Anaerobic threshold and respiratory compensation in pregnant women

Lotgering, F.K.; Struijk, P. C.; Doorn, Martijn van; Spinnewijn, Wilhelmina E.M.; Wallenburg, H. C. S.

doi:10.1152/jappl.1995.78.5.1772

Cited by 25 publications

(12 citation statements)

References 7 publications

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“…It is well documented that HR is augmented both at rest and during submaximal exercise and that these differences in HR compared with the nonpregnant state decrease with increasing exercise intensity (21). Finally, although the effects of pregnancy on maximal aerobic power are controversial (29), existing studies indicate that T vent is not changed (16,30). Thus our results are consistent with and confirm the results of earlier studies of the effects of human pregnancy on generalized metabolic and cardiorespiratory responses to exercise.…”

Section: Discussionsupporting

confidence: 92%

“…§ Significant change within group from cycling at 70% ventilatory threshold (T vent ) to cycling at 110% T vent , P Ͻ 0.05. both at rest and during submaximal exercise relative to the nonpregnant state (21,22). RER does not appear to be altered at work rates below the onset of blood lactic acid accumulation (16,29). It is well documented that HR is augmented both at rest and during submaximal exercise and that these differences in HR compared with the nonpregnant state decrease with increasing exercise intensity (21).…”

Section: Discussionmentioning

confidence: 92%

“…The first test was used to determine the ventilatory threshold (T vent ) and to assess aerobic working capacity. The protocol involved 5 min of resting data collection and a 4-min warm-up at 20 W, followed by an increase in work rate of 20 W/min until a heart rate (HR) of 170 beats/min was reached (9,16). Respiratory responses were measured on a breath-by-breath basis by using a computerized system (First Breath) that incorporates a respiratory mass spectrometer (Perkin-Elmer, MGA 1100) with a volume turbine (VMM-1100) as described by Hughson et al (7).…”

Section: Subjectsmentioning

confidence: 99%

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Plasma acid-base regulation above and below ventilatory threshold in late gestation

Heenan

Wolfe

2000

Journal of Applied Physiology

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Stewart's physicochemical approach was used to study the effects of pregnancy on acid-base regulation in arterialized blood. Responses of 15 healthy pregnant women (PG; gestational age, 37.1 +/- 0.2 wk) were compared with those of 15 nonpregnant controls (CG) at rest and during cycling at 70 and 110% of the ventilatory threshold (T(vent)). Hydrogen ion concentration ([H(+)]) was lower in the PG vs. CG at rest and during exercise (P < 0.05 at rest and 70% T(vent)). Exercise-induced changes in [H(+)] were similar between groups. Lower resting [H(+)] values in the PG vs. CG resulted from lower values for arterialized PCO(2) (Pa(CO(2))) and total weak acid ([A](tot)), which were partly offset by a lower strong-ion difference ([SID]). Reductions in [A](tot) and [SID] at rest were primarily the result of reductions in albumin [Alb] and sodium [Na(+)], respectively. In the transition from rest to 70% T(vent), small increases in Pa(CO(2)) and [A](tot) contributed to moderate increases in [H(+)] in both groups, however [SID] increased in the PG and decreased in the CG (P < 0.05 between groups). In the transition from rest to 110% T(vent), decreases in [SID] made a significantly greater contribution to changes in [H(+)] in the CG vs. PG. Exercise-induced increases in [H(+)] are similar in the pregnant vs. nonpregnant state, but there is a reduced contribution of [SID] both above and below T(vent) during pregnancy.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 92%

Section: Subjectsmentioning

confidence: 99%

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Plasma acid-base regulation above and below ventilatory threshold in late gestation

Heenan

Wolfe

2000

Journal of Applied Physiology

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“…The women in our study reported mild‐to‐moderate persistent activity‐related breathlessness, as evidenced by a ∼3.5 unit decrease in the BDI focal score from PP to TM 3 . Consistent with the results of previous studies (Sady et al 1989; Lotgering et al 1995), however, aerobic working capacity was well preserved in late gestation: women exercised to at least 100% of their predicted maximum work rate and in TM 3 and PP, respectively.…”

