Caffeine Report

Discussion
Our results indicate that consumption of caffeinated coffee in comparison with decaffeinated coffee causes a slight rise in the mean change in pulse and respiration rate. However, the range bars of those that consumed caffeinated coffee and those that consumed decaffeinated coffee in The Mean Change in Pulse Rate graph overlap. Similarly the range bars in The Mean in Change in Respiration Rate graph overlap. This suggests that the mean change in pulse rate of decaffeinated and caffeinated groups are not accurate enough to be used to make a definitive decision on whether the null hypotheses are accepted or rejected. The t-test (Refer to appendix 3) showed that there is no significant difference in the mean change in pulse rate (P>0.05) between those participants ingesting caffeine in comparison to those that did not consume caffeine and therefore the null hypothesis, HO, was accepted (Refer to appendix 2 for hypotheses). Similarly, there is no significant difference between the mean change in respiration rate (P>0.05) of subjects that consumed caffeine and subjects that did not consume caffeine. Therefore the null hypothesis, HO, was accepted. (Refer to appendix 2 for hypotheses)

The study done by Kruk et al. (2001) was consistent with our results. Kruk et al. (2001) reported that caffeine was not shown to have any significant effect on heart rate.
Nishijima et al. (2002) examined the effects of caffeine ingestion during endurance exercise and found no significant differences in heart rate. Contrary to our results, Piha, 1994 found that the heart rates of her subjects that consumed caffeine were lower than those that consumed decaffeinated beverage. The study done by Hadjicharalambous et al. (2006) where they examined the effects of caffeine on endurance exercise were also inconsistent with our results. Hadjicharalambous et al. (2006) found that the respiration rate was significantly higher in participants that did not consume caffeine and that the heart rate in participants that ingested caffeine was significantly higher those that ingested placebo.
The inconsistency in results may be due to the limitations of our experiment. One limitation of may come from the fact that we did not take into consideration the physical characteristics of participants such as health, height, age and gender. Piha, 1994 used healthy males and Graham et al. (1998) used healthy and fit subjects. Further study should be conducted with subjects of similar physical characteristics in order to obtain more accurate data with which to draw conclusions from. Another limitation that may have been the reason behind inconsistent results across various studies is the number of subjects that participated in each study. The relatively large group of participants used in this study (n=112) in comparison to the smaller groups used in the study conducted by Piha, 1994 (n=9) and Graham et al. (1998) (n=9) have a larger range in a variety of physical characteristics which may be attributed to the overlapping range bars. Graham et al. (1998) suggested that the effects of caffeine were affected by other components in coffee. This should be a subject of further study in order to definitively conclude that caffeine have no significant effect on pulse and respiration rate. Our equipment and methods were another limitation of our study. The study conducted by Nishijima et al. (2002) used an electrocardiogram to measure the heart. This technology is far more accurate than the methods we used and thus further research should be conducted which involves the use of this technology in order to obtain more accurate results.

Even though the t-tests of this study showed the null hypotheses to be accepted, we cannot be certain about the effects of caffeine on change in pulse and respiration rate after exercise due to inconsistencies between studies. The need to conduct further studies is therefore crucial and should involve participants with similar physical attributes, smaller group sizes to minimize variation in physical characteristics, and better equipment like the electrocardiogram. Until further study is conducted to provide us with more accurate results, the null hypotheses remain accepted.