Effect of Age on Sex Differences in the Inspiratory Muscle Metaboreflex

It is currently unknown whether sex differences exist in the cardiovascular consequences of the inspiratory muscle metaboreflex. We hypothesized that the activation of the inspiratory muscle metaboreflex will lead to less of an increase in mean arterial pressure (MAP) and limb vascular resistance (LVR) and less of a decrease in limb blood flow (Q̇L) in women compared with men. Twenty healthy men ( n = 10, 23 ± 2 yr) and women ( n = 10, 22 ± 3 yr) were recruited for this study. Subjects performed inspiratory resistive breathing tasks (IRBTs) at 2% or 65% of their maximal inspiratory mouth pressure (PIMAX). During the IRBTs, the breathing frequency was 20 breaths/min with a 50% duty cycle. At rest and during the IRBTs, MAP was measured via automated oscillometry, Q̇L was measured via Doppler ultrasound, and LVR was calculated. EMG was recorded on the leg to ensure no muscle contraction occurred. The 65% IRBT led to attenuated increases ( P < 0.01) from baseline in women compared with men for MAP (W: 7.3 ± 2.0 mmHg; M: 11.1 ± 5.0 mmHg) and LVR (W: 17.7% ± 14.0%; M: 47.9 ± 21.0%), as well as less of a decrease ( P < 0.01) in Q̇L (W: −7.5 ± 9.9%; M: −23.3 ± 10.2%). These sex differences in MAP, Q̇L, and LVR were still present in a subset of subjects matched for PIMAX. The 2% IRBT resulted in no significant changes in MAP, Q̇L, or LVR across time or between men and women. These data indicate premenopausal women exhibit an attenuated inspiratory muscle metaboreflex compared with age-matched men.

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Cardiovascular consequences of the inspiratory muscle metaboreflex: effects of age and sex

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00818.2016 ◽

2017 ◽

Vol 312 (5) ◽

pp. H1013-H1020 ◽

Cited By ~ 15

Author(s):

Joshua R. Smith ◽

Andrew M. Alexander ◽

Shane M. Hammer ◽

Kaylin D. Didier ◽

Stephanie P. Kurti ◽

...

Keyword(s):

Older Adults ◽

Sex Differences ◽

Older Women ◽

Young Men ◽

Premenopausal Women ◽

Older Men ◽

Inspiratory Muscle ◽

Muscle Metaboreflex ◽

Resistive Breathing ◽

Younger Men

With inspiratory muscle metaboreflex activation, we hypothesized that, compared with their younger counterparts, older men and women would exhibit greater 1) increases in mean arterial pressure (MAP) and limb vascular resistance (LVR) and 2) decreases in limb blood flow (Q̇L) but 3) no sex differences would be present in older adults. Sixteen young adults [8 young men (YM) and 8 young women (YW), 18–24 yr] and 16 older adults [8 older men (OM) and 8 older women (OW), 60–73 yr] performed inspiratory resistive breathing tasks (IRBTs) at 2% and 65% of their maximal inspiratory pressure. During the IRBTs, breathing frequency was 20 breaths/min with a 50% duty cycle. At baseline and during the IRBTs, MAP was measured via automated oscillometry, Q̇L was determined via Doppler ultrasound, and LVR was calculated. The 65% IRBT led to significantly greater increases in MAP in OW (15.9 ± 8.1 mmHg) compared with YW (6.9 ± 1.4 mmHg) but not ( P > 0.05) between OM (12.3 ± 5.7 mmHg) and YM (10.8 ± 5.7 mmHg). OW (−20.2 ± 7.2%) had greater ( P < 0.05) decreases in Q̇L compared with YW (−9.4 ± 10.2%), but no significant differences were present between OM (−22.8 ± 9.7%) and YM (−22.7 ± 11.3%) during the 65% IRBT. The 65% IRBT led to greater ( P < 0.05) increases in LVR in OW (48.2 ± 25.5%) compared with YW (19.7 ± 15.0%), but no differences ( P > 0.05) existed among OM (54.4 ± 17.8%) and YM (47.1 ± 23.3%). No significant differences were present in MAP, Q̇L, or LVR between OM and OW. These data suggest that OW exhibit a greater inspiratory muscle metaboreflex compared with YW, whereas no differences between OM and YM existed. Finally, sex differences in the inspiratory muscle metaboreflex are not present in older adults. NEW & NOTEWORTHY Premenopausal women exhibit an attenuated inspiratory muscle metaboreflex compared with young men; however, it is unknown whether these sex differences are present in older adults. Older women exhibited a greater inspiratory muscle metaboreflex compared with premenopausal women, whereas no differences were present between older and younger men.

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Sex Differences in Muscle Metaboreflex Activation following Static Handgrip Exercise

Medicine & Science in Sports & Exercise ◽

10.1249/mss.0000000000002747 ◽

2021 ◽

Vol Publish Ahead of Print ◽

Author(s):

Jordan B. Lee ◽

Karam Notay ◽

Jeremy D. Seed ◽

Massimo Nardone ◽

Lucas J. Omazic ◽

...

