Copyright is owned by the Author of the thesis.  Permission is given for 
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EFFECT OF CAFFEINE SUPPLEMENTATION ON METABOLISM 
AND PHYSICAL AND COGNITIVE FUNCTION IN FEMALE 
INTERMITTENT GAMES PLAYERS 
 
 
 
 
 
By 
 
 
 
 
Jemma May O?Donnell 
 
 
 
 
 
 
A thesis presented in partial fulfilment for the requirements of a Master of Science in Human 
Nutrition at Massey University, Auckland, New Zealand 
 
 
 
 
 
 
March 2012 
 
 
 
 
 
 
 
 
 
 
ii 
 
ACKNOWLEDGMENTS 
 
 
The first thank you must of course go to the girls who volunteered their time to be 
participants for this demanding research. Without them none of this would have been 
possible! 
 
Acknowledgements must also go to my supervisors Dr. Ajmol Ali, Dr. Andrew Foskett, and 
Dr. Pam von Hurst. Their assistance and advice has helped me turn an idea into a fully-
fledged Masters project, and their continued time and efforts have helped me successfully 
complete my MSc. 
 
Huge thanks must also go to Mr. Simon Bennett who?s technical and practical contributions 
have been absolutely invaluable! To the third year students who assisted me on this project, 
Mr. David Wolf, Miss Rebecca Watkin, and Mr. Naser Naser, thank you for providing that 
often essential second pair of hands. I hope that in taking on a research assistant role, this has 
furthered your own understanding and knowledge, possibly even tempted you onto the 
postgraduate pathway. 
 
 
 
 
 
 
 
 
 
 
 
 
 
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ABSTRACT 
 
 
Purpose: To investigate the effects of caffeine ingestion on metabolism and physical and 
cognitive performance in female team-sport players taking a monophasic oral contraceptive. 
Method: In a randomized, double-blind, placebo-controlled crossover design, 10 participants  
(age 23.6 ? 4.1 y; height 1.62 ? 0.06 m; body mass 59. O2 max 50.0 ? 5.3 
ml?kg-1?min-1) completed a 90 min intermittent treadmill-running protocol twice, during days 
5-8 and 18-22 of their pill cycle. All participants were taking a monophasic oral contraceptive 
of the same hormonal composition (Levlen ED, Nordette, Monofeme, or Microgynon). 
During the familiarisation session participants completed a maximal oxygen uptake test, 
practiced the cognitive, strength, power testing, and underwent 30 min of the running 
protocol. Upon arrival at the laboratory for the main trials, hydration status was measured via 
urine specific gravity (USG) using a handheld refractometer and a heart rate (HR) monitor 
fitted. A capsule containing 6 mg?kg-1 body mass (BM) of anhydrous caffeine or placebo 
(Maltodextrin, 1.62 kJ?g-1) was administered 45 min before commencing exercise with a 500 
ml bolus of water. Further 3 ml?kg-1 BM boluses of water were provided every 15 min during 
exercise. Before, during and after the exercise protocol, venous blood samples were taken and 
cognitive (Choice Reaction Time, CRT; Digit Vigilance, DV; Stroop test), perceptual 
(Ratings of Perceived Exertion, RPE; Feeling Scale, FS; Felt Arousal Scale, FAS; Profile of 
Mood States, POMS), and physical tests (countermovement jump, CMJ; strength testing on 
the isokinetic dynamometer) were administered. These tests were then all performed again at 
a follow-up 12 h post session in the morning, including a venipuncture blood sample, and the 
addition of sleep quality assessment using the Leeds Sleep Evaluation Questionnaire (LSEQ). 
Results: There were no significant effects of caffeine supplementation on HR, USG, CMJ, 
isometric strength, RPE, cognitive performance or glucose and insulin concentrations. 
Caffeine supplementation improved levels of pleasure, activation and vigour compared to 
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placebo, and reduced levels of fatigue (P < 0.05). Caffeine supplementation also improved 
average power in eccentric contractions of the knee extensors and flexors, and peak torque in 
the eccentric contractions of the knee flexors (P < 0.05). Getting to sleep and subsequent 
quality of sleep was impaired following caffeine supplementation (P < 0.05). Free fatty acid 
(FFA) concentration increased over the duration of exercise (P < 0.05), and increased at a 
greater rate on the caffeine trial (P < 0.05).  Conclusions: This is the first controlled study to 
examine caffeine supplementation in female games players who are taking a low-dose 
monophasic oral contraceptive, using an intermittent based running protocol. These athletes 
experienced an improved performance in various strength and power aspects, but no 
improvement in cognitive performance. Perceptual and mood responses were also improved 
as a result of caffeine supplementation. Metabolically, caffeine had an effect on markers of 
fat metabolism but not on carbohydrate metabolism. 
  
