A preliminary study conducted at the University at Buffalo has found that although trained athletes derive performance benefits from caffeine, most sedentary or lightly active adults do not like exercise more – or perceive their exertion to be less – when given caffeine.

What caffeine does do, according to the study, is make them exercise for longer periods, which could increase their likelihood of achieving the American College of Sports Medicine recommendations for physical activity.

The study, “Acute and chronic caffeine administration increases physical activity in sedentary adults,” was recently published online. Its authors are Patrick Schrader and Leah M. Panek, graduate students in the UB of Department of Exercise and Nutrition Sciences, UB School of Public Health and Health Professions, and Jennifer Temple, professor in the Department of Exercise and Nutrition Sciences.

What is important about this study, Temple said in a news release, is that it indicates that the ergogenic, or performance-enhancing, properties of caffeine are quite different for trained athletes than for sedentary adults.

Previous studies with athletes have found that caffeine enhances their performance and reduces their scores on the rated perceived exertion scale, or RPE. The UB researchers hypothesized that caffeine ingestion would have the same effect on sedentary adults, that is, it would increase their capacity for physical exertion by eliminating fatigue symptoms and reducing their perception of exertion while exercising.

The researchers found:

• Caffeine did little to modify the subjects’ capacity for physical exertion or their ratings of how much exertion they had expended during periods of exercise.

• As time went on, however, subjects engaging in exercise said they liked physical activity more and more, regardless of their caffeine-ingestion status, and it lowered their ratings on the RPE scale.

Women who had been treated with caffeine showed a particular increase in their “liking” of exercise, while women treated with placebo and male subjects treated with either caffeine or placebo, did not.

• During the last study session most participants increased the time they spent in self-determined exercise, but this effect was significantly greater in participants who were given caffeine immediately before they exercised in this session, regardless of their caffeine treatment during the rest of the study.

The study involved 35 subjects between the ages of 18 and 50, half men and half women, who attended eight laboratory sessions, 60 to 75 minutes in length, over the course of two weeks. All were asked to abstain from caffeine for 24 hours before each session and asked to refrain from engaging in physical activities on the day of their visits.

At each session, half the participants were given caffeine (3 mg/kg) and half a placebo in a sports drink. At each visit, participants rated how much they liked the activity and how much exertion they thought they had expended. The length of their self-determined exercise sessions was also recorded and analyzed.