week 5: The muscular system: Acute muscular responses to exercise: anaerobic performance Flashcards
anaerobic metabolism most needed in
first 30 seconds of maximal exercise
energy systems that contribute
ATP-Pc system
glycolysis
aerobic metabolism
major pathways of anaerobic ATP pathways
- creatin kinase reactions
- anaerobic glycolysis
- adenylate kinase reaction
creatine kinase reaction
Pcr + H+ +ADP -> ATP + Cr
Pcr immediate defense
combines with proton and ADP
allows reformation of highh energy phosphate in form of ATP
anaerobic glycolysis
glycogen + 3ADP + Pi ->
3ATP + 2La- + 2H+
glycogen converted to lactate and proton
adenylate kinase reaction
2ADP -> ATP + AMP
with AMP quickly degraded IMP & NH4+ via AMPD
two key factors why anaerobic metabolism is important to skeletal muscles during exercise
- slow response of oxidative metabolism (increase in mitochondria uptake of oxygen) to turn on (O2 deficit)
- maximal rate of ATP provision is limited by oxidative metabolism
ATP needed for
- cross bridge cycling
Myosi ATPase> contraction - Ca2+ ATPase> relaxation
two major challenges during immediate exercise
- depletion of PCr
- lactate (and H+) accumulation
depleting stores of PCr occurs when and the consequence of it
limits maximum capacity to maintain high power outputs
occurs as ex intensity increases as % of VO2 max
when does glycolysis occur in cytosol (anaerobic)
pyruvate cant enter mitochondria
if anaerobic glycolysis in cytosol occurs at more rapid rate than what NADH can be reoxidised and pyruvate can enter mitochondria
lactic acid produced
(lactate and H+)
associated with acidosis
exercise induced acidosis
anaerobic exercise can challenge acid-base balance due to increased H+ production
detrimental for muscle performance
sources of acidosis during exercise - aerobic
aerobic metabolism of glucose> carbonic acid > H+
sources of acidosis during exercise - anaerobic
anaerobic metabolism (glycolysis) of glucose > lactate> H+
another source of acidosis during exercise
ATP breakdown and release of H+
anaerobic athletes and buffering capacity
many anaerobic athletes have high capacity to buffer increases in H+
anaerobic training allows an increase in muscle buffering capacity by up to 50%
first line of defense buffers located
muscle
second line of defense buffers located
blood
cellular buffer systems
bicarbonates
phosphates
proteins
carnosine
transport of H+ out of muscle
blood buffer systems
bicarbonate
phosphates
proteins
respiratory compensation for metabolic acidosis
blow off excess CO2 from lungs
key H+ transport mechanisms linking muscle-to-blood
sodium-hydrogen exchanger
(NHE)
monocarboxylate transporters (MCT)
sodium hydrogen exchanger
Na+ moves into muscle from blood
H+ moves out of muscle into blood
monocarboxylate transporter
lactate moves into blood from muscle
H+ moves into blood from muscle
power output over repeated sprints with rest
power output decreases
(peak and mean)
reasoning for decreasing power output over repeated sprints
relative contribution of anaerobic metabolism reduced with increasing sprint number
very significant (ie 65% between sprint 1-10) in anaerobic energy provision
ATP turnover rate decreased
