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PubMed1995

Exercise-induced rise in arterial potassium is enhanced in patients with impaired exercise tolerance.

We assessed the changes in arterial potassium concentration during exercise and recovery in relation to exercise tolerance in patients with impaired exercise tolerance. Sixteen patients with cardiac disease were subjected to a cardiopulmonary exercise test on a cycle ergometer. Arterial potassium and lactate concentrations were measured every minute during and after exercise, and ventilatory threshold (VT) and lactate threshold (LT) were identified. Before exercise, arterial potassium concentration was 3.8 +/- 0.3 mEq/l. It increased to 4.1 +/- 0.3 mEq/l at LT (p < 0.002 versus at rest), to 4.2 +/- 0.3 mEq/l at VT, and to 4.8 +/- 0.5 mEq/l at peak exercise (p < 0.001 versus at LT, p < 0.001 versus at VT). At an exercise intensity equivalent to 30, 40, 50 or 60% of predicted maximum oxygen uptake, the increase in arterial potassium showed a negative and significant correlation with %LT (r = -0.62 approximately -0.72, p < 0.01 approximately 0.05) and %VT (r = -0.62 approximately -0.75, p < 0.001 approximately 0.05), where %LT and %VT represent the ratios of LT and VT to the predicted maximum oxygen uptake, respectively. There was a good correlation between the rate of fall in potassium concentration during recovery and its increase during exercise. It was concluded that in patients with impaired exercise tolerance, the greater the degree of exercise intolerance, the greater the increase in arterial potassium concentration during exercise, and the steeper the fall in potassium concentration during recovery. Because the rise in potassium concentration during exercise and its fall during recovery were greater when the exercise level exceeded the anaerobic threshold, exercise levels below the anaerobic threshold are recommended for patients with cardiac diseases.

Aged↗

PubMed2000

Dipyridamole and exercise SPET provide different estimates of myocardial ischaemic areas: role of the severity of coronary stenoses and of the increase in heart rate during exercise.

In patients unable to perform a maximal exercise test, dipyridamole single-photon emission tomography (SPET) has a higher capacity than exercise SPET to detect coronary artery disease (CAD). However, in patients with myocardial ischaemia who are able to perform a maximal exercise test, it is not known whether these two tests may be equally used to assess the areas of myocardial ischaemia. This study was aimed at comparing the results provided by dipyridamole and exercise SPET in CAD patients with documented exercise myocardial ischaemia. Forty CAD patients who had undergone exercise thallium-201 SPET and who had myocardial ischaemia documented by an unequivocally positive exercise test underwent an additional 201Tl SPET study after dipyridamole infusion and low-level (40 W) exercise. The extent of defects was compared between the two tests and predictors of discrepant results were sought among data from exercise testing and coronary angiography. The extent of SPET defects was equivalent between the two tests in only 11 patients (28%), larger defects being observed with exercise in 18 [average difference: 12%+/-5% of left ventricle (LV)] and with dipyridamole in 11 (average difference: 15%+/-11% of LV). The best independent predictors of discrepancies between the two tests were: (1) increase in heart rate at exercise SPET, with defects being smaller at exercise than after dipyridamole in none of the patients with an increase >60 bpm (0/14), but in 42% of the others (11/26; P=0.004); and (2) an ischaemic territory related to a <70% coronary stenosis, for which SPET defects were always induced at exercise (10/10) but in only 30% (3/10) with dipyridamole (P=0.0004). Exercise and dipyridamole SPET provide different estimates of myocardial ischaemic areas. Dipyridamole allows the unmasking of perfusion abnormalities in patients who have low increases in heart rate at exercise SPET. However, dipyridamole is also much less efficient at inducing perfusion abnormalities in the ischaemic areas supplied by coronary stenoses of intermediate severity at rest angiography.

Coronary Angiography↗

PubMed2003

Effect of order of exercise intensity upon cardiorespiratory, metabolic, and perceptual responses during exercise of mixed intensity.

