Dennis Jensen

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The healthy human respiratory system has impressive ventilatory reserve and can easily meet the demands placed upon it by strenuous exercise. Several acute physiological adaptations during exercise ensure harmonious neuromechanical coupling of the respiratory system, which allow healthy humans to reach high levels of ventilation without perceiving undue(More)
Progressive activity-related dyspnea dominates the clinical presentation of patients afflicted by chronic obstructive and restrictive lung diseases. This symptom invariably leads to activity limitation, global skeletal muscle deconditioning and an impoverished quality of life. The effective management of exertional dyspnea remains an elusive goal but our(More)
This study examined the effects of menstrual cycle phase on ventilatory control. Fourteen eumenorrheic women were studied in the early follicular (FP; 1-6 days) and mid-luteal (LP; 20-24 days) phase of the menstrual cycle. Blood for the determination of arterial PCO(2) (PaCO(2)) , plasma strong ion difference ([SID]), progesterone ([P(4)]), and(More)
The purpose of this study was to evaluate the physiological basis for sex-differences in exercise-induced dyspnea in patients with mild COPD. We compared operating lung volumes, breathing pattern and dyspnea during incremental cycling in 32 men (FEV(1)=86±10% predicted) and women (FEV(1)=86±12% predicted) with mild COPD and 32 age-matched controls. There(More)
We tested the hypothesis that neuromechanical uncoupling of the respiratory system forms the mechanistic basis of dyspnea during exercise in the setting of "abnormal" restrictive constraints on ventilation (VE). To this end, we examined the effect of chest wall strapping (CWS) sufficient to mimic a "mild" restrictive lung deficit on the interrelationships(More)
We examined the effects of dead space loading (DSL) on ventilation (V˙E), neural respiratory drive (EMGdi%max, diaphragm EMG expressed as a % of maximal EMGdi), contractile respiratory muscle effort (Pes,tidal%P(Imax), tidal esophageal pressure swing expressed as a % of maximal inspiratory Pes) and exertional dyspnea intensity ratings in 11 healthy adults(More)
This study examined the effects of human pregnancy and advancing gestation on the intensity of respiratory discomfort (dyspnea) during cycle exercise. Fourteen pregnant women (PG) performed a progressive cycle ergometer exercise test involving 20 W/min increases in work rate to symptom limitation and/or a heart rate of 170-175 beats/min at 19.7+/-1.2 weeks(More)
NEW FINDINGS What is the central question of this study? Does the combination of a higher neural respiratory drive and greater dynamic mechanical ventilatory constraints during exercise in healthy women versus men form the mechanistic basis of sex differences in activity-related dyspnoea? What is the main finding and its importance? Sex differences in(More)
This study examined the effects of human pregnancy on the central chemoreflex control of breathing. Subjects were two groups (n=11) of pregnant subjects (PG, gestational age, 36.5+/-0.4 wk) and nonpregnant control subjects (CG), equated for mean age, body height, prepregnant body mass, parity, and aerobic fitness. All subjects performed a hyperoxic CO2(More)
This study examined the role of pregnancy-induced changes in wakefulness (or non-chemoreflex) and central chemoreflex drives to breathe, acid-base balance and female sex hormones in the hyperventilation of human pregnancy. Thirty-five healthy women were studied in the third trimester (TM(3); 36.3+/-1.0 weeks gestation; mean+/-S.D.) and again 20.2+/-7.8(More)