ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

W.W. WINDER. Control of hepatic glucose production during exercise.Med. Sci. Sports Exerc., Vol. 17, No. 1, pp. 2–5, 1985. Major advancements have occurred recently in study of the mechanisms of regulation of glycogenolysis and gluconeogenesis in perfused livers and isolated hepatocytes. Many questions remain unanswered, however, with respect to the control of these processes in the live exercising animal. Additional studies will be necessary to determine the relative roles of α- and β-adrenergic receptor-mediated effects of circulating catecholamines, of glucagon, glucocorticoids, angiotensin II, vasopressin, insulin, and of the direct sympathetic innervation in regulation of hepatic glycogenolysis and gluconeogenesis during exercise.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

J.A. DAVIS. Anaerobic threshold: review of the concept and directions for future research.Med. Set. Sports Exerc. Vol. 17, No. 1, pp. 6–18, 1985. Although the term anaerobic threshold was introduced 20 years ago, the concept that an exercise-induced lactic acidosis occurs at a particular oxygen uptake which varies among subjects is over 50 years old. The surge of new interest in the parameter relates to its strong relationship to prolonged exercise performance. The average marathon running speed has been shown to be closely related to the running speed at the anaerobic threshold. Numerous studies have shown that the parameter can be validly measured during incremental exercise from the gas exchange consequences of the increased carbon dioxide and hydrogen ion levels in blood resulting from bicarbonate buffering of lactic acid. Refinement of the noninvasive detection scheme has made the parameter attractive to investigators in preventative, rehabilitative, and occupational medicine and to researchers in the exercise sciences. Controversy exists regarding the specific cause for the onset of exercise-induced metabolic acidosis. As experimentation continues to unravel the mechanisms of lactate production and ventilatory control during exercise, the anaerobic threshold concept can be further evaluated.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

G.A. BROOKS. Anaerobic threshold: review of the concept and directions for future research.Med. Sci. Sports Exerc., Vol. 17, No. 1, pp. 22–31, 1985. The concentration of lactate in the blood is the result of (1) those processes which produce lactate and contribute to its appearance in the blood and (2) those processes which catabolize lactate after its removal from the blood. Consequently, the concentration of lactate in the blood provides minimal information about the rate of lactate production in muscle. The accumulation of lactate beyond the lactate threshold [T(lact)] does provide an indication that the mechanisms of lactate removal fail to keep pace with lactate production. Lactate is produced in skeletal muscle as a direct result of increased metabolic rate and glycolytic carbon flow. Factors which influence lactate production in muscle include: the Vmaxof lactic dehydrogenase (LDH), which is several times greater than the combined activities of enzymes which provide alternative pathways of pyruvate metabolism; the kMof LDH for pyruvate, which is sufficiently low to assure maximal stimulation of LDH in the conversion of pyruvate to lactate; and the K‘eqof pyruvate to lactate conversion, which exceeds 1000. Recent studies on dog gracilis musclein situclearly indicate that lactate production occurs in contracting pure red muscle for reasons other than an O2limitation on mitochondrial ATP production. In addition to failure of the essential assumption of the anaerobic threshold [T(an)] hypothesis that there exist limitations on O2availability in muscles of healthy individuals during submaximal exercise, several groups of investigators have produced results which indicate that parameters associated with changes in pulmonary minute ventilation [i.e., the ventilatory threshold, T(vent)] do not always track changes in blood lactate concentration. Therefore, the T(an) hypothesis fails on the bases of theory and prediction. A series of kinetic tracer experiments to better understand lactate kinetics during exercise is proposed.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

