Final answer:
During the Iron Man triathlon, muscle cells initially use creatine phosphate for quick energy, then glycolysis to produce ATP from glycogen, leading to lactic acid buildup. Mitochondria in muscle cells produce ATP but rely on lactic acid fermentation when oxygen is low, causing fatigue and soreness. Adaptations like angiogenesis and myoglobin storage improve endurance by enhancing oxygen supply and waste removal.
Step-by-step explanation:
When you are running the Iron Man triathlon, your muscle cells undergo several processes to meet the energy demands. Initially, muscle cells use creatine phosphate to supply energy rapidly, but this lasts only for 8-10 seconds. Then, the cells shift to using glycogen to produce ATP from glucose through glycolysis, which can supply energy for about 90 seconds without the need for oxygen, leading to the production of lactic acid.
Muscle cells have a high concentration of mitochondria, crucial for ATP production during aerobic respiration. During the triathlon, when muscle cells run low on oxygen, mitochondria are unable to produce sufficient ATP, thus the cells also rely on lactic acid fermentation. This process produces ATP in the absence of oxygen but leads to an accumulation of lactic acid in the muscles, causing soreness and fatigue.
To sustain longer activities, muscle cells adapt through a process called angiogenesis, forming an extensive network of capillaries that help in the supply of oxygen and removal of metabolic waste. This adaptation, alongside the presence of myoglobin in the sarcoplasm which stores oxygen, helps to cater for the energy demands during endurance activities like the Iron Man triathlon.