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PubMed1993

[Comparison of VVI and DDD cardiac stimulation during exercise test evaluated by respiratory gas exchange measurement. Study of patients with normal systolic function and complete atrioventricular block unchanged during exercise test].

The aim of this study was to compare respiratory gas exchanges during exercise during VVI and DDD modes of cardiac pacing, the latter offering the possibility of preserving the atrio-ventricular sequence and of increasing the heart rate during exercise. Ten patients with normal systolic function (6 men, 4 women; average age 51 years), complete atrioventricular block and no acceleration of the heart rate during exercise, undergoing implantation of a dual-chamber pacemaker, performed maximal exercise stress testing after programming VVI or DDD modes successively with a one hour interval between the two investigations. The parameters recorded at peak exercise capacity were compared according to the pacing mode. Exercise duration (8 +/- 2 mn), maximal heart rate (133 +/- 10 bpm), systolic blood pressure (175 +/- 24 mmHg), work load (104 +/- 20 watts) were significantly higher in the DDD than in the VVI mode (6 +/- 2 mn, 73 +/- 8 bpm, 147 +/- 22 mmHg, 84 +/- 17 watts respectively, p < 0.001 for each parameter). Above all, peak oxygen uptake in the DDD mode was 23.2 +/- 6 ml/kg/mn compared to 19.2 +/- 5.1 ml/kg/mn in the VVI mode (p < 0.001). The increased heart rate obtained with DDD pacing seems to be the main factor which explains the differences observed. At lower exercise levels, there was no significant difference in ventilatory threshold between VVI and DDD pacing. The absence of underlying cardiac disease and a single, fixed atrioventricular delay may reduce the value of maintaining the atrioventricular sequence at more moderate exercise levels. This study shows that dual-chamber pacing increases maximal exercise capacity. These observations may be useful when considering the choice of a cardiac pacemaker.

Adolescent↗

PubMed2001

Assessing the effect of exercise training in men with heart failure; comparison of maximal, submaximal and endurance exercise protocols.

AIMS: No consensus exists regarding the most appropriate exercise testing protocol for patients with congestive heart failure. This study describes the effect of exercise training on performance using three different protocols (maximal, submaximal and endurance testing) in patients with heart failure. METHODS AND RESULTS: Thirty men (mean age 67+/-8 years) with congestive heart failure in NYHA class III (mean ejection fraction 32+/-5%) were evaluated prior to and following exercise training. A maximal exercise cycle test with gas exchange measurements, a submaximal 6 min walk test and an endurance treadmill test with blood lactate sampling were used to evaluate exercise capacity after 12 weeks of exercise training. There was a 44.6% (P<0.001) increase in work performed during the maximal cycle test, with no significant increase in peak VO(2). The distance covered by the submaximal 6 min walk test increased by 8.1% (P<0.001). Lactate measured as area under the curve during the matched work intensity treadmill endurance test was reduced by 19.5% (P<0.005). CONCLUSION: We demonstrated a significant improvement in maximal, submaximal and endurance exercise capacity following 12 weeks of exercise training in patients with congestive heart failure. Endurance tests may be more sensitive and appropriate when assessing the efficacy of intervention in this population. Specifically, demonstration of reduced lactate production at matched work intensities suggests more efficient work and decreased dependence on anaerobic metabolism following training. Although maximal cycle tests are commonly used in clinical work, submaximal and endurance testing might be preferable for evaluating new treatment regimens in this population as they are easy to perform, are reproducible, and reflect daily tasks better than the maximal cycle test in this population.

Aged↗

PubMedDate not supplied

Short-term exercise training in patients with chronic atrial fibrillation: effects on exercise capacity, AV conduction, and quality of life.

PURPOSE: A randomized study was conducted to determine whether short-term exercise training in patients with chronic atrial fibrillation (AF) might improve exercise capacity and quality of life (QOL), and influence atrioventricular conduction. METHODS: Atrial fibrillation patients (age 64 +/- 7 years) were randomized to exercise training (n = 15) or a 2-month control period (n = 15) followed by the training program. Twenty-four training sessions consisted of aerobic exercise and muscle strengthening. A cycle ergometer test and a 15-minute resting high-frequency spectral electrocardiogram analysis were performed and a QOL questionnaire (SF-36) was completed before and after training. Because there were no changes after 2 months in the control group, pooled data for all patients are presented before and after training. RESULTS: Cumulated work at Borg scale 17 increased by 41% +/- 36%. Heart rate at rest and after 10 minutes of exercise decreased from 75 +/- 14 to 68 +/- 14 bpm and 145 +/- 19 to 137 +/- 21 bpm, respectively. HF increased from 81 +/- 17 to 91 +/- 22 milliseconds. Four of the 8 scales and 1 of the 2 summary scales of the Short-Form-36 improved. P <.05 for all results. CONCLUSIONS: Exercise capacity, heart rate variability, and QOL improved after 2 months of exercise training in patients with chronic AF. Heart rates at rest and during exercise decreased.

Aged↗

PubMed1990

Effects of humid air breathing during arm or treadmill exercise on exercise-induced bronchoconstriction and refractoriness.

Although it has been reported that inhibitory prostaglandins may be a causal factor in exercise refractoriness, it is still unclear whether exercise-induced bronchoconstriction (EIB) and/or other specific "exercise factors" are necessary to trigger their release and render a subject refractory to subsequent exercise. The purpose of this study was to determine whether non-EIB-producing exercise with the legs or arms could produce refractoriness to a standard treadmill challenge. Eight asthmatic subjects with EIB completed three sessions consisting of two exercise challenges separated by a 30-min rest. In all sessions, the second challenge was done on a treadmill while breathing dry air. Conditions for Challenge 1 were the following: Session A = treadmill, dry air; Session B = treadmill, humid air; Session C = arm cranking, humid air. All three conditions produced a significant degree of refractoriness. There was a tendency for the percent protection index to be greater for Session A; however, no significant differences were found among the three sessions. Therefore, it can be concluded that although both exercise and bronchoconstriction may play a role in producing the refractory period, neither severe bronchoconstriction nor intense exercise with the same muscle groups are required to produce refractoriness.

