Featured Research

from universities, journals, and other organizations

Amphetamines can delay exhaustion during exercise in heat -- at a cost

Date:
May 28, 2014
Source:
Indiana University
Summary:
When people or animals exercise in the heat, exhaustion is a safety gauge telling the body it is time to stop. Exhaustion occurs when the body's core temperature reaches a potentially dangerous point. The use of amphetamines is banned in many sports because they increase time to exhaustion. Amphetamines can delay exhaustion during exercise in the heat by increasing the temperature at which it occurs. The potential cost? The risk of suffering from exertional heat stroke.

Indiana University researchers put male rats to the test to determine the role amphetamines play when used in conjunction with exercise.

When people or animals exercise in the heat, exhaustion is a safety gauge telling the body it is time to stop. Exhaustion occurs when the body's core temperature reaches a potentially dangerous point. The use of amphetamines is banned in many sports because they increase time to exhaustion.

What they found: Amphetamines can delay exhaustion during exercise in the heat by increasing the temperature at which it occurs. This potentially ergogenic effect, however, comes at the risk of suffering from exertional heat stroke.

"Amphetamine increases Vo2max and time to exhaustion at the expense of body temperature and economy" was discussed during the heat stress session of the American College of Sports Medicine annual meeting in Orlando, Fla.

Daniel E. Rusyniak, M.D., associate professor of emergency medicine at the IU School of Medicine, and colleagues in the Department of Emergency Medicine and the Department of Health and Rehabilitation Sciences, hypothesized that amphetamines increase the time to exhaustion by allowing the core temperature to climb higher before exhaustion occurs. Rusyniak and his team also wanted to determine whether oxygen consumption was affected and whether it played a role in the threshold for exhaustion.

The rats were familiarized with running on the treadmill for several days before the experiment. On that day, with the room at 89.6 degrees Fahrenheit, a control group of rats was given saline injections, while two other groups were given amphetamine injections of either 1 milligram or 2 milligrams per kilogram of body weight.

As predicted, the animals receiving amphetamine had significantly higher core temperatures when they reached exhaustion. What was not predicted is that animals receiving the higher dose of the amphetamine achieved this critical temperature faster so that their time to exhaustion was not increased.

The researchers also determined that muscles consumed oxygen at a higher rate in the group receiving the larger amphetamine dosage, but there was no evidence that the efficiency or "economy" of the oxygen use was improved.

"The benefit of amphetamine use was probably not related to anything other than raising the temperature at which exhaustion occurs, which from a medical safety standpoint is not a benefit at all," Rusyniak said.


Story Source:

The above story is based on materials provided by Indiana University. Note: Materials may be edited for content and length.


Cite This Page:

Indiana University. "Amphetamines can delay exhaustion during exercise in heat -- at a cost." ScienceDaily. ScienceDaily, 28 May 2014. <www.sciencedaily.com/releases/2014/05/140528180047.htm>.
Indiana University. (2014, May 28). Amphetamines can delay exhaustion during exercise in heat -- at a cost. ScienceDaily. Retrieved August 2, 2014 from www.sciencedaily.com/releases/2014/05/140528180047.htm
Indiana University. "Amphetamines can delay exhaustion during exercise in heat -- at a cost." ScienceDaily. www.sciencedaily.com/releases/2014/05/140528180047.htm (accessed August 2, 2014).

Share This




More Health & Medicine News

Saturday, August 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Texas Quintuplets Head Home

Texas Quintuplets Head Home

Reuters - US Online Video (Aug. 1, 2014) After four months in the hospital, the first quintuplets to be born at Baylor University Medical Center head home. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Patient Coming to U.S. for Treatment

Ebola Patient Coming to U.S. for Treatment

Reuters - US Online Video (Aug. 1, 2014) A U.S. aid worker infected with Ebola while working in West Africa will be treated in a high security ward at Emory University in Atlanta. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Vaccine Might Be Coming, But Where's It Been?

Ebola Vaccine Might Be Coming, But Where's It Been?

Newsy (Aug. 1, 2014) Health officials are working to fast-track a vaccine — the West-African Ebola outbreak has killed more than 700. But why didn't we already have one? Video provided by Newsy
Powered by NewsLook.com
Study Links Certain Birth Control Pills To Breast Cancer

Study Links Certain Birth Control Pills To Breast Cancer

Newsy (Aug. 1, 2014) Previous studies have made the link between birth control and breast cancer, but the latest makes the link to high-estrogen oral contraceptives. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins