Yannick Molgat-Seon1,2, Paolo B Dominelli1, Andrew H Ramsook2, Michele R Schaeffer2, Lee M Romer3,4, Jeremy D Road5, Jordan A Guenette2, A William Sheel1. 1. School of Kinesiology, University of British Columbia, Vancouver, CANADA. 2. Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, CANADA. 3. Centre for Human Performance, Exercise and Rehabilitation, College of Health and Life Sciences, Brunel University London, Uxbridge, UNITED KINGDOM. 4. Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University London, Uxbridge, UNITED KINGDOM. 5. Division of Respiratory Medicine, Faculty of Medicine, University of British Columbia, Vancouver, CANADA.
Abstract
PURPOSE: To characterize the effects of age, sex, and their interaction on inspiratory muscle activation patterns during exercise. METHODS: Twenty younger (20-30 yr, n = 10 women) and 20 older (60-80 yr, n = 10 women) subjects performed an incremental cycle exercise test. Electromyography (EMG) of the scalene (EMGsca) and EMG of the sternocleidomastoid (EMGscm) muscles were measured using skin surface electrodes, whereas diaphragm EMG (EMGdi) and esophageal and transdiaphragmatic pressures were measured using an esophageal catheter. Electromyography data were transformed into root mean square with a 100-ms time constant. Esophageal and diaphragmatic pressure-time products were used as indices of total inspiratory muscle pressure production and diaphragmatic pressure production, respectively. RESULTS: At absolute minute ventilations (V˙E), women and older subjects had greater EMGdi than men and younger subjects, respectively (all P < 0.05), but no differences were noted when V˙E was expressed in relative terms (all P > 0.05). Women had greater EMGsca activity than men at absolute and relative levels of V˙E (all P < 0.05). Older subjects had greater EMGsca than younger subjects when V˙E was expressed in relative (all P < 0.05) but not absolute terms (all P > 0.05). At absolute and relative levels of V˙E, women and older subjects had greater EMGscm than men and younger subjects, respectively (all P < 0.05). Women and older subjects had a greater esophageal and diaphragmatic pressure-time products at a V˙E of 70 L·min than men and younger subjects, respectively (both P < 0.05), but no differences were noted when V˙E was expressed in relative terms (all P > 0.05). No significant interactions between age and sex were noted (all P > 0.05). CONCLUSIONS: Age and sex significantly affect inspiratory muscle activation patterns during exercise; however, the extent of the effects depends on whether comparisons are made at absolute or relative V˙E.
PURPOSE: To characterize the effects of age, sex, and their interaction on inspiratory muscle activation patterns during exercise. METHODS: Twenty younger (20-30 yr, n = 10 women) and 20 older (60-80 yr, n = 10 women) subjects performed an incremental cycle exercise test. Electromyography (EMG) of the scalene (EMGsca) and EMG of the sternocleidomastoid (EMGscm) muscles were measured using skin surface electrodes, whereas diaphragm EMG (EMGdi) and esophageal and transdiaphragmatic pressures were measured using an esophageal catheter. Electromyography data were transformed into root mean square with a 100-ms time constant. Esophageal and diaphragmatic pressure-time products were used as indices of total inspiratory muscle pressure production and diaphragmatic pressure production, respectively. RESULTS: At absolute minute ventilations (V˙E), women and older subjects had greater EMGdi than men and younger subjects, respectively (all P < 0.05), but no differences were noted when V˙E was expressed in relative terms (all P > 0.05). Women had greater EMGsca activity than men at absolute and relative levels of V˙E (all P < 0.05). Older subjects had greater EMGsca than younger subjects when V˙E was expressed in relative (all P < 0.05) but not absolute terms (all P > 0.05). At absolute and relative levels of V˙E, women and older subjects had greater EMGscm than men and younger subjects, respectively (all P < 0.05). Women and older subjects had a greater esophageal and diaphragmatic pressure-time products at a V˙E of 70 L·min than men and younger subjects, respectively (both P < 0.05), but no differences were noted when V˙E was expressed in relative terms (all P > 0.05). No significant interactions between age and sex were noted (all P > 0.05). CONCLUSIONS: Age and sex significantly affect inspiratory muscle activation patterns during exercise; however, the extent of the effects depends on whether comparisons are made at absolute or relative V˙E.
Authors: Yannick Molgat-Seon; Andrew H Ramsook; Carli M Peters; Michele R Schaeffer; Paolo B Dominelli; Lee M Romer; Jeremy D Road; Jordan A Guenette; A William Sheel Journal: J Physiol Date: 2019-01-18 Impact factor: 5.182