ISSN:0195-9131    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Sapega, A. A., D. P. Sokolow, T. J. Graham, and B. Chance. Phosphorus nuclear magnetic resonance: a non-invasive technique for the study of muscle bioenergetics during exercise.Med. Sci. Sports Exerc.,Vol. 19, No. 4, pp. 410–420, 1987. Phosphorus nuclear magnetic resonance (31P NMR) spectroscopy is a non-destructive analytical laboratory technique that, due to recent technical advances, has become applicable to the study of high-energy phosphate metabolism in both animal and human extremity muscles (in vivo).31P NMR can assay cellular phosphocreatine, ATP, inorganic phosphate, the phosphorylated glycolytic intermediates, and intra-cellular pH in either resting or exercising muscle, in a non-invasive manner. NMR uses non-perturbing levels of radio-frequency energy as its biophysical probe and can therefore safely study intact muscle in a repeated fashion while exerti no artifactual influence on ongoing metabolic processes. Compare with standard tissue biopsy and biochemical assay techniques, NMR possesses the advantages of being non-invasive, allowing serialin situstudies of the same tissue sample, and providing measurements of only active (unbound) metabolites. NMR studies of exercising muscle have yielded information regarding fatigue mechanisms at the cellular level and are helping resolve longstanding questions regarding the metabolic control of glycolysis, oxidative phosphorylation, and post-exercise phosphocreatine re-synthesis. NMR is also being utilized to measure enzymatic reaction ratesin vivo.In the near future, other forms of NMR spectroscopy may also permit the non-invasive measurement of tissue glycogen and lactate content.

ISSN:0195-9131    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

STRICKER, P. R., B. H. HARDIN, and J. C. PUFFER. An unusual presentation of liver laceration in a 13-yr-old football player.Med. Sci. Sports Exerc.,Vol. 25, No. 6, pp. 667–672, 1993. Abdominal injury occurs infrequently from athletic trauma, yet when it does occur, it can be very serious. Although rupture of a major blood vessel can lead to rapid loss of blood, insidious blood loss can also result from apparently insignificant injury of the spleen, liver, or kidney and lead to delayed problems. Awareness of the potential for such injury is vital because outcome can be adversely affected by a low index of suspicion, and this can be compounded by the fact that the initial physical examination is not always a reliable indicator of the severity of injury. Classic reports of these injuries describe splenic injury from a left-sided blow and hepatic injury from right-sided trauma. We present a case report of liver laceration in a young football player not only to comment on its unusual mechanism and presentation, but also to illustrate the importance of rapid assessment and transport of the athlete with a serious abdominal injury to avoid the consequences of delayed diagnosis and treatment.

ISSN:0195-9131    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

POTTEIGER, J. A., J. C. WELCH; and J. C. BYRNE. From parturition to marathon: a 16-wk study of an elite runner.Med. Sci. Sports Exerc.,Vol. 25, No. 6, pp. 673–677, 1993. This study monitored a 34-yr-old distance runner for 16 wk immediately postparturition, as she trained for the 1992 United States Olympic Marathon Trials. Weight (WT), percent fat (%FAT), aerobic power (VO2max), and energy intake/expenditure were evaluated 4, 8, 12, and 16 wk post-parturition. WT declined steadily throughout the investigation, while %FAT decreased through the first 12 wk. Minimal changes in VO2max(4wk: 52.2 ml-kg-1.min-1to 16 wk: 55.3 ml.kg-1.min-1) occurred; however, there were substantial changes in oxygen uptake at the lactate threshold (VO2-LT) and at the onset of blood lactate accumulation (VO2-OBLA). VO2-LT increased from 35.6 ml.kg-1min-1at 4 wk to 43.5 ml.kg-1.min-1at 8 wk. VO2OBLA increased from 40.1 ml.kg-1.min-1at 4 wk to 51.2 ml.kg-1.min-1at 8 wk. VO2-LT and VO2-OBLA did not change during the final 8 wk of training. Energy intake was consistently below energy expenditure. No physical or medical complications were encountered during training. This subject was able to improve VO2-LT and VO2-OBLA through high-intensity training without compromising her health. The evidence indicates that well-trained female athletes, while under physician care, may participate in rigorous physical activity soon after pregnancy.

