Affiliation:
1. Laboratory of Cardiovascular Science National Institute on Aging Baltimore MD
2. Longitudinal Studies Section National Institute on Aging Baltimore MD
3. Department of Medicine Johns Hopkins School of Medicine Baltimore MD
4. Loyola University Maryland Baltimore MD
5. Laboratory of Clinical Investigation National Institute on Aging Baltimore MD
6. Department of Medicine Northwestern University Feinberg School of Medicine Chicago IL
Abstract
Background
Lower ankle‐brachial index (ABI) values within the 0.90 to 1.40 range are associated with poorer mitochondrial oxidative capacity of thigh muscles in cross‐sectional analyses. Whether ABI decline is associated with greater declines in thigh muscle oxidative capacity with aging is unknown.
Method and Results
We analyzed data from 228 participants (100 men) of the BLSA (Baltimore Longitudinal Study of Aging), aged 39 to 97 years, with an ABI between 0.9 and 1.40 at baseline and at follow‐up (mean follow‐up period of 2.8 years). We examined mitochondrial oxidative capacity of the left thigh muscle, by measuring the postexercise phosphocreatine recovery rate constant (
k
PCr) from phosphorus‐31 magnetic resonance spectroscopy. Greater
k
PCr indicated higher mitochondrial oxidative capacity. Although
k
PCr was available on the left leg only, ABI was measured in both legs. Longitudinal rates of change (
Change
) of left and right ABI and
k
PCr of the left thigh muscle were estimated using linear mixed effects models, and their association was analyzed by standardized multiple linear regressions. In multivariate analysis including sex, age, baseline
k
PCr, both left and right baseline ABI, and ABI change in both legs, (
k
PCr)
Change
was directly associated with ipsilateral (left) (ABI)
Change
(standardized [STD]‐β=0.14;
P
=0.0168) but not with contralateral (right) (ABI)
Change
(
P
=0.22). Adjusting for traditional cardiovascular risk factors, this association remained significant (STD‐β=0.18;
P
=0.0051). (
k
PCr)
Change
was steeper in White race participants (STD‐β=0.16;
P
=0.0122) and body mass index (STD‐β=0.13;
P
=0.0479). There was no significant association with current smoking status (
P
=0.63), fasting glucose (
P
=0.28), heart rate (
P
=0.67), mean blood pressure (
P
=0.78), and low‐density lipoprotein (
P
=0.75), high‐density lipoprotein (
P
=0.82), or triglycerides (
P
=0.15).
Conclusions
In people without peripheral arterial disease, greater decline in ABI over time, but not baseline ABI, was associated with faster decline in thigh mitochondrial oxidative capacity in the ipsilateral leg. Further studies are needed to examine whether early interventions that improve lower extremity muscle perfusion can improve and prevent the decline of muscle energetics.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Cardiology and Cardiovascular Medicine
Cited by
2 articles.
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