Exercise of mixed intensities can be of benefit in many different ways. However, whether physiological interaction exists between exercises of different intensity is questionable. As such, the primary aim of this study was to examine the effect of order of exercise intensity upon cardiorespiratory, metabolic, and perceptual responses during exercise of mixed intensity. Eight males and four females volunteered to serve as subjects for the study. They were informed of the purpose of the experiment and gave their written consent to participate. Each subject completed a peak oxygen uptake ( VO(2peak)) test and two submaximal exercises of mixed intensity on three separate laboratory visits. During each submaximal exercise trial, subjects performed a 15-min (high intensity) exercise at 70% VO(2peak) that was followed by another 15-min (low intensity) exercise at 50% VO(2peak) (high/low, H/L), or a 15-min exercise at 50% VO(2peak) that was followed by another 15-min exercise at 70% VO(2peak) (low/high, L/H). Oxygen uptake ( VO(2)), respiratory exchange ratio ( R), expired ventilation ( V(E)), heart rate (HR) and ratings of perceived exertion (RPE) were measured every 5 min throughout exercise. Energy expenditure and carbohydrate and fat oxidation were calculated from VO(2) adjusted for substrate metabolism using R and then accumulated for each phase of exercise intensity as well as for the entire exercise session. VO(2) and HR were higher ( P<0.05), while R was lower ( P<0.05) at the lower intensity in H/L than in L/H. V(E) and RPE were lower ( P<0.05) at the higher intensity in H/L than in L/H. While no differences in caloric expenditure and carbohydrate oxidation between the two trials were observed, fat oxidation was higher ( P<0.05) both at the lower intensity and for the entire trial in H/L than in L/H. It appears that during exercise of mixed intensity, placing some periods of moderate intensity exercise prior to a milder one is a more favorable sequence in that it can elicit a greater fat oxidation while being felt less stressful.

Adipose Tissue↗

PubMed2001

Substrate oxidation during acute exercise and with exercise training in lean and obese women.

The purpose of this study was to examine the rates of substrate oxidation in lean and obese women during short-duration, high-intensity exercise and to examine the effects of a 16-week exercise training program on substrate oxidation during 30 min of exercise in lean and obese individuals. Fat and carbohydrate oxidation were measured in 8 non-obese (Non-Ob), 11 lower-body obese (LBO) and 12 upper-body obese (UBO) women at rest and during 30 min of treadmill exercise at 70% of peak oxygen uptake. The obese women participated in 16 weeks of aerobic training (3 times per week at 70% of maximum oxygen uptake). Total fat and carbohydrate oxidation were measured using indirect calorimetry. The respiratory exchange ratio (R) was similar between groups at rest and was found to decrease throughout the exercise session (P< 0.01). Fat oxidation was greater at 15 min of exercise than at rest (P<0.01) but did not increase significantly more at 30 min of exercise. Obese women had significantly greater fat oxidation (both absolute concentrations and when expressed per kg of fat free mass, FFM) at 30 min of exercise than the Non-Ob women [Non-Ob 23.5 (3.7) micromol.kg FFM(-1).min(-1), LBO 35.2 (3.1) micromol.kg FFM(-1).min(-1), UBO 33.2 (2.6) micromol.kg FFM(-1).min(-1); P<0.01]. Carbohydrate oxidation also increased (P < 0.01) in response to exercise, but no group differences were found. The pattern of fat distribution (LBO vs UBO) did not affect the resting or exercise fat oxidation (P=NS). Sixteen weeks of aerobic exercise did not result in significant changes in resting or exercise fat oxidation in the obese women (n = 10; P=NS), but did significantly increase carbohydrate oxidation [pretraining 8.6 (1.4) micromol.kg FFM(-1), post-training 13.6 (2.1) micromol.kg FFM(-1).min(-1); P<0.01]. Unlike earlier studies, this shorter-duration, higher-intensity exercise resulted in a greater whole-body fat oxidation in the obese women than in the Non-Ob women, and exercise training did not result in any changes in fat oxidation, but did increase exercise carbohydrate oxidation.

