Role of Lactic Acidosis in the Ventilatory Response to Heavy Exercise

Jeyaranjan, Richard; Goode, R. C.; Duffin, James

doi:10.1159/000195735

Cited by 9 publications

(4 citation statements)

References 18 publications

(21 reference statements)

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“…Wassermann and Whipp (1975) reported a close relationship between RCP and metabolic acidosis: however, numerous investigators have challenged the causal relationship between hyperventilation and lactic acidosis (Hagberg et al 1982;Heigenhauser at al. 1983;Gaesser et al 1984;Jeyaranjan et al 1989;Busse et al 1992). Correlations observed between metabolic and respiratory markers have often been suggested to be coincidental.…”

Section: Discussionmentioning

confidence: 99%

Accuracy of neuro-fuzzy logic and regression calculations in determining maximal lactate steady-state power output from incremental tests in humans

Smekal

Scharl

Duvillard

et al. 2002

European Journal of Applied Physiology

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The aim of this study was to employ neuro-fuzzy logic and regression calculations to determine the accuracy of prediction of the power output ( P) of the maximal lactate steady-state (MLSS) on a cycle ergometer calculated from the results of incremental tests. A group of 17 male and 17 female sports students underwent two incremental tests (a 1 min test T(1): initial exercise intensity 0.2 W x kg(-1) increasing 0.2 W x kg(-1) every minute; a 3 min test T(3): initial exercise intensity 0.6 W x kg(-1) increasing 0.6 W x kg(-1) every 3 min) and at least four constant-intensity tests of 30 min duration. Two models for MLSS calculation were developed using the data from T(1) and T(3), a forward stepwise linear regression model (REG) and a neuro-fuzzy model (FUZ). A group of 26 randomly selected subjects (model group, MG) were used to generate the REG and the FUZ models. The data from the remaining 8 subjects (4 men and 4 women; verifying group, VG) were used to verify the REG and FUZ models. The precision of the MLSS calculation in MG produced a better correlation when using data from T(1) (REG r=0.95, FUZ r=0.99) than data from T(3) (REG r=0.88, FUZ r=0.98). Our calculation models were confirmed using data from VG for T(1) (REG r=0.97, FUZ r=0.98) as well as for T(3) (REG r=0.97, FUZ r=0.97). Based on our subject population of young, healthy sport students, our results suggest that a single incremental test may be used for prediction of P at the MLSS using a cycle ergometer. Furthermore, the results from T(1) yielded higher correlations compared to T(3). Calculations from REG were similar to FUZ but the precision of REG and FUZ was better compared to calculations derived using data from a single threshold.

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Section: Discussionmentioning

confidence: 99%

Accuracy of neuro-fuzzy logic and regression calculations in determining maximal lactate steady-state power output from incremental tests in humans

Smekal

Scharl

Duvillard

et al. 2002

European Journal of Applied Physiology

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“…However, new aspects are turning up, especially regarding the relative role of individual stimuli. For example a recent study by Jeyaranjan, Goode & Duffin (1989) has seriously challenged the widely accepted concept about the role of lactic acid in the ventilatory response to heavy exercise. This study has shown that other factors, perhaps of neurogenic origin, must also be involved in regulation of breathing under these conditions.…”

Section: Introductionmentioning

confidence: 99%

Analysis of co‐ordination between breathing and exercise rhythms in man.

