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Physical Education [3/4] Question Thread
anotherworld2b:
Hi I am a WACE student and was hoping if I could have some help.
My teacher gave us questions to answer in regards to a experiment on heart rate.
It involved a person jogging at a steady pace for 400 m with their heart rate being recorded at each interval of 100 m. (100, 200, 300 and 400m)
The graph for this experiment showed the subject's heart rate increased dramatically from 0m to 100m but only gradually each time for 100- 200, 200 -300 and 300- 400m.
I tried to explain why heart rate would only gradually increase from 200m to 400m and was wondering if someone could tell me if my explanation would be correct.
Spoilerslowly repaid.
howey:
--- Quote from: anotherworld2b on July 22, 2017, 06:43:37 pm ---Hi I am a WACE student and was hoping if I could have some help.
My teacher gave us questions to answer in regards to a experiment on heart rate.
It involved a person jogging at a steady pace for 400 m with their heart rate being recorded at each interval of 100 m. (100, 200, 300 and 400m)
The graph for this experiment showed the subject's heart rate increased dramatically from 0m to 100m but only gradually each time for 100- 200, 200 -300 and 300- 400m.
I tried to explain why heart rate would only gradually increase from 200m to 400m and was wondering if someone could tell me if my explanation would be correct.
SpoilerInitially anaerobic respiration allows cells to produce some energy in the absence of oxygen from glucose. This resulted in the accumulation of lactic acid in the muscles and an oxygen debt from combining lactic acid with oxygen to form glucose and eventually glycogen. Heart rate continues to increase as the subject deplete their anaerobic sources of energy and starts to switch to aerobic energy production from 200 metres to 400 metres. As the subject’s speed and activity intensity remains the same from 200 metres onwards, the amount of oxygen required for the activity remains the same. This meant a sharp increase in heart rate was not necessary to maintain a steady jog. Heart rate and stroke volume is a key determinant of how much oxygen can be delivered to the working muscles. To provide sufficient oxygen necessary for aerobic respiration to maintain muscle activity and to ensure that blood supply to the muscles is adequate, heart rate will increase gradually from 200 metres onwards. The increased heart rate allows lactic acid to be carried away by the blood to the liver, where it is broken down. It also allows the oxygen debt incurred by the body to be slowly repaid.
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Good question! First of all, I should just say I know nothing about the WACE study design or expected answers, so I can only answer this from a VCE point of view.
You're on the right track. My key points in this answer would be:
- At the start of exercise oxygen deficit would occur as the body's cardiovascular and respiratory systems respond to physical activity (you've said oxygen debt - I know in VCE oxygen debt only occurs at the end of exercise, oxygen deficit occurs at the start)
- Once the athlete has hit the 100m mark (or 200m mark, if you're only talking about that in your answer), oxygen supply is very close to equalling oxygen demand, as the exercise intensity is constant
- Therefore, the athlete's heart rate will remain fairly steady, as they don't need to take in any more oxygen as the intensity is constant
Note: If the athlete were to have a completely steady HR, you could talk about how they have entered steady state - where oxygen supply equals oxygen demand.
I hope this helps!! :)
anotherworld2b:
Would a oxygen deficit also be due to anaerobic respiration at 0m to 100m?
So basically once the athlete has hits the 100m mark and onwards, oxygen supply is very close to equalling oxygen demand, as the exercise intensity is constant. Therefore, the athlete's heart rate will remain fairly steady, as they don't need to take in any more oxygen as the intensity is constant
But How would you explain why heart rate would still increase from 200m to 400m but to a lesser degree? is it due to the oxygen deficit?
--- Quote from: howey on July 23, 2017, 11:01:11 am ---Good question! First of all, I should just say I know nothing about the WACE study design or expected answers, so I can only answer this from a VCE point of view.
You're on the right track. My key points in this answer would be:
- At the start of exercise oxygen deficit would occur as the body's cardiovascular and respiratory systems respond to physical activity (you've said oxygen debt - I know in VCE oxygen debt only occurs at the end of exercise, oxygen deficit occurs at the start)
- Once the athlete has hit the 100m mark (or 200m mark, if you're only talking about that in your answer), oxygen supply is very close to equalling oxygen demand, as the exercise intensity is constant
- Therefore, the athlete's heart rate will remain fairly steady, as they don't need to take in any more oxygen as the intensity is constant
Note: If the athlete were to have a completely steady HR, you could talk about how they have entered steady state - where oxygen supply equals oxygen demand.
I hope this helps!! :)
--- End quote ---
howey:
--- Quote from: anotherworld2b on July 23, 2017, 12:19:51 pm ---Would a oxygen deficit also be due to anaerobic respiration at 0m to 100m?
So basically once the athlete has hits the 100m mark and onwards, oxygen supply is very close to equalling oxygen demand, as the exercise intensity is constant. Therefore, the athlete's heart rate will remain fairly steady, as they don't need to take in any more oxygen as the intensity is constant
But How would you explain why heart rate would still increase from 200m to 400m but to a lesser degree? is it due to the oxygen deficit?
--- End quote ---
Yes, the oxygen deficit from 0 to 100m would be because the anaerobic energy systems are producing the majority of the ATP.
The slight increase is interesting - usually in these type of questions HR remains constant after a certain point (e.g. 200m). Heart rate would increase because there is a greater demand for oxygen than is currently being supplied. Usually, this is because exercise intensity increases. In this case, there may just be a slight increase because the athlete hasn't quite settled into steady state yet - so yes, there would be a small oxygen deficit because the anaerobic energy systems are still providing a small amount of the energy from 200m-400m, and their contribution is slowly decreasing (hence the slowly increase in HR as the aerobic system provides more of the energy).
anotherworld2b:
Does that mean that oxygen deficit would be occurring throughout the exercise? (0m to 400m)
Wouldn't aerobic respiration begin from 200 metres and onwards? Would oxygen deficit still be present?
--- Quote from: howey on July 23, 2017, 12:37:13 pm ---Yes, the oxygen deficit from 0 to 100m would be because the anaerobic energy systems are producing the majority of the ATP.
The slight increase is interesting - usually in these type of questions HR remains constant after a certain point (e.g. 200m). Heart rate would increase because there is a greater demand for oxygen than is currently being supplied. Usually, this is because exercise intensity increases. In this case, there may just be a slight increase because the athlete hasn't quite settled into steady state yet - so yes, there would be a small oxygen deficit because the anaerobic energy systems are still providing a small amount of the energy from 200m-400m, and their contribution is slowly decreasing (hence the slowly increase in HR as the aerobic system provides more of the energy).
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