1. Effects of Caffeine on Basal Metabolic Rate and Metabolism of Fat and Carbohydrate During Moderate Exercise By: Adam Michalik
2. Introduction The purpose of this study was:
1) To analyze the effects of caffeine on basal metabolic rate (BMR).
2) To analyze the effect caffeine has on the percentage of calories burned as fat versus calories burned as carbohydrate during moderate exercise.
3. Hypotheses There will be a significant increase in resting energy expenditure when caffeine is consumed prior to measurement of basal metabolic rate.
The percentage of calories burned as fat will increase while percentage of calories burned as carbohydrate will decrease during moderate exercise.
Decreasing RQ value towards 0.70
4. Methods Two separate trials consisting of a basal metabolic rate test along with two five minute exercise periods, one at 2.5 mph and the other at 4.0 mph.
BMR Test Protocol
Trial one - only water
Trial two - consume approx. 300 mg of caffeine 1-1.5 hours before arriving to the HHP lab.
Expired air was analyzed for both tests to determine BMR, BMR RQ, exercise HR, exercise oxygen consumption, and exercise RQ for both caffeinated and non-caffeinated states.
5. Methods Equipment used
VO2 metabolic measurement system
Motor driven treadmill
Multiple Paired T-tests
6. Descriptive Statistics
7. Results: BMR and RQ
8. Results: Heart Rate
9. Results: Oxygen Consumption
10. Discussion The comparison between caffeinated and non-caffeinated exercise HR @ 2.5 mph resulted in a significant difference (P<0.05).
Bell claimed that “HR increased over time, and values were further increased after caffeine ingestion.” 2
Caffeine tended to produce higher values for BMR, exercise HR, and exercise oxygen consumption at 2.5 mph.
Acheson reports that “caffeine/coffee stimulates the metabolic rate in both control and obese individuals.” 1
“Caffeine produced a small but significant increase in VO2 after 15 minutes of exercise for both users and nonusers [of caffeine].”2
11. Discussion Exercise oxygen consumption at 4.0 showed slight decrease with caffeine (0.25 mL/kg.min)
Exercise and resting RQ increased while caffeinated
Data suggests increased CHO utilization
Acheson – increased plasma FFA’s result in increased fat oxidation. This is masked through alteration of RQ by hyperventilation.
Cox – inability to measure substrate utilization
12. Summary Caffeine significantly increased exercise HR @ 2.5 mph
Caffeine produced higher values for BMR, exercise HR, and exercise oxygen consumption at 2.5 mph
Caffeine decreased exercise O2 consumption @ 4.0 mph
Exercise and resting RQ increased with caffeine use
For the future
Standardization of testing, caffeine consumption, more subjects
13. Acknowledgements A special thanks to…
14. References 1) Acheson, K. J., Zahorska-Markiewicz, B., Pittet, Ph., Anantharam, K., Jequier, E. (1980). Caffeine and coffee: their influence on metabolic rate and substrate utilization in normal weight and obese individuals. The American Journal of Clinical Nutrition, 33, 989-997.
2) Bell, Douglas G., McLellan, Tom M. (2002). Exercise endurance 1, 3, and 6 h after caffeine ingestion in caffeine users and nonusers. Journal of Applied Physiology, 93, 1227-1234.
3) Cox, G. R., Desbrow, B., Montgomery, P. G., Anderson, M. E., Bruce, C. R., Macrides T. A., Martin D. T., Moquin, A., Roberts, A., Hawley, J. A., Burke, L. M. (2002). Effect of different protocols of caffeine intake on metabolism and endurance performance. Journal of Applied Physiology, 93, 990-999.
4) Haldi, J., Bachmann, G., Ensor, C., Wynn, W. (1940). The Effect of Various Amounts of Caffeine on the Gaseous Exchange and the Respiratory Quotient in Man. The Journal of Nutrition, 307-320.
5) Hallal, Janice C. (1986). Caffeine: Is It Hazardous to Your Patient’s Health? The American Journal of Nursing, 84(4), 422-425