Keyword(s):

Sex Differences ◽

Handgrip Exercise ◽

Muscle Metaboreflex

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Sex differences in the perceived intensity of breathlessness during exercise with advancing age

Journal of Applied Physiology ◽

10.1152/japplphysiol.00079.2008 ◽

2008 ◽

Vol 104 (6) ◽

pp. 1583-1593 ◽

Cited By ~ 54

Author(s):

Dror Ofir ◽

Pierantonio Laveneziana ◽

Katherine A. Webb ◽

Yuk-Miu Lam ◽

Denis E. O'Donnell

Keyword(s):

Sex Differences ◽

Older Women ◽

Cross Sectional Study ◽

Inspiratory Muscle ◽

Cross Sectional ◽

Respiratory Impairment ◽

Mechanical Constraints ◽

Age Related ◽

Underlying Mechanisms ◽

Age Related Changes

The prevalence of activity-related breathlessness increases with age, particularly in women, but the specific underlying mechanisms have not been studied. This novel cross-sectional study was undertaken to examine the effects of age and sex, and their interaction, on the perceptual and ventilatory responses to incremental treadmill exercise in 73 healthy participants (age range 40–80 yr old) with normal pulmonary function. Age-related changes at a standardized oxygen uptake (V̇o2) during exercise included significant increases in breathlessness ratings (Borg scale), ventilation (V̇e), ventilatory equivalent for carbon dioxide, and the ratio of tidal volume (Vt) to dynamic inspiratory capacity (IC) (all P < 0.05). These changes were quantitatively similar in women ( n = 39) and in men ( n = 34). For the group as a whole, exertional breathlessness ratings increased as resting static inspiratory muscle strength diminished ( P = 0.05), as exercise ventilation increased relative to capacity ( P = 0.013) and as the Vt/IC ratio increased ( P = 0.003) during exercise. Older women (60–80 yr old, n = 23) reported greater ( P < 0.05) intensity of exertional breathlessness at a standardized V̇o2 and V̇e than age-matched men ( n = 16), despite similar age-related changes in ventilatory demand and dynamic ventilatory mechanics. These increases in breathlessness ratings in older women disappeared when sex differences in baseline maximal ventilatory capacity were accounted for. In conclusion, although increased exertional breathlessness with advancing age is multifactorial, contributory factors included higher ventilatory requirements during exercise, progressive inspiratory muscle weakness, and restrictive mechanical constraints on Vt expansion related to reduced IC. The sensory consequences of this age-related respiratory impairment were more pronounced in women, who, by nature, have relatively reduced maximal ventilatory reserve.

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Effect of diaphragm fatigue on subsequent exercise tolerance in healthy men and women

Journal of Applied Physiology ◽

10.1152/japplphysiol.00630.2018 ◽

2018 ◽

Vol 125 (6) ◽

pp. 1987-1996 ◽

Cited By ~ 4

Author(s):

Joseph F. Welch ◽

Bruno Archiza ◽

Jordan A. Guenette ◽

Christopher R. West ◽

A. William Sheel

Keyword(s):

Exercise Test ◽

Exercise Tolerance ◽

Inspiratory Muscle ◽

Whole Body ◽

Time To Exhaustion ◽

Men And Women ◽

Muscle Metaboreflex ◽

Healthy Men ◽

Pressure Threshold ◽

Diaphragmatic Fatigue

Women are more resistant to diaphragmatic fatigue (DF) and experience an attenuated inspiratory muscle metaboreflex relative to men. The effects of such sex-based differences on whole body exercise tolerance are yet to be examined. It was hypothesized that DF induced prior to exercise would cause less of a reduction in subsequent exercise time in women compared to men. Healthy men ( n = 9, age = 24 ± 3 yr) and women ( n = 9, age = 24 ± 3 yr) completed a maximal incremental cycle test on day 1. On day 2, subjects performed isocapnic inspiratory pressure-threshold loading (PTL) to task failure followed by a constant load submaximal time-to-exhaustion (TTE) exercise test at 85% of the predetermined peak work rate. On day 3, subjects performed the same exercise test without prior induced DF. Days 2 and 3 were randomized and counterbalanced. Magnetic stimulation of the phrenic nerve roots was used to nonvolitionally assess DF by measurement of transdiaphragmatic twitch pressure ( Pdi,tw). A similar degree of DF was produced in both sexes following PTL [ Pdi,tw (% change from baseline): M = −24.6 ± 7.8%, W = −23.1 ± 5.4%; P = 0.54)]. There was a significant reduction in TTE with prior induced DF compared with the control condition in both men (10.9 ± 3.5 min vs. 13.0 ± 3.2 min, P = 0.05) and women (10.1 ± 2.4 min vs. 12.2 ± 3.3 min, P = 0.03) that did not differ in magnitude between the sexes (M = −15.8 ± 19.5%, W = −14.5 ± 19.2%, P = 0.89). In conclusion, DF negatively and equally impairs exercise tolerance independent of sex. NEW & NOTEWORTHY Women are more resistant to diaphragmatic fatigue (DF) relative to men. The effect of DF on exercise tolerance is currently being debated. Our findings show that DF negatively and equally affects exercise tolerance in healthy men and women. Mechanisms beyond the inspiratory muscle metaboreflex (e.g., dyspnea, central fatigue, breathing pattern) may explain the absence of a sex-based difference.

