week 7-muscle adaptations 2

myoglobin response

increase up to 75-80% in rodents

in humans training at hypoxia leads to no change in Hb

proportionate to change in fibre type

mitochondrial biogenesis

Simplified signal transduction pathway

Specific detail will relate directly to the different tissues and different situations.

multiple targets: metabolic pathways, gene expression, protein dynthesus

signals are intracellular e.g. calcium, ADP, ATP

PGC-1a

co-activator responsible for increase in mitochondrial proteins

structural proteins

for the site of ETC

muscle glycogen

more glycogen stores in trained endurance athletes

can take up to 48hrs to get glycogen into the muscle

insulin sensitivity

time spent exercising is important to improve insulin sensitivity

GLUT-4 expression

In humans GLUT 4 mRNA expression is significantly elevated immediately after a single exercise bout.

Remains elevated for several hours after exercise.

Returns to pre-exercise levels within 24hrs.

Training induced responses from repeated transient increases in GLUT 4 transcription

glycogen synthase

higher in trained people

intramuscular triglycerol

trained muscle of exhaustive exercise has higher IMTAG

large variability suggests contamination from adipose tissue

intramyocellular lipids

greater levels after exercise training

oxidative enzyme activity

increases the more trained someone is

positive linear change in CO2

cross sectional studies on leg muscle enzyme activities suggest that the more trained someone is, the higher SDH and CS is

fat oxidation

endurance training can markedly increase fat oxidation during submax exercise

Key adaptation to consider is the increase in mitochondrial proteins:- Increased activities of the krebs cycle and electron transport chain

RER decreased significantly at same absolute intensity and same relative intensity

fat oxidation increase

increase in fatty acid enzyme activity

reversibility

CV and respiratory adaptations

Metabolic adaptations require the adequate delivery of oxygen

Therefore the CV and respiratory adaptations remain key:
– increase V E max
– increase cardiac output and stroke volume
– increase extraction of oxygen from blood flowing through the working muscle