Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Drug use among athletes has become a recognised problem in sports. Athletes may use drugs for therapeutic indications, for recreational or social reasons, as ergogenic aids or to mask the presence of other drugs during drug testing. Stimulants were some of the first drugs used and studied as ergogenic aids. Amphetamines may increase time to exhaustion by masking the physiological response to fatigue. Caffeine may improve utilisation of fatty acids as a fuel source thereby sparing muscle glycogen. Cocaine and other sympathomimetic drugs have little or no effect on athletic performance. Anabolic steroids appear to have the potential to increase lean muscle mass and strength under certain conditions. Human growth hormone may also be used for an anabolic effect, but data on this effect are lacking. Erythropoietin may represent a pharmacological alternative to blood doping by increasing red blood cell mass. The use of narcotic analgesics is not necessarily ergogenic but can be harmful if used to allow participation of an athlete with a severe injury. According to the American College of Sports Medicine alcohol does not possess an ergogenic effect. However, it may be used to reduce anxiety or tremor prior to competition. Marijuana does not increase strength. Tobacco products may produce psychomotor effects or control appetite which may be beneficial to some athletes. Other drugs used by athletes include beta-blocking agents, diuretics, and a variety of nutritional supplements. In addition, diuretics and probenecid may be taken to mask drug contents in the urine. Whether the ergogenic effects are real or perceived, the potential for adverse effects exists for all of these drugs. Potential health complications represent a serious risk to an otherwise healthy population. Further research on the long term health risks in athletes taking ergogenic drugs is needed.
 ...
PMID:Enhancement of athletic performance with drugs. An overview. 168 20

We investigated whether fatigue of the expiratory muscle, that is, the abdominal muscle, may account for a change in the respiratory effort sensation in normal subjects during expiratory threshold loading. The respiratory effort sensation was scored using a modified Borg scale. Expiratory muscle fatigue was assessed both from changes in the maximal static expiratory pressure and in the centroid frequency (fc) of the abdominal muscle electromyogram (EMG). Expiratory threshold loading (magnitude of threshold; 40 to 60% of the maximal expiratory pressure at FRC, breathing frequency = 15/min, and duty cycle = 0.5) was continued until exhaustion or for 30 min. Loading was repeated following a 15-min recovery period after the end of the first expiratory loading. The maximal static expiratory pressure during loading (Pmmax) decreased initially and then remained decreased. Decreases were smaller with the 40% load (22 +/- 6%, SEM) than with the 60% load (37 +/- 3%) (p less than 0.05). The decrease during the second run of the 60% load was greater than during the first (p less than 0.01 by ANOVA). The maximal expiratory pressure at TLC before the second run of the 60% load was decreased by 9 +/- 3% compared with the control (p less than 0.02) but that with the 40% load was not. The fc with the 60% load decreased initially by 8 +/- 1% and then remained constant, although no change was observed with the 40% load.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Relationship of respiratory effort sensation to expiratory muscle fatigue during expiratory threshold loading. 173 58

In a retrospective study of 632 patients with pituitary disease we diagnosed pituitary insufficiency without hypersecretion of any pituitary hormone in 122 patients. Patients were substituted with sex hormones (76%), hydrocortisone (74%) and/or L-thyroxine (77%). 76% had additional growth hormone deficiency, as shown by an increase of growth hormone of less than 5 ng/ml after i.v. administration of L-arginine. In 17% of all patients the diagnosis of osteoporosis was proven or suspected radiologically. 57% had low bone mass of lumbar spine (dualphotonabsorptiometry) and 73% had low bone mass of the proximal forearm (singlephotonabsorptiometry). BMD values of pituitary insufficient patients were in the same range as those of patients with established osteoporosis. More than half of all patients (53%) complained of tiredness, exhaustion and muscle weakness. 40% suffered from adipositas. 77% had hyperlipidemia (68% hypertriglyceridemia and 42% hypercholesterinemia), 18% had hypertension. 14% of the patients had arteriosclerotic events in their history (myocardial infarction or stroke). These figures are higher than incidences shown in the German PROCAM-study. These data show an increased prevalence of osteoporosis and vascular diseases. This is in contrast to the general opinion, that patients with pituitary insufficiency are adequately treated by substitution with adrenal, thyroid and sex hormones. Whether other factors such as the additional growth hormone deficiency are responsible for these diseases has to be examined in prospective studies.
 ...
PMID:[Increased prevalence of osteoporosis and arteriosclerosis in conventionally substituted anterior pituitary insufficiency: need for additional growth hormone substitution?]. 176 81

