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Chronic Aerobic Exercise Training Reduces Cerebrovascular Reactivity to a Breath Hold Stimulus in Middle‐aged and Older Adults
Author(s) -
DuBose Lyndsey E.,
Wharff Conner,
Schmid Phillip,
Muellerleile Michael,
Sigurdsson Gardar,
Reist Lauren,
Pierce Gary L.,
Voss Michelle W.
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.lb431
Subject(s) - cardiorespiratory fitness , aerobic exercise , hypercapnia , medicine , physical therapy , vo2 max , cerebral blood flow , cardiology , heart rate , physical medicine and rehabilitation , blood pressure
Habitual aerobic exercise is hypothesized to attenuate age‐related declines in cognitive performance mediated in part by alterations in cerebrovascular reactivity (CVR). However, cross‐sectional studies using fMRI blood oxygen level dependent (BOLD) imaging demonstrate paradoxically lower CVR (cerebral blood flow response to experimental hypercapnia) among middle‐aged and older (MA/O) adults with high compared with low aerobic fitness.1,2 It remains unknown if greater moderate‐to‐vigorous physical activity (MVPA) or initiating chronic aerobic exercise training in previously inactive MA/O adults alters CVR to hypercapnia. We hypothesized that 1) greater MVPA and cardiorespiratory fitness (VO 2max ) is associated with lower CVR; 2) CVR is attenuated after 3‐months of habitual aerobic exercise training in previously inactive MA/O adults. Methods Fifty‐six MA/O adults (mean ± SE: 64.5 ± 0.8 yrs, range: 50–76 yrs) were studied. VO 2max was considered as a percentile based on age and sex (VO 2 %). CVR (3T fMRI) was quantified as the change in the BOLD signal in response to acute hypercapnia using a blocked breath hold design from a region‐of‐interest (ROI) analysis for cortical networks known to be affected by aging. Average minutes per day of MVPA (accelerometry) were measured at baseline in a subset (n = 33) to delineate the role of MVPA from VO 2max . After baseline testing, the subset of MA/O adults were randomized to either 3‐months of aerobic (40 minutes/session, 3 sessions/week at ~70% HRmax) or passive exercise control training on a cycle ergometer. VO 2max and fMRI testing were repeated post‐intervention. Mixed model regressions were used to test the effects of the predictors (VO 2 % and MVPA) on CVR, and whether this relation varied by cortical network, adjusted for covariates of interest (scanner and subject motion). Results In the entire cohort, there was a quadratic relation between VO 2 % and CVR at baseline, shown by the significant coefficient forVO 2 % 2 (β = −0.12 ± 0.05, p = 0.01 ) but not VO 2 % (β = 0.14 ± 0.08, p = 0.08), and network ROI significantly improved model fit (χ 2 (2) = 42.17, p < 0.001). Post‐hoc tests showed the strongest quadratic effect in the somatomotor network (β = −0.12 ± 0.06, p = 0.05). However, the general pattern was similar across ROIs; CVR increased until the 30 th percentile of VO 2 % after which CVR declined. In the subset, baseline MVPA was not associated with CVR (p = 0.33). In the intervention cohort, CVR declined after the exercise intervention in the aerobic exercise, but not passive control, group (significant three‐way interaction term, time x VO 2max x intervention , β = −0.15 ± 0.05, p = 0.008). Conclusions Moderate intensity aerobic exercise training in inactive MA/O adults may attenuate CVR to hypercapnia. Future studies are needed to determine the mechanism by which chronic aerobic exercise paradoxically reduces CVR to a physiological stimulus. Support or Funding Information NIH 1R21 AG043722, U54 TR001013 and 5KL2 RR24980‐5 This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .