- Explain to students that at the count of three they are to count the number of heart beats
- Have Time Watcher count aloud to three
- On three tell students to record their heart rate
- The Time Watcher should count 60 seconds by watching the clock
- After 60seconds the Time Watcher should shout “Stop”
- Record each students heart rate
- Perform Jumping jacks
- Rest at least two minutes breathing normally allowing your heart rate to normalize.
- Tell the 10 students to spread out with enough space to perform jumping jacks
- Tell the students to begin performing Jumping Jacks.
- The Time Watcher should count 45 seconds using the clock.
- After 45 seconds the Time Watcher should shout “Stop”
- Record Heart Rate for 60 seconds of exercise
- Tell the 10 students to find their pulse.
- For purposes of consistency the pulse area will be the neck
- Place two fingers on the center of your chin
- Run your two fingers down until you feel your Adams apple
- Slightly move your two fingers to the right applying pressure
- Stop moving fingers once a thumping sensation is felt on fingers
- Explain to students that at the count of three they are to count the number of heart beats
- Have Time Watcher count aloud to three
- On three tell students to record their heart rate
- The Time Watcher should count 60 seconds by watching the clock
- After 60seconds the Time Watcher should shout “Stop”
- Record each students heart rate
- Record Heart Rate for 90 seconds of exercise
- Repeat steps 4a-4e replacing 45 seconds with 90 seconds.
- Repeat steps 5a-5g
Data Table:
* Because time wasn’t directly involved in calculations it became unnecessary to record uncertainty
Calculations:
Sample Calculation for Average Heart Rate in beats per minute
Average Heart Rate in beats per minute = (Subject 1 Trial 1 + Subject 1 Trial 2 + Subject 2 Trial 1 + Subject 2 Trial 2 + Subject 3 Trial 1 + Subject 3 Trial 2 + Subject 4 Trial 1+ Subject 4 Trial 2+ Subject 5 Trial 1 + Subject 5 Trial 2+ Subject 6 Trial 1 + Subject 6 Trial 2+ Subject 7 Trial 1 + Subject 7 Trial 2 + Subject 8 Trial 1 + Subject 8 Trial 2 + Subject 9 Trial 1 + Subject 9 Trial 2 + Subject 10 Trial 1 + Subject 10 Trial 2)
Increment One = 0 Seconds
Total Number of Trials= 20
Average Heart Rate in beats per minute = (60+74+76+80+78+82+78+84+84+58+70+98+72+96+74+96+66+74+90+96) / (20)
Average Heart Rate in beats per minute “increment one of 0 seconds” = 79.30 seconds
Average Heart Rate in beats per minute “increment two of 45 seconds” =135.6 seconds
Average Heart Rate in beats per minute “increment three of 90 seconds” = 152.2 seconds
Round to 4 significant figures in all cases to keep consistent with the bigger heart rates.
Sample Calculation for Standard Deviation
Input column “Increment One 0 Seconds” into graphing calculator
Calc “1-Var Stats”
One Standard Deviation = 11.38902981 seconds
Round to 4 significant figures because smallest unit of data in the averages is 4 significant figures
One Standard Deviation = 11.40 seconds
One Standard Deviation “Increment One 0 seconds” = 11.40 seconds
One Standard Deviation “Increment Two 45 seconds”= 19.03 seconds
One Standard Deviation “Increment Three 90 seconds” = 18.48 seconds
Sample Calculatoin for T-Test
- Identify the Null hypothesis
The Average Heart Rate between increment one and increment two are not significantly different
- Identify the Significance Level (a)
- = .05
- Calculate Degrees of Freedom
Degrees of freedom = Sum of sample sizes(n)-2
n= 20
n2=20
n3=20
Degrees of freedom = 20+20-2
38=40-2
- Calculate Sample Size
n= 20
n2=20
n3=20
- Find Value of t from t table
Value of t = 1.684
- Find Rejection Region (RR)
- Find t calculated and probability value (p)
T calculated= -11.06
P= 2.64 * 10-12
- Decision
T calculated is greater than t table value -1.684
Reject null hypothesis
- Conclusion
- Since t- calculated is inside the rejection region at -11.06 the average Heart Rate for increment one 0 seconds is significantly different from the average Heart Rate for increment two 45 seconds.
Calculations Data Table:
Conclusion:
The Duration of exercise that a person undergoes has a positive effect on their heart rate. In order to arrive at this conclusion 10 students preformed two trials each of three different time increments for exercise. As the duration of exercise increased, the average heart rate in beats per minute also increased. This is visible because the average heart rate for increment one of 0 seconds was 79.3 beats per minute while the average heart rate for increment two was even higher at 135.6 beats per minute. This positive effect held true through all three increments increasing average heart rate during increment three of 90 seconds at 152.2 beats per minute. To further verify these results standard deviation was calculated to clarify the distribution of data and also to see if any of it overlapped. The error bars appearing on the graph do not overlap between increments one and two but do overlap quite a bit between increments two and three. This shows us that while the duration of exercise does increase heart rate as shown in comparing increments one and two, its effect on heart rate begins to level off explaining the overlap between increments two and three.
Since the error bars between increment one and increment two did not overlap, a t-test was performed in order to identify whether the difference between the two increments was significantly different. Results showed that since t-calculated was -11.06 ( well inside the rejection region) the average Heart Rate for increment one 0 seconds is significantly different than the average Heart Rate for increment two 45 seconds.
While these results agree with what was expected to happen, it seems strange that after doubling the duration of exercise, a lot of data ends up overlapping shown by the error bars between increments two and three. One possible explanation for these results is a failure to control the nature of the student’s jumping jacks. It was noticed during data collection that while the students were jumping jacks the pace varied from student to student. What this means is that some were exercising at a more rigorous pace while others at a slower pace. While this was not significant enough to discard the duration of exercise as a factor affecting heart rate, it did inhibit the conclusion in terms of how effective duration of exercise is and continually affecting heart rate. Another Weakness is the way in which people recorded their pulse. While everyone recorded their pulse by using their neck some students reported issues with finding their pulse during the seconds following their exercise. This means that after long durations of exercising greater and greater amounts of beats were never recorded impacting the data to the point where increments two and three significantly overlapped in their error bars.
In order to improve the lab and reduce the overlap of the error bars exhibiting standard deviation the procedure should be modified with at least two changes. The first improvement would be assigning a lead student who would set the pace of jumping jacks which would ensure that everyone would be exercising at the same rate. Another improvement would be having each student pair up with another student. Half the students could do jumping jacks while half the students watch. Once done jumping jacks, the resting students could record their partner’s jumping jacks for them. To do this they would learn how to find their partners pulse beforehand. This would effectively eliminate the beats lost to error in finding one’s own heartbeat. Together these improvements would help reduced the overlap that occurs in the error bars of standard deviation by making results more consistent in two ways. The type of exercise is streamlined even more and the method for recording pulse is improved.