The physiological response to continuous and intermittent handgrip exercise was evaluated. Three experiments were performed until exhaustion at 25% of maximal voluntary contraction (MVC): experiment 1, continuous handgrip (CH) (n = 8); experiment 2, intermittent handgrip with 10-s rest pause every 3 min (IH) (n = 8); and experiment 3, as IH but with electrical stimulation (ES) of the forearm extensors in the pauses (IHES) (n = 4). Before, during, and after exercise, recordings were made of heart rate (HR), arterial blood pressure (BP), exercising forearm blood flow, and concentrations of potassium [K+] and lactate [La-] in venous blood from both arms. The electromyogram (EMG) of the exercising forearm extensors and perceived exertion were monitored during exercise. Before and up to 24 h after exercise, observations were made of MVC, of force response to electrical stimulation and of the EMG response to a 10-s test contraction (handgrip) at 25% of the initial MVC. Maximal endurance time (tlim) was significantly longer in IH (23.1 min) than in CH (16.2 min). The ES had no significant effect on tlim. During exercise, no significant differences were seen between CH and IH in blood flow, venous [K+] and [La-], or EMG response. The HR and BP increased at the same rate in CH and IH but, because of the longer duration of IH, the levels at exhaustion were higher in this protocol. The subjects reported less subjective fatigue in IH. During recovery, return to normal MVC was slower after CH (24 h) than after IH (4 h).(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Physiological effects of micropauses in isometric handgrip exercise. 176 52

This study describes the responses of 20 paraplegic athletes (mean age: 26.8 +/- 1.6 years) to a continuous incremental workload test until exhaustion on an arm cranking ergometer (ACE) and on a wheelchair ergometer (WCE). Both ergometers used the same electromagnetic braking device allowing a fair comparison between results. Tests were conducted at a 24 hour interval at the same time of the day. Oxygen uptake (VO2), heart rate (HR), workload (W), blood pressure (BP), Borg index, and mechanical efficiency (ME) were measured at every minute during the effort and the cool down periods of both tests. The purpose of this study was to analyse the different responses obtained on ACE and on WCE during maximal effort by paraplegics, and also to determine which ergometer permits the higher ME. Results indicate that paraplegics reached the same max HR on ACE and on WCE (97% of the predicted max HR). The lack of significant difference (p less than 0.05) between ACE and WCE in terms of maximal values of VO2, VE and HR suggests that the subjects reached their maximal capacity on each test regardless of the type of ergometer. Nevertheless, W max (in Watts) was 26% higher on ACE than on WCE. Maximal ME values were respectively 16% and 11.6% on ACE and WCE. Results suggest that ergometers and protocol used in this study are appropriate to measure physiological responses of paraplegic athletes during arm cranking and wheelchair exercise without excessive or early arm fatigue.
 ...
PMID:Physiological responses to maximal exercise on arm cranking and wheelchair ergometer with paraplegics. 178 11

Although there is no documented, objective evidence that symptomatic post-polio subjects are rapidly losing strength, they have a number of neuromuscular deficits related to a more severe poliomyelitis illness that may explain why they complain of problems with strength, endurance, and local muscle fatigue. Symptomatic post-polio subjects were hospitalized longer during the acute poliomyelitis, recovered more slowly, and had electromyographic evidence of greater loss of anterior horn cells. Additionally, recent assessment demonstrated that they were weaker, had a reduced work capacity, and recovered strength less readily after activity in the quadriceps muscles as compared to asymptomatic subjects. Of great clinical importance, rating of perceived exertion in the muscle during exercise was the same in symptomatic and asymptomatic post-polio and control subjects, indicating that symptomatic subjects have a mechanism to monitor local muscle fatigue that could be used to avoid exhaustion. A study of pacing (interspersing activity with rest breaks) showed that symptomatic subjects had less local muscle fatigue and greater strength recovery when they paced their activity than when they worked at a constant rate to exhaustion. We recommend that post-polio individuals pace their daily activity to avoid excessive fatigue.
 ...
PMID:Neuromuscular function in polio survivors. 178 50

Although fats and protein contribute to energy demands of exercise, carbohydrate, principally glycogen, is the preferred fuel for muscular activity. Because of its limited storage, depletion of muscle glycogen has been shown to be one factor responsible for fatigue and exhaustion during prolonged exercise. Thus, dietary carbohydrate plays a key role in exercise performance and training. When the athlete's diet is low in carbohydrate, little glycogen is resynthesized between training sessions, leaving the individuals with low muscle glycogen and a state of chronic fatigue. The most sensitive period for glycogen resynthesis is within the first few hours after exercise. Optimal recovery from an exhaustive exercise bout depends on a reasonably rich carbohydrate diet soon after the exercise. Such feedings serve to replenish carbohydrate stores in both liver and muscles. Exertional hypoglycemia can occur when liver glucose output falls below the rate of muscle glucose uptake. Though this seldom occurs in well-fed and highly trained individuals, sugar feedings during long-term exercise has been shown to enhance performance. Thus, the important role of dietary carbohydrate before, during and after endurance activities is well established, whereas our understanding of the nutritional needs for protein and fat remain unclear.
 ...
PMID:Carbohydrate for athletic training and performance. 181 89