 
Keywords: caffeine, female, metabolism, performance, intermittent exercise 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
v 
 
Table of contents 
Page 
 
Acknowledgments          ii 
Abstract           iii 
Table of contents          v 
List of figures           viii 
List of tables           xi 
 
1.0 INTRODUCTION         1 
1.1 Overview of thesis        7 
 
2.0 LITERATURE REVIEW        8 
 
2.1 Caffeine as an intervention to overcome fatigue and improve performance 8 
2.1.1 Absorption, metabolism, elimination      8 
 
2.2 Caffeine and peripheral mechanisms of action     10 
2.2.1 Fat oxidation and glycogen sparing      10 
2.2.2 Blood glucose         12 
2.2.3 Lactate         14 
2.2.4 Catecholamines        15 
2.2.5 Ionic balance         16 
 
2.3 Central Mechanisms of action ? adenosine antagonism    18 
2.3.1 Pain perception        19 
2.3.2 Ratings of Perceived Exertion (RPE)      21 
2.3.3 ?-endorphins         22 
 
2.4 The role of genetics and caffeine       23 
 
2.5 Caffeine and cognition, mood and perception     24 
2.5.1 Cognition         24 
2.5.2 Mood (POMS)        26 
2.5.3 Perception         27 
 
2.6 Caffeine, strength and power       29 
 
2.7 Caffeine and sleep quality        31 
 
2.8 The effect of caffeine on performance in team sports players   33 
 
 
vi 
 
 
2.9 Caffeine and women/sex effects       36 
2.9.1  Effect of menstrual cycle on caffeine metabolism    36 
2.9.2 OCS use and the effect on caffeine metabolism     37 
2.9.3 OCS use and intermittent exercise      38 
2.9.4 Performance in female athletes with caffeine supplementation  40 
 
2.10 Summary          42 
 
3.0 METHODOLOGY         43 
 
3.1 Participants          43 
3.2 Subject control 
3.2.1 Dietary control        43 
3.2.2 Oral contraceptive use and cycle control     44 
3.3 Description of physiological tests and measures     44 
3.3.1 Height and mass measurements      44 
3.3.2 Heart rate measurements       45 
3.3.3 Urine analysis         45 
3.3.4 Expired air collection        45 
3.3.5 Strength and power testing       45 
3.3.5.1 Isokinetic dynamometer       45 
3.3.5.2 Countermovement jump (CMJ)      47 
3.3.6 Blood sampling and analysis       47 
3.3.6.1 Sample collection        47 
3.3.6.2 Treatment, storage, and analysis of blood samples   47 
3.3.7 Maximal oxygen uptake test ( O2max)      48 
3.4 Description of cognitive measures       49 
3.4.1 Cognitive testing        49 
3.4.1.1 Choice Reaction time test (CRT)      50 
3.4.1.2  Stroop test        50 
3.4.2 Profile of Mood States questionnaire (POMS)    50 
3.5 Description of perceptual scales       51 
3.5.1 Ratings of Perceived Exertion (RPE)      51 
3.5.2 Feeling Scale (FS)        51 
3.5.3 Felt arousal scale (FAS)       51 
3.6 Description of sleep quality measures      52 
3.6.1 Leeds Sleep Evaluation questionnaire (LSEQ)    52 
3.7 Description of intermittent treadmill running protocol    52 
3.8 Preliminary familiarisation testing       53 
3.9 Study design          54 
3.10 Statistical analysis         57 
 
 
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4.0 RESULTS          58 
 
4.1 Strength and power data        58 
4.2 Cognitive data         60 
4.3 Perceptual data         61 
4.4 Mood data          65 
4.5 Blood analysis         66 
4.6 Sleep quality          69 
4.7 Other data          72 
 
5.0 DISCUSSION          73 
5.1 Conclusions          83 
5.2 Limitations          83 
5.3 Future directions         84 
 
6.0 REFERENCES          85 
 
7.0 APPENDICES          102 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
viii 
 
LIST OF FIGURES 
 
Figure 2.1 ? A visual depiction of the circumplex model used for plotting the perceptual 
responses to exercise. 
 
