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Manipulation of mechanical ventilatory constraint during moderate intensity exercise does not influence dyspnoea in healthy older men and women
Author(s) -
MolgatSeon Yannick,
Ramsook Andrew H.,
Peters Carli M.,
Schaeffer Michele R.,
Dominelli Paolo B.,
Romer Lee M.,
Road Jeremy D.,
Guenette Jordan A.,
Sheel A. William
Publication year - 2019
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jp277476
Subject(s) - medicine , intensity (physics) , ventilation (architecture) , physical therapy , work of breathing , ventilatory threshold , cardiology , exercise intensity , physical medicine and rehabilitation , mechanical ventilation , vo2 max , heart rate , blood pressure , mechanical engineering , physics , quantum mechanics , engineering
Key points The perceived intensity of exertional breathlessness (i.e. dyspnoea) is higher in older women than in older men, possibly as a result of sex‐differences in respiratory system morphology. During exercise at a given absolute intensity or minute ventilation, older women have a greater degree of mechanical ventilatory constraint (i.e. work of breathing and expiratory flow limitation) than their male counterparts, which may lead to a greater perceived intensity of dyspnoea. Using a single‐blind randomized study design, we experimentally manipulated the magnitude of mechanical ventilatory constraint during moderate‐intensity exercise at ventilatory threshold in healthy older men and women. We found that changes in the magnitude of mechanical ventilatory constraint within the physiological range had no effect on dyspnoea in healthy older adults. When older men and women perform moderate intensity exercise, mechanical ventilatory constraint does not contribute significantly to the sensation of dyspnoea.Abstract We aimed to determine the effect of manipulating mechanical ventilatory constraint during submaximal exercise on dyspnoea in older men and women. Eighteen healthy subjects (aged 60–80 years; nine men and nine women) completed two days of testing. On day 1, subjects were assessed for pulmonary function and performed a maximal incremental cycle exercise test. On day 2, subjects performed three 6‐min bouts of cycling at ventilatory threshold, in a single‐blind randomized manner, while breathing: (i) normoxic helium‐oxygen (HEL) to reduce the work of breathing ( W b ) and alleviate expiratory flow limitation (EFL); (ii) through an inspiratory resistance (RES) of ∼5 cmH 2 O L −1 s −1 to increase W b ; and (iii) ambient air as a control (CON). Oesophageal pressure, diaphragm electromyography, and sensory responses (category‐ratio 10 Borg scale) were monitored throughout exercise. During the HEL condition, there was a significant decrease in W b (men: –21 ± 6%, women: –17 ± 10%) relative to CON (both P < 0.01). Moreover, if EFL was present during CON (four men and five women), it was alleviated during HEL. Conversely, during the RES condition, W b (men: 42 ± 19%, women: 50 ± 16%) significantly increased relative to CON (both P < 0.01). There was no main effect of sex on W b ( P = 0.59). Across conditions, women reported significantly higher dyspnoea intensity than men (2.9 ± 0.9 vs . 1.9 ± 0.8 Borg scale units, P < 0.05). Despite significant differences in the degree of mechanical ventilatory constraint between conditions, the intensity of dyspnoea was unaffected, independent of sex ( P = 0.46). When older men and women perform moderate intensity exercise, mechanical ventilatory constraint does not contribute significantly to the sensation of dyspnoea.