Section: Discussionsupporting

confidence: 91%

Mechanical ventilatory constraints during incremental cycle exercise in human pregnancy: implications for respiratory sensation

Jensen

Webb

Davies

et al. 2008

The Journal of Physiology

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The aim of this study was to identify the physiological mechanisms of exertional respiratory discomfort (breathlessness) in pregnancy by comparing ventilatory (breathing pattern, airway function, operating lung volumes, oesophageal pressure (P oes )-derived indices of respiratory mechanics) and perceptual (breathlessness intensity) responses to incremental cycle exercise in 15 young, healthy women in the third trimester (TM 3 ; between 34 and 38 weeks gestation) and again 4-5 months postpartum (PP). During pregnancy, resting inspiratory capacity (IC) increased (P < 0.01) and end-expiratory lung volume decreased (P < 0.001), with no associated change in total lung capacity (TLC) or static respiratory muscle strength. This permitted greater tidal volume (V T ) expansion throughout exercise in TM 3 , while preserving the relationship between contractile respiratory muscle effort (tidal P oes swing expressed as a percentage of maximum inspiratory pressure (P Imax )) and thoracic volume displacement (V T expressed as a percentage of vital capacity) and between breathlessness and ventilation (V E ). At the highest equivalent work rate (HEWR = 128 ± 5 W) in TM 3 compared with PP:V E , tidal P oes /P Imax and breathlessness intensity ratings increased by 10.2 l min −1 (P < 0.001), 8.8%P Imax (P < 0.05) and 0.9 Borg units (P < 0.05), respectively. Pulmonary resistance was not increased at rest or during exercise at the HEWR in TM 3 , despite marked increases in mean tidal inspiratory and expiratory flow rates, suggesting increased bronchodilatation. Dynamic mechanical constraints on V T expansion (P < 0.05) with associated increased breathlessness intensity ratings (P < 0.05) were observed near peak exercise in TM 3 compared with PP. In conclusion: (1) pregnancy-induced increases in exertional breathlessness reflected the normal awareness of increasedV E and contractile respiratory muscle effort; (2) mechanical adaptations of the respiratory system, including recruitment of resting IC and increased bronchodilatation, accommodated the increased V T while preserving effort-displacement and breathlessness-V E relationships; and (3) dynamic mechanical ventilatory constraints contributed to respiratory discomfort near the limits of tolerance in late gestation.

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“…Protocols that have been reported are remarkably similar. After a 2-to 4-min warm-up during which the patient pedals against little or no resistance, resistance is increased by 20-30 W/ min to volitional fatigue [34,[36][37][38][39][40]. Upright leg cycle ergometry protocols have been used successfully from 16 to 35 weeks of gestation to 12 weeks postpartum.…”

Section: Maximal Exercise Testsmentioning

confidence: 99%

Clinical Exercise Testing during Pregnancy and the Postpartum Period

Toole¹,

Artal²

2002

Clinical Exercise Testing

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Cardiopulmonary exercise testing of pregnant women may be done for either diagnostic or nondiagnostic reasons. The most common reason to exercise test healthy young women, pregnant or not, is to acquire information with which to develop individualized exercise prescriptions. Pregnant women can be tested either during weight-bearing activity (e.g., treadmill walking) or during an activity that is independent of body weight (e.g., cycle ergometry). Semi-recumbent cycle ergometry appears to be the most comfortable modality. Short incremental protocols (8-12 min) to maximal subjective effort provide good information and appear to be safe during all stages of pregnancy for both mother and fetus. Single-stage submaximal protocols are also safe and may provide useful information, particularly when substrate or hormonal responses are of interest. For proper interpretation of results, individuals involved in conducting exercise testing of pregnant women should be aware of the anatomical and physiological changes that may alter cardiopulmonary responses to exercise during pregnancy.

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Anaerobic threshold and respiratory compensation in pregnant women

Cited by 25 publications

References 7 publications

Plasma acid-base regulation above and below ventilatory threshold in late gestation

Plasma acid-base regulation above and below ventilatory threshold in late gestation

Mechanical ventilatory constraints during incremental cycle exercise in human pregnancy: implications for respiratory sensation

Clinical Exercise Testing during Pregnancy and the Postpartum Period

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