M.J. O'DONOVAN. Developmental regulation of motor function: an uncharted sea.Med. Sci. Sports Exerc., Vol. 17, No. 1, pp. 35–43, 1985. The field of developmental neurobiology is entering a very exciting phase, in which the application of new techniques promises to lead to major advances in our understanding of basic developmental processes. There is a need to apply much of this new knowledge to problems of spinal cord and muscle development, about which little is known at present. An understanding of the development of muscle fiber types and the spinal circuitry controlling locomotion would have a major impact on fundamental problems in motor control and exercise physiology. Significant progress is likely to be made in these areas in the next few years, but only if researchers interested in motor control and related areas take an interest in development. Among the most immediate problems that need to be addressed are: the lineage analysis of spinal neurons; identification of the factors controlling neuron differentiation; identification of the molecular basis for directed axon growth; and analysis of the factors controlling network assembly in the spinal cord. In muscle development, an understanding of how fiber type proportions are generated would have great significance for disciplines related to motor performance. The interaction and exchange of ideas between developmental biologists and exercise scientists promises to accelerate understanding and progress in both fields of endeavor.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

E.C. FREDERICK. Synthesis, experimentation, and the biomechanics of economical movement.Med. Sci. Sports Exerc., Vol. 17, No. 1, pp. 44–47, 1985. An issue that should concern sports biomechanists is the need for more synthesis of ideas and experimental testing of those ideas. Descriptive analysis is overemphasized at present, and more stress on synthesis of existing data and experimental testing of new ideas should generate new theories that will give us insights into the mechanical behavior of structures and the kinetics and kinematics of sports movements. One area where this approach may be especially helpful is in studying the question of what makes movements energetically economical. Twenty-six behavioral and mechanical factors have been shown to have an association with the economy of movement. A synthesis should be undertaken which probes the meaning of these various data. Trends in these findings point to intra- and intersegmental energy transfer, center of mass excursion, and elastic energy storage as potential areas for expanding our understanding of the biomechanics of economical movement. These possibilities might be explored by enhancing link-segmental mathematical models to predict what makes movements economical and then testing these predictions by using biofeedback techniques to train subjects to perform the correct movements while being monitored. Optimization models might offer an additional strategy for developing a theory of mechanically and energetically economical movement.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

J.F. MOSHER. Current concepts in the diagnosis and treatment of hand and wrist injuries in sports.Med. Sci. Sports Exerc., Vol. 17, No. 1, pp. 48–55, 1985. The hand is the most commonly injured part in sport. Fortunately, most injuries are minor and do not interfere with the sport participation, but even these leave residual functional deficits that may increase with time. More severe injuries of the hand are appreciated instantly by the player and health care personnel and generally receive better care. The goal is to maintain the best functioning hands now for the sport and in the future for the life's work of the hand. A program is herein described outlining the care of minor and major sports injuries to the hand that tries to return the injured player quickly to the sport participation while not jeopardizing the future. Because injuries to this most important tool are so frequent, it is recommended that a lecture be given to each sport group prior to the season to describe and raise the awareness of the players regarding hand and finger injury.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

A.B. LOUCKS and S.M. HORVATH. Athletic amenorrhea: a review.Med. Sci. Sports Exerc., Vol. 17, No. 1, pp. 56–72, 1985. Secondary amenorrhea in athletes is reviewed with respect to its incidence, treatment, associated characteristics, proposed mechanisms, and endocrine profile. Athletic amenorrhea is classified within the general category of chronic anovulation syndrome, but no mechanism has been demonstrated. The wide range in observed incidences (1–44%) is due to the lack of a standard definition for secondary amenorrhea and differences between the populations surveyed. The currently recommended treatment is outlined briefly. Several descriptive characteristics of amenorrheic athletes have led to a variety of proposed mechanisms involving body composition, training regimen, reproductive maturity, sport specificity, diet, and psychological stress. Basal hormone concentrations in eumenorrheic women after training and in amenorrheic athletes, as well as transitory endocrine responses to exercise, are the basis for evaluating these proposals. Methodological errors which have led to conflicting results are identified, and the proposed mechanisms are evaluated on the basis of the presently available data.

ISSN:0195-9131    

出版商:OVID    

年代:1985

数据来源: OVID