Bernasconi

Kohl

1993

The Journal of Physiology

147

163

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SUMMARY1. The purpose of the present study was to analyse the incidence and type of coordination between breathing rhythm and leg movements during running and to assess the effect of co-ordination on the running efficiency, as well as to compare the results with those found during cycling.2. The experiments were carried out on thirty-four untrained volunteers exercising at two work loads (60 and 80% of subject's physical work capacity 170) on a treadmill. In addition nineteen of the subjects exercised at the same two work loads on a bicycle ergometer. The subjects were running at both work loads in three different modes in randomized order: with normal arm movements, without arm movements and with breathing paced by an acoustic signal which was triggered by the leg movement.3. Respiratory variables, oxygen uptake and leg movements were continuously recorded and evaluated on-line. The degree of co-ordination was expressed as a percentage of inspirations and/or expirations starting in the same phase of the step or pedalling cycle.4. The average degree of co-ordination was higher during running (up to 40%) than during cycling (about 20%) during both work loads. The difference in the degree of co-ordination between running and cycling is probably not due to the lack of arm movements during cycling since the degree of co-ordination during running with and without arm movements was the same.5. The degree of co-ordination during running increased slightly but not significantly with increasing work load and could be increased significantly by paced breathing.6. The co-ordination between breathing and running rhythms occurred in three different patterns: (a) breathing was co-ordinated all the time with the same phase of step, (b) co-ordination switched suddenly from one phase of step to another and (c) co-ordination ensued alternatively once on the right and once on the left leg movement. During cycling the pattern described in (a) occurred almost exclusively.7. During running with a high degree of co-ordination, oxygen uptake for a given work load was slightly but significantly lower than during running with weak coordination.MS 1640 23 PHY 471 P. BERNASCONI AND J. KOHL

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“…We conclude that EFL or even impending EFL during heavy and maximal exercise and with added dead space in fit subjects causes EELV to increase, reduces the VT, and constrains the increase in respiratory motor output and ventilation. dead space; helium-oxygen; feedback inhibition; respiratory muscle loading/unloading THE HYPERVENTILATORY response to high-intensity exercise has been attributed to one or more neurohumoral stimuli (4,6,16). There is also some indirect evidence that these ventilatory responses may be influenced by the mechanical constraints presented by the airways and/or inspiratory muscles, at least in many highly fit subjects capable of achieving higher than normal maxi-mal metabolic rates and minute ventilations (V E) (17,28).…”

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confidence: 99%

Role of expiratory flow limitation in determining lung volumes and ventilation during exercise

McClaran

Wetter

Pegelow

et al. 1999

Journal of Applied Physiology

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We determined the role of expiratory flow limitation (EFL) on the ventilatory response to heavy exercise in six trained male cyclists [maximal O2 uptake = 65 +/- 8 (range 55-74) ml. kg-1. min-1] with normal lung function. Each subject completed four progressive cycle ergometer tests to exhaustion in random order: two trials while breathing N2O2 (26% O2-balance N2), one with and one without added dead space, and two trials while breathing HeO2 (26% O2-balance He), one with and one without added dead space. EFL was defined by the proximity of the tidal to the maximal flow-volume loop. With N2O2 during heavy and maximal exercise, 1) EFL was present in all six subjects during heavy [19 +/- 2% of tidal volume (VT) intersected the maximal flow-volume loop] and maximal exercise (43 +/- 8% of VT), 2) the slopes of the ventilation (DeltaVE) and peak esophageal pressure responses to added dead space (e.g., DeltaVE/DeltaPETCO2, where PETCO2 is end-tidal PCO2) were reduced relative to submaximal exercise, 3) end-expiratory lung volume (EELV) increased and end-inspiratory lung volume reached a plateau at 88-91% of total lung capacity, and 4) VT reached a plateau and then fell as work rate increased. With HeO2 (compared with N2O2) breathing during heavy and maximal exercise, 1) HeO2 increased maximal flow rates (from 20 to 38%) throughout the range of vital capacity, which reduced EFL in all subjects during tidal breathing, 2) the gains of the ventilatory and inspiratory esophageal pressure responses to added dead space increased over those during room air breathing and were similar at all exercise intensities, 3) EELV was lower and end-inspiratory lung volume remained near 90% of total lung capacity, and 4) VT was increased relative to room air breathing. We conclude that EFL or even impending EFL during heavy and maximal exercise and with added dead space in fit subjects causes EELV to increase, reduces the VT, and constrains the increase in respiratory motor output and ventilation.

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Role of Lactic Acidosis in the Ventilatory Response to Heavy Exercise

Cited by 9 publications

References 18 publications

Accuracy of neuro-fuzzy logic and regression calculations in determining maximal lactate steady-state power output from incremental tests in humans

Accuracy of neuro-fuzzy logic and regression calculations in determining maximal lactate steady-state power output from incremental tests in humans

Analysis of co‐ordination between breathing and exercise rhythms in man.

Role of expiratory flow limitation in determining lung volumes and ventilation during exercise

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