Abdomen↗

PubMedDate not supplied

The impact of adjunctive adenosine infusion during exercise myocardial perfusion imaging: Results of the Both Exercise and Adenosine Stress Test (BEAST) trial.

BACKGROUND: Failure to achieve an adequate heart rate limits the sensitivity of exercise myocardial perfusion imaging (MPI) for the detection of coronary artery disease. In addition, it is often not possible to discontinue medications that may blunt the heart rate response to exercise, because of conditions such as hypertension or angina. However, if pharmacologic stress testing is performed, the ability to assess functional capacity is lost. Accordingly, we developed a protocol that incorporates adenosine stress with symptom-limited exercise. METHODS AND RESULTS: As part of a multicenter study, 35 patients were enrolled prospectively and underwent both exercise MPI and exercise MPI with a 4-minute adenosine infusion on a separate day. Technetium 99m sestamibi was injected at or near peak exercise (exercise only) and at 2 minutes into the adenosine infusion (combined exercise and adenosine). The perfusion images were interpreted in a blinded fashion. The combined adenosine and exercise protocol was well tolerated. The summed stress scores and summed difference scores were greater in the exercise-plus-adenosine group than in the exercise-only group (10.0 vs 8.5, P =.02, and 4.9 vs 3.3, P =.002, respectively). Exercise time was slightly but significantly less with the exercise-plus-adenosine protocol (8 minutes 46 seconds vs 8 minutes 11 seconds, P =.027). CONCLUSION: A protocol combining 4 minutes of adenosine infusion with symptom-limited exercise was safe and well tolerated. Furthermore, this protocol resulted in a greater amount of myocardial ischemia detected on MPI while allowing for the assessment of functional capacity. A combined exercise and adenosine protocol may be a useful test for patients undergoing MPI who are unlikely to achieve an adequate chronotropic response.

Adenosine↗

PubMedDate not supplied

Physiotherapy exercise programmes: are instructional exercise sheets effective?

Effective compliance with physiotherapy exercises is only possible if patients remember the exercises accurately. The purpose of this study was to assess how well elderly in-patients remembered simple physiotherapy exercises, by comparing the ability to accurately reproduce a set of exercises in a group of patients that had received a written exercise sheet, with a group that had not. The study also aimed to investigate the relationship between memory for exercises and cognition. Sixty-four in-patients in an acute hospital were taught 3 exercises. Half of the subjects were randomised to receive exercise sheets to reinforce the teaching (Group 1). The rest of the subjects did not receive this memory aid (Group 2). Two to three days later subjects were asked to demonstrate their exercises. The accurate recall of the exercises was scored using a new assessment scale with a maximum score of 24. The mean exercise score was 17.19 for group 1 (SD = 5.91) and 16.24 for Group 2 (SD = 6.01). There was no significant difference in exercise score between groups (Mann Whitney U test p = 0.44). There was a statistically significant small positive correlation between exercise score and cognition (tau = 0.263). The study showed that older adult in-patients do not remember physiotherapy exercises effectively after a single teaching session and that their memory is not significantly improved by provision of an exercise sheet.

Aged↗

PubMed2000

"It's exercise or nothing": a qualitative analysis of exercise dependence.

OBJECTIVES: To explore, using qualitative methods, the concept of exercise dependence. Semistructured interviews were undertaken with subjects screened for exercise dependence and eating disorders. METHODS: Female exercisers, four in each case, were allocated a priori to four groups: primary exercise dependent; secondary exercise dependent, where there was a coincidence of exercise dependence and an eating disorder; eating disordered; control, where there was no evidence of either exercise dependence or eating disorder. They were asked about their exercise and eating attitudes and behaviour, as well as about any history of psychological distress. Their narratives were taped, transcribed, and analysed from a social constructionist perspective using QSR NUD*IST. RESULTS: Participants classified as primary exercise dependent either showed no evidence of exercise dependent attitudes and behaviour or, if they exhibited features of exercise dependence, displayed symptoms of an eating disorder. Only the latter reported a history of psychological distress, similar to that exhibited by women classified as secondary exercise dependent or eating disordered. For secondary exercise dependent and eating disordered women, as well as for controls, the narratives largely confirmed the a priori classification. CONCLUSIONS: Where exercise dependence was manifest, it was always in the context of an eating disorder, and it was this comorbidity, in addition to eating disorders per se, that was associated with psychological distress. As such, these qualitative data support the concept of secondary, but not primary, exercise dependence.

