Question

2. Creatine is a substance normally found in muscle tissue. How is the function of creatine related to the use of ATP? (2) b. In general, what is the scientific reasoning for why creatine might/might work as a supplement to improve exercise performance (2) It is known that in adults over the age of 50, muscular strength declines due to loss of muscle tissue may contribute to a decreased ability to perform activities of daily living and increase the risk of falls. In one study designed to test the effect of creatine supplementation in this group, men from 60 to 85 years of age were randomly placed into two study groups. Both groups exercised, but one group was given placebo while the other group was given creatine supplements. a. Their lean (muscle) mass was measured before and after the 12-week study. The 89 results of the test are shown in the figure to 24 the right. Do the results support the use of creatine supplements for this group? Be sure to explain your answer in terms of the ol data presented. (3) CREPLA b. Additionally, the power of their muscles was measured by having each group perform knee extension and flexion exercises at the beginning of the study, at a mid-point, and again at the end of 12 weeks. The results of this study are shown in the bottom figure to the right. Provide your best explanation for the results for the placebo as well as the creatine group explaining exercise and creatine function. (3) F

Answer 1

a.

The phosphorylated form of creatine (PCr) resynthesizes ATP by adding its phosphate group to ADP. Thus it helps in recycling ATP molecules.

b.

During high-end anaerobic exercise, using creatine supplements can increase the concentration of PCr available in muscle cells which acts as a reservoir of ATP (because PCr can quickly regenerate ATP). Hence it energy output is improved.

a.

The mean mass increment of experiment group is higher than that of the control group.

Also, the difference in mean mass increment between experiment and control groups is significantly higher than the standard deviation of mean mass increment in both groups.

Hence the test results are valid.

~~ I don't know if increase in muscle mass is actually an indicator of the creatine supplements working, but assuming it is, the experiment supports the use of the supplements. ~~

b.

Performance of the experiment group increased with time. This is as expected.

Performance of the control group finally got lower than the experiment group (as expected) but was similar at the mid-point. This could be attributed to the placebo effect.

(Placebo effect would be stronger in this case than in the experiment involving muscle mass, because while actual performance might depend on the person's belief that he/she has taken supplements, this 'belief' would probably not influence the amount of muscle mass he/she has.)

However, difference in performance at the end of 12 weeks is comparable to the standard deviation of results.

(~~So the experiment tells that creatine supplements do work if you wish to gain weight, but as far as performance is concerned it just might be cheaper to use placebo pills instead~~)