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 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The relationships between age and cardiorespiratory and metabolic adjustments during cycle ergometer exercise and treadmill walking were investigated at 30%, 60%, 80%, and maximal aerobic power (VO2max). The subjects were 18 females between the ages of 17-40. Tr-admill walking resulted in an 8 percent greater maximal aerobic power than that observed during cycle ergometer exercise. Higher lactate concentrations, respiratory exchange ratios and lower heart rates during the cycle ergometer test supported the possibility of localized fatigue from anaerobic metabolism as a limitation to aerobic power potential. Contrary to previous observations in males, female subjects die not demonstrate a lower stroke volume or higher heart rate during submaximal cycling compared to treadmill walking. At exercise intensities above 30% Vi2max, plasma bicarbonate and pH were consistently lower following exercise on the cycle ergometer. Respiratory compensation as calculated from "excess ventilation," delta VE/delta HCO3-, was approximately 4 1 min-1/mEq 1-1. Compensation was found to be independent of the type of exercise but linearly related (r=0.99) to the resultant metabolic acidosis. It was concluded that cardiovascular responses to equivalent cycle ergometer and treadmill exercise are similar; however, occurrence of a greater metabolic acidosis during cycle ergometer exercise suggests that a smaller muscle mass is used.
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PMID:Cardiovascular, metabolic, and ventilatory responses of women to equivalent cycle ergometer and treadmill exercise. 739 96

The authors have isolated, by means of factorial analysis on a specimen group of 86 stroke patients, a group of 23 subjects who showed, to a significant extent, lapses in concentration, intellectual fatigue and memory deterioration, and have therefore considered them as being subject to psycho-coronary syndrome. From the comparison made with the other coronary-thrombosis victims in this research, these subjects appeared to be attended to by authoritarian physicians, had been hospitalized for a greater length of time, had remained absent from work for longer, and had accepted restrictions upon their physical activity and habits by both their doctor and family. Furthermore, they showed a remarkable level of self-depressive tendencies and fear of improbable relapse, not corresponding to the severity of the stroke. The factorial analysis has thus allowed us to evidentiate the reality of the psycho-coronary syndrome as a clinical condition.
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PMID:Factorial analysis in psycho-coronary syndrome. 741 11

Setchenov showed in 1903 that the amount of work he could perform with his right arm after a pause, during which he had worked with his nonfatigued left arm was greater than if he had rested passively between bouts. Asmussen and Mazin have shown that recuperation after local muscle fatigue was influenced by a central nervous factor. In this paper 10 stroke patients were examined and the muscular activity of the deltoid was measured by means of EMG. The intact deltoid behaved according to Setchenov's observation. In 4 patients the diverting activity did not have any beneficial effect on the paretic muscle. It is assumed that in some of the stroke patients the brain damage affects the facilitatory centers which are needed for the recuperation after muscular fatigue.
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PMID:Recovery after muscular fatigue in hemiparesis. 746 75

To determine if a 36-h fast affects the central and peripheral components of VO2 during submaximal exercise and peak oxygen uptake (VO2 peak), 10 physically healthy males exercised first for 10 min at approximately 60% of their VO2 peak and then to fatigue. Their cardiovascular responses were compared with those of 10 physically healthy controls (males) who were individually matched by VO2 peak values. Fasting had no significant effect on the central (heart rate, HR; stroke volume, SV; cardiac output, Q) and peripheral (arteriovenous oxygen content difference, a-vO2 diff.) components of VO2 during submaximal exercise. The respiratory exchange ratio (RER) during submaximal exercise was significantly decreased in the fasted subjects. Based on the RER, fasting altered substrate utilization of the muscle and thereby increased the contribution of fat during submaximal exercise. Fasting had no significant effect on VO2 peak, HR or O2 pulse, but RER was significantly lower during incremental exercise to fatigue. These results demonstrate that VO2 during submaximal exercise in fasted subjects is achieved by similar central and peripheral responses as found in non-fasted subjects, and that fasting does not reduce VO2 peak.
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PMID:Influence of a 36-h fast on the central and peripheral components of VO2 during submaximal exercise and peak oxygen uptake. 747 40

The objectives of exercise testing in congestive heart failure (CHF) may be summarized as follows: (a) detect impaired cardiac performance, (b) grade severity of cardiac failure and classify functional capability, and (c) assess effects of interventions. Several different methods are available to make these assessments, and we have to ask ourselves how well exercise testing achieves these objectives. It has to be kept in mind that the power generated by the exercising muscles is dependent on the oxygen delivery to the skeletal muscles. Oxygen uptake is the result of an integrated performance of the lungs, heart, and peripheral circulation. In patients, as well as in normal subjects, oxygen uptake is related to hemodynamic indices such as cardiac output, stroke volume, or exercise duration when a stepwise regulated maximal exercise protocol is used. However, there are major differences in the concept of a true maximum in normal subjects versus heart failure patients. Fit-normal subjects will achieve a real maximal oxygen uptake, whereas patients may stop testing before a maximum is reached because of symptoms such as dyspnea or leg fatigue. Therefore, it is better if the actual oxygen uptake can be measured. "Peak" rather than true maximal oxygen uptake has been suggested for the classification of the severity of heart failure. Peripheral factors modify the cardiac output through such factors as vascular resistance, organ function, and hormonal release. Maximal exercise will stress the cardiovascular system to a point where the weakest chain will impose a limiting effect.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The role of exercise testing in heart failure. 751 35