ISSN:0195-9131    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

MACKINNON, L. T. and D. G. JENKINS. Decreased salivary immunoglobulins after intense interval exercise before and after training.Med. Sci. Sports Exerc.,Vol. 25, No. 6, pp. 678–683, 1993. Endurance athletes have been shown to suffer a high incidence of upper respiratory tract infection (URTI). Previous studies have shown that concentration and flow rate of secretory immunoglobulin A (IgA), the major effector of host resistance to URTI, decrease after intense endurance exercise. The purpose of this study was to determine whether salivary IgA concentration and flow rate decrease after brief intense interval exercise, and whether the response to exercise changes with training. Twelve male subjects performed five 60-s bouts of supramaximal interval exercise at 0.075 g.kg-1body mass on a cycle ergometer; each bout was separated by 5-min rest. Subjects then trained for 8 wk by performing the same interval exercise protocol three times per week. Timed, whole unstimulated saliva samples were obtained before and after the interval exercise protocol, before and after training. Salivary IgA, IgG, and IgM concentrations were measured by ELISA and flow rates calculated. IgA and IgM concentrations relative to total protein decreased after each exercise session; IgG concentration relative to total protein did not change after exercise. IgA, IgM, and IgG flow rates decreased 50–65% after interval exercise. There was no effect of training on any immune parameter measured, although total work performed in the five 60-s bouts increased after training. These data show that the output of salivary IgA and IgM decrease after brief supramaximal interval exercise, and that the decreased output is due, at least partially, to the decrease in saliva flow. In addition, there appears to be a specific effect of intense exercise on IgA concentration greater than that due to decreased saliva flow alone. These data suggest that decreases in secretory IgA output after repeated bouts of supramaximal exercise may be one mechanism contributing to the high incidence of upper respiratory tract infection among athletes.

ISSN:0195-9131    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

R. D. MACARTHUR, S. D. LEVINE, and T. J. BIRK. Supervised exercise training improves cardiopulmonary fitness in HIV-infected persons.Med. Sci. Sports Exerc.,Vol. 25, No. 6, pp. 684–688, 1993. We attempted to measure cardiopulmonary effects, CD4 counts, and perceived sense of well-being in 25 individuals moderately to severely immunocompromised from HIV infection (mean entry CD4 count = 144-μl-1) before and after a 24-wk program of exercise training. Only six subjects completed the 24-wk program. All six showed evidence of a training effect. Statistically significant improvements were seen in maximal oxygen consumption (VO2max), oxygen pulse, and minute ventilation. Submaximal exercise performance improved significantly by 12 wk in the 10 individuals available for testing: decreases were seen in heart rate, rate pressure product, and rate of perceived exertion. White blood cell counts and T-lymphocyte subsets were stable at 12 and 24 wk in the subjects available for testing. High depression/anxiety scores on a mental health inventory (General Health Questionnaire) correlated with low CD4 counts. Scores did not correlate with compliance with the exercise program. There was a trend (P< 0.10) for scores to improve over time among those individuals who attended ≥80% of scheduled exercise sessions. We conclude that exercise training is feasible and beneficial for some HIV-infected individuals.

ISSN:0195-9131    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

ROWLAND, T. W. Does peak VO2reflect VO2max in children?: evidence from supramaximal testing.Med. Sci. Sports Exerc.,Vol. 25, No. 6, pp. 689–693, 1993. A plateau in oxygen uptake during the terminal phases of a progressive exercise test has been considered a requisite indicator of achievement of a true VO2max.Whether this concept is valid in pediatric subjects is unclear, however, since children do not often demonstrate such a VO2plateau during exercise testing. In this study, nine children underwent three treadmill tests with successively higher supramaximal workloads after an initial standard progressive test to exhaustion. Three subjects (33%) satisfied the criterion for a VO2plateau on the initial test. Mean peak oxygen uptake values during the supramaximal tests did not increase significantly above that achieved on the progressive test. These results suggest that peak VO2on the initial test was indicative of true VO2maxdespite the absence of a VO2plateau. The findings further imply that a VO2plateau should not be used as a requirement for defining a maximal exercise test in children.

