This study examines the impact of increasing energetic stress during an 8-hour fast on metabolic pathways in human skeletal muscle. Specifically, participants will undergo two 8-hour fasting sessions in a randomized crossover fashion, with the addition of low-intensity arm exercise in one of the sessions. Changes in metabolic pathways will be examined in resting (leg) muscle before, during, and after the fast.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
10
School of Kinesiology and Health Studies
Kingston, Ontario, Canada
Peroxisome proliferator activated receptor gamma co-activator 1-alpha (PGC-1α) messenger ribonucleic acid (mRNA) expression
PGC-1α gene expression (indirect indicator of PGC-1α activity)
Time frame: 15 min before fast; after 4 and 8 hours of fasting
Catecholamine concentrations
Epinephrine and norepinephrine concentrations in plasma samples
Time frame: 15 min before fast; after exercise; after 4 and 8 hours of fasting
Glucose and insulin concentrations
Glucose and insulin concentrations in plasma samples
Time frame: 15 min before fast; after 4 and 8 hours of fasting
total and phosphorylated AMP activated protein kinase (AMPK)
active AMPK relative to total AMPK protein content
Time frame: 15 min before fast; after 4 and 8 hours of fasting
total and phosphorylated SIRT-1
active SIRT-1 relative to total SIRT1 protein content
Time frame: 15 min before fast; after 4 and 8 hours of fasting
total and phosphorylated mammalian target of rapamycin (mTOR)
active mTOR relative to total mTOR protein content
Time frame: 15 min before fast; after 4 and 8 hours of fasting
total and phosphorylated Akt/Protein Kinase B
active Akt relative to total Akt protein content
Time frame: 15 min before fast; after 4 and 8 hours of fasting
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total and phosphorylated acetyl coenzyme A carboxylase (ACC)
active ACC relative to total ACC protein
Time frame: 15 min before fast; after 4 and 8 hours of fasting
total and phosphorylated p38 mitogen activated protein kinase (MAPK)
active p38 MAPK relative to total p38 MAPK protein
Time frame: 15 min before fast; after 4 and 8 hours of fasting
phosphorylated protein kinase A (PKA) substrates
phosphorylated PKA substrates (indirect measure of PKA activity)
Time frame: 15 min before fast; after 4 and 8 hours of fasting
acetylated p53
p53 acetylation status (indirect measure of SIRT-1 deacetylase activity)
Time frame: 15 min before fast; after 4 and 8 hours of fasting
Sirtuin 1 (SIRT1) mRNA expression
gene expression of the deacetylase enzyme SIRT1
Time frame: 15 min before fast; after 4 and 8 hours of fasting
Sirtuin 3 (SIRT3) mRNA expression
gene expression of the deacetylase enzyme SIRT3
Time frame: 15 min before fast; after 4 and 8 hours of fasting
Pyruvate dehydrogenase kinase isoenzyme 4 (PDK4) mRNA expression
gene expression of the PGC-1α target PDK4
Time frame: 15 min before fast; after 4 and 8 hours of fasting
p53 mRNA expression
gene expression of the tumour suppressor protein p53
Time frame: 15 min before fast; after 4 and 8 hours of fasting
Leucine rich pentatricopeptide repeat containing protein (LRP130) mRNA expression
gene expression of RNA-binding protein LRP130
Time frame: 15 min before fast; after 4 and 8 hours of fasting
General control non-repressible 5 (GCN5) mRNA expression
gene expression of the acetyltransferase GCN5
Time frame: 15 min before fast; after 4 and 8 hours of fasting
PGC-1α protein content
Protein content of the transcriptional co-activator PGC-1α
Time frame: 15 min before fast; after 4 and 8 hours of fasting
Cytochrome C oxidase subunit 4 (COX-IV) protein content
Protein content of the mitochondrial enzyme COX subunit 4
Time frame: 15 min before fast; after 4 and 8 hours of fasting
Intramuscular glycogen content
Muscle glycogen content
Time frame: 15 min before fast; after 4 and 8 hours of fasting
Intramuscular triglyceride (IMTG) content
Muscle IMTG content
Time frame: 15 min before fast; after 4 and 8 hours of fasting