Can someone explain this question

[shaq786]

The ECG can also be used to count the number of heartbeats per minute(the cardiac rate). Which person would most likely have the slowest cardiac rate at rest?

A. An infant
B. A marathon runner
C. A weight lifter
D. A sedentary adult




Can someone explain the logic. The answer is B.

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[!dr_nick!]

The ECG can also be used to count the number of heartbeats per minute(the cardiac rate). Which person would most likely have the slowest cardiac rate at rest?

A. An infant
B. A marathon runner
C. A weight lifter
D. A sedentary adult

Can someone explain the logic. The answer is B.

Marathon runner

 

[Freakedout]

The marathon runner would have the strongest heart, which means that they would pump the most blood for each beat hence they wouldnt need to pump as fast as someoneelse whose heart is weaker , so their cardiac output would be slower

 

[bgreet]

The marathon runner has the most efficient heart, having a large stroke volume and a lower bpm. Therefore by raising the bpm in a marathon runner, you greatly increase the amount of blood circulation.

 

[Aladdin Sane]

The ECG can also be used to count the number of heartbeats per minute(the cardiac rate). Which person would most likely have the slowest cardiac rate at rest?

A. An infant
B. A marathon runner
C. A weight lifter
D. A sedentary adult




Can someone explain the logic. The answer is B.

runners have a low resting heart rate and you can lower yours if you start running, just a little something i picked up from PE in college. but yeah that's the reasoning, if the heart is more efficient, the lower the resting heart rate

 

[doctorstudent]

let me think about it little bit


Normally when someone runs very fast he/she uses their fast oxidative (Type IIA) fibers which produces ATP at fast rate but accumlate lactic acids (anaerobic).

accumlated lactic acids will then return back to the liver and oxidized back to pyruvate through (glyconeogensis) and finally to glycose (( and this processe required oxygen )) and this explains why the heart beats at high rate during a rest when someone runs very fast.

But during a long-term event such as a mamathon race, most ATP is produced aerobically and thus accumulation of lactic acid will not occurs.As a result no oxygen is needed at rest and the heart will not going to beat at high rate.

 

[Medikit]

Okay, how about Lance Armstrong vs. Bill Marathonrunner?

 

[bgreet]

let me think about it little bit


Normally when someone runs very fast he/she uses their fast oxidative (Type IIA) fibers which produces ATP at fast rate but accumlate lactic acids (anaerobic).

accumlated lactic acids will then return back to the liver and oxidized back to pyruvate through (glyconeogensis) and finally to glycose (( and this processe required oxygen )) and this explains why the heart beats at high rate during a rest when someone runs very fast.

But during a long-term event such as a mamathon race, most ATP is produced aerobically and thus accumulation of lactic acid will not occurs.As a result no oxygen is needed at rest and the heart will not going to beat at high rate.

I think this reasoning is a little out there......

 

[stoleyerscrubz]

The conditioning of endurance athletes includes the goal of increasing your VO2 MAX as well as your increasing your lactic acid threshhold so some of what was said is valid but a marathon runner and a sprinter are supposedly going to recruit different composition of fiber types yet their resting heart rates would be expected to both be low.

The baby should be the first one to dismiss since their resting heart rates are above 100bpm. your heart rate is at it's greatest as an infant.

The sedentary adult should be dismissed next for obvious reasons

That leaves the weight lifter and marathon runner. The marathon runner is going to be able to able to increase their VO2 MAX and also anaerobic threshhold much easier since you need to get your heart rate well above 75% MAX Heart Rate to accomplish this.

You really don't need to know all of this info to get to the right answer though.

 

[LowlyPremed]

I think the simplest explanation is that endurance training increases the oxygen carrying capacity of the blood i.e increases erythrocytes volume and consequently increases in hemaglobin volume (at least in men). Total plasma volume also increases. In addition to the other posts, this would all explain why trained athletes have a lower resting heart rate. Since a trained athlete can pump more blood with each heart beat and that volume of blood has a higher capacity for oxygen, this is a reasonable explanation. Do you agree?

 

[doctorstudent]

Dopefish Lives !!!!!

what do u think then ??!!!

 

[bgreet]

What I think is that its a VERY simple and straight forward question and there is no need to delve into lactic acid production, or fermentation. A more healthy person has a stronger heart, able to pump more efficiently and like lowly said has a elevated plasma levels. And your right, Dopefish does live!

 

[Bhavesh]

runners have a low resting heart rate and you can lower yours if you start running, just a little something i picked up from PE in college. but yeah that's the reasoning, if the heart is more efficient, the lower the resting heart rate

That was my initial reasoning.

 

[OSUdoc08]

The ECG can also be used to count the number of heartbeats per minute(the cardiac rate). Which person would most likely have the slowest cardiac rate at rest?

A. An infant
B. A marathon runner
C. A weight lifter
D. A sedentary adult




Can someone explain the logic. The answer is B.

i wish i got questions this easy on the mcat

 

[scooter31]

Dont forget that with running (more so than other forms of exercise), you are inducing L Ventricular hypertrophy, thereby creating a higher baseline CO, which in turn causes a lessened need for your heart to beat as frequently. There are also vagal factors that are included in creating a lower resting HR that are exercise induced but I forget what they are and are far beyond the scope of the MCAT.

Lance vs marathon man would have similar HR resting, almost indiscernible. I think Lance may have the upper hand with this one-- maybe high 30's vs low 40's for BPM.