ISSN:0195-9131    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Exertional heatstroke usually occurs among healthy, fit individuals who are motivated to perform strenuous exercise because of peer pressure, discipline, or athletic competition. In fact, exertional heatstroke deaths among high school athletes in the United States (ranked third only to head and neck injuries and heart failures), and the reluctance of race directors to cancel or postpone mass participation road races during periods of severe heat and humidity, emphasize a continuing need for widespread dissemination of information. The purposes of this symposium are 1) to convey essential information to the members of ACSM who are involved in exercise prescription, patient care, or athletic training; and 2) to disseminate recent scientific theories and research concerning exertional heatstroke.

ISSN:0195-9131    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Exertional heatstroke (EH) occurs when heat production, generated by muscular exercise, exceeds the body's heat dissipation capacities. This illness has been reported among young, active individuals, laborers, and religious pilgrims. Although EH includes a rectal temperature above 39.5°C (depending on the timing of the measurement) and elevation of serum enzymes, altered mental status is the universally accepted sign which distinguishes EH from heat exhaustion. Once EH is suspected, cooling therapy should be initiated immediately and investigation of multiple-system involvement should be undertaken. Delay in diagnosis occurs more commonly in moderate environments, when suspicion of EH is low. Complications of EH include the central nervous, cardiovascular, pulmonary, and gastrointestinal systems, often with renal and hematologic involvement. Treatment at the point of collapse should focus on clearing the airway, measurement of rectal temperature, whole body cooling, intravenous therapy, and prompt evacuation. Hospital treatment should emphasize whole body cooling, control of convulsions, monitoring of acid-base status, cardiac function, and renal function. The incidence of EH has been reduced markedly in Israel, by using the following simple guidelines: rest periods during exercise in the heat, medical monitoring of strenuous activities, use of meteorological indices, and evaluation of medical history.

ISSN:0195-9131    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

This manuscript compares the whole body cooling techniques in the emergency treatment of heatstroke. Historically, the use of cold water immersion with skin massage has been quite successful in rapidly lowering body temperature and in avoiding severe complications or death. Recent studies have suggested alternative therapies, including the use of a warm air spray, the use of helicopter downdraft, and pharmacological agents. While evidence exists to support these methods, they have not been shown to reduce fatalities as effectively as ice water immersion. Although several cooling methods may have clinical use, all techniques rely on the prompt recognition of symptoms and immediate action in the field.

ISSN:0195-9131    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

This symposium focuses on exertional heatstroke, with emphasis on predisposing factors, clinical observations, diagnosis, treatment and recovery. The serious challenge to cardiovascular stability presented by exercise hyperthermia and some aspects of regulatory failure was reviewed in the introduction. The intent of this review, to understand how heat stress is translated into heat strain at the cellular level, is not to downplay the seriousness of the systemic condition. If we are successful, this may stimulate further interest on the impact of heat on the cell as a model for other factors which alter membrane integrity and permeability, lead to new experimental paradigms, and improve the diagnosis and treatment of other disorders such as toxic, hypovolemic, or ischemic shock. This review may also stimulate interesting research regarding more subtle threats to homeostasis such as chronic exercise, hypohydration and thirst, ion imbalance, and sleep deprivation. Since the original article on heat stroke pathophysiology was published (39), we have discussed the relationship of this concept to carbohydrate metabolism (40), thirst (41), and the cellular aspects of heat illness treatment (99). This article will attempt to integrate and extend some of those ideas.

ISSN:0195-9131    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Great individual variability exists in the ability to sustain heat stress. Some individuals are more susceptible to heat than others. Those individuals, among the young active population (athletes, military recruits, laborers), are at risk to contract exertional heat stroke. Low tolerance to heat results from either functional factors, or from congenital or acquired disturbances. In most cases heat intolerance can be foreseen. Cases of dehydration, overweight, low physical fitness, lack of acclimatization, febrile or infectious diseases, and skin disorders should be regardeda priorias predisposing factors for heat intolerance. Special attention should be paid to subjects with previous heat stroke episodes since it might reflect an underlying cause for heat susceptibility. The heat tolerance of these subjects should be tested 8–12 wk postepisode to detect a possible residual injury in the ability to thermoregulate adequately in the heat.

