Chapter 15 - Aerobic training (Muscular adaptations) Flashcards
How does increase mitochondria density and number lead to improved performance?
Mitochondria are the aerobic powerhouses of the body where aerobic production of ATP occurs.
There is an increase in both size and number of mitochondria throughout slow twitch muscle fibres.
This results in an increased capacity for aerobic respiration. This increase in mitochondria increases the oxidative enzymes that allow endurance athletes to work a higher percentage of their VO2 max without accumulating lactate, decreasing the onset of fatigue, delaying LIP.
How does increase myoglobin stores lead to improved performance?
Myoglobin is similar to haemoglobin in that it attaches to oxygen.
The difference between the two is that haemoglobin transports oxygen in the blood and myoglobin provides for intramuscular oxygen storage.
Increased myoglobin stores mean that more oxygen can be stored and is available, hence more ATP is produced aerobically
How does increase capillary density lead to improved performance?
As the muscles’ demand for blood flow increases during exercise and training, the body adapts by increasing the number of capillaries surrounding individual muscle cells.
This greatly improves the oxygen exchange capacity between capillary and fibre by providing a greater surface area for the gas exchange and by reducing the distance oxygen molecules must travel after they are released from haemoglobin.
Increased capillary density and uptake of oxygen by active muscle tissue accounts for much of the increase in maximal oxygen consumption and improvements in VO2 observed in athletes.
How does increased use of fat during submaximal exercise lead to improved performance?
The increased use of fat appears to inhibit carbohydrate use during the first 30 minutes of exercise, especially at submaximal levels.
This results in glycogen sparing and also makes more glycogen available later during endurance performance.
An increase in triglyceride stores, free fatty acids and oxidative enzymes assist the muscles ability to oxidise fat.
How does increased stores and use of intramuscular triglycerides lead to improved performance?
Having a greater number of triglycerides also adds to the glycogen-sparing possibilities of slow-twitch muscle fibres.
Combined with a large blood flow and high mitochondria density, these triglycerides are ideal when performing low-intensity and submaximal exercise.
How does increased oxidative enzymes lead to improved performance?
Glycogen synthase is the enzyme responsible for converting glucose to glycogen.
Aerobic training leads to increases in its concentration and thus the ability to convert and store glycogen.
Glycogen can be broken down aerobically (aerobic glycolysis) or anaerobically (anaerobic glycolysis) to supply ATP -
Aerobically is preferred because it doesn’t result in fatiguing by-products, it occurs more quickly and easily, and it allows performance to continue with little fatigue.
How does oxygen extraction (arteriovenous oxygen difference) lead to improved performance?
The arteriovenous oxygen difference is expressed as the difference in oxygen concentration between the arterioles and the venules, after passing through muscles.
Aerobic training results in greater amounts of oxygen being extracted from the blood by muscles.
How does increased VO2max lead to improved performance?
An increase in oxygen delivery to the working muscles (cardiac output) and an increase in the ability of the muscles to extract the oxygen from the blood (AVO2 diff), enabling more ATP to be produced aerobically, therefore increasing VO2 max, VO2 max = SV × HR × a-vO2 diff
