4.4 Anaerobic Pathways

• lactic acid fermentation

  • after glycolysis, pyruvate molecules create lactate from H atoms from NADH
  • when O2 available, lactate converts to pyruvate in the liver
• during strenuous exercise, muscle cells respire faster than O2 can be supplied resulting in lactate production which is why we pant because it is the body's way of repaying O2 debt
• ethanol fermentation

  • after glycolysis occurs, pyruvate undergoes decarboxylation creating acetaldehyde and releasing CO2
  • acetaldehyde receives H atom from NADH which creates ethanol
  • used in yeast, brewing beer, etc.
• anaerobic respiration vs. fermentation

  • anaerobic respiration does not require O2, it uses another inorganic molecule as a final electron acceptor
  • fermentation does not require O2 and uses an organic molecule as an electron acceptor but does not utilize an ETC
• VO2 max is the measure of max volume of O2 that cells of the body can remove from the bloodstream in one minute per kg of body mass while body experiences maximal exertion
• individuals with higher VO2 max are more aerobically fit as these individuals can more utilize O2
• since O2 cannot reach all the body's mitochondria, lactate fermentation occurs continuously as you exercise; as exercise intensity increases, lactate production does too
• lactate threshold is the value of exercise intensity at which blood lactate concentration begins to increase sharply
• exercising above or below the intensity may be sustainable for some time, but exercising beyond the LT may limit duration of exercise because of increased pain, muscle stiffens and fatigue
• beetroot juice is considered performance enhancing because it is high in nitrates which is broken down to nitrite and a small raise in nitric oxide provides a reduction in the body's need for oxygen, hence the performance enhancement