Adult↗

PubMed2000

Capsaicin-induced muscle hyperalgesia in the exercised and non-exercised human masseter muscle.

AIMS: Strong jaw muscle exercises such as tooth grinding in sleep bruxism are frequently believed to be a predisposing factor in myogenous types of temporomandibular disorders. However, it is not known whether tooth grinding in sleep bruxism is associated with increased sensitivity to intramuscular stimuli. This study therefore compared the hyperalgesic effects of an intramuscular injection of capsaicin into the right masseter with and without a prior experimental tooth-grinding exercise. METHODS: Ten healthy men participated in 2 randomized sessions (exercise, non-exercise session) separated by 1 week. In the exercise session, 0.1 mL capsaicin (100 micrograms/mL) was injected into the right masseter immediately after 45 minutes of experimental tooth grinding. In the non-exercise session, the exact same paradigm was used, except that the experimental tooth grinding was omitted. The perceived intensity of pain evoked by intramuscular capsaicin was scored on a 100-mm visual analog scale (VAS). Pain detection thresholds (PDTs) to pressure stimuli and maximal voluntary occlusal force (MVOF) were measured before capsaicin injection; 5, 15, and 45 minutes after the injection; and once a day for the following 3 days. RESULTS: Injections of capsaicin into an exercised or non-exercised masseter did not cause significant differences in peak pain intensity on the VAS (57 +/- 6 mm in exercised masseter vs. 53 +/- 6 mm in non-exercised masseter; P = 0.464). The PDTs in the exercised masseter were significantly decreased for up to 1 day after the capsaicin injection (P < or = 0.038), whereas PDTs in the non-exercised masseter were decreased for only 5 minutes (P = 0.017). The MVOF on the right side was decreased 5 minutes after the capsaicin injection in both sessions (P < 0.010). The MVOF on the left side was significantly reduced for up to 15 minutes after the capsaicin injection in the exercise session only (P < 0.019). CONCLUSION: Increased sensitivity to percutaneous pressure stimuli probably reflects a post-exercise muscle soreness following tooth grinding, whereas intramuscular sensitivity to noxious chemical stimuli immediately following exercise seems to be unchanged.

Adult↗

PubMed1996

Effects of exercise intensity and environmental stress on indices of oxidative stress and iron homeostasis during exercise in the horse.

The effects of prolonged variable-intensity and short-term high-intensity exercise on indices of oxidative stress and iron homeostasis were compared in six fit horses under cool [20 degrees C, 40% relative humidity (RH)] or hot/humid (30 degrees C, 80% RH) environmental conditions. The exercise protocols were designed to simulate equine competition, including racing (intense exercise) or the speed and endurance phase of a 3-day event (prolonged exercise). Increased plasma concentrations of lipid hydroperoxides and haemolysate concentrations of oxidised glutathione (GSSG) were measured within 30 min of the completion of exercise, indicating production of reactive oxygen species (ROS) and lipid membrane peroxidation. The horses were unable to complete the prolonged exercise protocol at high temperature and humidity. This coincided with higher maximal values of lipid hydroperoxides [138.2 (17.7) microM and GSSG [110.6 (18.2) microM], compared to high-intensity [105.2 (14.9) microM and 63.6 (8.6) microM, respectively] or prolonged [100.7 (18.7) microM and 86.2 (9.1) microM, respectively] exercise performed under cooler environmental conditions. Significant correlations were found between the duration of the final stage of exercise during hot/humid environmental conditions and increased levels of lipid hydroperoxides (r = 0.85), GSSG (r = 0.94), xanthine (r = 0.92) and uric acid (r = 0.96). Exercise also decreased the iron (Fe)-binding antioxidant activity of the plasma and increased the total plasma Fe levels, although this was only significant for prolonged exercise in ambient conditions. There was no detectable free Fe in the plasma at any stage of exercise. Other changes in biochemical parameters had returned to pre-exercise levels within 24 h after exercise. The results show that exercise can induce changes in biochemical parameters that are indicative of oxidative stress in the fit horse and that this was, exacerbated during exercise at high temperature and humidity.

