摘要:

Vigorous exercise is currently being encouraged for health maintenance. There is much evidence that a moderate amount of exercise is needed for the maintenance of functional integrity of the cardiovascular system, muscles, bones, and ligaments. There is also fragmentary evidence of a preliminary nature suggesting that regularly performed exercise may protect against and have beneficial effects on coronary artery disease, diabetes, and hypertension. However, the scientific evidence that strenuous exercise has long-term health benefits or slows aging is meager and unconvincing. Even in the case of coronary artery disease, diabetes, and hypertension, the majority of studies have provided either negative or inconclusive results or have resulted in only minor improvements. Taken together, available evidence is inadequate to serve as a basis for recommending regular participation in strenuous exercise for middle-aged and older individuals. This is particularly true because the theories that exercise may accelerate the aging process as a result of increases in metabolic rate and stress hormone production have never been disproved. Therefore, because of the major public health implications of exercise, large-scale, well-controlled studies of the effects of exercise on coronary artery disease, adult onset diabetes, hypertension, and various aspects of the aging process are urgently needed. Important barriers to progress in this area are the current dearth of exercise physiologists interested in research on health maintenance and well trained in human exercise physiology and the lack of an appropriate research funding mechanism for large-scale, interdisciplinary studies of the effects of exercise on chronic disease processes and aging.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Synthesis is an important concept and process in the field of biomechanics and biochemistry. A significant development and direction in sports medicine and exercise science will be the “synthesis” or integration of methods of biomechanics and biochemistry to study connective tissues and their responses to specific levels of physical activity.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Within the past decade, knowledge of knee ligament injuries, although far from being complete, has increased significantly. The development of new clinical tests has enabled the clinician to make more accurate diagnoses of both the acutely and chronically injured knee and has led to the recognition of the importance of injury to the anterior cruciate ligament, posterior cruciate ligament, and the posterolateral capsule. These tests have also helped to differentiate medial collateral ligament and other combined ligament injuries from the “isolated” medial collateral ligament injury, allowing for non-operative treatment of the latter. The reported natural history studies of those with anterior or posterior cruciate ligament deficiency have helped to define our indications for surgery better. The less than satisfactory long-term outcomes of primary repair of anterior cruciate ligament injuries have resulted in more refined surgical techniques of repair and to the concept of repair and tendon augmentation. The reports that those with severe functional instability have a high probability of developing significant early traumatic arthritis have led to a more aggressive surgical approach. The short-term results of a number of different procedures have been encouraging. Advances in the field of sports science have had significant impact in the treatment of knee ligament injuries. The recent development of sophisticated knee testing devices will facilitate better evaluation of the biomechanical stability of the knee joint after reconstructive procedures and for comparisons between these procedures. More detailed knowledge of the adverse changes that occur in muscle has led to the concept of early functional rehabilitation in order to limit the deleterious effect that immobilization has on muscle, ligament, and articular cartilage.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

During exercise, internal body (core) temperature (Tc) rises to new plateau levels with increasing intensities of steady-state exercise independent of ambient temperature over a wide range (prescriptive zone). This rise in Tc is proportional to relative rather than absolute work load and provides the central stimulus to sweating and cutaneous vasodilation. The system seems to function in the same way during rest and exercise since the rise in Tc during exercise can be explained in fundamental terms of heat production and heat dissipation. Changes in sweating and skin blood Dow (SBF) are largely explained by changes in core and skin temperatures; however, there is strong evidence for non-thermal input into the control of these responses. The control of SBF is more complex than the control of sweating because SBF is influenced by cardiovascular as well as temperature regulations. Moreover, hydration state can markedly alter these effectors, indicating that fluid volume and/or fluid composition also contribute to these control mechanisms. Major advances in the future will come from the further development of animal models that allow for studies designed to elucidate the interaction between regulatory systems and the neurochemistry underlying central effector mechanisms.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Body composition has become a major field of interest for many exercise and sport scientists as well as clinicians who specialize in the prevention of and rehabilitation from hypokinetic diseases. This paper discusses the state of the art within selected areas of body composition, identifying significant areas of controversy and proposing specific problems where research should be focused. The areas addressed include the following: the use of body density to estimate relative body fat in selected populations, the use of anthropometric equations to estimate body composition, body composition assessment for profiling and counseling athletes, and alterations in appetite and body composition resulting from acute bouts of exercise and from exercise training.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

