muscular adaptations to endurance Flashcards
muscle fibre types
endurance trained individuals have a high % of type 1 fibres
endurance training promotes fast to slow shift in skeletal muscle fibre types
major effect of aerobic training is to convert some type 2x to type 2a and type 1 fibres
endurance training is a potent stimulus for altered myosin heavy chain (MHC) gene expression
muscle angiogenesis
exercise training induces angiogeneis (increased capillaries)
increased SA for diffusion
myoglobin response
reported increase of up to 75-80%
specificity to trained muscle group
most studies looked at the changes in muscle in mammals rather than humans
myoglobin- oxygen storage in muscle
mitochondrial biogenesis
simplified signal transduction pathway
specific detail will relate directly to the different tissues and different situations
signals in muscles during exercise- muscle lengthening, changes in intracellular calcium, changes ATP:AMP, availability of NADH going into ETC- as a primary stimulation of cascade
PGC-1a- coactivator responsible for increase in mitochondrial proteins
structural proteins for the site of ETC
otehr proteins involved in fatty acid oxidation
muscle glycogen
trained individuals can store significantly more glycogen in the muscle
linked to GLUT-4 transporter - insulin sensitivity
chnage is greater in groups who had exercised for longer, rather than the intensity of the exercise
improving the uptake of glucose in the muscle
glut 4 expression
in humans, glut 4 MRNA expression is sig elevated immediatly after a single exercise bout
remains elevated for seceral hours after exercise
returns to pre exercise levels within 24 hours
training induced responses from repeated transient increases in glut 4 transcription- longer the exercise= greater adaptations
glycogen synthase- higher levels in endurance athletes - key enzyme in building up glycogen stores
transport of FFA
triglycerides in adipose tissue broken down to free fatty acids and glycerol
glycerol and ffa enter bloodstream
FFA are transported into muscle via VLDL (very low density lipoproteins)
FFA can be oxidised in the muscle mitochondria (TCA cycle) to produce ATP
fat and CHO stored in the muscle fibre as IMTG and glycogen
glycerol can leave muscle, to blood and be converted to glucose in liver
VLDL- carry TG/FFA synthesised in liver/intestines to capillary beds in skeletal muscle and adipose tissue
process of getting glucose into muscle to be stored as glycogen
intramuscular triglycerol
study
in 10 males, daily unilateral leg extension, lifted a weighted boot
had bilateral biopsies
iMATG increased in trained leg, was significanly higher in trained leg compared to control
intramyocellular lipids
study
9 untrained, healthy males, alternating endurance and interval training
3 days standardised diet
after training- greater storage of these fats in the muscle
oxidative enzyme activity
over 7 months of training
sig changes in succinate dehydrogenate activity (aerobic enzyme)
independent changes in mitochondrial numbers
SDH- oxidises succinate to fumarate (FAD rediced to FADH2)
citrate synthase is also studied- catalyses the condensation reaction forming citrate (marker of intact mitochondria)
changes in level of SDH seem to determine levels of changes in otehr oxidative enzymes
fat oxidation
endurance training can markedly increase fat oxidation during submax exercise
key adaptation to consider is the increase in mitochondrial proteins- increased activity of the krebs cycle and ETC]
increase in fat oxidation
why does it increase
mitochondrial fa oxidation- significant increase post training programme
CPT-1- transports fatty acids into mitochondria - also increases post training programme
if there are more FA being transported at faster rate, more FA can be oxidised in mitochondria
can utilise fats at higher rates of exercise intensity
CV and respiratory adaptations
integration with both
- metabolic adaptations require adequate delivery of o2
- CV and resp adaptations remain key
- increase in VE max
- increase Q and SV
- increased extraction from blood through the working model