Animals↗

PubMed2005

Influence of exercise order on the number of repetitions performed and perceived exertion during resistance exercises.

This study examined the performance effects of exercise order during a resistance-training session composed of only upper-body exercises. The 10 repetition maximum of 14 men and 4 women with at least 6 months of previous weight-training experience was determined for 5 upper-body exercises. Each subject then completed 2 training sessions separated by 48 hours in a counterbalanced crossover design. One session began with exercises of the large-muscle group and progressed to exercises of the small-muscle group (sequence A), whereas the other session was performed with the opposite exercise sequence (sequence B). The exercise order for sequence A was free-weight bench press (BP), machine lat pull-down (LPD), seated machine shoulder press (SP), standing free-weight biceps curl (BC) with a straight bar, and seated machine triceps extension (TE). The exercise order for sequence B was TE, BC, SP, LPD, and BP. During both sequences, 3 sets of each exercise were performed to concentric failure, with 2-minute recovery intervals between sets and exercises. Performing exercises of both the large- and the small-muscle groups at the end of an exercise sequence resulted in significantly fewer repetitions in the 3 sets of an exercise. This decrease in the number of repetitions performed was especially apparent in the third set when an exercise was performed last in an exercise sequence.

Adult↗

PubMed2003

Effects of three different types of exercise on blood leukocyte count during and following exercise.

CONTEXT: High-intensity exercise causes tissue damage, production of stress hormones, and alterations in the function and quantity of various immune cells. Many clinical-physical stressors such as surgery, trauma, burns and sepsis induce a pattern of hormonal and immunological response similar to that of exercise. It has thus been suggested that heavy exercise might be used to cause graded and well-defined amounts of muscle trauma, thereby serving as an experimental model for inflammation and sepsis. OBJECTIVE: In order to explore whether some form of strenuous exercise might provide an useful model for the inflammatory process, we studied the effects of three different exercise protocols on blood leukocyte count during and following exercise. DESIGN: Four different experimental conditions, using a randomized-block design. SETTING: Defence and Civil Institute of Environmental Medicine, North York, Ontario, Canada. PARTICIPANTS: Eight healthy and moderately fit males. PROCEDURES: Participants were each assigned to four experimental conditions. Subjects performed 5 minutes of cycle-ergometry exercise at 90%, 2 hours of cycle-ergometry exercise at 60%, a standard circuit of resistance exercises with 3 sets of 10 repetitions at 60 to 70% of one-repetition maximum (1-RM) force at each of 5 different stations; or they remained seated for 5 hours. DIAGNOSTIC TEST USED: Flow cytometric analysis. MAIN MEASUREMENTS: Blood samples were analyzed for total leukocyte counts, total T cells, T helper/inducer cells, T suppressor/cytotoxic cells, B cells, cytolytic T cells, and natural killer cells. RESULTS: The peak aerobic and prolonged submaximal exercise induced similar alterations in cell counts. These changes were generally larger than those produced by the resistance exercise, although both resistance and peak aerobic exercise resulted in a significantly longer-lasting decrease in the CD4+/CD8+ ratio than the submaximal exercise bout did. CONCLUSION: The data suggest that, of the three exercise patterns tested, prolonged aerobic exercise induced the largest and most readily measured patterns of immune response. Nevertheless, the changes provided only a partial model for the clinical inflammatory process.

Adult↗

PubMed1997

Respiratory oxygen cost for dead space challenge is characteristically increased during exercise in patients with chronic heart failure: does it further decrease exercise capacity?

