Investigating the effect of exercise on heart rate

Giacomo Cetta

Design

Research QuestionThe research question of our biology class practical is: how does exercise affect the intensity of the heart beat? This question will help us during the investigation stage and the practical part of our experiment. The heart, pumps blood to all the body, we need blood because it carries oxygen to all the parts of the body. But what happens to the heart when we do exercise? To find this out, we will measure our heart rate at rest, and then after doing exercise, we will also measure the time that our heart takes to go back to its original rate.

HypothesisI have an idea of what will happen to our heart beat after the exercise. I think that our heart rate will increase, so if at rest we do 69 beats per minute, on exercise we will do 110 beats. This is because the demand of oxygen from our body, increases since we will need more oxygen to make our body work under exercise, and this oxygen will be pumped by the heart to the body by arteries. To recover instead, it will not take a lot because as soon as you stop exercising, we spend one minute taking deep breaths that gives us a lot of spare oxygen that makes us recover in not more than three minutes.

Equipment Chronometer (for keeping time of the duration of the exercise) Pen and paper (for writing the data) Calculator (for measuring the heart rate change)

VariablesTo make this experiment a “fair experiment”, we have to count all the dependent variables, independent variables and all the controlled variables. The dependent variables are the variables that we measure, which are the change in heart rate (resting and exercise), and the speed of recovery (after exercise). The independent variables are the variables that we change, so we have to count if people exercise more than five hours a week or less. If people exercise more than five hours, their heart is more trained to do exercise, so their heart beat will be less frequent and their speed of recovery will be faster. The last, are the controlled variables. These variables make the test fair and they are variables that we control. For our experiment, our controlled variables are: the same distance and age, the same type of activity, and the same gender.

MethodThe first thing I need to do with my group is to draw a rough table on which I can write the results. Then we had to decide what exercise we will do for the experiment on the heart beat. We decided to: go up and down parts of the stairs for ten times. Done that, we can start to fill our table with our heart rate at rest; We measure how many heart beats we have in one minute.Then with my group we can start doing the actual practical. As soon as it ends we carefully measure our heart rate, even in this case the time that we measure the beats of the heart is one minute. Then for measuring the recovery time, we all sit down so we are sure that we don’t move any more and our body completely rests. To be sure that we completely recover, we measure our heart beat every minute for eleven minutes.The last part of the practical will be to measure the heart rate change, which is measured by taking away the at rest heart rate from the after exercise heart rate.

AnalysisValentina David Giacomo Beatrice

At Rest 66 60 72 84After Exercise 96 120 150 168+1 minute 87 112 146 163+2 minute 81 104 139 154+3 minute 74 97 132 147+4 minute 69 91 126 141+5 minute 65 83 119 135+6 minutes 65 77 111 129+7 minutes 65 69 97 116+8 minutes 64 62 93 108+9 minutes 65 60 84 95+10 minutes 65 60 78 89+11 minutes 65 60 70 83H. R. Change 96-66=30 120-60=78 150-72=78 168-84=84

Heart Beat Graph

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ConclusionThe first thing to say is that my hypothesis was partially wrong, since I said that after exercise the heart beat would increase and it did. But I said that in no more than three minutes we would had recover our original heart beat instead it took eleven minutes. So I learned that the heart rate takes a lot of time to recover from an exercise.

EvaluationI think my method worked very well since the results of the practical were possible as results. We also made sure that the recovery part was the same for every one since we were all sitting down. We also counted all the possible variables, so I think that we couldn’t had improved it in anyway. Maybe the only weakness was the keeping the count of the heart beat that we did by ourselves by placing our finger on our chest or on our wrist or on our neck, here, maybe someone didn’t feel the exact number of beats.