摘要:

SCHEDL, H. P., R. J. MAUGHAN, and C. V. GISOLFI. Intestinal absorption during rest and exercise; implications for formulating an oral rehydration solution (ORS).Med. Sci. Sports Exerc., Vol. 26, No. 3, pp. 267–280, 1994. Formulation of oral rehydration solutions (ORS) is reviewed in the context of methods for measuring absorption of water and component substrates, transport mechanisms of substrates and water, requirements of the athlete, and effects of exercise on absorption. The triple lumen tube intubation perfusion method is the optimal technique for obtaining absorption data from the human small intestine during rest and exercise. Factors that must be considered when interpreting absorption data obtained by this technique include the role of the mixing segment in altering composition of the infused solution, defining optimal segment length, effects of ORS osmolality, and absorption of “nonabsorbed” indicators. Absorption data are applicable only to the test segment and may lack relevance to ORS transport proximal and distal to the test segment. Absorption rate of an ORS measured by perfusion may not correlate with absorption rate following ingestion. Transport of water, electrolytes, carbohydrates, and other solutes including glutamine and amino acids is considered in relation to ORS formulation. Factors affecting absorption of an ORS including the unstirred layer, motility, intestinal blood flow, and maximal absorptive capacity of the alimentary tract are considered. Exerciseper seat 30–70% VO2maxfor 60–90 min probably has minimal effects in limiting absorption of an ORS. Consideration relevant to supplying needs of the athlete during prolonged exercise in relation for ORS formulation are discussed.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

TUCKER, A. M. Shoulder pain in a football player.Med. Sci. Sports Exerc., Vol. 26, No. 3, pp. 281–284, 1994. A 19-yr-old college football player presents with a 1.5-yr history of right shoulder pain and associated easy fatigability of the right arm. The history is significant for an automobile accident 3 yr prior to presentation in which the right shoulder struck the dashboard of the car. An extensive workup proved unremarkable. Treatment included multiple trials of anti-inflammatory medication and extensive physical therapy without benefit. The patient underwent a first rib resection for thoracic outlet syndrome with significant relief of symptoms. Thoracic outlet syndrome (TOS) may mimic other more common causes of shoulder and arm symptoms. Diagnosis may be difficult as tests are often nonconfirmatory. Conservative treatment usually is adequate. In resistant cases, surgery may be indicated.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

SAGIV, M., D. BEN-SIRA, A. SAGIV, G. WERBER, and A. ROTSTEIN. Left ventricular responses during prolonged treadmill walking with heavy load carriage.Med. Sci. Sports Exerc., Vol. 26, No. 3, pp. 285–288, 1994. This study examined with metabolic cart and echo-Doppler the influence of different load carriage 4 h of treadmill walking on left ventricular systolic function, hemodynamics, and cardiovascular responses. Twenty-six aerobically well-trained male subjects (VO2max= 65.2 ± 5 ml·kg-1) volunteered for this study. Subjects carried a load of 38 kg during one session and a load of 50 kg during the other session. Following the 4-h exercise in each session, significant (P<0.05) differences were noted between the 38-kg and 50-kg workloads with regard to VO2; 14.4 ± 2 and 19 ± 5 ml·kg-1; heart rate: 104 ± 14 and 125 ± 17 beats·min-1; diastolic blood pressure: 69 ± 4 and 79 ± 4 mm Hg; and rate pressure product 140.4 ± 15 and 173.8 ± 20 index·10-2; respectively. No significant differences were noted between the workloads in regard to systolic blood pressure, perceived exertion rating, and aortic valve Doppler indices. We concluded that during prolonged treadmill walking in well-trained young subjects, the additional load above 50% up to 66% of body weight did not change the steady state of left ventricular systolic function, hemodynamics, and cardiovascular responses throughout the course of the 240 min of effort.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

