ISSN:0112-1642    

DOI:10.2165/00007256-199519060-00001

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryIn many sports, training for successful competition has become virtually a year-round endeavour. To assist in better preparation, a competitor’s year may be divided into phases such as off-season and in-season, indicating reduced or increased competition commitments, respectively. A number of studies have described the effects of seasons or periods of competition, training, detraining and reduced training on aspects of physical fitness. Depending on performance level, the type of sport and the fitness parameter in question, the swings in fitness variables reported may be as high as 18% from one season to another.In elite competitors, anaerobic parameters, heart frequencies, subcutaneous fat, flexibility and haemoglobin levels remain relatively unchanged throughout the year. Aerobic metabolism and muscular strength may demonstrate noticeable (mostly unfavourable) changes, and plasma hormonal levels normally follow changes in training intensities. Aspects related to long term fatigue and genetics, and to appropriate training are just a few explanations for these observations. It is still not known whether greater fitness gains attainable with longer off-season training programmes can be successfully maintained over the duration of the competition season. However, the consensus would seem to be that specialised training (based on technique and competition tactics only) is inadequate for fitness maintenance and/or improvements. This is perhaps supported by the general trends found in the literature regarding muscular strength: while supervised off-season conditioning programmes may result in significant improvements for both recreational and competitive athletes, no such changes are normally observed after competition seasons. These findings may reflect, amongst other factors, a lack of optimal training intensity to bring about strength increases during in-season periods.In novices and in athletes at low competitive levels, training seasons may lead to considerable functional improvements of the cardiorespiratory system, coupled with occasional increases in muscular strength and decreases in body fat. Relatively low fitness levels at the beginning of training have been put forward as an explanation for these improvements. Seasons of training and competition result in no significant changes in flexibility measurements.Similar changes to those found in novices and in athletes at low competitive levels may also be seen in children and adolescents engaged in sport, although their fitness improvements are consistent with normal patterns of growth and development. No differences have been identified between male and female athletes participating at different competition levels.

ISSN:0112-1642    

DOI:10.2165/00007256-199519060-00002

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryDuring exercise, leucocytes are recruited to the blood, and if muscle damage occurs the cytokine level is enhanced. After prolonged, intense exercise the number of lymphocytes in the blood is reduced, and the function of natural killer cells is suppressed; furthermore, secretory immunity is impaired. During this time of immunodepression, often referred to as ‘the open window’, the host may be more susceptible to micro-organisms bypassing the first line of defence. This is of interest to top athletes who perform frequent severe exercise. Clinical observations regarding an increased risk of infections in top athletes are compatible with this model. However, in those performing regular moderate exercise the immune system will often be temporarily enhanced and this will protect these individuals from infections.

ISSN:0112-1642    

DOI:10.2165/00007256-199519060-00003

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryAthletic strength and power refer to the forces or torques generated during sporting activity. Their assessment can be used for strength diagnosis or talent identification, to monitor the effects of training interventions and to estimate the relative significance of strength and power to particular athletic pursuits. However, strength and power assessment is a difficult task. Reasons for this include: the fledgling status of research within the area, our limited understanding of the mechanisms underpinning strength and power performance and development, and limitations associated with various forms of dynamometry. This article describes a frame work for the collection of data which may ultimately lead to recommendations for the assessment of strength and power in sporting contexts. Such a framework will be evolutionary and depends upon synergistic improvements in our understanding of: the physiological mechanisms underpinning strength and power development; the effect that various training regimens have upon the development of strength and power; and factors influencing the validity and reliability of dynamometry.Currently, isometric, isoinertial and isokinetic dynamometry are employed in assessment. Each form has its supporters and detractors. Basically, proponents and critics of isokinetic and isometric dynamometry emphasise their apparently high external and apparently low internal validity respectively. While the converse applies for isoinertial dynamometry. It appears that all 3 modalities can have acceptable reliability, however this should be established rather than assumed, as the reliability of each can be threatened by a number of considerations (e.g. instruction for isometric tasks, the impact of weight used during weighted jumping tasks, and the effects of gravity and feedback on isokinetic performance). While reliability is a seminal issue in assessment, it is not the only critical issue. Specifically, there has been little research into the correlation between strength and power measures and athletic performance. This work is central to the use of such indices in talent identification. To date, this work has generally been limited to heterogeneous rather than homogeneous groups. More work is required in this area. Furthermore, not all modes of assessment are sensitive or similarly sensitive to various training interventions. This suggests that these modalities are measuring different neuromuscular qualities. How these qualities relate to performance requires more work, and will determine the contexts in which various strength and power assessment modalities and protocols are used. Following are conclusions from the review: (i) it is unlikely that one assessment procedure can be used for a multitude of ends (e.g. talent identification and monitoring the effects of training); (ii) different levels of athlete ability within a given sport may require different assessment regimens; (iii) minor changes in procedure may alter the usefulness of a procedure and (iv) we must be prepared to question assumptions pervading the field which are based upon anecdotal evidence. There are limitations with, and should be delimitations in the use of the various protocols and forms of dynamometry.

ISSN:0112-1642    

DOI:10.2165/00007256-199519060-00004

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryThe competitive athlete who participates in a sport requiring overhead motion depends on a shoulder with optimal function. An acute episode of injury or a gradual onset of symptoms in the shoulder can affect the athlete’s ability to perform. An understanding of shoulder anatomy and function is essential, and an accurate diagnosis of the underlying pathology is critical for planning treatment options. The correct diagnosis may be less clear when the athlete presents with an insidious onset of shoulder pain. A detailed history and physical examination, as well as an evaluation of the overhead motion and onset of pain, is important when the diagnosis of instability or impingement is considered. Rehabilitation of the rotator cuff often succeeds in alleviating symptoms and restoring function. Surgery is considered when symptoms and diminished function persist despite appropriate nonoperative treatment. Operative repair or reconstruction must be anatomical in nature. Postoperative rehabilitation is equally important in this setting, and a motivated athlete helps to ensure success.

ISSN:0112-1642    

DOI:10.2165/00007256-199519060-00005

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryIn 1993 there was an estimated 12.6 million in-line skaters in the US. In-line skating is popular because of its affordability and its exercise and recreational value. The main risk factors for injury include speed, obstacles and hard surfaces. Using the National Electronic Injury Surveillance System in US hospitals, 31 000 skaters were reported injured over a 12 month period. Fractures, dislocations, sprains, strains and avulsion made up 67% of all injuries. It is recommended that skaters wear protection equipment including, helmet, wrist guards, knee-pads and elbow-pads. Although head injuries from skating appear low in numbers, helmet protection is also recommended. Further studies are required that assess risk factors for injury and environmental and behavioural aspects.

ISSN:0112-1642    

DOI:10.2165/00007256-199519060-00006

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS