Science Buddies: "Ask an Expert"

Our science fair project is based off of the question does caffeine affect athletic performance in adults and teenagers. We are going to be testing the same adults and teenagers with caffeine and without caffeine. We will be testing them with certain athletic tests such as sprinting a 100 meters, hand-eye coordination with a tennis ball and measuring strength by seeing how far they can throw a baseball. One of the issues we were worried about were whether or not it would affect their athletic performance if they did both caffeine and not caffeine on the same day (starting with no caffeine) and if they ate food while they're waiting for the caffeine to sink into their systems to its peak (we were thinking around an hour or so). It would be so helpful if we could find some advice pertaining to these two questions as well as any another advice about our project as well. Thanks so much!

Hey there Jabloopy!

I'll put it this way: If the effect of caffeine is what you're trying to measure, just try to make sure that all other variables remain constant. At least as much as is possible. If they were given a fresh start for the test without caffeine, they should also probably be given a fresh start for the test with caffeine. And if they eat before hand, they should all probably eat the same thing/same amount/etc.

Hope that helps, and good luck!

Hello there,

I also agree with cbrambley that you should try to keep all other variables as constant as possible between all your subjects. If your subjects are starting off in the beginning of the day without caffeine and are given those athletic tests, and then given the time to eat and consume caffeine before doing those tests again on the same day, their performances on those tests could be dependent on whether they're already tired from the previous tests, on the food they eat, or on the caffeine they consume, and indeed it will be difficult to tell whether better or worse performance is solely dependent on caffeine. If it were me personally, I would do the tests on two separate days. If you are to allow your subjects to eat while they wait for the caffeine to sink in prior to the athletic tests, I would probably have them eat the same thing in the no caffeine condition as well and allow them to wait the exact same amount of time prior to the tests to at least take out the food being a variable in affecting athletic performance. Other experts, please chime in if you agree and/or disagree, or if you have anything to add!

Best of luck,
Connie

Hi Jabloopy,

I agree with what the other Experts have said. You will want to keep as many variables constant as you can, except for the caffeine consumption. You should have the subjects perform the tests at the same time of day, with the same amount of rest before and in between tests, and with the same eating conditions. Also make sure to conduct all the tests in the same order. Ideally, the only variable that will change is the caffeine.

Also, it's a good idea for you to survey your subjects to find out how much caffeine they normally consume. Regular caffeine consumers can build up a tolerance, so that their performance on caffeine might be their "normal" performance. In contrast, someone who does not normally consume caffeine would give his or her "normal" performance on the control day, and will have different effects on the caffeine day. Just something to consider when you look at your data.

Please post again (in this same thread) if you have any more questions.

Heather

Thank you all for your replies! They were all extremely helpful and advanced the progress of our experiment. We were wondering however, since we do not have many available dates to perform these tests on, if we did do the same day for both caffeine and no caffeine, what would be the best amount of time to wait in between tests? If regular caffeine consumers build up a tolerance, should we only pick non-regular caffeine consumers? Again, thanks so much!

Hi Jabloopy,

I strongly encourage you to perform the tests on two days (one with caffeine, one without), for the reasons we explained previously. If you absolutely cannot do that, make sure to do all the tests without caffeine first, then do them with caffeine. If you do the tests in that order, you will not have to wait for the effects of caffeine to go away. You will, however, want to wait for about 20 to 30 minutes for the effects of the caffeine to kick in.

You could pick only people who do not regularly consume caffeine, or you can use all the subjects you can find and make sure to note their caffeine consumption. I think it would be especially interesting to find out if caffeine affects everyone the same way, or if the effects are different depending on whether they are used to having caffeine.

I hope that helps! Please keep us posted on your progress.

Heather