BACKGROUND: Although the work of the respiratory muscles is markedly increased during exercise in patients with chronic heart failure, the role of this abnormality in exercise intolerance is still controversial. This issue may be clarified directly by dead space challenge, as this technique increases minute ventilation. Therefore, in this study, the effects of an external dead space on exercise ventilation, gas exchange data, and exercise capacity in patients with chronic heart failure were examined. METHODS AND RESULTS: Dead space challenge was performed by adding an external dead space to the airway in 20 patients with chronic heart failure and 10 normal subjects. Two hours after completion of the control maximal bicycle exercise, the second exercise was performed under application of an external dead space equivalent to 10% of peak tidal volume. Respiratory gas exchange data were collected during exercise. Aerobic exercise capacity was assessed from the exercise time and the time to anaerobic threshold. The sensation of exertional dyspnea was assessed using Borg's rating scale. As compared with data during the control exercise, minute ventilation was increased by approximately 25% with the external dead space throughout exercise in both groups. A parallel 20% increase in systemic oxygen uptake was observed in the heart failure group, likely reflecting an increase in respiratory muscle work. This response was not observed in the normal group. Despite an additional increase in respiratory muscle work, neither aerobic exercise capacity nor exertional dyspnea was exacerbated in the heart failure group by the external dead space. CONCLUSIONS: Dead space challenge appears to be a unique technique that characteristically increases the work of respiratory muscles during exercise in patients with chronic heart failure. By use of this technique, it was demonstrated that an increase in respiratory muscle work is not important in reducing exercise capacity of patients with chronic heart failure.

Adult↗

PubMed2001

Post exercise hypotension is sustained during subsequent bouts of mild exercise and simulated activities of daily living.

Our purpose was to examine whether the transient suppression of blood pressure that occurs during the hours following acute exercise (termed post exercise hypotension) persists throughout an active period of subsequent mild exercise and simulated activities of daily living (ADL) using direct measurements of arterial pressure. Eight recreationally active participants, with low borderline systolic hypertension completed 30 min of cycle ergometry at 70% VO(2Peak) and 30 min of quiet seated rest on separate days (randomised order). Following exercise and rest, subjects completed a 70-min protocol of mild exercise and simulated ADL. Blood pressure was monitored throughout by catheterisation of the radial artery. Exercise resulted in lower systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) throughout the post exercise ADL period compared to control measurements taken without prior exercise. The maximal difference in SBP, DBP and MAP between trials was 26, 7 and 13 mm Hg respectively. Average differences in SBP, DBP and MAP between trials were 16, 5 and 8 mm Hg respectively. This relative hypotension occurred in spite of higher heart rates during the ADL measurement period following the prior exercise. Furthermore, many of the blood pressure measurements during the post exercise period were significantly lower than the pre-exercise values during the same trial. We conclude that post exercise hypotension persists during mild exercise and simulated ADL. Although the duration of this relative hypotension needs to be determined, acute exercise may serve as a non-pharmacological aid in the treatment of hypertension.

Activities of Daily Living↗

PubMed1999

Beneficial effects of exercise training in heart failure patients with low cardiac output response to exercise - a comparison of two training models.