KANNUS, P. and S. NITTYMÄKI. Which factors predict outcome in the nonoperative treatment of patellofemoral pain syndrome? A prospective follow-up study.Med. Sci. Sports Exerc., Vol. 26, No. 3, pp. 289–296, 1994. This study determined prospectively the outcome-predictive role of 22 background variables in the nonoperative treatment of chronic patellofemoral pain syndrome. The general variables registered age, sex, body composition, athletic activity, and duration of symptoms. The remaining variables measured clinically and radiologically the biomechanical malalignments in the lower extremities. In 49 consecutive patients, these variables were measured at the entry of the 6-wk treatment protocol (rest, NSAIDs, and intense isometric quadriceps exercises), and the outcome was determined at 6 wk and 6 months using improvements in the 100-mm Visual Analog Scale and the Lysholm and Tenger knee scores as outcome criteria: A multiple stepwise regression analysis indicated that age was the only factor which significantly (P<0.05 to 0.005) but not very strongly associated with the outcome: the younger the patient the better the outcome (r = −0.34 to −0.41 at 6 wk, and −0.25 to −0.41 at 6 months). Inclusion of any of the other predictive variables in the analytic model did not significantly improve the prediction. This results suggests that quadriceps rehabilitation is worth trying for every patient (70% experienced complete recovery) regardless patient's age, sex, body composition, athletic level, duration of symptoms, or biomechanical malalignments in the lower extremities.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

HOLDERNESS, C. C., J. BROOKS-GUNN, and M. P. WARREN. Eating disorders and substance use: a dancing vs a nondancing population.Med. Sci. Sports Exerc., Vol. 26, No. 3, pp. 297–302, 1994. The association between eating disorders, substance use, and emotional distress is well recognized in the literature. To determine whether dancers who are known to be at risk for eating disorders were also at risk for other emotional disorders, the co-occurrence of eating disorders, substance use, and emotional distress among dancers (N= 50) and nondancers (N= 56) was examined. These young adult women were part of a longitudinal study of the complications of decreased bone density. Participants filled out questionnaires about eating behavior, substance use, and emotional functioning. A clinical interview determined the existence of eating disorders (DSM-III-R). Physiological data, including an assessment of current health, also were collected. There were no differences in disordered eating between the two subject groups. Associations existed within each group, however. Many associations including substance use and emotional distress were found among the nondancers, while no associations were found among the dancers. Thus, eating disorders in a group of subjects at risk because of professional pressures to remain thin revealed a profile which differed significantly from that of women developing eating disorders in the general population.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

WARD, S. A. Assessment of peripheral chemoreflex contributions to exercise hyperpnea in humans.Med. Sci. Sports Exerc., Vol. 26, No. 3, pp. 303–310, 1994. The inaccessibility of the peripheral chemoreceptors (carotid bodies) precludes their direct investigation in exercising humans. As a result, a range of indirect techniques has been developed to assess the carotid body contribution to ventilatory control in exercise. The considerable controversy surrounding their involvement in this control process is a reflection, in part, of the limitations associated with current estimators of their reflex responsiveness. Most estimators of carotid chemosensitivity rely on the premise that, as the carotid bodies appear to be the sole mediators of the ventilatory response to hypoxia in humans, the entire ventilatory response to an hypoxic challenge necessarily should be ascribed to carotid chemoreceptor activation. Other estimators rely on the assumption, in humans, inhalation of 100% oxygen effectively “silences” the carotid chemoreflex. This article will review these estimators, and present a critical evaluation of their relative merits and limitations.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