Figure 3.1 ? Isokinetic dynamometer (Biodex) setup. 
 
Figure 3.2 ? COMPASS software for administering cognitive tests. 
 
Figure 3.3 ? Intermittent treadmill running protocol based on each participants O2 max 
(Atkinson, et al., 2005). 
 
Figure 3.4 ? Detailed schematic of main trials. 
 
Figure 4.1 ? Mean power output during eccentric contractions of knee extensors in caffeine 
and placebo trials. Values are mean ? SD. The ?pre? time point represents before 
caffeine/placebo administration; ?mid? is after block 3 during the 15 min break; and post 
following the final block of exercise. 
 
Figure 4.2 ? Mean power output during eccentric contractions of the knee extensors in 
caffeine and placebo trials. Values are mean ? SD. The ?pre? time point represents before 
caffeine/placebo administration; ?mid? is after block 3 during the 15 min break; and post 
following the final block of exercise. 
 
ix 
 
Figure 4.3 ? Mean RPE scores for all participants in caffeine and placebo trials. Each block 
was 15 min long, and blocks 1, 2, 4, and 5 were separated by a 4 min break; after block 3 
there was a 15 min break. 
 
Figure 4.4 ? Mean FS scores for all participants in caffeine and placebo trials. Each block 
was 15 min long, and blocks 1, 2, 4, and 5 were separated by a 4 min break; after block 3 
there was a 15 min break. 
 
Figure 4.5 ? Mean FAS scores for all participants in caffeine and placebo trials. Each 
block was 15 min long, and blocks 1, 2, 4, and 5 were separated by a 4 min break; after 
block 3 there was a 15 min break. 
 
Figure 4.6 ? Mean FS and FAS values plotted as Cartesian coordinates in a circumplex 
model. 4.6A represents caffeine values and 4.6B is placebo values. 
 
Figure 4.7 ? Figure 4.7A depicts the fatigue scores in the POMS, and 4.7B depicts the vigour 
score. POMS ? Profile of Mood States questionnaire. 
 
Figure 4.8 ? Mean ? SD values of plasma caffeine concentration over duration of study. 
Time values on the horizontal axis indicate total time since 45 min prior to caffeine ingestion, 
which is represented as time 0 min. * significant difference between trials, P<0.05. 
 
Figure 4.9 ? Individual values for plasma caffeine concentration over duration of caffeine 
trial. Time values on the horizontal axis indicate total time since 45 min prior to caffeine 
ingestion, which is represented as time 0 min. 
x 
 
Figure 4.10 ? Mean ? SD plasma glucose concentrations. Time values on the horizontal axis 
indicate total time since 45 min prior to caffeine ingestion, which is represented as time 0 
min. 
 
Figure 4.11 ? Mean ? SD plasma insulin concentrations. Time values on the horizontal axis 
indicate total time since 45 min prior to caffeine ingestion, which is represented as time 0 
min. 
 
Figure 4.12 ? Mean ? SD plasma FFA concentrations. Time values on the horizontal axis 
indicate total time since 45 min prior to caffeine ingestion, which is represented as time 0 
min. * significant difference between trials, P<0.05. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
xi 
 
LIST OF TABLES 
 
 
Table 2.1 ? Summary of literature pertaining to caffeine supplementation and team sports. 
 
Table 2.2 ? Summary of literature pertaining to caffeine supplementation and exercise 
performance in women. 
 
Table 4.1 ? Data from the Leeds Sleep Evaluation Questionnaire. 
 
Table 4.2 ? Nutritional composition of diet from 48 h food diaries.