Adenosine triphosphate (ATP) is the sole fuel for muscle contraction. During near maximal intense exercise the muscle store of ATP will be depleted in < 1s, therefore, to maintain normal contractile function ATP must be continually resynthesized. During intense exercise (from approximately 75% VO2 max to near maximal workloads) this is achieved principally by the oxidation of carbohydrate and the anaerobic utilisation of phosphocreatine (PCr) and carbohydrate. The relative contribution of carbohydrate oxidation to total energy provision decreases, while that from anaerobic utilization increases. During prolonged intense exercise (approximately 75% VO2 max), the oxidation of glucose derived from skeletal muscle and liver glycogen stores is the primary pathway for ATP resynthesis. It is widely accepted that the availability of carbohydrate limits performance during this type of exercise as the point of exhaustion has been shown to be closely related to the depletion of muscle and liver glycogen stores. It is probable that carbohydrate depletion results in the inability of skeletal muscle to maintain the required rate of ATP resynthesis and therefore, the work intensity must be reduced for exercise to continue. During short lasting near maximal exercise (0-30 s), the anaerobic utilization of muscle PCr and glycogen will fuel muscle contraction. Evidence is available to indicate that fatigue during this type of exercise is related to the inability of type II fibres to maintain the required very high rate of ATP resynthesis. This has been suggested to result from a rapid depletion of type II fibre PCr stores and an insufficiency of the glycogenolytic rate to compensate for the fall in ATP production when the PCr store is depleted. In this situation the force generation has to decrease due to insufficient energy supplies.
 ...
PMID:Skeletal muscle energy metabolism and fatigue during intense exercise in man. 184 55

Nursing is a stressful activity and therefore it is necessary for nurses to develop effective coping mechanisms, or to strengthen existing ones in a healthy manner, in order to be capable of dealing with stress, arising from their personal and professional lives. It is, however, not solely stress itself which predisposes nurses to fatigue (physical, psychological and emotional exhaustion) but rather the chronic nature and excessive amount of stressors which place excessive demands on the energy resources and coping, mechanisms of nurses resulting in the ineffective handling of stress which in turn leads to the eventual development of fatigue. The detrimental results of this experience are, however, not confined to the nurse herself, but extends further to the patient and the organization. Thus, if fatigue is not controlled or dealt with, all parties and organizations concerned could suffer. This research covers the accompaniment function of the psychiatric nurse specialist in the prevention of fatigue in psychiatric nurses by strengthening their mental preparedness. As a possible solution to the experience of fatigue, a structured, accompanied program of three days was offered to a group of psychiatric nurses. The Solomon four group design was followed in order to eliminate influences on the subjects resulting from the completion of the self-evaluation scale as pre-test. The data which was obtained from the test results was statistically compared. Results showed that there was a definite decrease in the levels of fatigue experienced by the experimental group that received the structured accompanied programme, but no real change occurred in the control group that had merely been provided with relevant literature.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:[Counseling in the prevention of fatigue in psychiatric nurses]. 184 35

The purpose of this study was to determine whether induction of inspiratory muscle fatigue might impair subsequent exercise performance. Ten healthy subjects cycled to volitional exhaustion at 90% of their maximal capacity. Oxygen consumption, breathing pattern, and a visual analogue scale for respiratory effort were measured. Exercise was performed on three separate occasions, once immediately after induction of fatigue, whereas the other two episodes served as controls. Fatigue was achieved by having the subjects breathe against an inspiratory threshold load while generating 80% of their predetermined maximal mouth pressure until they could no longer reach the target pressure. After induction of fatigue, exercise time was reduced compared with control, 238 +/- 69 vs. 311 +/- 96 (SD) s (P less than 0.001). During the last minute of exercise, oxygen consumption and heart rate were lower after induction of fatigue than during control, 2,234 +/- 472 vs. 2,533 +/- 548 ml/min (P less than 0.002) and 167 +/- 15 vs. 177 +/- 12 beats/min (P less than 0.002). At exercise isotime, minutes ventilation and the visual analogue scale for respiratory effort were larger after induction of fatigue than during control. In addition, at exercise isotime, relative tachypnea was observed after induction of fatigue. We conclude that induction of inspiratory muscle fatigue can impair subsequent performance of high-intensity exercise and alter the pattern of breathing during such exercise.
 ...
PMID:Effect of respiratory muscle fatigue on subsequent exercise performance. 186 88


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>