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At least 541 records · Page 30Linked to original sources

PubMed2006

Effect of prolonged exercise on arterial oxygen saturation in athletes susceptible to exercise-induced hypoxemia.

This study examined the effect of prolonged endurance exercise on the development of exercise-induced hypoxemia (EIH) in athletes who had previously displayed EIH during an incremental maximal exercise test. Five male and three female endurance-trained athletes participated. Susceptibility to EIH was confirmed through a maximal incremental exercise test and defined as a reduction in the saturation of arterial oxygen (SpO(2)) of >/=4% from rest. Sixty minutes of running was conducted, on a separate day, at an oxygen consumption corresponding to 95% of ventilatory threshold. Immediately following the 60 min exercise bout, athletes commenced a time trial to exhaustion at 95% maximal oxygen consumption (VO(2max)). The reduction in SpO(2) was significantly greater during the maximal incremental test, than during the 60 min, or time trial to exhaustion (-8.8+/-1.4%, -3.3+/-1.1%, and -4.1+/-2.3%, P<0.05, respectively). The degree of desaturation during the 60 min was significantly related to the relative intensity of exercise at 95% ventilatory threshold (adjusted r(2)=0.54, P=0.02). In conclusion, athletes who did not exercise at greater than 73% VO(2max) during 60 min of endurance exercise did not display EIH, despite being previously susceptible during an incremental maximal test.

Adolescent↗

PubMed2004

Paroxetine administration failed [corrected] to influence human exercise capacity, perceived effort or hormone responses during prolonged exercise in a warm environment.

The purpose of the experiment was to examine whether selective serotonin (5-HT) re-uptake transporter blockade by paroxetine has any effect on perceived effort (RPE) during exercise or the time to reach volitional fatigue and on the prolactin and cortisol responses during prolonged exercise performed in a warm environment. Eight healthy males performed two cycle rides to exhaustion in a warm (32 degrees C) environment at 60% of maximum oxygen uptake. Paroxetine (20 mg) or placebo was administered 5 h before exercise trials in a randomised double blind fashion. Time to exhaustion was not significantly influenced by administration of paroxetine: median (range) time to exhaustion was 93.3 (76.2-175.0) min on the placebo trial and 92.5 (66.0-151.0) min on the paroxetine trial. Rectal temperature was higher at rest and throughout exercise on the paroxetine trial. The serum concentrations of prolactin and cortisol were determined throughout exercise as peripheral markers of central 5-HT activity. RPE increased over time but was not influenced by paroxetine administration. Prolactin and cortisol levels increased over time but paroxetine administration did not influence the hormone responses during exercise. In conclusion, acute administration of paroxetine failed to alter RPE, exercise capacity or the response of the determined peripheral hormone markers of central 5-HT activity during prolonged exercise in a warm environment.

Adult↗

PubMed2003

No effect of pre-exercise meal on substrate metabolism and time trial performance during intense endurance exercise.

To determine the effect of macronutrient composition of pre-exercise meals on exercise metabolism and performance, 8 trained men exercised for 30 min above lactate threshold (30LT), followed by a 20-km time trial (TT). Approximately 3.5 h before exercise, subjects consumed a carbohydrate meal (C; 3 g carbohydrate/kg), an isoenergetic fat meal (F; 1.3 g fat/kg) or a placebo meal (P; no energy content) on 3 separate occasions in randomized order. Treatments had no effect on carbohydrate oxidation during exercise, but C decreased whole-body fat oxidation during the last 5 min of 30LT and TT, respectively (3.2 +/- 1.6 and 4.8 +/- 2.1 micromol/kg(-1) x min(-1), p < .05) when compared to F (13.3 +/- 1.6 and 16.5 +/- 2.7 micromol x kg(-1) x min(-1)) and P (15.9 +/- 2.7 and 17.0 +/- 3.2 micromol x kg(-1) x min(-1)). Glucose rate of appearance (Ra) and disappearance (Rd), and muscle glycogen utilization were not significantly different among treatments during exercise. TT performances were similar for C, F, and P (32.7 +/- 0.5 vs. 33.1 +/- 1.1 and 33.0 +/- 0.8 min, p > 0.5). We conclude that the consumption of a pre-exercise meal has minor effects on fat oxidation during high-intensity exercise, and no effect on carbohydrate oxidation or TT performance.