This paper was presented as the eleventh Joseph B. Wolffe Memorial Lecture at the Twenty-Ninth Annual Meeting of the American College of Sports Medicine in Minneapolis, Minnesota, May 26–29, 1982.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Although fatigue is a well-known phenomenon and the phrase “exercised until exhaustion” is commonly understood, there is no unequivocal agreement on the fundamental nature of the fatigue process. Ammonia was linked to the development of fatigue as early as 1922, when ammonia production was observed from stimulated nerve and the question whether there could be a relationship between ammonia production and the muscle activity was raised. The immediate source of ammonia from muscle appears to be a result of the deamination of AMP and is more apparent in fast-twitch than in slow-twitch fibers. More recently, increases in blood ammonia levels have been reported in rats after swimming and in humans after arm work, maximal cycle ergometry, and treadmill exercise. Elevated blood ammonia has also been linked to a surprising variety of functional and metabolic neurological disturbances other than exercise and fatigue, including the development of hepatic coma, convulsions from ammonia toxicity precipitated by high-pressure oxygen breathing, epileptic seizures, and decreased neuronal excitability. In addition, a number of genetic disorders (inborn errors in metabolism, or IEMs) are characterized by elevated blood ammonia concentrations. Symptoms of neural disability in all of the above conditions have been related to the concentration of ammonia in blood. Although these studies do not relate to exercise or fatigue directly, it is conceivable that our understanding of the effect of high concentrations of blood ammonia in these clinical conditions may provide valuable insight into the effect of ammonia during exercise. This paper reviews the effect of ammonia production during exercise and other conditions upon purposeful activity and the development of fatigued states.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

We tested the hypothesis that running down an incline, during which muscles primarily perform eccentric contractions, causes greater delayed-onset muscle soreness and greater increases in plasma enzyme activities than does running on the level, during which muscles perform similar amounts of concentric and eccentric contractions. Subjective sensations of muscular soreness and plasma activities of CPK and LDH were assessed in seven subjects at 0, 24, 48, and 72 h after 45 min of running (one time on the level and a second time down a 10% incline). Following downhill running (57% of VO2max), significant delayed-onset soreness was experienced in gluteal, quadricep, anterior leg, and posterior leg muscles, and plasma CPK (but not LDH) activity was significantly increased (351% at 24 h). In contrast, following level running (78% of VO2max), no statistically significant soreness occurred in any muscle group, and plasma CPK and LDH activities were not elevated. Thus, our results generally support the hypothesis. Secondarily, we investigated whether delayed-onset soreness with downhill running is accompanied by increases in peripheral white blood cell counts suggestive of inflammation. No such association was observed. We suggest that both delayed-onset muscular soreness and plasma enzyme activities are affected by structural changes in muscle tissue resulting from eccentric contractions.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Two healthy females and twelve healthy males, aged 19–24 yr, underwent strength training for periods of 9–21 wk. The muscles trained included extensor digitorum brevis (N=3), soleus (N=7), brachioradialis (N=4), and the hypothenar muscles (N=3). The effect of training on motoneuron excitability was measured as the degree to which two reflex responses (V1and V2) were potentiated by voluntary effort. Strength training was found to increase V1and V2potentiation by 49.7 and 38.9%, respectively, (P< 0.01) for pooled muscle comparisons with the exception of the soleus V2wave, which was rarely seen and excluded from this analysis. There was a positive correlation (r = 0.83,P< 0.01) between the change in the V1and V2potentiation. It was argued that strength training may cause an increased ability to raise motoneuron excitability during voluntary effort.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

The purpose of this study was to determine and compare the resultant joint torques exerted during similar arm curl exercises performed at slow, medium, and fast rates of lifting using a barbell and a weight machine. Three men experienced in strength-training performed lifts under nine different conditions of load and rate of lifting. The resultant torque at the elbow was determined for one trial under each condition. The following conclusions appear to be warranted:1. For the seated arm curls performed with a barbell, the resultant elbow torques, exerted at all but the extremes of the range of motion, were independent of the rate of lifting. For arm curls performed with a Universal weight machine, the elbow torques required to lift a given load were independent of the rate of lifting except when the duration of the lift was less than 2 s.2. Inertial effects were greatest at fast lifting rates and declined asymptotically as the rate of lifting decreased.3. Because the form of the results for all three subjects was essentially the same despite pronounced differences in the subjects' heights and weights, conclusions based on an analysis of the performances of any other subjects experienced in weight training would probably be the same as those reached in the present study.If it is accepted that muscular strength can best be increased by repeatedly requiring the muscles to produce forces close to the maximum of which they are capable, as the Overload Principle states, the results obtained in this study also suggest that:1. For a given load, a fast rate of lifting is likely to yield a slightly better rate of strength development than slower rates of lifting.2. Neither of the two pieces of equipment used in the study is inherently superior to the other in terms of strength development.

ISSN:0195-9131    

出版商:OVID    

年代:1983

数据来源: OVID