1. The Effect of Caffeine on Heart Rate During Physical Activity
Madisyn Waage
Aberdeen Central High School
Purpose
Data Analysis
1. Two-Sample T-Test and CI: Control, With Monster   
Difference = mu (Control) - mu (With Monster)
Estimate for difference:
95% CI for difference: (-46.7, 15.4)
T-Test of difference = 0 (vs not =): T-Value = P-Value = DF = 9
Results
The data above are results of the statistical T-test using the calculated percent increase of heart rate for each participant. This is the percent increase from initial resting heart rate in both instances. When the participant drank the Monster, their resting heart rate increased before they started the workout. This is not showing results from the elevated resting heart rate. This graph shows how one’s heart rate increases from the initial resting heart rate before any variables come into play. Percent increase was calculated using the following formula: [(Maximum heart rate- Initial heart rate)/Initial heart rate] X 100.
2. Two-Sample T-Test and CI: Control, With Monster
Estimate for difference: 10.3
95% CI for difference: (-19.4, 40.1)
T-Test of difference = 0 (vs not =): T-Value = P-Value = DF = 9
The above data shows the statistical analysis of the percent increase of heart rate from each participant’s final resting heart rate. In the trial in which participant’s had to drank Monster Energy Drink, their resting heart rate after the Monster was in their system for twenty minutes is used in the above results. This value is different than the initial resting heart rate because once participants drank the Monster, their resting heart rate increased.
3. Two-Sample T-Test and CI: Control, With Monster
Estimate for difference:
95% CI for difference: (-15.72, 3.38)
T-Test of difference = 0 (vs not =): T-Value = P-Value = DF = 9
The above results are the statistical analysis of the maximum heart rates of the participants. The maximum heart rate occurred at the end of the workout, after twelve minutes of intervals.
4. Two-Sample T-Test and CI: Control, With Monster
  Difference = μ (Control) - μ (With Monster)
Estimate for difference:
95% CI for difference: (-17.28, 4.61)
T-Test of difference = 0 (vs ≠): T-Value = P-Value = DF = 9
The above data compares the resting heart rates of the participants in each of the two trials. Trial one is the control in which there were no variables. The second trial is when participants drank Monster Energy Drink. The resting heart rate increased after consuming caffeine in trial two, and the graphs above show this observation.
5. Two-Sample T-Test and CI: Control, With Monster
Difference = μ (Control) - μ (With Monster)
Estimate for difference:
95% CI for difference: (-15.46, 5.46)
T-Test of difference = 0 (vs ≠): T-Value = P-Value = DF = 9
The above data compares the average heart rates measured during the twelve minute interval workout. Heart Rate was recorded every three minutes during the treadmill workout.
6. Two-Sample T-Test and CI: Control, With Monster  
Estimate for difference:
95% CI for difference: (-18.38, 10.05)
T-Test of difference = 0 (vs ≠): T-Value = P-Value = DF = 9
Along with heart rate during exercise, each participant’s heart rate was collected during a twelve minute recovery period directly following the interval workout. The above statistical analysis reflects the collected data pertaining to average heart rate during this recovery period for each trial.
Conclusion
The results show that a person’s heart rate will increase by a smaller percentage when caffeine is consumed. Caffeine causes one to feel less fatigued because it increases the release of adrenaline into the blood, stimulating the release of extra fat earlier in exercise. This sparing of carbohydrates allows more glycogen to be available further into the workout, which postpones fatigue. In conclusion, I fail to reject the null hypothesis that caffeine has no effect on heart rate during interval training. Although caffeine had an effect on percent increase of heart rate, maximum heart rate, and average heart rate, the effect was not significant enough to reject the null hypothesis. The data does show that if one wants to complete an interval workout at an increased heart rate to improve running performance, caffeine consumption will increase one’s heart rate by an average of five beats per minute. The original hypothesis for this experiment was that a participant’s resting to maximum active heart rate will increase at a smaller percentage while completing an interval workout when one has consumed caffeine beforehand. The results support the original hypothesis; at the same time, the p-value of is not significant enough to reject the null. After drinking Monster, the participants’ resting heart rate increased in each trial. Then, the percent increase from that elevated heart rate to the maximum heart rate during exercise was less than the percent increase in the control trial. This data, along with the observation by every participant stated that the interval workout felt easier after consuming caffeine, leads to the conclusion that caffeine makes an interval workout less strenuous. The results obtained in the experiment do not support the hypothesis well enough to support a conclusion that caffeine causes a person’s percent increase in heart rate to be a reduced when completing interval training.
PHOTOS
The photo on the left shows the Garmin Forerunner 405 sports watch and heart rate monitor used to measure heart rate during experimentation.
The photo on the right shows the can of Monster Energy Drink participants consumed before working out.
Graphs of Data Analysis
The purpose of this experiment was to discover how caffeine effects heart rate during interval training on a treadmill. As runners train to compete at increasing levels of competition, heart rate is used to measure the intensity of workouts. Caffeine’s affect during sprint workouts and marathons have been studied intensely, but the effect it has on interval training between eight and thirty minutes has barely been tested. This experiment tests how caffeine affects participants during their twelve minute interval workout. 1 2 3 4 5 6
Hypothesis
A participant’s resting to maximum active heart rate will increase at a smaller percentage while completing an interval workout when one has consumed caffeine beforehand.
Materials
Garmin Forerunner 405 Sports Watch
Garmin Heart Rate Monitor
16 oz. Monster Energy Drink
12-Speed Treadmill
Methods
Measure the participant’s resting heart rate.
Have the participant consume caffeine by drinking 16 oz. of a Monster Energy Drink. After twenty minutes, measure his/her heart rate again.
The participant must complete this twelve minute treadmill workout immediately following the heart rate measurement:
Run on treadmill at 7.0 mph for four minutes
Increase speed to 8.0 mph for one minute
Decrease speed to 7.0 mph for one minute
Increase speed to 8.5 mph for one minute
Increase speed to 9.0 mph for one minute.
During the workout, measure the participant’s heart rate every three minutes.
After the participant completes the workout, they may rest, but are not excused to leave.
While the participant is recovering, continue measuring heart rate every three minutes for another twelve minutes. Once all measurements have been taken, the participant is free to go.
Calculate the percent increase of heart rate from the participant’s resting (with caffeine) heart rate to measured maximum heart rate.
Calculate the participant’s average heart rate.
This same workout must be repeated by the participant without the consumption of caffeine beforehand. Skip Step 2.
Replicate this procedure for all participants.
Photos taken by Madisyn Waage
All tables, Charts, graphs and images are created by Madisyn Waage