ISSN:0195-9131    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Our understanding of the time course of recovery from exertional heatstroke (EH) and the heat acclimation ability of prior EH patients is limited. This manuscript reviews previous findings regarding recovery from EH and presents original research involving the heat acclimation ability of 10 prior EH patients (PH) and 5 control subjects. Heat acclimation, by definition, distinguishes heat-intolerant from heat-tolerant prior heatstroke patients. Nine PH exhibited normal heat acclimation adaptations (40.1°C, 7 d, 90 min·d−1), thermoregulation, sweat gland function, whole-body sodium and potassium balance, and blood values at 61 ± 7 d after EH. One PH (subject A) did not adapt to exercise in the heat, was defined heat intolerant, but subsequently was declared heat tolerant (11.5 months post-EH). Three PH exhibited large, unexpected increases in serum CPK levels, which resolved upon subsequent testing, and were probably related to their detrained state and the exercise which they performed. It was concluded that: 1) sleep loss and generalized fatigue were the most common predisposing factors for PH; 2) recovery from EH was idiosyncratic and may require up to 1 year in severe cases; 3) PH were not hereditarily heat intolerant, prior to EH; 4) no measured variable predicted recovery from EH, or heat acclimation responses; 5) heat intolerance occurs in a small percentage of prior heatstroke patients, and may be transient or persistent.

ISSN:0195-9131    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The effects of exercise and exercise conditioning on blood platelet function were investigated in six healthy individuals who had not engaged in regular exercise for at least 1 yr prior to the study. The subjects (three men and three women) had a mean age of 28 (range 23–32) and participated in a supervised program of treadmill exercise. Subjects exercised for 20 min, three times weekly, for 12 wk at 70–80% of estimated maximum heart rate. Samples for platelet counts, platelet aggregation, and plasma β-thromboglobulin (β-TG) were obtained prior to training and after 6 and 12 wk of training. All subjects responded with an increase in aerobic capacity during training. Resting mean systolic and diastolic blood pressures decreased after training (P< 0.05). Platelet counts increased after exercise, and the increment in week 12 exceeded that in the 1st wk by 57%. Platelet aggregation studies in platelet rich plasma (PRP) showed an increase in slope after exercise (week 1,P< 0.05) which decreased with training (week 1 vs week 12,P< 0.01). Aggregation studies utilizing impedance aggregometry in diluted native whole blood showed an acceleration of both spontaneous aggregation (P< 0.01 weeks 6 and 12) and aggregation using epinephrine as an agonist (P< 0.05) following exercise. Plasma β-TG levels did not increase significantly after exercise; however, resting concentrations of β-TG decreased with training (P< 0.03). These data support the conclusion that platelet counts increase and platelet aggregation is accelerated by exercise but that platelet responsiveness decreases with exercise training.

ISSN:0195-9131    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

It has been concluded from studies using retrospective data and thus quasi-experimental designs that menarche may be delayed by prepubertal athletic training. Furthermore, a causal relationship between the age of initiation of training (AIT) and the age of menarche (AOM) has been proposed. To investigate the possibility that these conclusions were erroneous and based upon analytical artifact, a computer program was used to generate random and independent AOM and AIT for a population of 30,000 “athletes”. The generated mean AOM (&OV0398; = 13.4 yr) and mean AIT (&OV0398; = 10.0 yr) were similar to those reported in recent literature. The sampling procedure was designed such that no relationship existed between AOM and AIT in these hypothetical athletes (r = 0.002). When two subgroups (pre- or post-menarcheal training) were compared, the pre-training group was found to have a significantly later AOM than the post-trained group (&OV0398; = 13.9 yr vs &OV0398; = 11.7 yr;P< 0.05). Significant correlations were found for each subgroup between AOM and AIT (r = 0.46 and 0.40 pre- and post-menarcheal training, respectively), similar to values previously reported. In conclusion, the sampling procedures performed in the present study and in similar data sets result in biased estimates of the statistical parameters. This bias accounts for the reported relationship between AOM and AIT derived using this type of quasi-experimental design, and therefore it would appear appropriate to state that the age of menarche in athletes is “later” rather than “delayed”.

ISSN:0195-9131    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

This introductory review considers some concepts of energy supply and demand from the perspective of a systems engineer looking at comparative physiology. The non-steady-state response of oxygen uptake shows major differences between animal species. Similarly, maximal oxygen uptake shows between-species differences. It is suggested that the systems engineering approach could help in understanding questions concerning the interrelationship of these observations.

ISSN:0195-9131    

出版商:OVID    

年代:1990

数据来源: OVID