Adult↗

PubMed1999

Effects of exercise training on the recovery of the autonomic nervous system and exercise capacity after acute myocardial infarction.

This study investigated the effects of aerobic exercise training on the early phase of the recovery process following acute myocardial infarction (AMI) in terms of the autonomic nervous system, cardiac function and exercise capacity. Twenty-eight patients in the first week after the onset of AMI were assigned randomly to either a training group or a control group. The training group performed aerobic exercise for 2 weeks. Cardiopulmonary exercise testing was performed 3 times during the 3 months after the onset. Heart rate variability, plasma norepinephrine (NE) levels, and cardiac index (CI) during exercise were measured. In the training group, plasma NE level and deltaCI (peak CI-rest CI) were significantly improved from 1 to 3 weeks after the onset, and the high frequency of heart rate variability and peak oxygen uptake were significantly increased up to 3 months after the onset. In the control group, the plasma NE level and the deltaCI during the 1-3 weeks post-AMI, the high frequency of heart rate variability and the peak oxygen uptake showed a tendency to improve up to 3 months after the onset. These results indicate that sympathetic nervous activity improves soon after the onset of AMI, in conjunction with improvement in cardiac function, and that this improvement is not affected by exercise training. In contrast, the recovery of parasympathetic nervous activity requires a longer period, along with the recovery of exercise capacity, which is facilitated by even short-term aerobic exercise training.

Aged↗

PubMed2000

Effect of long-term exercise training on blood viscosity during endurance exercise at an anaerobic threshold intensity.

Blood viscosity (etaB) is low in athletes, but the effect of exercise training on etaB during endurance exercise at an anaerobic threshold (AT) intensity in non-athletes is not well known, although it is known that exercise training sometimes induces the hyperviscosity syndrome. Fourteen subjects were recruited and divided into 2 groups: those who trained at an AT intensity for 30 min/day, 3 times weekly for 1 year (Group T, n=8), and sedentary subjects (Group C, n=6). The test protocol consisted of a single 30-min treadmill exercise at each individual's AT intensity, which was determined in advance. The etaB, plasma viscosity (etaP), and hematocrit were measured just before and at the end of the treadmill exercise. The subjects were not allowed to drink any water before exercise. In the Group C subjects, the hematocrit and etaP increased significantly and the etaB tended to increase. However, in the Group T subjects, the hematocrit and etaP did not increase and the etaB decreased significantly. These data indicate that long-term exercise training attenuates the increase in blood viscosity during exercise.

Adult↗

PubMed1990

Real and pseudo late asthmatic reactions after submaximal exercise challenge in patients with bronchial asthma. A new definition for late asthmatic responses after exercise challenge.

The late asthmatic reaction after exercise challenge remains a controversial issue. In this study, 21 patients recorded peak expiratory flow rate (PEFR) on two control days without performing exercise. There was no difference between both control days when PEFR at 1 h was compared with baseline PEFR and when PEFR at 4 to 13 hours was compared with baseline PEFR. After analyzing variation coefficients of baseline PEFR on a control day and exercise day, PEFR was not allowed to differ more than 15.3 percent in the same patient when comparing exercise day and control day for the late fall in PEFR in the study. In 17 of 81 patients, a late asthmatic reaction after exercise challenge was present when PEFR fall was greater than or equal to 20 percent compared with baseline PEFR value. In eight of the 17 patients, a real late asthmatic reaction to exercise challenge was present with a PEFR fall greater than or equal to 20 percent on at least three successive time points and who had a PEFR fall greater than or equal to 20 percent compared with corresponding clocktime on a control day. The late asthmatic reaction to exercise challenge is characterized not as a nonspecific epiphenomenon, but as a fall in PEFR of greater than or equal to 20 percent compared with baseline PEFR value and with corresponding clocktime on a control day on at least three successive time points. Graphic illustration of airway responses following exercises may facilitate the detection of a late asthmatic response.

Adult↗

PubMed2002

[Changes in blood volume in the muscles of the thigh and calf during exercise and recovery and their relationships to exercise tolerance in patients with cardiac disease].

OBJECTIVES: This study compared the blood-volume changes and recovery in the thigh and calf during leg exercise and evaluated the relationships to exercise tolerance. METHODS: The peak oxygen uptake and total hemoglobin level(blood-volume index), oxyhemoglobin level, and deoxyhemoglobin level in the thigh and calf were measured by near-infrared spectroscopy during leg ergometer exercise and recovery in 13 patients with cardiac disease(mean age: 66 +/- 6 years, left ventricular ejection fraction: 31-82%). RESULTS: There was no significant difference between the increase in blood-volume index during exercise in the thigh and that in the calf. The increase in the blood-volume index during recovery in the calf was significantly greater than that in the thigh, mainly due to the difference in deoxyhemoglobin levels. There were no positive relationships between the peak oxygen uptake and increases in blood-volume index except for the increase in blood-volume index in the thigh during exercise(r = 0.73). CONCLUSIONS: There was no significant difference between the increase in blood-volume index in the thigh and that in the calf during exercise, whereas the increase in blood-volume index during recovery in the calf was significantly greater than that in the thigh in patients with cardiac disease. Only the increase in the blood-volume index in the thigh during exercise is related to the leg-exercise tolerance in patients with cardiac disease.

Aged↗

PubMed2002