NYE, P. C. G. Identification of peripheral chemoreceptor stimuli.Med. Sci. Sports Exerc., Vol. 26, No. 3, pp. 311–318, 1994. This short review considers the essential structure and stimulus-response characteristics of the carotid body chemoreceptors and attempts to relate the latter to their role in the generation of exercise hyperpnea. It shows that the arterial chemoreceptors do contribute substantially to the drive to breathe in exercising man and it suggests that this extra drive results from an increase in discharge which occurs in spite of the fact that the classical stimuli to its discharge, do not change. The possibility that in exercise the carotid body is excited by activation of its sympathetic innervation, and by raised arterial potassium, is considered. The idea that breath-by-breath oscillations of arterial blood gas tension convey accurate information about the whole body rate of carbon dioxide production is described and found wanting.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ELDRIDGE, F. L. Central integration of mechanisms in exercise hyperpnea.Med. Sci. Sports Exerc.Vol. 26, No. 3, pp. 319–327, 1994. Many hypotheses have been advanced to explain the hyperpnea of exercise and its close relations to the level of metabolic work, expressed as oxygen uptake (VO2) and carbon dioxide production (VCO2). Evidence is presented that a neural central command mechanism from the hypothalamus is important in the driving of both respiration and circulatory adjustments during locomotion or exercise, and that short-term potentiation of neurons in the medulla makes an important contribution. Both are probably augmented by receptors in working muscle and by the effects of increased [K+] acting on the carotid bodies. Feedback from “respiratory” mechanisms, including CO2and O2mediated mechanisms and inputs from the lungs, are important in stabilizing ventilation at the level primarily dictated by the major neural mechanisms.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

FORSTER, H. V. and L. G. PAN. The role of the carotid chemoreceptors in the control of breathing during exercise.Med. Sci. Sports Exerc.Vol. 26, No. 3, pp. 328–336, 1994. Our objective was to gain insight into the role of the carotid chemoreceptors (CC) in the exercise hyperpnea. Humans and ponies were studied at rest and during submaximal exercise breathing room air. In healthy humans, alveolar ventilation (VA) was tightly matched to CO2production (CO2) resulting in PaCO2deviating during exercise less than 1–2 mm Hg from rest. In contrast, ponies' VAincreased proportionately more than VCO2during exercise resulting in a workload dependent hypocapnia. Attenuating CC activity through hyperoxia had no effect on exercise PaCO2of humans but hyperoxia accentuated the exercise hypocapnia of ponies. Similarly, CC denervation accentuated the exercise hypocapnia of ponies. Healthy humans were also studied while external airway resistance was increased, which, while breathing room air, resulted in a workload dependent hypercapnia, and this hypercapnia was accentuated by hyperoxia. Finally, a majority of asthmatic humans studied-were hypercapnic during exercise while breathing room air and the hypercapnia was accentuated by hyperoxia. We conclude that the CC do not provide a primary drive for the exercise hyperpnea but they “fine tune”. VAto minimize disruptions of arterial blood gases. In healthy humans, attenuating CC activity has no effect on PaCO2because the primary VAdrive is closely matched to VCO2.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

WHIPP, B. J. Peripheral chemoreceptor control of exercise hyperpnea in humans.Med. Sci. Sports Exerc., Vol. 26, No. 3, pp. 337–347, 1994. Estimates of the proportional contribution of the peripheral chemoreceptors (i.e., the carotid bodies) to human ventilatory control during moderate exercise (i.e., below the lactate threshold, ·1) suggest that they: (a) exert no discernible influence on the initial (usually rapid) phase I component; (b) provide significant modulation of the slower, exponential phase II dynamics, therefore contributing to the tightness of arterial PCO2regulation and the magnitude of the transient hypoxemia in this phase; and (c) account for ∼20% of the steady-state phase III drive, which can rise to over 50% in hypoxia (PaO2∼50 mm Hg). Above &thetas;1, the carotid bodies constrain the transient fall in arterial pH by mediating much (but not all) of the compensatory hyperventilation for the metabolic acidemia. The carotid body contribution above &thetas;1, estimated by Dejours O2testing, is not appreciably different from subthreshold estimates, suggesting that: (a) the respiratory alkalosis in blood and cerebrospinal fluid resulting from the hyperventilation may suppress carotid chemonsitivity; (b) an artifact resulting from secondary hyperoxia-induced stimulation of central chemoreceptors may lead to underestimation of the carotid body contribution; or (c) the carotid bodies may not be entirely “silenced” by hyperoxia during a metabolic acidemia.

ISSN:0195-9131    

出版商:OVID    

年代:1994

数据来源: OVID