BACKGROUND: Exercise capacity of patients with chronic heart failure (CHF) correlates poorly with estimates of cardiac function. Yet, it has been suggested that only patients without severely impaired cardiac output (CO) benefit from exercise training. Comparisons of different training models have not been made in the same study. AIMS: To evaluate whether the response to different training models diverges according to the cardiac output response to exercise in patients with chronic heart failure. METHODS: Sixteen CHF patients (63 +/- 11 years) with an ejection fraction of 30 +/- 11% underwent a baseline cardiopulmonary exercise test, right heart catheterization and leg muscle biopsy. Cardiac output (CO) response to exercise was defined as the ratio between CO increase and the increase in oxygen uptake (CO response index) during exercise. Patients were randomized into two training regimens, differing with regard to active muscle mass, i.e. whole body and one-legged exercise. RESULTS: Baseline exercise capacity expressed as W kg-1 correlated with the CO response index (r = 0.51, P < 0.05). Exercise capacity on the cycle ergometer increased in both groups but more in the one-legged than in the two-legged training group (P < 0.05). The improvement in exercise capacity did not correlate with base-line exercise capacity. It correlated with CO response index in the one-legged (r = 0.75, P < 0.01) but not in the two-legged training group. CO response index correlated negatively with the pulmonary capillary wedge pressure at peak exercise (r = - 0.60, P < 0.05). The increase in leg muscle citrate synthase activity after training correlated negatively with the baseline CO response index (r = - 0. 50, P < 0.05). CONCLUSIONS: The improvement of exercise capacity after one-legged training correlates with the CO increase in relation to the O2 uptake before training. In patients with low CO response, individualization of the exercise regimen is needed and the benefits of training a limited muscle mass at a time deserve further study.

Adult↗

PubMed2002

Effects of exercise training plus normalization of hematocrit on exercise capacity and health-related quality of life.

The limitation to exercise capacity in hemodialysis patients has been attributed to anemia. We report the effects of normalization of hematocrit levels by using r-hu-recombinant erythropoietin and exercise training on exercise capacity and self-reported physical functioning in hemodialysis patients. Sixty-five patients were randomized into 1 of 4 groups: usual hematocrit (30%-33%) with no exercise training (UH); usual hematocrit (30%-33%) plus exercise training (UHX); normalized hematocrit (40%-42%) with no exercise training (NH); and normalized hematocrit (40%-42%) plus exercise training (NHX). Treadmill exercise testing was conducted at baseline and at 5 months after the initiation of the interventions. Analysis was performed on the data collapsed for 48 patients who met the criteria for hematocrit and exercise adherence and completed both baseline and post intervention (5.6 +/- 1.6 months) testing. Significant effects of exercise were found in peak oxygen uptake measurements (P = 0.03) and in self-reported physical functioning as measured by the Short Form-36 questionnaire (P = 0.01). There was a significant effect of hematocrit on the General Health scale on the SF-36 (P = 0.03). The changes in peak oxygen uptake with exercise training were small and levels remained lower than age-predicted values at the end of the study. These results indicate that there are other physiologic limitations to exercise capacity that are not overcome by exercise training or normalization of hematocrit. The effects of exercise training on self-reported physical functioning may be of clinical importance because these scores have been shown to be highly predictive of outcomes such as hospitalizations and mortality in hemodialysis patients.

Adult↗

PubMed2000

Exercise-induced bronchoconstriction depends on exercise load.

UNLABELLED: Exercise-induced bronchoconstriction (EIB) is often used as a measure of bronchial hyperresponsiveness and employed in epidemiological studies. Different tests are used, including free running tests with poor standardization of exercise load. The present study aimed to assess the role of exercise load in relationship to level of EIB. METHODS: 20 asthmatic children, 9-17 years old with a history of EIB, underwent two treadmill test with 85% and 95% exercise load. The children ran with increasing speed for the first 2 min until reaching a heart rate of 85% or 95% of calculated maximum (220-age) and maintained this speed for the last 4 min. Lung function was measured before running, and 0, 3, 6, 10 and 15 min after the run. Borg scale for perceived exertion was employed for children's self-evaluation of exercise load. RESULTS: Peak heart rate, mean Borg score during 85% exercise load was 178.7/13.6 and during 95% was 194.3/18.2 (P<0.001). Maximum fall in FEV1 after 85% exercise load was 8.84% vs. 25.11% after 95% (P<0.001). Nine subjects (40%) fell > or = 10% in FEV1 after 85% exercise load vs. 20 subjects (100%) after 95% exercise load. EIB from the 95% exercise load test had markedly higher correlation with serum ECP (r=0.77, P<0.001). CONCLUSION: Exercise load is essential for the interpretation of EIB, and strict standardization of exercise tests should be undertaken. The EIB from the high exercise load tests seemed better correlated to inflammatory activity than the low exercise load test.

