| Date | November 2020 | Marks available | 2 | Reference code | 20N.3.SL.tz0.1 |
| Level | Standard Level | Paper | Paper 3 | Time zone | time zone 0 |
| Command term | Calculate | Question number | 1 | Adapted from | N/A |
Question
A study tested the effects of a caffeine drink on physical performance in soccer. Eighteen female players took part in two soccer games. They consumed a caffeine drink 60 minutes before Game 1 and a placebo 60 minutes before Game 2.
Each player wore a GPS device to record their distance travelled and speed. Mean running distance (m) for each game is shown.
[Source: Reprinted by permission from Springer-Verlag Wien: Springer Nature, Lara, B., Gonzalez-Millán, C., Salinero, J.J. et al.
Caffeine-containing energy drink improves physical performance in female soccer players. Amino Acids 46, 1385–1392 (2014).
© Copyright 2014. https://doi.org/10.1007/s00726-014-1709-z.]
Identify the running speed, in km h–1, at which the difference in running distance between the two conditions is greatest.
Calculate the difference in mean running distance, in metres, for the speed identified in 1(a)(i).
Comment on the statistical significance of the effect of the caffeine drink in this study.
Outline two reasons for a placebo condition in the study.
Explain the benefits of caffeine use for a soccer player.
Markscheme
3.1–8.0 <km h–1>;
2800−2500;
= 300 <m>;
Accept in different order. ECF.
Running distance in the caffeine condition was significantly greater at 3.1–8.0/8.1–13.0/>18 km h–1;
there was no significant effect at other speeds/0–0.4/0.5–3.0/13.1–18.0 km h–1 ;
To control for the placebo effect where:
the observed effect can only be attributable to the caffeine drink;
to counteract the psychological effects of increased effort due to the perceived use of a caffeine drink;
improve concentration;
improved alertness/improved reaction time;
longer time to exhaustion/reduced fatigue;
increased energy levels/ metabolism;
facilities lipolysis / inhibits glycogenolysis;
increased strength / facilitates motor unit recruitment;
increases in calcium permeability of the sarcoplasmic reticulum;
benefits experienced in low to moderate dosage;
Examiners report
No issues.
No issues.
No issues.
Most candidates knew what a placebo was but had difficulty explaining the importance of placebos and their benefits in research.
Candidates were more adept at identifying caffeine benefits of concentration, alertness, and increased time to exhaustion. They were less able to identify changes to more detailed physiological aspects like the effect on lipolysis, calcium permeability, and glycogenolysis.
