Results of a study of 25 long-distance runners from Western New York who consumed diets consisting of low, medium and high percentages of fat-15, 30 and 45 percent, respectively-showed that endurance time increased and that there was more muscle strength after an exhausting run when the percentage of dietary fat was increased.

In addition, levels of lactic acid, a measure of oxygen delivery, decreased after four weeks on the high-fat diet, indicating an increase in energy reserve.

Study results were presented April 14 at the annual meeting of the Federation of American Societies for Experimental Biology.

The athletes couldn't consume enough calories to meet the energy needs of their training on the low-fat diet. In addition, HDL cholesterol levels were lower on the 15-percent-fat regimen, indicating implications for cardiovascular risk factors.

This study is a follow-up to research reported in 1994 that showed similar results.

"Our conclusion is, for trained distance runners, a very low-fat diet may not be the best practice for their performance," said Peter J. Horvath, UB associate professor of nutrition and physiology and a lead researcher. "If you want the calories necessary to do high-intensity training, you need to liberate yourself from a low-fat diet. We found also that in terms of cardiovascular risk factors, runners on a high-fat diet did not increase their cardiovascular risk factors, while on a low-fat diet, some of the cardiovascular risk factors were increased, similar to those of sedentary individuals."

Participants in the study were male and female runners between the ages of 18 and 53 who ran an average of 40 miles per week. Some were top-ranked regional competitors. Before beginning the study, the researchers established the fat level of each participant's current diet, which averaged about 20 percent. Blood pressure, heart rate, percentage of body fat, body weight, total cholesterol, HDL cholesterol, apoprotein levels-a more definitive measure of LDL and HDL-and serum triglycerides were measured. Subjects also were put through a series of endurance and VO2 max-oxygen consumption-tests.

All subjects then spent four weeks on the low-and medium-fat diets, with original assessments and testing repeated between diets. Only 12 subjects were able to raise their dietary fat close to the 45-percent level. This group spent an additional four weeks at that level and all initial tests were repeated at the end of the study.

Results of the performance tests on the medium-fat diet compared to the low-fat diet showed that endurance time increased 14 percent while the decrease in force after the endurance run was significantly less-11 percent. While endurance time did not increase on the high-fat diet, lactate levels were lower, indicating more efficient energy metabolism.

"The dietary intake of vitamin E, calcium, magnesium and zinc were at or below the recommended levels on the low-fat diet. As individuals increased their total calories and dietary fat, levels of zinc, magnesium, calcium and vitamin E also increased," Horvath said. The distance runners in this study did not have any negative effects on performance, nutrition or health on the high-fat diet," Horvath said. "Endurance athletes require a lot of calories. A very-low-fat diet for these athletes may not provide the required nutrition. A higher-fat diet may result in more energy availability and other metabolic, nutritional and performance advantages."

Other researchers in the study were Colleen K. Eagen and Jill Rowland, master's degree candidates in UB's nutrition program; John J. Leddy, UB clinical assistant professor of orthopaedics, medicine and family medicine, and David R. Pendergast, UB professor of physiology. The study was funded in part by an educational grant from Mars, Inc.