Blood Glucose↗

PubMed1994

The influence of dietary carbohydrate and pre-exercise glucose consumption on supramaximal intermittent exercise performance.

The present study examined whether a pre-exercise consumption of glucose by subjects having adhered to a 3-day low carbohydrate (CHO) or normal CHO diet would influence supramaximal intermittent exercise performance. Sixteen moderately active men volunteers (mean(s.d.) age 20.0(1.3) years) agreed to undertake three exercise tests over an 8-day period; in addition to completing a VO2max test, the subjects performed two identical maximal interval tests (MIT1 and MIT2). Periods of 3 days separated each of the three tests. The interval tests involved five 60-s 'all-out' cycling bouts working against a resistance of 0.075 kg kg-1 body mass; each bout was separated by 5 min of passive recovery. For 3 days preceding the first interval test (MIT1), all subjects adhered to a 'moderate' CHO diet which comprised 59.1% (approximately 4.1 g kg-1 body mass) of the daily energy intake as CHO. Following MIT1 and for 3 days before MIT2 subjects were randomly assigned to follow either a moderate CHO diet (60.8%) or a low CHO diet (14.4% or 1.1 g kg-1 body mass). All food and drink consumed during the experimental period was weighed and recorded for later dietary analysis. One hour before MIT2, eight subjects were administered (in single blind fashion) a 15% glucose solution (1 g kg-1 body mass) while the other eight subjects consumed a low-energy sweetened placebo. During both interval tests, values of work, exercise VO2, plasma glucose, plasma lactate and venous blood pH were statistically analysed. No changes in performance between MIT1 and MIT2 across conditions were found (P > 0.05). However, those subjects who consumed the glucose solution before MIT2 (irrespective of their dietary CHO intake) consumed significantly less oxygen during exercise than those who had been given the placebo solution (P<0.05). While these findings question the ergogenic potential of consuming glucose before supramaximal exercise, the VO(2) data implicate a possible shift in substrate utilization during repeated sprint exercise after pre-exercise glucose ingestion.

Adult↗

PubMed1999

Exercise four hour redistribution thallium-201 single photon emission computed tomography and exercise induced ST segment elevation in detecting the viable myocardium in patients with acute myocardial infarction.

OBJECTIVE: To investigate the specificity and sensitivity of the combination of redistribution in exercise thallium-201 single photon emission computed tomography (SPECT) and exercise induced ST elevation for detecting the viable myocardium in patients with acute myocardial infarction. DESIGN: 37 patients were studied within seven weeks of onset of Q wave myocardial infarction (anterior in 22, inferior in 15). All patients underwent exercise four hour redistribution thallium-201 SPECT and positron emission tomography using fluorine-18-fluorodeoxyglucose (FDG) and nitrogen-13 ammonia under fasting conditions. RESULTS: Sixteen patients showed exercise induced ST elevation >/= 1.5 mm, and 15 of these had increased FDG uptake in the infarct region. Eleven of 16 patients (10 of 11 patients with anterior infarctions) with irreversible thallium-201 defects and increased FDG uptake showed exercise induced ST elevation. The sensitivity, specificity, and predictive accuracy of redistribution, exercise induced ST segment elevation, or both for detecting increased FDG uptake were 82%, 75%, and 67% (94%, 75%, and 91% for anterior infarctions), respectively. CONCLUSIONS: In patients with acute Q wave myocardial infarction, the combination of redistribution in exercise thallium-201 SPECT and exercise induced ST elevation can detect the viable myocardium in the infarct region with high sensitivity and specificity, especially in patients with anterior infarctions.

Adult↗

PubMed1996

Differences in cardiovascular responses to supine exercise and to standing after exercise in two clinical subgroups of Shy-Drager syndrome (multiple system atrophy).

