The aim of this study is to characterize the relation between skeletal muscle mitochondrial metabolism and muscle health in elderly, physically compromised humans. To study this relation, a cross-sectional study will be performed in well-defined, distinct subject groups. Thus, to obtain insight in the relation between mitochondrial health and muscle function, not only subjects that differ in mitochondrial function (based on physical activity) will be compared but also subjects with high- versus low muscle function will be selected.
Aging is associated with a decline of mitochondrial and skeletal muscle volume, -quality and -function. If a causal link exists between the loss of mitochondrial function and muscle health is unknown, however, both appear with advancing age and are associated with the loss of functional capacity, which increases comorbidities and annual healthcare costs. The aim is to test the hypothesis that a compromised muscle function in sedentary elderly is related to an impaired mitochondrial health. A detailed characterization of mitochondrial metabolism and muscle function is performed in well-defined, (physically compromised) elderly humans, in a cross-sectional design. To obtain insight in the relation between mitochondrial health and muscle function, not only elderly subjects that differ in mitochondrial function (based on physical activity) will be compared but also elderly subjects with high versus low muscle physical function will be selected. Healthy, young (20-30 years,) individuals with normal physical activity levels will be included as absolute controls.
Study Type
OBSERVATIONAL
Enrollment
59
Maastricht University
Maastricht, Limburg, Netherlands
Rate of ex vivo mitochondrial State 3 respiration
Ex vivo mitochondrial capacity, ADP-stimulated respiration expressed by O2flux in pmol/mg wet weight/second
Time frame: Day 4
Insuline sensitivity
Measured by 1-step hyperinsulinemic euglycemic. Insulin-stimulated glucose disposal, expressed as the rate of disappearance of the glucose (Rd glucose in μmol\*kg-1\*bw\*min-1
Time frame: Day 1
Physical functionality, 6MWT
Measured by a standardized 6-minute walk test. Physical functionality expressed in the distance (in meters) the subject is able to walk over a total of six minutes
Time frame: Day 2
VO2max
Maximal oxygen uptake measured by maximal cycling test (ml\*kg-1\*min-1)
Time frame: Day 2
Body composition
Measured by BodPod and expressed by percentages of fat mass (%)
Time frame: Day 3
Dynamic gait stability
Characterized by using the CAREN-system locomotion assessment and expressed by amount of steps necessary to regain normal walking pattern
Time frame: Day 3
Muscle strength in upper-leg
Extensor and flexor muscles of the knee joint measured by dynamometer (Biodex) expressed in peak torque 70° extension and flexion knee (Nm/kg)
Time frame: Day 3
Energy expenditure in rest and during sub-maximal exercise
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indirect calorimetry during 45 minutes in resting state (in KJ/min) and 1-hour exercise bout at 50% of maximal power output (in KJ/min)
Time frame: Day 4
Muscle oxidative capacity in vivo (PCr-MRS recovery)
In vivo skeletal muscle PCr-recovery expressed by PCr halftime (s)
Time frame: Day 5
Muscle metabolism in vivo (H-MRS acetylcarnitine)
In vivo skeletal muscle acetylcarnitine concentrations in rest measured by H-MRS and expressed by mmol/kgww
Time frame: Day 5
Muscle volume upper-leg
Muscle volume measured by MRI
Time frame: Day 5