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Pulmonary and Inspiratory Muscle Function Response to a Mountain Ultramarathon

Journal of Sports Science and Medicine ◽

10.52082/jssm.2021.706 ◽

2021 ◽

pp. 706-713

Author(s):

Ignacio Martinez-Navarro ◽

Eladio Collado ◽

Bárbara Hernando ◽

Carlos Hernando

Keyword(s):

Sex Differences ◽

Muscle Function ◽

Respiratory Function ◽

Time Course ◽

Handgrip Strength ◽

Cardiopulmonary Exercise Test ◽

Forced Expiratory Volume ◽

Inspiratory Muscle ◽

Running Speed ◽

Finish Line

The study aimed to provide within-race data on the time course of pulmonary function during a mountain ultramarathon (MUM). Additionally, we wanted to assess possible sex differences regarding pre- to post-race change in pulmonary and inspiratory muscle function. Lastly, we were interested in evaluating whether changes in respiratory function were associated with relative running speed and due to general or specific fatigue. 47 athletes (29 males and 18 females; 41 ± 5 years) were submitted to a cardiopulmonary exercise test (CPET) before a 107-km MUM. Spirometric variables: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC and peak expiratory flow (PEF); maximal inspiratory pressure (MIP); squat jump (SJ) and handgrip strength (HG) were assessed before and after the race. Additionally PEF was measured at three aid stations (33rd, 66th and 84th km) during the race. PEF declined from the 33rd to the 66th km (p = 0.004; d = 0.72) and from the 84th km to the finish line (p = 0.003; d = 0.90), while relative running speed dropped from the first (0-33 km) to the second (33-66 km) race section (p < 0.001; d = 1.81) and from the third (66-84 km) to the last race section (p < 0.001; d = 1.61). Post-race, a moderate reduction was noted in FVC (-13%; p < 0.001; d = 0.52), FEV1 (-19.5%; p < 0.001; d = 0.65), FEV1/FVC (-8.4%; p = 0.030; d = 0.59), PEF (-20.3%; p < 0.001; d = 0.58), MIP (-25.3%; p < 0.001; d = 0.79) and SJ (-31.6%; p < 0.001; d = 1.42). Conversely, HG did not change from pre- to post-race (-1.4%; p = 0.56; d = 0.05). PEF declined during the race in parallel with running speed drop. No sex differences were noted regarding post-race respiratory function, except that FEV1/FVC decay was significantly greater among women. The magnitude of pre- to post-race respiratory function decline was uncorrelated with relative running speed.

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Sex differences in age- and performance-related patterns of brain activity during episodic encoding and retrieval of spatial contextual details

10.1101/535617 ◽

2019 ◽

Author(s):

Sivaniya Subramaniapillai ◽

Sricharana Rajagopal ◽

Abdelhalim Elshiekh ◽

Stamatoula Pasvanis ◽

Elizabeth Ankudowich ◽

...

Keyword(s):

Sex Differences ◽

Brain Activity ◽

Memory Performance ◽

Memory Decline ◽

Retrieval Accuracy ◽

Age Related ◽

Episodic Encoding ◽

And Performance ◽

Effect Of Age ◽

Context Memory

AbstractAging is associated with episodic memory decline and alterations in memory-related brain function. However, it remains unclear if age-related memory decline is associated with similar patterns of brain aging in women and men. In the current task fMRI study, we tested the hypothesis that there are sex differences in the effect of age and memory performance on brain activity during episodic encoding and retrieval of face-location associations (spatial context memory). Forty-one women and 41 men between the ages of 21 to 76 years participated in this study. Between-group multivariate partial least squares (PLS) analysis of the fMRI data was conducted to directly test for sex-group differences and similarities in age-related and performance-related patterns of brain activity. Our behavioural analysis indicated no significant sex differences in retrieval accuracy on the fMRI tasks. In relation to performance effects, we observed similarities and differences in how retrieval accuracy related to brain activity in women and men. Both sexes activated dorsal and lateral prefrontal cortex (PFC), inferior parietal cortex (IPC) and left parahippocampal gyrus (PHG) at encoding and this supported subsequent memory performance. However, there were sex differences in retrieval activity in these same regions and in lateral occipital-temporal and ventrolateral PFC. In relation to age effects, we observed sex differences in the effect of age on memory-related activity within PFC, IPC, PHG and lateral occipital-temporal cortices. Overall, our findings suggest that the neural correlates of age-related spatial context memory decline differ in women compared to men.

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