Skeletal muscle mitochondria in the elderly: effects of physical fitness and exercise training.
BACKGROUND
Sarcopenia is thought to be associated with mitochondrial (Mito) loss. It is unclear whether the decrease in Mito content is consequent to aging per se or to decreased physical activity.


OBJECTIVE
The objective of the study was to examine the influence of fitness on Mito content and function and to assess whether exercise could improve Mito function in older adults.


METHODS
Three distinct studies were conducted: 1) a cross-sectional observation comparing Mito content and fitness in a large heterogeneous cohort of older adults; 2) a case-control study comparing chronically endurance-trained older adults and sedentary (S) subjects matched for age and gender; and 3) a 4-month exercise intervention in S.


METHODS
The study was conducted at a university-based clinical research center.


RESULTS
Mito volume density (MitoVd) was assessed by electron microscopy from vastus lateralis biopsies, electron transport chain proteins by Western blotting, mRNAs for transcription factors involved in M biogenesis by quantitative RT-PCR, and in vivo oxidative capacity (ATPmax) by (31)P-magnetice resonance spectroscopy. Peak oxygen uptake was measured by graded exercise test.


RESULTS
Peak oxygen uptake was strongly correlated with MitoVd in 80 60- to 80-year-old adults. Comparison of chronically endurance-trained older adults vs S revealed differences in MitoVd, ATPmax, and some electron transport chain protein complexes. Finally, exercise intervention confirmed that S subjects are able to recover MitoVd, ATPmax, and specific transcription factors.


CONCLUSIONS
These data suggest the following: 1) aging per se is not the primary culprit leading to Mito dysfunction; 2) an aerobic exercise program, even at an older age, can ameliorate the loss in skeletal muscle Mito content and may prevent aging muscle comorbidities; and 3) the improvement of Mito function is all about content.
Department of Physiology (N.T.B., C.G., F.A.), School of Biology and Medicine, University of Lausanne, Lausanne CH-1005, Switzerland; Department of Clinical Research, Magnetic Resonance Spectroscopy, and Methodology (A.B., R.K., C.B.), University of Bern, CH-3010 Bern, Switzerland; Nestle Institute of Health Sciences (M.B., C.C.), Lausanne CH-1015, Switzerland; Service of Endocrinology, Diabetes, and Metabolism (A.D., F.A.), Service of Cardiology (L.S.), Center for Bone Disease (D.H.), and Sports Medicine Unit (G.G.), University Hospital, CH-1011 Lausanne, Switzerland; and Endocrinology and Metabolism Research Center (F.A.), School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213.
Nicholas T
NT
Broskey
Chiara
C
Greggio
Andreas
A
Boss
Marie
M
Boutant
Andrew
A
Dwyer
Leopold
L
Schlueter
Didier
D
Hans
Gerald
G
Gremion
Roland
R
Kreis
Chris
C
Boesch
Carles
C
Canto
Francesca
F
Amati
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D008931:Mitochondria, Muscle / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*