Adolescent↗

PubMed1997

The asthmatic athlete: metabolic and ventilatory responses to exercise with and without pre-exercise medication.

To determine whether asthmatic athletes have normal physiological responses to exercise without pre-exercise medication, we studied 17 female and male asthmatic subjects, 9 highly trained (HT) and 8 moderately trained (MT) under 2 conditions: salbutamol (S) 200 micrograms taken via inhaler 15 minutes prior to exercise or placebo (PL). The exercise task was 4 continuous 5 minute increments representing 25, 50, 75 and 90% of the subject's VO2max.VO2, minute ventilation (VE), respiratory exchange ratio (RER), % saturation (SaO2), and HR were continuously measured during exercise. Blood lactate (LA) was measured each minute throughout exercise and recovery. Post-medication, exercise, and recovery measurements of peak expiratory flow rates (PEFR) were made using a Mini-Wright flow meter. No differences (p > 0.05) between treatment conditions were found at any stage of exercise with respect to VO2, VE, RER, HR and SaO2. However, among the HT group the mean HR for the 4 exercise conditions was significantly higher under PL (PL = 151.7;S = 147.2; p = 0.01). No difference was found in LA during exercise or in recovery. Pre-exercise PEFR was significantly higher when pretreatment was S(S = 582; PL = 545 l.sec-1; p = 0.003). During the exercise and recovery conditions mean PEFR measures were significantly higher (S = 600.1; PL = 569.6; p = 0.002) with the S treatment. Bonferroni's test detected a difference in PEFR measures between S and PL at 25% and 50% VO2max and 3 and 15 minutes into recovery. There was no difference in the physiological response to exercise between groups based on training status. It was concluded that although S affects the PEFR these asthmatic athletes do not have altered metabolic or ventilatory responses during this incremental exercise protocol.

Adult↗

PubMed1993

Reduction of mismatch of global ventilation and perfusion on exercise is related to exercise capacity in chronic heart failure.

BACKGROUND: The inability to match lung perfusion to ventilation because of a reduced cardiac output on exercise contributes to reduced exercise capacity in chronic heart failure. OBJECTIVE: To quantify ventilation to perfusion matching at rest and at peak exercise in patients with chronic heart failure and relate this to haemodynamic and ventilatory variables of exercise capacity. DESIGN: Eight men in New York Heart Association class II underwent maximal bicycle ergometry with expired gas analysis. MAIN OUTCOME MEASURES: On separate days, ventilation and perfusion gamma camera imaging was performed at rest, and at 80% of previous peak exercise heart rate during bicycle ergometry. The vertical distribution of mismatch between ventilation and perfusion (V/Q) was estimated from subtracted profiles of activity (ventilation and perfusion) to derive a numerical index of global mismatch. RESULTS: Maximal mean (SD) oxygen consumption on bicycle ergometry was 16.0 (4.5) ml min-1 kg-1. There was a reduction in the global V/Q mismatch index from 23.96 (5.90) to 14.88 (7.90) units (p < 0.01) at rest and at peak exercise. Global V/Q mismatch index at peak exercise correlated negatively with maximal minute ventilation (R = -0.90, p < 0.01) and with maximal mean arterial pressure (R = -0.79, p < 0.05), although no relation was seen with maximal oxygen consumption. The reduction in global V/Q mismatch index from rest to peak exercise correlated with maximal oxygen consumption (R = 0.88, p < 0.01), and with maximal minute ventilation (R = 0.87, p < 0.01). CONCLUSIONS: During exercise in patients with chronic heart failure, there is a reduction in the global V/Q mismatch index. A lower global V/Q mismatch index at peak exercise is associated with higher maximal ventilation. The reduction in global V/Q mismatch index on exercise correlates well with maximal exercise capacity. This may imply that the inability to perfuse adequately all regions of lung on exercise and match this to ventilation is a factor determining exercise capacity in chronic heart failure.

Aged↗