BACKGROUND: In chronic autonomic failure of varying aetiologies, there are differences in the cardiovascular responses to supine leg exercise and to standing after exercise. Whether this occurs between the different subgroups with Shy-Drager syndrome (SDS) is unknown. METHODS: Fourteen patients with the cerebellar form (SDS-C) and 11 patients with parkinsonian features (SDS-P) were studied. RESULTS: Both groups had a similar degree of autonomic failure and postural hypotension. Their responses were compared with nine patients with idiopathic Parkinson's disease (IPD) and 15 normal subjects (controls), all with normal autonomic function. With supine exercise, blood pressure and heart rate rose similarly in controls and patients with IPD and there was no fall in blood pressure on standing after exercise. In both SDS groups there were abnormal responses to exercise: blood pressure fell in SDS-C, but did not fall or rise in SDS-P. Heart rate increased similarly in both SDS groups, calculated systemic vascular resistance fell similarly, but cardiac index rose more in SDS-P than SDS-C. Resting plasma noradrenaline concentrations were subnormal in both forms of SDS, and did not increase with exercise. Postural hypotension was enhanced after exercise to the same extent in SDS-C and SDS-P. CONCLUSIONS: The greater cardiovascular abnormalities in response to exercise in SDS-C suggests that cerebellar or brain stem autonomic pathways are impaired to a greater extent in SDS-C than in SDS-P. Pooling SDS subgroups, therefore, may obscure pathophysiological differences to certain stimuli. Clinically when postural hypotension is being assessed, separation of the subgroups may not be essential, as they responded similarly.

Adult↗

PubMed1998

Exercise-induced muscle injury augments forearm vascular resistance during leg exercise.

The purpose of the present investigation was to examine the effect of exercise-induced muscle injury on hemodynamic responses during exercise. Ten subjects performed unilateral isometric knee extensions (IKE) at 30% of preinjury maximum voluntary contraction to fatigue and for 3 min before and 48 h after muscle injury. Muscle injury was elicited by performing 8 sets of 10 repetitions of eccentric muscle actions of the knee extensor muscles (i.e., quadriceps muscles) by lowering a weight equivalent to 75% of eccentric maximum load. Exercise time to fatigue for IKE at 30% of maximum voluntary contraction in the injured leg was significantly decreased from preinjury to postinjury IKE (257 +/- 21 to 203 +/- 23 s; n = 10), but was unchanged in the control leg (244 +/- 16 to 254 +/- 20 s; n = 7). With the use of a 10-cm visual analog scale, ratings of muscle soreness in the injured leg increased from 0 to 5. 1 +/- 0.7 cm (P < 0.001) but were not changed in the control leg (0 both times). Both heart rate and mean arterial pressure responses to exercise were unchanged following muscle injury. Forearm blood flow and forearm vascular resistance were not different at rest and during the first minute of exercise before and after muscle injury. However, after muscle injury, forearm blood flow was significantly lower and forearm vascular resistance was significantly higher (P < 0.03) during the second and third minutes of exercise. There were no significant changes in any variables with the contralateral control leg. In four subjects, resting magnetic resonance images demonstrated a 23% greater relative cross-sectional area of the knee extensor muscles with an elevated transverse relaxation time in the injured versus control leg. The results indicate that forearm vascular resistance is augmented during isometric knee extension following muscle injury of the knee extensor muscles. The data suggest that muscle injury alters vascular control to non-exercising skeletal muscle during exercise.

Adult↗

PubMed1992

Exercise training prevents decline in stroke volume during exercise in young healthy subjects.

Stroke volume (SV) increases above the resting level during exercise and then declines at higher intensities of exercise in sedentary subjects. The purpose of this study was to determine whether an attenuation of the decline in SV at higher exercise intensities contributes to the increase in maximal cardiac output (Qmax) that occurs in response to endurance training. We studied six men and six women, 25 +/- 1 (SE) yr old, before and after 12 wk of endurance training (3 days/wk running for 40 min, 3 days/wk interval training). Cardiac output was measured at rest and during exercise at 50 and 100% of maximal O2 uptake (Vo2max) by the C2H2-rebreathing method. VO2max was increased by 19% (from 2.7 +/- 0.2 to 3.2 +/- 0.3 l/min, P less than 0.001) in response to the training program. Qmax was increased by 12% (from 18.1 +/- 1 to 20.2 +/- 1 l/min, P less than 0.01), SV at maximal exercise was increased by 16% (from 97 +/- 6 to 113 +/- 8 ml/beat, P less than 0.001) and maximal heart rate was decreased by 3% (from 185 +/- 2 to 180 +/- 2 beats/min, P less than 0.01) after training. The calculated arteriovenous O2 content difference at maximal exercise was increased by 7% (14.4 +/- 0.4 to 15.4 +/- 0.4 ml O2/100 ml blood) after training. Before training, SV at VO2max was 9% lower than during exercise at 50% VO2max (P less than 0.05). In contrast, after training, the decline in SV between 50 and 100% VO2max was only 2% (P = NS). Furthermore, SV was significantly higher (P less than 0.01) at 50% VO2max after training than it was before. Left ventricular hypertrophy was evident, as determined by two-dimensional echocardiography at the completion of training. The results indicate that in young healthy subjects the training-induced increase in Qmax is due in part to attenuation of the decrease in SV as exercise intensity is increased.

