, previously untrained individuals. A mechanism by which this may occur is unknown, but research undertaken to date suggests there may be a reduction in skeletal muscle damage, although this has not been assessed directly. The response of resistance trained and older individuals to HMB administration is less clear. While the results of research conducted to date appear encouraging, caution must be taken when interpreting outcomes as most manuscripts are presented in abstract form only, not having to withstand the rigors of peer review. Of the literature reviewed relating to HMB administration during resistance training, only 2 papers are full manuscripts appearing in peer reviewed journals. The remaining 8 papers are published as abstracts only, making it difficult to critically review the research. There is clearly a need for more tightly controlled, longer duration studies to verify if HMB enhances strength and muscular hypertrophy development associated with resistance training across a range of groups, including resistance trained individuals.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS

摘要:

Injuries to the upper extremity in paediatric and adolescent athletes are increasingly being seen with expanded participation and higher competitive levels of youth sports. Injury patterns are unique to the growing musculoskeletal system and specific to the demands of the involved sport. Shoulder injuries include sternoclavicular joint injury, clavicle fracture, acromioclavicular joint injury, osteolysis of the distal clavicle, little league shoulder, proximal humerus fracture, glenohumeral instability and rotator cuff injury. Elbow injuries include supracondylar fracture, lateral condyle fracture, radial head/neck fracture, medial epicondyle avulsion, elbow dislocation and little league elbow. Wrist and hand injuries include distal radius fracture, distal radial physeal injury, triangular fibrocartilage tear, scaphoid fracture, wrist ligamentous injury thumb metacarpalphalangeal ulnar collateral ligament injury, proximal and distal interphalangeal joint injuries and finger fractures. Recognition of injury patterns with early activity modification and the initiation of efficacious treatment can prevent deformity/disability and return the youth athlete to sport.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS

摘要:

Participation in sport activities for people with disabilities continues to gain in popularity. With participation in sports, there is an inherent risk of injury. A review of current sport epidemiological studies was used and we concluded that injury patterns for this population are similar to those for athletes without disabilities. Injury data from Paralympic competitions dating back to 1976 indicate that most elite athletes with disabilities seek medical care for illness and musculoskeletal injuries. However, there are very limited injury data regarding Winter Paralympic events or skiing injuries. For those athletes who participate in Summer Paralympic events, abrasions, strains, sprains and contusions are more common than fractures and dislocations. However, location of injuries appears to be disability and sport dependent. Lower extremity injuries are more common in ambulatory athletes (visually impaired, amputee, cerebral palsy) and upper extremity injuries are more frequent in athletes who use a wheelchair. While it appears that the majority of the injuries occurring in this population are minor in nature, inconsistencies in the definition of injury in the literature make this conclusion tenuous. When injuries are expressed as time lost in participation, 52% of injuries resulted in 7 days lost or less, 29% in 8 to 21 days lost and 19% in greater than 22 days lost. The only prospective study addressing injury rates of athletes with disabilities in a manner consistent with other sport epidemiological studies found an injury rate of 9.3 injuries per 1000 athlete-exposures (AE). This injury rate is less than American football (10.1 to 15/1000 AE) and soccer (9.8/1000 AE), and greater than basketball (7.0/1000 AE). It is unclear whether comparative statistics such as these take into consideration the number of illness and injury episodes that resulted from the disability. Further complicating epidemiological studies for athletes with disabilities is the definition of the population and samples of convenience which are frequently used. These samples are often not representative of the multiplicity of disability conditions, levels of competition and range of sport activities available. Prospective studies comparing athletes to sedentary control individuals to measure differences in injury rates, type and frequency between and within disability groups, sports and levels of competition are desperately needed to further the knowledge of injury trends and develop and establish accurate injury prevention programmes.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS