摘要:

Injuries secondary to sporting activities have increased significantly in the past decade. Traditional treatment programs for these maladies have frequently failed to meet the physiological expectations of the athlete. Forced rest or immobilization result in predictable musculoskeletal atrophy with impaired function. Furthermore, the rehabilitation process has commonly focused on the management of the acute problem with minor attention to the etiology and pathomechanics of the injury (preventive medicine). Many sports injuries, as a result of overuse, can be avoided by scientific coaching and contemporary sports medicine.

ISSN:0195-9131    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Currently, there is strong public interest in exercise conditioning, especially endurance types of dynamic exercise. In addition to the short-term benefits of enhanced fitness and health, there is a growing expection of long-term benefits in relation to possible reduction of morbidity, disability, and mortality from chronic disease, especially cardiovascular disease. Physical exercise increases aerobic metabolism and the associated pulmonary and cardiovascular responses needed to deliver the required oxygen. Functional aerobic capacity or maximal oxygen consumption (&OV0312;O2max) defines the functional limits of the cardiovascular system. Aerobic capacity can be measured or be reasonably estimated by appropriate methods of exercise testing, and is probably the best integrated measure of the functional limits of the whole body which can define the effects of the aging process. The rate of decline in &OV0312;O2maxobserved in longitudinal studies of the same subjects substantially exceeds that observed in cross-sectional studies sampling male subjects of different ages. This rate is twice as great in sedentary as in physically active male subjects. When these provocative findings are considered in relation to trends observed in survival of populations vs the nearly constant limit of the average life span, the need for appropriately designed long-term prospective, definitive studies becomes apparent.

ISSN:0195-9131    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Extensive psychophysical experiments have established that the sense of respiratory effort bears a power function relationship to the force generated by respiratory muscles and the frequency and duration of their contraction, and an inverse relationship to respiratory muscle strength. Using this information an approach to the assessment of dyspnea is developed which has several components. First, the response to exercise, in terms of the metabolic and gas exchange demands is established. Second, the ventilatory responses are analyzed in terms of total ventilation, the pattern of breathing (tidal volume and breathing frequency), and the timing of breathing (inspiratory and expiratory times). Third, the exercise measurements are considered in relation to the elastic and resistive components of the respiratory system that impede volume and the flow:volume characteristic. Finally, measurements of the maximum inspiratory pressure against an occluded airway reflects respiratory muscle strength. Dyspnea, the sensation of increased respiratory effort, is usually due to a combination of abnormalities—increased metabolic demand, increased ventilatory response, increased impedance to breathing, and reduced respiratory muscle power. Management of abnormality in each of these components is distinctly separate.

ISSN:0195-9131    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

This manuscript emphasizes the physiology of fluid-electrolyte-hormonal responses during the prolonged inactivity of bed rest and water immersion. An understanding of the total mechanism of adaptation (deconditioning) should provide more insight into the conditioning process. Findings that need to be confirmed during bed rest and immersion are: 1) the volume and tissues of origin of fluid shifted to the throax and head; 2) interstitial fluid pressure changes in muscle and subcutaneous tissue, particularly during immersion; and 3) the composition of the incoming presumably interstital fluid that contributes to the early hypervolemia. Better resolution of the time course and source of the diuretic fluid is needed. Important data will be forthcoming when hypotheses are tested involving the probable action of the emerging diuretic and natriuretic hormones, between themselves and among vasopressin and aldosterone, on diuresis and blood pressure control.

ISSN:0195-9131    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Research of neuromuscular performance offers a unique possibility for integration of biomechanics, muscle physiology, and neurophysiology. This integration is especially desirable in situations where recording of neuromuscular function is made under normal movement conditions of the entire physiological range. This would improve the possibilities to investigate more exactly the interrelationship between structural aspects of the neuromuscular system and performance characteristics. Stretch-shortening cycle, a normal way of muscle function needs also to be investigated more both from the neurophysiological and mechanical viewpoints. Understanding of this stretch-shortening cycle would improve our possibilities to examine the mechanical efficiency of exercise more objectively. This paper discusses these aspects in an attempt to outline directions for future research in neuromuscular performance.

ISSN:0195-9131    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The classical “oxygen debt” hypothesis formulated by Hill and associates in the 1920s was an attempt to link the metabolism of lactic acid with the O2consumption in excess of resting that occurs after exercise. The O2debt was hypothesized to represent the oxidation of a minor fraction (1/5) of the lactate formed during exercise, to provide the energy to reconvert the remainder (4/5) of the lactate to glycogen during recovery. In 1933 Margaria et al. modified this hypothesis by distinguishing between intial, fast (“alactacid”), and second, slow (“lactacid”), O2-debt curve components. They hypothesized that the fast phase of the post-exercise O2consumption curve was due to the restoration of phosphagen (ATP + CP). It is now probable that the original lactic acid explanation of the O2debt was too simplistic. Numerous studies on several species have provided evidence demonstrating a dissociation between the kinetics of lactate removal and the slow component of the post-exercise &OV0312;o2. The metabolism of lactate, a readily oxidizable substrate, following exercise appears to be directed primarily toward energy production in mitochondria. The elevated concentration of lactate present at the end of exercise may be viewed as a “reservoir of carbon,” which may serve as a source of oxidative ATP production or as a source of carbon skeletons for the synthesis of glucose, glycogen, amino acids, and TCA cycle intermediates. The metabolic basis of the elevated post-exercise &OV0312;o2may be understood in terms of those factors which directly or indirectly influence mitochondrial O2consumption. Included among these factors are catecholamines, thyroxine, glucocorticoids, fatty acids, calcium ions, and temperature. Of these, elevated temperature is perhaps the most important. As no complete explanation of the post-exercise metabolism exists, it is recommended that the term “O2debt” be used to describe a set of phenomena during recovery from exercise. The terms “alactacid debt” and “lactacid debt,” which suggest a mechanism, are inappropriate. Use of alternative terms, e.g., “excess post-exercise oxygen” consumption“ (EPOC) and ”recovery O2,“ will avoid implication of causality in describing the elevation in metabolic rate above resting levels after exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Osteporosis is an accepted fact of the female's aging process. This decrease in bone mass is most often linked to a lack of estrogen; however, prolonged inactivity is also known to cause atrophy in both muscle and bone. The purpose of this study was to investigate the relationship between the degree of osteoporosis and the physical activity levels of a group of post-menopausal women. Forty women between the ages of 60–69 yr were selected at random from a group of volunteers. The possible existence of a correlation between cortical diameter and activity level was investigated by using linear-model analysis. The width of the cortex may be related to many factors in addition to activity level. Some of the more important factors also considered were height, weight, ponderal index, age, years since taking estrogen, and total metacarpal diameter. The inclusion of these terms in the linear-model analysis allowed for an accounting of variability as associated with variables that could not be held constant. The variables showing the most significant relationship with the cortical diameter were the activity level and the use of estrogen. The relationships investigated through the linear-model analysis do not need to be independent. It is possible that combinations of these variables act to retard or enhance osteoporosis. Therefore, because the primary concern of the investigators was the relationship between physical activity and osteoporosis, at-test was performed comparing the 10 most active women with the 10 most sedentary. The cortical diameters of the physically active women are significantly (t=2.77) wider, indicating less osteoporosis. It would appear from the results of this study that physical activity, in conjunction with the other variables considered, is indeed a definite factor in the retardation of osteoporosis. However, its effects without the influence of estrogen still need investigation.

ISSN:0195-9131    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Five subjects exercised at an ambient temperature of 6.2°C, five exercised at 37.7°C, and five served as non-exercise controls. Each subject in the exercise groups performed one 45-min treadmill run a day for five consecutive days at heart rates that represented 80% of their maximum capacity. Sperm production was quantified the week preceding treatment and from 6–10 wk post-treatment. Plasma testosterone levels (PTL) were measured before each exercise test and immediately, 30 min, and 60 min after the first and fifth tests. The initial pre-exercise sample was taken immediately preceding the first test. Rectal temperature (Tre) and heart rate were monitored during all tests. No significant differences were found for sperm production. Plasma testosterone levels were 32.9% greater on the fourth and fifth day of testing than they were on day one (P< 0.018). The 6.2°C group (1202.7 ng%) had higher resting PTL than either the 37.7°C (897.3 ng%) or the control (968.8 ng%) groups throughout the exercise period (P< 0.001); PTL were 46.6% greater on day 5 than they were on day 1 for the 6.2°C group (P< 0.021). The change in Tre attributed to exercise was significantly greater in the 37.7°C group (2.5°C) when compared to the 6.2°C group (1.1°C;P0.001). In summary, the changes in PTL and Tre that occurred as a result of 5 d of heavy exercise did not affect sperm production rates in humans.

ISSN:0195-9131    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

To determine whether sleep is necessary for the peripheral sympathetic nervous system response to exercise, we compared eight subjects' sympathoadrenal responses to treadmill walking at a constant exercise rate eliciting a heart rate around 160 beats·min-1after normal sleep with those measured after a 50-h sleepless period. We found that sleeplessness left the sympathetic response to exercise intact. After 12 min of exercise, heart rate and plasma norepinephrine, epinephrine, and dopamine levels were similar in both situations. In addition, we could find no other alterations in the physiological response to exercise after sleep loss, and minute ventilation, oxygen uptake, blood lactate levels, and rectal and skin temperatures were identical in the two conditions. Nevertheless, despite both unaltered physiological responses to exercise and doubled monetary incentives to perform, sleep loss reduced time to exhaustion by 20% (P< 0.01). We concluded that sleep loss does not diminish the peripheral sympathetic nervous system response to exercise, although it reduces exercise tolerance through mechanisms that are unexplained as yet.

ISSN:0195-9131    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The purpose of this study was to identify anatomical variables associated with plantar-fasciitis sufferers. Selected anatomical variables which were chosen for measurement were leg length, pronation of the subtalar joint, plantar and dorsiflexion ability, and arch height of the foot, as well as the variables height, weight, age, and miles run per week. The means and standard deviations revealed that leg-length inequality, pronation of the subtalar joint, and arch height were not good indicators of plantar-fasciitis sufferers. According to the discriminant-function analysis in which 64% of the subjects were assigned to the appropriate group, plantar flexion, dorsiflexion, and height were good predictors of the recovered and non-recovered suffers, but could predict no more than 50% of the present sufferes. Therefore, a set of predictor variables was not found for the prediction of plantar-fasciitis sufferers.

ISSN:0195-9131    

出版商:OVID    

年代:1984

数据来源: OVID