Adult↗

PubMed1998

Low energy availability, not stress of exercise, alters LH pulsatility in exercising women.

We tested two hypotheses about the disruption of luteinizing hormone (LH) pulsatility in exercising women by assaying LH in blood samples drawn at 10-min intervals over 24 h from nine young, habitually sedentary, regularly menstruating women on days 8, 9, or 10 of two menstrual cycles after 4 days of intense exercise [E = 30 kcal.kg lean body mass (LBM)-1.day-1 at 70% of aerobic capacity]. To test the hypothesis that LH pulsatility is disrupted by low energy availability, we controlled the subjects' dietary energy intakes (I) to set their energy availabilities (A = I - E) at 45 and 10 kcal.kg LBM-1.day-1 during the two trials. To test the hypothesis that LH pulsatility is disrupted by the stress of exercise, we compared the resulting LH pulsatilities to those previously reported in women with similar controlled energy availability who had not exercised. In the exercising women, low energy availability reduced LH pulse frequency by 10% (P < 0.01) during the waking hours and increased LH pulse amplitude by 36% (P = 0.05) during waking and sleeping hours, but this reduction in LH pulse frequency was blunted by 60% (P = 0.03) compared with that in the previously studied nonexercising women whose low energy availability was caused by dietary restriction. The stress of exercise neither reduced LH pulse frequency nor increased LH pulse amplitude (all P > 0.4). During exercise, the proportion of energy derived from carbohydrate oxidation was reduced from 73% while A = 45 kcal.kg LBM-1.day-1 to 49% while A = 10 kcal.kg LBM-1.day-1 (P < 0.0001). These results contradict the hypothesis that LH pulsatility is disrupted by exercise stress and suggest that LH pulsatility in women depends on energy availability.

Adolescent↗

PubMed2006

The effect of functional tasks exercise and resistance exercise on health-related quality of life and physical activity. A randomised controlled trial.

BACKGROUND: Data regarding the effect of exercise programmes on older adults' health-related quality of life (HRQOL) and habitual physical activity are inconsistent. OBJECTIVE: To determine whether a functional tasks exercise programme (enhances functional capacity) and a resistance exercise programme (increases muscle strength) have a different effect on the HRQOL and physical activity of community-dwelling older women. METHODS: Ninety-eight women were randomised to a functional tasks exercise programme (function group), a resistance exercise programme (resistance group), or normal activity group (control group). Participants attended exercise classes three times a week for 12 weeks. The SF-36 Health Survey questionnaire and self-reported physical activity were obtained at baseline, directly after completion of the intervention (3 months), and 6 months later (9 months). RESULTS: At 3 months, no difference in mean change in HRQOL and physical activity scores was seen between the groups, except for an increased SF-36 physical functioning score for the resistance group compared with the control group (p = 0.019) and the function group (p = 0.046). Between 3 and 9 months, the self-reported physical functioning score of the function group decreased to below baseline (p = 0.026), and physical activity (p = 0.040) decreased in the resistance group compared with the function group. CONCLUSIONS: Exercise has a limited effect on the HRQOL and self-reported physical activity of community-living older women. Our results suggest that in these subjects HRQOL measures may be affected by ceiling effects and response shift. Studies should include performance-based measures in addition to self-report HRQOL measures, to obtain a better understanding of the effect of exercise interventions in older adults.

