Dataset Information

Skeletal muscle mitochondrial energetics are associated with maximal aerobic capacity and walking speed in older adults.

ABSTRACT:

Background

Lower ambulatory performance with aging may be related to a reduced oxidative capacity within skeletal muscle. This study examined the associations between skeletal muscle mitochondrial capacity and efficiency with walking performance in a group of older adults.

Methods

Thirty-seven older adults (mean age 78 years; 21 men and 16 women) completed an aerobic capacity (VO2 peak) test and measurement of preferred walking speed over 400 m. Maximal coupled (State 3; St3) mitochondrial respiration was determined by high-resolution respirometry in saponin-permeabilized myofibers obtained from percutanous biopsies of vastus lateralis (n = 22). Maximal phosphorylation capacity (ATPmax) of vastus lateralis was determined in vivo by (31)P magnetic resonance spectroscopy (n = 30). Quadriceps contractile volume was determined by magnetic resonance imaging. Mitochondrial efficiency (max ATP production/max O2 consumption) was characterized using ATPmax per St3 respiration (ATPmax/St3).

Results

In vitro St3 respiration was significantly correlated with in vivo ATPmax (r (2) = .47, p = .004). Total oxidative capacity of the quadriceps (St3*quadriceps contractile volume) was a determinant of VO2 peak (r (2) = .33, p = .006). ATPmax (r (2) = .158, p = .03) and VO2 peak (r (2) = .475, p < .0001) were correlated with preferred walking speed. Inclusion of both ATPmax/St3 and VO2 peak in a multiple linear regression model improved the prediction of preferred walking speed (r (2) = .647, p < .0001), suggesting that mitochondrial efficiency is an important determinant for preferred walking speed.

Conclusions

Lower mitochondrial capacity and efficiency were both associated with slower walking speed within a group of older participants with a wide range of function. In addition to aerobic capacity, lower mitochondrial capacity and efficiency likely play roles in slowing gait speed with age.

SUBMITTER: Coen PM

PROVIDER: S-EPMC3593613 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature

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Publications

Skeletal muscle mitochondrial energetics are associated with maximal aerobic capacity and walking speed in older adults.

Coen Paul M PM Jubrias Sharon A SA Distefano Giovanna G Amati Francesca F Mackey Dawn C DC Glynn Nancy W NW Manini Todd M TM Wohlgemuth Stephanie E SE Leeuwenburgh Christiaan C Cummings Steven R SR Newman Anne B AB Ferrucci Luigi L Toledo Frederico G S FG Shankland Eric E Conley Kevin E KE Goodpaster Bret H BH

The journals of gerontology. Series A, Biological sciences and medical sciences 20121009 4

<h4>Background</h4>Lower ambulatory performance with aging may be related to a reduced oxidative capacity within skeletal muscle. This study examined the associations between skeletal muscle mitochondrial capacity and efficiency with walking performance in a group of older adults.<h4>Methods</h4>Thirty-seven older adults (mean age 78 years; 21 men and 16 women) completed an aerobic capacity (VO2 peak) test and measurement of preferred walking speed over 400 m. Maximal coupled (State 3; St3) mito ...[more]

PMID: 23051977

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Project description:To determine the degree to which self-selected walking speed (SSWS), maximal walking speed (MWS), and walking speed reserve (WSR) are associated with fall status among community-dwelling older adults.WS and 1-year falls history data were collected on 217 community-dwelling older adults (median age = 82, range 65-93 years) at a local outpatient PT clinic and local retirement communities and senior centers. WSR was calculated as a difference (WSRdiff = MWS - SSWS) and ratio (WSRratio = MWS/SSWS).SSWS (P < 0.001), MWS (P < 0.001), and WSRdiff (P < 0.01) were associated with fall status. The cutpoints identified were 0.76 m/s for SSWS (65.4% sensitivity, 70.9% specificity), 1.13 m/s for MWS (76.6% sensitivity, 60.0% specificity), and 0.24 m/s for WSRdiff (56.1% sensitivity, 70.9% specificity). SSWS and MWS better discriminated between fallers and non-fallers (SSWS: AUC = 0.69, MWS: AUC = 0.71) than WSRdiff (AUC = 0.64).SSWS and MWS seem to be equally informative measures for assessing fall status in community-dwelling older adults. Older adults with SSWSs less than 0.76 m/s and those with MWSs less than 1.13 m/s may benefit from further fall risk assessment. Combining SSWS and MWS to calculate an individual's WSR does not provide additional insight into fall status in this population.Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES:: Upon completion of this article, the reader should be able to: (1) Describe the different methods for calculating walking speed reserve and discuss the potential of the metric as an outcome measure; (2) Explain the degree to which self-selected walking speed, maximal walking speed, and walking speed reserve are associated with fall status among community-dwelling older adults; and (3) Discuss potential limitations to using walking speed reserve to identify fall status in populations without mobility restrictions.Advanced: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The Association of Academic Physiatrists designates this activity for a maximum of 1.5 AMA PRA Category 1 Credit(s). Physicians should only claim credit commensurate with the extent of their participation in the activity.

Dataset Information

Skeletal muscle mitochondrial energetics are associated with maximal aerobic capacity and walking speed in older adults.

Background

Methods

Results

Conclusions

Publications

Skeletal muscle mitochondrial energetics are associated with maximal aerobic capacity and walking speed in older adults.

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