Daphnia Report Essay
“The consumption of oral creatine monohydrate has become increasingly common among professional and amateur athletes” (Poortmans and Francaux, 2000). Creatine is a substance used by athletes and bodybuilders to increase the production of Adenosine Triphosphate (ATP), which gives them the energy they need to perform. In this experiment, creatine is added to water and its effects on Daphnia is tested. By observing the heart rate, one can determine if the creatine increases or decreases heart rate. Heart rate was chosen to be measured because one can then see how creatine affects the heart.
If it is unhealthy for the Daphnia, it could potentially be unhealthy for humans. “Long-term safety of creatine supplementation has been questioned. This retrospective study was performed to examine markers related to health, the incidence of reported side effects and the perceived training benefits in athletes supplementing with creatine monohydrate” (Schilling et al. 2001). The hypothesis is that the heart rate will increase as the concentration of the creatine increases. The anticipation is that the creatine will have little effect on the heart rate.
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In another study where creatine was given to athletes prior to a workout, the results showed that, “ No statistically significant differences in heart rate were observed between the treatments either during anaerobic or aerobic exercise” (Vanakoski et al. 1998). Another study, with the experiment being similar, said that creatine, “had no significant effect on peak power, work output, RPE, or peak heart rate” (Crow et al. 2006). One study was done in which athletes who were paralyzed were given creatine and then asked to perform.
They then recorded the heart rate and concluded that there was no significant gain or loss due to the creatine (Perrot, 2006). Methods We first began the experiment by creating a 10% creatine solution. This was done by mixing 5 grams of creatine in 200 mL of water. Then, we obtained 10 daphnia and placed them into a petri dish which contained a small amount of the 10% creatine solution. We then took three daphnia out of the petri dish and put them each in their own dish, with a small amount of the 10% creatine solution.
Next, we used a dissection microscope to determine the heart rate of the 3 separtated daphnia. This was done by placing, one at a time, each individual daphnia and under the microscope, and then counting the number of heart beats over a 10 second period. We then had to multiply that number by 6, in order to get the number of beats per minute (BPM). After we did this once, we wait 5 minutes, and repeat the counting process. This goes on every ten minutes for an hour, resulting in 13 different time intervals (ranging from 0 to 60).
We also had to calculate the death rate by counting the number of dead daphnia at each interval. This same experiment is being tried by 4 other groups. The only exception being the concentration of creatine (0%, 2%, 5%, and 20%). The control variable for the experiment is the concentration of creatine. The indepent variables are the heart rate and death rate of the daphnia. At the end of the experiment, we exchanged data from each of the other 4 groups, so that everyone has all the data. Results Table 1 Table one shows the heart rate of the daphnia (vertical column) and the time (horizontal column).
The heart rate in all of the daphnia increased within the first ten minutes, but then started to plateau or decrease. One thing to point out is that the heart rate at the end of the experiment. The daphnia in the 0% creatine has a higher average heart rate than the daphnia in the 20%. It actually goes in order, with the 0% having the highest, then 2%, 5%, 10%, and 20% having the lowest. Table 2 Table 2 shows the number of daphnia dead (vertical column) and the time (horizontal column). Only 6 daphnia died total out of all of the experiments, and all 6 were from the same concentration.
If you compare the graphs of heart rate and death rate of the 2% concentration, you will notice that the heart rate decreases significantly as the death rate increases. Discussion The results show that concentration of creatine had little effect on the heart rate of the daphnia. This is known because of the inconsistency of the heart beats each time interval. All of the daphnia experienced an increase in heart rate, and then a plateau, and then for some, a decrease. The data refutes my hypothesis because the concentration of the creatine had no effect on the heart rate.
My results support the results of other scientists who have done similar experiments (stated in the introduction) because the creatine was a non-factor on the heart rate. The experiment concludes that heart rate is not dependent on creatine, and those who use creatine can actually have a lower heart rate after a long period of time, than those who use none at all. There are other studies that could be done on creatine and heart rate, based upon the experiment performed here. One experiment could be how creatine affects heart rate over a long time of use.
This would be a viable experiment because the results in this experiment showed that the creatine lowered heart rate over time. Literature Cited Crowe, M. J. , A. Leicht, W. Spinks. 2006. Physiological and cognitive responses to caffeine during repeated, high-intensity exercise. International Journal of Sports Nutrition and Exercise Metabolism 5: 528-544. Perret, C. , G. Mueller, H. Knecht. 2006. Influence of creatine supplementation on 800m wheelchair performance: a pilot study. Spinal Cord 5: 275-279. Poortmans, JR. , M. Francaux. 2000. Adverse effects of creatine supplementation – Fact or fiction?.
Sports Medicine 3: 155-170. Schilling, B. K. , M. Stone, A. Utter, J. Kearney, M. Johnson, R. Coglianese, L. Smith, H. O’Bryant, A. Fry, M. Starks, R. Keith, M. Stone. Creatine supplementation and health variables: a retrospective study. Medicine and Science in Sports and Exercise 2: 183-188. Vanakoski, J. , V. Kosunen, E. Meririnne, T. Seppala. 1998. Creatine and caffeine in anaerobic and aerobic exercise: effects on physical performance and pharmacokinetic considerations. International Journal of Clinical Pharmacology and Therapeutics 5: 258-262.