Activities of Daily Living↗

PubMed1981

Acute and long-term effects of vasodilator therapy on resting and exercise hemodynamics and exercise tolerance.

The acute hemodynamic response to vasodilators in patients with chronic heart failure has been well characterized, but less is known about the long-term hemodynamic effects of vasodilator therapy. We measured hemodynamic variables at rest and during upright exercise in 11 patients during the initiation of therapy with oral hydralazine and sublingual isosorbide dinitrate and, in eight of these, after 3 months of continuous treatment. Marked initial increases in resting cardiac output and stroke volume and reductions in wedge pressure were sustained during chronic therapy. Similarly, the early improvement in exercise hemodynamic measurements persisted in most subjects. Exercise tolerance, quantified as the maximum duration of treadmill exercise, increased modestly (7.7 +/- 2.6 to 8.9 +/- 3.3 minutes, 0.05 less than p less than 0.10) after several days on vasodilators and further (10.2 +/- 3.7 minutes, p less than 0.01) during long-term treatment. The acute hemodynamic effects of vasodilator therapy at rest or during exercise did not correlate well with the changes in exercise tolerance. Our findings suggest that the combination of hydralazine and isosorbide dinitrate improves cardiac performance at rest and during exercise in patients with chronic heart failure and that this improvement persists during chronic therapy. In most patients, this hemodynamic improvement is accompanied by greater exercise tolerance.

Acute Disease↗

PubMed1991

Reductions in exercise lactic acidosis and ventilation as a result of exercise training in patients with obstructive lung disease.

Though exercise training is part of most pulmonary rehabilitation programs, whether there is a physiologic basis for increased exercise tolerance is unclear. We sought to determine whether patients with chronic obstructive pulmonary disease (COPD) are capable of obtaining a physiologic training effect, as manifested by a reduction in blood lactate and ventilation (VE) at a given level of exercise. We also sought to determine whether training work rate determines the size of the training effect. Nineteen participants with COPD of predominantly moderate severity in an inpatient rehabilitation program performed two cycle ergometer exercise tests at a low and a high work rate for 15 min or to tolerance and also an incremental exercise test to tolerance. Arterial blood was sampled for blood gas and lactate analyses. Identical tests were performed before and after 5-day-per-week cycle ergometer training for 8 wk either for 45 min/day at a high work rate (average, 71 W) or for a proportionally longer time at a low work rate (average, 30 W). Average FEV1 was 56 +/- 12% predicted and did not change with training. Peak exercise lactate (average, 6.5 mEq/L) was not correlated with FEV1. For the high work rate training group, identical work rates engendered less lactate (4.5 versus 7.2 mEq/L) and less VE (48 versus 55 L/min) after training; the low work rate training group had significantly less lactate and VE decrease (p less than 0.01). Further, endurance time for the high constant work rate increased 73% in the high work rate training group but only 9% in the low work rate training group. At identical work rates, VE decrease average 2.5 L/min per mEq/L decrease in lactate (r = 0.75). We conclude that most COPD subjects studied increased blood lactate at low work rates. Many of these patients were able to achieve a physiologic training effect. Though total work was the same, training at a high work rate was more effective than was training at a low work rate. The lower VE requirement to perform exercise was in proportion to the lower lactate level, but the VE decrease for a given decrease in lactate was smaller than that seen in normal subjects (7.2 L/min/mEq/L), apparently because patients with COPD fall to hyperventilate in response to lactic acidosis (PaCO2 does not drop). These findings provide a physiologic rationale for exercise training of patients with COPD.

Acidosis, Lactic↗

PubMed2003

The effects of exercise and exercise-related changes in blood nitric oxide level on migraine headache.

OBJECTIVE: To observe the effects of moderate aerobic exercise on migraine headache, to assess exercise-related changes in blood nitric oxide (NO) levels, and to examine the impact of such changes on migraine attacks. DESIGN: Controlled clinical trial. SETTING: School of Physical Therapy and Rehabilitation. SUBJECTS: Forty women with general migraine attending the Neurology Department of the Faculty of Medicine Faculty of Dokuz Eylül University. INTERVENTION: Patients were assigned alternately into two groups: exercise group undertaking 1 hour aerobic exercise three times weekly, and a control group. MAIN OUTCOME MEASURES: Patients were assessed before and after treatment using three clinical scales--visual analogue scale for headache, Pain Disability Index and Quality of Life Scale--and chemiluminescence analysis for plasma nitric oxide. RESULTS: After the eight-week therapy period, patient complaints concerning the intensity, frequency and duration of pain had decreased significantly in both groups; however, visual analogue scale scoring showed better pain relief in the exercised group than in the controls (from 8.8 +/- 1.7 to 4.0 +/- 1.4 and from 8.5 +/- 0.8 to 7.0 +/- 0.9 respectively). Quality of life measures also revealed better migraine relief in the exercised women than in those who received medical treatment only. Blood NO rose significantly from pre- to post-therapy in the exercised group, but the change was not significant in the control group. CONCLUSION: The study showed that regular long-term aerobic exercise reduced migraine pain severity, frequency and duration possibly due to increased nitric oxide production.

Adult↗

PubMed1976

Effects of exercise on coronary collateralization--angiographic studies of six patients in a supervised exercise program.

The existence of coronary collaterals in man and a positive correlation of their extent with the degree of coronary artery obstruction has been shown. The theory that functional collateralization associated with coronary occlusive disease is a response to local hypoxia is widely advocated. It was theorized here that coronary heart disease patients might enhance coronary collateralization through exercise-induced myocardial hypoxia. This pilot study was carried out to test the specificity of coronary arteriography for measuring changes in collateralization after a period of exercise training. Reports of follow-up examinations 7 years after program termination are also included. Six volunteer, male subjects--3 months to 3 years post-myocardial infarction--completed 10-12 months of medically-supervised exercise. All had an intensive cardiovascular work-up, serial treadmill exercise tests and coronary arteriography before and after training. All demonstrated the expected physical, physiological, metabolic, and psychological benefits. Two showed some definite, increased collateralization, however, in both of these the changes may have been a response to some extension of the occlusive disease and not exclusively an exercise effect. It was evident that minute changes in coronary collaterals are detectable by selective coronary arteriography, but that the specific effect of exercise on the development of collaterals could only be determined by a large-scale, controlled program with randomization of the multiple, uncontrollable variables among exercise and non-exercise populations.

Adult↗

PubMed2003

Inflammatory markers and exercise: differences related to exercise type.

PURPOSE: To examine the relationship between elevated inflammatory markers (CRP, fibrinogen, and white blood cell levels) and various forms of exercise for the adult U.S. population while controlling for factors that might influence the relationship. METHODS: An analysis of the adults age 17 and over who participated in the National Health and Nutrition Examination Survey (NHANES) III was conducted. The main goal of the analysis was to determine whether exercise type was associated with systemic markers of inflammation. Bivariate statistics using chi-square to evaluate different types of exercise according to the presence of elevated and nonelevated inflammatory markers was initially performed. In addition, multivariate models were constructed using each type of exercise activity as the predictor variable and each inflammatory marker as the dependent variable. RESULTS: A total of 4072 people were included in the analysis. In bivariate analyses, compared with nonexercisers in a specific exercise type, a significant lower likelihood of elevated inflammatory markers was found among regular participants in jogging, swimming, cycling, aerobic dancing, calisthenics, and weight lifting but not for gardening. After controlling for possible confounding factors including age, race, sex, body mass index, smoking, and health status in logistic regression analysis, only regular participants in jogging and aerobic dancing remained significantly less likely to have elevated cardiovascular markers. CONCLUSIONS: The results of this study indicate that some forms of physical activity are associated with a lower likelihood of elevation of inflammatory markers, although we cannot exclude the possibility that differences may be due to exercise intensity or duration. Future research should be directed toward further exploration of the effects of different types of exercise activity on inflammatory markers and the role of exercise in the prevention of cardiovascular disease.

Adolescent↗

PubMed2003

Exercise behaviour change in 40 to 65-year-old women: The SWEAT Study (Sedentary Women Exercise Adherence Trial).