Tethered swimming forces (TSF), average distance achieved per stroke (D/S) during a submaximal effort swim, and time and D/S for a maximal effort swim were measured to determine changes occurring with staleness and recovery. Fourteen nationally ranked male and female swimmers were studied five times (i.e. early-, mid-, and late-season, during tapering, and after competition). ANOVA and Newman-Keuls post-hoc tests were used to assess changes during the season. Three swimmers were classified as stale and showed a deterioration (0.7%) in maximal performance time from early- to late-season which was significantly different (P < 0.05) from the improvement (3.1%) demonstrated by the non-stale swimmers. Daily self-ratings of fatigue, kept by the swimmers in log books during the season, were significantly higher (P < 0.001) for the stale compared with the non-stale swimmers. No significant differences were established between the stale and non-stale swimmers in TSF or D/S during the season or in the response to tapering. A significant improvement (P < 0.05) in TSF was observed from before to after tapering. It was concluded that TSF and D/S may not change significantly with staleness and that the recovery period of tapering prior to competition allows swimmers to generate greater forces in the water.
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PMID:Biomechanical responses of elite swimmers to staleness and recovery. 778 Jul 75

Sleep pattern and breathing in humans are altered following cerebrovascular accidents involving the brainstem. Sleep apnea is a well-established complication of stroke involving the brainstem. On the other hand, the effect of cerebral stroke on sleep and breathing has not been well defined. The diffuse cerebral symptoms such as cognitive deficits, depression or fatigue, after hemispheric stroke mimic those present in patients with sleep apnea. To define the breathing pattern in patients with stroke involving cerebral hemispheres without brainstem lesion and without the prior history of sleep-disordered breathing, we studied 10 patients within 1 year of their stroke. The data collected during polysomnography from the stroke patients were compared with a group of subjects matched for age, body mass index, presence of hypertension, and smoking history without stroke. Patients with stroke had an abnormal sleep architecture with significantly lower slow wave sleep and rapid eye movement (REM) sleep when compared with controls. Sleep was fragmented because of the presence of increased respiratory disturbances. Stroke patients had a respiratory disturbance index of 52 +/- 10 events per hour when compared with 3 +/- 1 in controls (p < .05). Majorities of respiratory events were obstructive apneas and were associated with arterial oxygen desaturations and arousals. The pathogenic mechanism of sleep-disordered breathing in patients with hemispheric stroke seems to be related to the physiological effect of sleep on already compromised upper airway muscle control. Patients with stroke and diffuse cerebral symptoms should be investigated for the possibility of sleep-disordered breathing.
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PMID:Sleep apnea in patients with hemispheric stroke. 781 Nov 79

The association of snoring with some cardiovascular risk factors was studied cross-sectionally by a postal survey among 3750 males aged 40-59 years. In univariate analyses, snoring associated statistically significantly (P < 0.01) with hypertension, smoking, obesity, heavy alcohol use, physical inactivity, dyspnoea, hostility and morning tiredness. In a multiple logistic regression model adjusted by age, snoring associated significantly with smoking, obesity, physical inactivity, hostility and morning tiredness. When smoking was excluded from the multivariate model, alcohol use was also associated significantly with snoring. The association of snoring with smoking, and with obesity seemed to be almost independent from other studied correlates of snoring. Our results indicate that in further studies on predictive value of snoring with regard to coronary heart disease and stroke, the associations of snoring with hypertension, smoking, obesity, heavy alcohol use, physical inactivity and hostility have to be considered, as these risk characteristics may cause confounding effects.
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PMID:Snoring and cardiovascular risk factors. 782 98

Swimming has become a popular recreational activity as well as a highly competitive sport in the United States. The repetitive nature of swimming can predispose the shoulder to mechanical impingement and microtrauma, which may lead to laxity, rotator cuff fatigue, and subsequent secondary impingement. Improper stroke mechanics can place the swimmer's shoulder at further risk. The purpose of this paper is to describe the pathology of secondary impingement in freestyle swimmers and to discuss the clinical implications for rehabilitation of swimmers with the pathology. A thorough subjective and objective evaluation is necessary to design a successful rehabilitation program. The rehabilitation program for swimmers with secondary impingement includes modification of training, flexibility, range of motion, strengthening, and mobilization as indicated. Functional and proprioceptive training may also be useful techniques in the rehabilitation of swimmer's shoulder. Improper stroke mechanics can also have clinical implications on swimmer's shoulders with secondary impingement. The clinical implication of secondary impingement in freestyle swimmers suggests that the primary goal of rehabilitation is to promote equilibrium of the shoulder complex while accounting for the demands of the sport.
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PMID:Clinical implications of secondary impingement of the shoulder in freestyle swimmers. 784 51

The purpose of this study was to describe and compare electrical activity patterns in 12 shoulder muscles during the breaststroke in 25 competitive swimmers who had normal shoulders and in 14 who had painful shoulders while they performed this stroke in a pool. The electromyographic analysis was synchronized with high-speed cinematography to discern phases of the breaststroke. Means, standard deviations, and t-tests were done for each phase. The differences in muscle activity between the two groups of swimmers demonstrated an increase in the internal rotators in the group with painful shoulders. They also demonstrated a decrease in the teres minor, supraspinatus, and the upper trapezius muscles. These factors increase the risk of impingement. Both the serratus anterior and teres minor muscles in the swimmers with normal shoulders consistently fired at or above 15% manual muscle test throughout the breaststroke cycle and were thus subject to fatigue. Based on these results, exercises for the breaststroke swimmer should be directed toward endurance training of the serratus anterior and teres minor muscles while balancing the internal and external rotators of the shoulder as well as the deltoid and supraspinatus muscles.
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PMID:The normal and the painful shoulders during the breaststroke. Electromyographic and cinematographic analysis of twelve muscles. 785 3


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