| Title |
Effects of caffeine, ephedrine and their combination on time to exhaustion during high-intensity exercise
|
|---|---|
| Published in |
European Journal of Applied Physiology, March 1998
|
| DOI | 10.1007/s004210050355 |
| Pubmed ID | |
| Authors |
Douglas G. Bell, Ira Jacobs, Jiri Zamecnik |
| Abstract |
This study investigated the effects of acute ingestion of caffeine (C), ephedrine (E) and their combination (C+E) on time to exhaustion during high-intensity exercise. Using a repeated-measures, double-blind design, eight male subjects exercised on a cycle ergometer at a power output that led to exhaustion after about 12.6 min during a placebo (P) control trial. They did this 1.5 h after ingesting either C (5 mg x kg[-1]), E (1 mg x kg[-1]), C+E, or P. Trials were separated by 1 week. Venous blood was sampled before and during exercise. The mean (SD) times to exhaustion were 12.6 (3.1) (P), 14.4 (4.1) (C), 15.0 (5.7) (E) and 17.5 (5.8) (C+E) min. Only the C+E treatment significantly increased time to exhaustion compared to P. Oxygen consumption (VO2), carbon dioxide production (VCO2), minute ventilation (VE) and the respiratory exchange ratio (RER) were similar during exercise for all trials. Heart rate during exercise was significantly increased for the C+E and C trials compared to P. Subjective ratings of perceived exertion during exercise were significantly lower after C+E compared to P. All treatments significantly increased lactate levels. Free fatty acid (FFA) levels were significantly increased by C ingestion. Glycerol levels were increased by C+E and C ingestion. Glucose levels were also higher with the drug treatments compared to P. Increased monamine availability after C+E treatment was suggested by measurements of catecholamines and dopamine. In conclusion, the combination of C+E significantly prolonged exercise time to exhaustion compared to P, while neither C nor E treatments alone significantly changed time to exhaustion. The improved performance was attributed to increased central nervous system stimulation. |
X Demographics
The data shown below were collected from the profile of 1 X user who shared this research output. Click here to find out more about how the information was compiled.
Geographical breakdown
| Country | Count | As % |
|---|---|---|
| Unknown | 1 | 100% |
Demographic breakdown
| Type | Count | As % |
|---|---|---|
| Members of the public | 1 | 100% |
Mendeley readers
The data shown below were compiled from readership statistics for 124 Mendeley readers of this research output. Click here to see the associated Mendeley record.
Geographical breakdown
| Country | Count | As % |
|---|---|---|
| Australia | 2 | 2% |
| Brazil | 1 | <1% |
| India | 1 | <1% |
| United Kingdom | 1 | <1% |
| United States | 1 | <1% |
| Unknown | 118 | 95% |
Demographic breakdown
| Readers by professional status | Count | As % |
|---|---|---|
| Student > Bachelor | 29 | 23% |
| Student > Master | 22 | 18% |
| Student > Ph. D. Student | 17 | 14% |
| Researcher | 9 | 7% |
| Professor | 7 | 6% |
| Other | 26 | 21% |
| Unknown | 14 | 11% |
| Readers by discipline | Count | As % |
|---|---|---|
| Sports and Recreations | 46 | 37% |
| Agricultural and Biological Sciences | 15 | 12% |
| Medicine and Dentistry | 15 | 12% |
| Biochemistry, Genetics and Molecular Biology | 9 | 7% |
| Nursing and Health Professions | 5 | 4% |
| Other | 18 | 15% |
| Unknown | 16 | 13% |
Attention Score in Context
This research output has an Altmetric Attention Score of 7. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 20 January 2022.
All research outputs
#4,835,465
of 25,373,627 outputs
Outputs from European Journal of Applied Physiology
#1,328
of 4,345 outputs
Outputs of similar age
#4,247
of 31,326 outputs
Outputs of similar age from European Journal of Applied Physiology
#4
of 16 outputs
Altmetric has tracked 25,373,627 research outputs across all sources so far. Compared to these this one has done well and is in the 79th percentile: it's in the top 25% of all research outputs ever tracked by Altmetric.
So far Altmetric has tracked 4,345 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 14.6. This one has gotten more attention than average, scoring higher than 68% of its peers.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 31,326 tracked outputs that were published within six weeks on either side of this one in any source. This one has done well, scoring higher than 85% of its contemporaries.
We're also able to compare this research output to 16 others from the same source and published within six weeks on either side of this one. This one has gotten more attention than average, scoring higher than 68% of its contemporaries.