ISSN:0195-9131    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

DEPALMA, M. T., W. M. KOSZEWSKI, J. G. CASE, R. J. BARILE, B. F. DEPALMA, and S. M. OLIARO. Weight control practices of lightweight football players.Med. Sci. Sports Exerc.,Vol. 25, No. 6, pp. 694–701, 1993. The objective of this research was to investigate the weight control practices of lightweight football players. In addition, the importance of several variables was examined for their clinical importance and ability to identify individuals at high risk for pathogenic eating behaviors. Male college lightweight football players (N= 131) were administered a 45-item version of the Diagnostic Survey For Eating Disorders (9). Results revealed that 74% had experienced binge eating, and 17% had experienced self-induced vomiting. During the month preceding questionnaire administration, 66% had fasted, nearly 4% had used laxatives, while less than 2.5% had used diet pills, diuretics, or enemas for the purpose of weight control. Furthermore, the “teacher/coach” seemed to be the individual who motivated dieting behavior, and more than 20% of the sample reported that their weight control practices interfered with their thoughts and extracurricular activities “often” or “always.” Most importantly, 42% of the sample evidenced a pattern of dysfunctional eating, while 9.9% of the sample engaged in binge-purge behavior to the degree that it might represent an eating disorder. Finally, discriminant analysis yielded several variables that might be useful in identifying individuals at risk for pathogenic eating behaviors.

ISSN:0195-9131    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

RAVEN, P. B. An overview of the problem: exercise training and orthostatic intolerance.Med. Sci. Sports Exerc.,Vol. 25, No. 6, pp. 702–704, 1993. The questions, whether endurance exercise training (a) induces orthostatic intolerance and (b) alters blood pressure regulation during orthostasis, have been debated since the early 1970s. This symposium presents data that both support and discount the concepts. In addition, data were presented that document invasive and noninvasive techniques of measurement used during investigations of baroreflex and hemodynamic mechanisms of blood pressure regulation during lower body negative pressure (LBNP), a laboratory technique that simulates orthostasis. These techniques and the results obtained enabled the formulation of a hypothetical mechanism of explanation of the “pro and con” of the debated questions.

ISSN:0195-9131    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

CONVERTINO, V. A. Endurance exercise training: conditions of enhanced hemodynamic responses and tolerance to LBNP.Med. Sci. Sports Exert.,Vol. 25, No. 6, pp. 705–712, 1993. In cross-sectional comparisons, several investigators have reported highly trained endurance athletes to have a prevalence toward orthostatic hypotension and intolerance compared with average fit individuals. These observations have raised concern that regular exercise designed to increase aerobic capacity may impair regulatory mechanisms of blood pressure control and that perhaps certain populations of individuals with a predisposition for fainting exhibit an inability to elevate heart rate, vasoactive hormones, and peripheral resistance during an orthostatic challenge. In longitudinal experiments, when exercise training was performed by subjects who increased their aerobic capacity by 20% but maintained VO2maxbelow 50 ml.kg-1.min-1, tolerance to lower body negative pressure (LBNP) was increased by 28%. Exercise training did not compromise baroreflex functions despite evidence of increased resting vagal cardiac tone and reduced sympathetic tone. In contrast to fainters, increased orthostatic tolerance in the exercised-trained subjects was associated with no alteration in their ability to elevate heart rate, vasoactive hormones, and peripheral resistance at peak LBNP. However, cardiac output and mean arterial blood pressure were maintained during higher submaximal LBNP levels by a 20% increase in stroke volume. The elevation in stroke volume during LBNP after training was associated with blood volume expansion. Although orthostatic tolerance may be reduced in some highly trained endurance athletes, data from this and other longitudinal experiments argue for the notion that orthostatic stability is not compromised by exercise training that does not increase VO2maxabove a critical threshold (-55–60 ml.kg-1.min-1) and provoke associated cardiovascular adaptations. Since average VO2max of astronauts and pilots fall below this threshold, there is no compelling evidence to suggest that these individuals should refrain from such regular exercise activity.

ISSN:0195-9131    

出版商:OVID    

年代:1993

数据来源: OVID