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J Gerontol A Biol Sci Med Sci. 2013 Apr;68(4):447-55. doi: 10.1093/gerona/gls196. Epub 2012 Oct 9.

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

Author information

1
Department of Health and Physical Activity, University of Pittsburgh, Trees Hall Rm 134D, Allequippa St. and Darragh St., Pittsburgh, PA 15260, USA. pmc17@pitt.edu

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.

PMID:
23051977
PMCID:
PMC3593613
DOI:
10.1093/gerona/gls196
[Indexed for MEDLINE]
Free PMC Article
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