Acute Responses
What are acute responses to exercise?
They are the immediate physiological changes that the body makes to accommodate the energy requirements of a specific activity which return to resting levels when exercise finishes.
When oxygen supply = oxygen demand, we are in a period of...
steady state
Name the by-product that causes fatigue of the anaerobic energy system.
H+ ions
Which energy system is the major contributor at a given point in time is dependant on which 2 factors?
Exercise intensity and duration.
What are the 2 factors that make up ventilation?
Tidal volume and respiratory rate.
Name 2 acute cardiorespiratory responses that increase at the onset of exercise to adjust to the new oxygen demand.
Respiratory rate, heart rate, tidal volume, stroke volume
What is the rate and yield of the anaerobic glycolysis system?
Rate - Fast 1.6mol/min
Yield - Low 2-3 ATP per glucose molecule
PC restoration is associated with a passive recovery. Identify the % of PC restored at 30s, 3 minutes and 10 minutes.
30s - 70%. 3mins - 98%. 10min - 100%.
What is the interplay of energy systems?
Interplay of energy systems refers to the energy systems working together but at different rates, to supply the ATP required for an activity
What is pulmonary diffusion and it's purpose during exercise?
Pulmonary diffusion is the exchange of oxygen and carbon dioxide molecules at the alveoli. It increases during exercise to allow the body to take in more oxygen to be used for ATP production and remove carbon dioxide.
What is oxygen deficit? When does it occur and what does this mean in relation to energy system contribution?
Oxygen deficit is the state in which there is a discrepancy between oxygen supply and demand. This occurs at the beginning of exercise or when exercise intensity increases. Anaerobic pathways provide energy during this time.
What is energy produced from breaking down ATP used for? What is the energy produced from the energy systems used for?
ATP - muscle contractions
ES - ATP resynthesis
Name 3 responses that can occur as a result of an active recovery?
Reduce heart rate to resting levels. Replenish oxygen levels in the bloody, body fluids and myoglobin. Remove higher lactate concentration levels. Accelerate oxidation as this boosts the clearance of lactate. Remove metabolic by-products. Prevent venous pooling.
Describe the interplay of energy systems during a 100m sprint.
All three system contribute to ATP resynthesis. ATP-PC system will be the major contributor for the duration of the 100m sprint as it is a maximal intensity, short duration effort that requires ATP at a fast rate. The anaerobic glycolysis system will increase it's contribution after the 6 second mark as PC stores deplete to continue to provide ATP at a rapid rate. The aerobic energy system will contribute a small amount during the 100m sprint, but will not become the major contributor due to the short duration and maximal intensity effort of the 100m sprint.
Define the term a-VO2 difference. What is this a measure of? What happens to it during exercise and how does this improve performance?
a-vO2 difference is the difference in oxygen concentration in the arterioles compared to the venules. It is a measure of how much oxygen the muscles are extracting from the blood. When exercising the muscles extract more oxygen. This means more oxygen is taken up by the blood and less is sent back to the heart and breathed out. This allows an athlete to continue to resynthesis ATP and work aerobically at a higher intensity for longer.
What is EPOC? Name 3 responses that occur during this phase.
EPOC = excess post exercise oxygen consumption = oxygen supply > oxygen demand.
ATP and PC restored. O2 and myoglobin restored. Core temp reduced. Metabolic by-products oxidised/removed. HR and RR to resting levels. Restore other body systems to pre-exercise conditions.
Describe the difference between glycolysis and lipolysis. When would you use these and what is the difference in rate and yield?
Glycolysis - breakdown of carbohydrates - faster rate 1.0mol/min but lower yield 36-38ATP compared to lipolysis - breakdown of fats - slower rate and much higher O2 cost <1.0mol/min but much higher yield ~129 per FFA or 441ATP per triglyceride.
CHO - exercise
Fats - rest or when glycogen sparing
Approximately how long does it take for muscle glycogen to deplete in submaximal events? What happens once it has depleted and what does this mean for exercise intensity?
90-120 mins. Once muscle glycogen depleted, there is an increased reliance on fats (require more O2 to breakdown)– therefore decrease in exercise intensity (50% of VO2 max).
Describe the energy system interplay of a 1500m race.
All three energy systems contribute to ATP resynthesis. The major contributor in the 1500m event will be the aerobic energy system, due to the longer duration of the event and the requirement for oxygen. In the initial take off phase of the event, the ATP-PC system will provide majority of the ATP for the explosive start out of the blocks for up to 6-10 seconds. Due to insufficient oxygen being present as the athlete will be in oxygen deficit, the anaerobic glycolysis system will take over as the major supplier after PC stores deplete at the 6-10 second mark of the race. At approximately the 30-45 second mark, when oxygen supply equals oxygen demand, the athlete will rely upon the aerobic energy system to be the major contributor for the duration of the event. As the athlete surges toward the finish line in the final stages of the event, the anaerobic glycolysis system will increase it's contribution to provide ATP at a rapid rate so the athlete can finish quickly.
Describe the 3 mechanisms responsible for increased venous return.
The muscle pump – when the muscles contract, veins are squashed together and the blood in them is forced back towards the heart.
The respiratory pump – during inspiration, veins are squashed together in the thorax and abdomen.
Venoconstriction (constriction of the veins) –reducing the capacity of the venous system, forcing the blood in the veins to be pushed out towards the heart.
Explain the changes in oxygen uptake from rest, during sub-maximal exercise and in recovery, and how this has an impact on ATP production.
At rest the body is easily able to take in the required oxygen. As exercise begins, oxygen demand increases and the body is unable to meet this demand. During this period of oxygen deficit, ATP is produced anaerobically. During steady state, the oxygen supply is equal to demand and ATP is produced aerobically. At the completion of the exercise, excess oxygen is taken in to enable the body to return to pre-exercise levels.
Describe the stages of the aerobic energy system and what happens at each of these stages, including the amount of ATP produced at each stage.
Stage 1: Glycolysis: Glycogen - Glucose = 2-3ATP
Stage 2: Krebs Cycle: Pyruvic Acid - Acetyl co-enzyme A - Carbon dioxide + Hydrogen = 2ATP
Stage 3: Electron Transport Chain - Hyrdogen combines with O2 to form water. By products are heat, water and carbon dioxide = 32-34ATP
Describe the bodies response to dealing with elevated core temperature as a result of continued aerobic exercise.
Increase in core temperature results in an increase in blood flow to the skin in an attempt to increase the rate of body cooling through the evaporation of sweat from the skin surface. This occurs through vasodilation. This increased surface blood flow reduces the amount of blood flow to the working muscles (redirection of blood flow) relative to the amount that would normally be directed to the muscles when exercising under cooler conditions. Increased sweating will also occur and heat from the body is used to evaporate fluid on the surface of the body. This reduces body temperature but also results in a drop in blood plasma and reduced electrolyte content of cells in the body. Decreased blood flow to working muscles means increased reliance upon anaerobic pathways.
Describe 1 similarity and 1 difference in the energy system interplay of a goal shooter and a centre player in netball.
Both players would require a large contribution from the ATP-PC systems to perform the short, sharp movements involved in the game. The centre player would need a larger contribution from the anaerobic glycolysis system throughout the game to continue to perform high-intensity movements as they have fewer rest periods (lower periods of walking and standing still) that would lead to the replenishment of the ATP-PC system in the goal shooter. The aerobic system would be important to both players for different purposes. The centre player would require a greater contribution from the aerobic system to continue to move over the whole court (constantly moving). The goal shooter would need a highly trained aerobic system to improve recovery times for the ATP-PC system.