OBJECTIVE: The purpose of this study was to examine the relation between self-reported psychological processes and changes in exercise behaviour in an 18-month longitudinal stage-based intervention trial in 115 initially sedentary women aged 40-65 years. DESIGN: A two-way factorial design was used. METHODS: Participants were assigned randomly to either moderate or vigorous and either home or centre-based exercise. After six months, all participants exercised at home. Participants completed questionnaires at baseline, six, 12 and 18 months which assessed stage of exercise behaviour, self-efficacy, decisional balance and processes of change. RESULTS: 28 patterns of stage change were identified across the 18 months with 6.1% remaining sedentary and 45% demonstrating linear movement from contemplation to action to maintenance to continued maintenance. Two interpretable clusters were identified within both the contemplation (at baseline) and action (at six months) stages. Cluster membership, however, did not influence behaviour change. For participants demonstrating a linear pattern of change, self-efficacy for overcoming barriers and behavioural processes increased from contemplation to action. Self-efficacy for exercise competence increased from contemplation to action but was more pronounced for the vigorous exercise groups. Decisional balance showed a three-way interaction and there was no change for experimental processes. There was no change in any variable from action to maintenance. CONCLUSIONS: The intervention was seen to be effective regardless of location or intensity of exercise. The relevance of substages is questionable in stage-based interventions as women with a profile suggesting less readiness to change or sustain change were just as likely to adopt or maintain exercise.

Adult↗

PubMed1999

Emerging concepts in the evaluation of ventilatory limitation during exercise: the exercise tidal flow-volume loop.

Traditionally, ventilatory limitation (constraint) during exercise has been determined by measuring the ventilatory reserve or how close the minute ventilation (VE) achieved during exercise (i.e., ventilatory demand) approaches the maximal voluntary ventilation (MVV) or some estimate of the MVV (i.e., ventilatory capacity). More recently, it has become clear that rarely is the MVV breathing pattern adopted during exercise and that the VE/MVV relationship tells little about the specific reason(s) for ventilatory constraint. Although it is not a new concept, by measuring the tidal exercise flow-volume (FV) loops (extFVLs) obtained during exercise and plotting them according to a measured end-expiratory lung volume (EELV) within the maximal FV envelope (MFVL), more specific information is provided on the sources (and degree) of ventilatory constraint. This includes the extent of expiratory flow limitation, inspiratory flow reserve, alterations in the regulation of EELV (dynamic hyperinflation), end-inspiratory lung volume relative to total lung capacity (or tidal volume/inspiratory capacity), and a proposed estimate of ventilatory capacity based on the shape of the MFVL and the breathing pattern adopted during exercise. By assessing these types of changes, the degree of ventilatory constraint can be quantified and a more thorough interpretation of the cardiopulmonary exercise response is possible. This review will focus on the potential role of plotting the extFVL within the MFVL for determination of ventilatory constraint during exercise in the clinical setting. Important physiologic concepts, measurements, and limitations obtained from this type of analysis will be defined and discussed.

Exercise↗

PubMed2004

Significance of post-exercise increment of urinary bicarbonate and pH in subjects loaded with submaximal cycling exercise.

We studied the changes in urinary bicarbonate, urinary pH and some physical parameters such as minute ventilation (VE), oxygen consumption (VO2), respiratory carbon dioxide (VCO2), heart rate, blood pressure, and blood lactate, before and after the submaximal exercise. Six male subjects aged 28-33 years were involved in the study. They performed the incremental exercise test using a bicycle ergometer until exhaustion. Levels of VE, VO2, VCO2, heart rate, and blood pressure increased continuously with an increase in cycling intensity. These parameters markedly decreased and reached the baseline levels within 5-10 minutes after the termination of exercise. According to an increase in cycling intensity, blood lactate increased continuously during exercise, but after termination of exercise the return of lactate to the baseline level was markedly retarded. Urinary bicarbonate and pH were within the range of those at 0 time (baseline levels) from the beginning until 30 minutes after the exercise. However, they began to increase abruptly about 30 minutes after the exercise, and continued to increase extensively for 2 hours thereafter. Such marked increase in urinary bicarbonate and pH seemed to be correlated with the aerobic metabolism of lactate in the muscles, liver, and kidney, finally producing CO2. It was also suggested that the measurement of urinary bicarbonate and pH may be useful for the estimation of physiological changes in the body after submaximal incremental cycling exercise loading.

Adult↗