摘要:

Pulmonary constraints limit prolonged performance of some highly trained endurance athletes during extreme exercise. Diffusion limitation is probably the most significant among the interrelated pulmonary deficiencies that cause reduced arterial hemoglobin oxygen saturation. Highly trained athletes are affected because they have developed adaptations in muscle tissue and cardiovascular function which surpass those of the less‐adaptive pulmonary system. Untrained people have not accrued muscle and cardiovascular adaptations, and therefore cannot achieve an exercise stress that exceeds the usual pulmonary system functional reserve.

ISSN:1057-8315    

DOI:10.1080/15438629009511883

出版商:Taylor&Francis Group    

年代:1990

数据来源: Taylor

摘要:

The frail elderly are usually extremely inactive. However, they should be encouraged to increase their physical activity as a means of improving their health status. Regular exercise can restore social contacts, improve cognition, mood state and perceived health, reduce cardiovascular risk, control both obesity and lean tissue loss, optimize functional ability, improve food intake and facilitate sleep. Potential risks include sudden cardiovascular death, musculo‐skeletal injury, and a poor adaptation to unfavorable environments. However, excessive pre‐exercise screening may be counterproductive. Prudent recommendations include gentle pre‐exercise stretching, a good warm‐up and warm‐down, and sufficient exercise to induce no more than pleasant tiredness the following day. The major challenge is to sustain motivation. Activity should be built in to the normal day, and gains presented in terms of the objectives of the individual patient. The frail elderly can benefit from frequent repetition of quite low intensity exercise. Persistence with a regular physical activity program can increase function by the equivalent of up to 20 years of aging. Exercise thus adds not only to longevity, but (more importantly) to the quality of the remaining years of life.

ISSN:1057-8315    

DOI:10.1080/15438629009511884

出版商:Taylor&Francis Group    

年代:1990

数据来源: Taylor

摘要:

The effect of dietary iron treatment on hematological parameters, serum iron status and physical performance was assessed in 12 female distance runners during severe physical training. The subjects were instructed to take a tablet containing 60 mg iron/day (iron supplement group:n =6) or a matching placebo tablet (placebo group:n= 6) in a randomized double‐blind fashion for 8 weeks during training. Except for the iron or placebo supplement, the subjects’activities of daily life and quantity of distance running training were similar in both groups. To assess the effect of iron dosage, the lactate threshold (LT), onset of blood lactate accumulation (OBLA) and maximal oxygen uptake (VO2max) were measured by treadmill incremental exercise tests. Resting hematological parameters and 3000 m running performance were obtained pre‐and post‐training with supplementation. In the iron supplement group, a significant improvement was observed in serum ferritin, running velocity both at LT (VLT) and OBLA (VOBLA), and the 3000 m running performance. In the placebo group, however, serum ferritin decreased significantly and there were no significant improvements in blood lactate variables (e.g., VLTand VOBLA) and running performance. These results indicate that by regular rigorous training without iron supplement, female distance runners have a tendency to induce an iron deficient condition, which, in turn, might disrupt improvement in running performance. In conclusion, the present study suggests that the 60 mg of regular iron supplement a day might be useful for prevention of iron deficiency in female athletes during periods of rigorous training.

ISSN:1057-8315    

DOI:10.1080/15438629009511885

出版商:Taylor&Francis Group    

年代:1990

数据来源: Taylor

摘要:

Data were collected during the 1986 and 1987 seasons from a representative stratified national sample of college football teams to assess the efficacy of prophylactic knee braces in reducing the incidence and/or severity of knee injuries in football players. Over the two seasons there were a combined total of 6,229 players involved, of whom 28.0% wore prophylactic knee braces, with a total of 445,856 athlete‐exposures to the possibility of being injured in a game or a practice. The results indicate that the total incidence of knee injuries was slightly higher in braced players. Further analyses indicate that braces have no impact in reducing the incidence of medial collateral ligament (MCL) injuries, and there is no apparent difference in incidence among various brands of braces. There is no difference in the severity of total knee injuries or MCL injuries in braced and unbraced players when measured in days lost from participation or degree of MCL injury. When injuries in games were isolated to control for the“intensity”; of exposure to the possibility of being injured, the analyses provided the same results as seen for games and practices combined.

ISSN:1057-8315    

DOI:10.1080/15438629009511886

出版商:Taylor&Francis Group    

年代:1990

数据来源: Taylor

ISSN:1057-8315    

DOI:10.1080/15438629009511887

出版商:Taylor&Francis Group    

年代:1990

数据来源: Taylor

ISSN:1057-8315    

DOI:10.1080/15438629009511888

出版商:Taylor&Francis Group    

年代:1990

数据来源: Taylor

ISSN:1057-8315    

DOI:10.1080/15438629009511889

出版商:Taylor&Francis Group    

年代:1990

数据来源: Taylor

摘要:

A modified method is suggested for the assessment of some anaerobic parameters measured during a vertical rebound jumping series. The test is based on the registration of flight and contact times of every single jump by means of a computer device fitted to a jumping platform. Mechanical power in the active phase of a jump, the height of a jump, acceleration and velocity were calculated according to the laws of mechanics during a 10 second test duration.The test‐retest correlation at different frequencies of jumps demonstrated a low reliability of measurement at frequencies of 60 and 80 per minute. Only a maximum frequency of jumps led to a sufficient reliability of the test, especially in younger age groups. From among the various modes of expression of the results the highest test‐retest correlation was found for the measurement of power in the active phase of jump per kg of body weight and acceleration in the active phase. Both were assessed from the mean of three maximal jumps in one trial.The described test allows measurement of important parameters of anaerobic capability in athletes using a relatively simple measurement device.

ISSN:1057-8315    

DOI:10.1080/15438629009511890

出版商:Taylor&Francis Group    

年代:1990

数据来源: Taylor

ISSN:1057-8315    

DOI:10.1080/15438629009511882

出版商:Taylor&Francis Group    

年代:1990

数据来源: Taylor