Pulmonary Physiology of Exercise

Dupont, D; Freedman, Allan P.

doi:10.1016/b978-0-12-119720-9.50009-2

Cited by 2 publications

(3 citation statements)

References 11 publications

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“…At the onset of lactic acidosis the increased C0 2 flux appears to parallel the increase in ventilation causing isocapnic buffering [2][3][4]. From this mechan~ ism stems the estimation of T 1 •• 1 by Tvent• Although deviations between lactate and ventilatory thresholds a re reported, for instance after endurance training [24], .the approximation of the T 1 act by Tvent is expenmentally well established [2,4,[8][9][10][11]. The physiological mechanisms, however, relating the VE response to the metabolic acidosis are not yet clear and most probably include metabolic, neurogenic and humoral influences [2,25].…”

Section: The Exercise Protocol; Estimation Of Exercise Variablesmentioning

confidence: 99%

“…From this mechan~ ism stems the estimation of T 1 •• 1 by Tvent• Although deviations between lactate and ventilatory thresholds a re reported, for instance after endurance training [24], .the approximation of the T 1 act by Tvent is expenmentally well established [2,4,[8][9][10][11]. The physiological mechanisms, however, relating the VE response to the metabolic acidosis are not yet clear and most probably include metabolic, neurogenic and humoral influences [2,25]. W ASSERMAN et al (3] and 0RR et al [21] stated that the most sensitive index of ~he anaerobic threshold, as assessed by gas exchange, IS the disproportionate increase in VE for an increment in Vo 2 • We applied the approach, suggested by ORR et al and performed linear regression analysis on the curve parts before and after Tvcnt• Moreover, a p~ra?olic regress!on analysis was applied to the (VEjVo 2 ) versus Vo 2 response, in order to find its minimum.…”

Section: The Exercise Protocol; Estimation Of Exercise Variablesmentioning

confidence: 99%

“…The lactate threshold (T 1 • 0 1 ) was independent of ramp slope of increase in workload [7,8]. Experimental evidence was found for the coincidence ofT,•c• and the threshold derived from the discontinuity in the ventilation response (Tveno) [2,4,[8][9][10][11].…”

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confidence: 99%

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Exercise responses in patients with an enzyme deficiency in the mitochondrial respiratory chain

Bogaard¹,

Busch²,

Scholte³

et al. 1988

Eur Respir J

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Responses to exercise were obtained in six patients with a biochemically diagnosed enzyme deficiency at the level of NADH-CoQ reductase. The responses were compared with those of a control group, consisting of fourteen patients with inexplicable dyspnoea or muscle pain during exercise, for which no firm diagnosis could be established and of which the exercise responses were in the normal range. Metabolic, ventilatory and cardiological variables such as oxygen uptake (VO2), minute ventilation (VE), respiratory exchange ratio (R), heart rate (HR) and difference in blood lactate or base-excess (BE) between rest and maximal workload were measured during cycle ergometry from samples obtained in the last minutes of four minute periods, in which the load increased stepwise by 30 W per four minutes. The threshold of lactate metabolism (Tlact) was assumed to be equal to the threshold determined both by the VO2 at which the VE versus VO2 response started to deviate from a straight line and the ventilatory equivalent for oxygen (VE/VO2) showed a minimum (Tvent), Tvent was estimated from the mean of these values, obtained by linear and parabolic regression analysis respectively. In the patient group, mean values for symptom limited maximal VO2 (VO2,max,sl; % of VO2,max,ref), Tvent (% of VO2,max,ref) and R at maximal workload were 43, 17 and 1.23 against 85, 47 and 1.06 for the same variables in the control group, respectively. The differences were highly significant (p less than 0.001; p less than 0.005 for mean R difference). Mean maximal HR and mean change in blood lactate or BE were not significantly different in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: The Exercise Protocol; Estimation Of Exercise Variablesmentioning

confidence: 99%

Section: The Exercise Protocol; Estimation Of Exercise Variablesmentioning

confidence: 99%

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Exercise responses in patients with an enzyme deficiency in the mitochondrial respiratory chain

Bogaard¹,

Busch²,

Scholte³

et al. 1988

Eur Respir J

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A Comparative Evaluation of a Minute Ventilation Sensing and Activity Sensing Adaptive‐Rate Pacemakers During Daily Activities

Lau

Wong

Leung

et al. 1989

Pacing Clinical Electrophis

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Most studies evaluating the rate response of adaptive-rate pacemakers have been based on treadmill or bicycle exercise. These studies disregard the fact that few pacemaker recipients voluntarily undertake such activities. The rate responses of nine patients (mean age 62 years, range 33-79 years) with implanted minute ventilation sensing (Meta) pacemakers were studied. The indications for pacing were complete heart block (seven patients), sick sinus syndrome (one patient), and five nodal disease (one patient). Significant improvement in maximum distance covered during a 12-minute walking test was observed in the rate adaptive compared to the VVI pacing mode (989 +/- 104 vs 921 +/- 90 m, P less than 0.02). The rate responses of this pacemaker during daily activities were recorded with telemetry during a variety of structured daily activities. The rate responses were also compared to those of an externally attached Activitrax pacemaker in each patient and to a group of ten age and sex matched volunteers. For less strenuous activities such as walking, descending stairs, washing, and bed making, both pacemakers achieved adequate rate responses compared to normal subjects. For more strenuous activities, the Activitrax pacemaker failed to achieve an adequate rate response. For example, the pacing rate achieved on ascending stairs was lower than that achieved on descending stairs (92 +/- 3 vs 102 +/- 3 bpm, P less than 0.02). The direction of rate responses was more appropriate for the Meta pacemaker. Similar to the normal subjects, the maximum rate was reached before the end of an activity with the Activitrax pacemaker.(ABSTRACT TRUNCATED AT 250 WORDS)

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Pulmonary Physiology of Exercise

Cited by 2 publications

References 11 publications

Exercise responses in patients with an enzyme deficiency in the mitochondrial respiratory chain

Exercise responses in patients with an enzyme deficiency in the mitochondrial respiratory chain

A Comparative Evaluation of a Minute Ventilation Sensing and Activity Sensing Adaptive‐Rate Pacemakers During Daily Activities

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