The 42nd Annual Meeting of the American College of Sports Medicine was held in Minneapolis from May 31 to June 3, 1995. A wide variety of topics of interest to this very diverse group of scientists were presented, including symposia on molecular biology and disorders of the heart, outcomes measurements in cardiac rehabilitation and other preventative strategies, and space medicine. Studies in two areas of preventive cardiology are discussed below. The abstracts may be found in the May 1995 issue of Medicine and Science in Sports and Exercise, the official journal of the ACSM.

Physical Activity And Mortality

An inverse relationship between mortality and levels of physical activity have been previously demonstrated in several populations. A group from the University of Minnesota analyzed data from the Multiple Risk Factor Intervention Trial (MRFIT) at the 15.8 year of follow-up. Analysis at two earlier points in the follow-up period (7 and 10.5 years) in this study of 12,138 middle-aged men at higher risk for developing coronary heart disease revealed a higher death rate from CHD and all-causes for those in the lowest tertile of leisure-time physical activity. At almost 16 years of follow-up, the least active tertile continues to have a statistically significant higher mortality rate than the more active groups, although the gap is narrowing. Of note, the group that had rated themselves as "much less active than others" had about twice the all-causes mortality rate than those who had rated themselves as more active. Further analysis of data from this group will be performed to assess for other factors that may have increased the risk. (MSSE Abstract 323)

While obesity is less prevalent among those who are physically active, there are many who exercise regularly, but are not thin. Physical activity is prescribed to reduce the risk of cardiovascular and all-causes mortality. Obese individuals, if active and fit, may accrue these same benefits from regular exercise. To assess the relationship between physical activity, mortality, and body composition, the Cooper Institute for Aerobics Research studied a group of 25,389 men (ages 20-88 years of age) for a period of about 8 years and tracked mortality as the major endpoint. The study group was tested for level of fitness, as well as for body composition. When divided into three levels of fitness, it was found that the inverse relationship between fitness and mortality was preserved in the more obese subjects (body mass index > 30 and between 27 and 30), as well as in the non-obese group (BMI < 27). Multivariate analysis assessing for the effects of age and coronary risk factors did not alter these findings. (MSSE Abstract 324)

Lipids And Exercise

Recent studies have demonstrated an increased risk for the development of coronary heart disease in groups with higher plasma levels of lipoprotein(a). This unique lipoprotein fraction in found in the upper density range of plasma low density lipoprotein and is usually present in small quantities. In addition to its atherogenic potential when oxidized, Lp(a) also possesses a pro-thrombotic effect as the apoprotein has structural similarities to plasminogen. While considerable data exists on the effects of acute and chronic exercise on levels of total, LDL, and HDL cholesterol, little exists on the effects of acute and chronic exercise upon Lp(a) levels.

A group from the University of South Carolina presented several abstracts concerning this topic of interest. To assess the impact of exercise training on Lp(a) levels in premenopausal women, a group of 26 inactive women were randomly assigned to a control group (no training), a high intensity training program (at 80% VO2max), and a low intensity training program (at 40% VO2max). The training groups exercised an average of 3.4 days per week for a 12 week period. Despite a significant increase in VO2max in trained groups, there were no significant changes in Lp(a) after training in either exercise group. (MSSE Abstract 384)

The same laboratory studied men who were divided into three activity level groups based upon their chronic exercise habits. Each cohort was profiled, analyzing for VO2max, plasma cholesterol levels (total, LDL, and HDL), plasma triglyceride and Lp(a) levels. As expected, the VO2max values were significantly higher in the moderately active and highly active groups when compared to the low activity group. Plasma HDL was significantly higher in the most active versus the other groups (58 mg% vs. 45 mg% for moderately active and 41 mg% for inactive). Plasma triglyceride levels were significantly lower for both "active" subjects when compared to the inactive subjects. There were no significant differences for either plasma LDL or Lp(a) between the groups. (MSSE Abstract 385)

Another study was performed to assess for acute changes in Lp(a) after a single 30-minute bout of low and high intensity exercise. A group of 12 physically active men were randomized to either a low (50% of VO2max) or high (80% of VO2max) intensity bout of exercise. The study was again repeated at the other intensity level. Plasma total cholesterol, triglycerides and Lp(a) levels were determined before and immediately after exercise. There were no significant differences between the pre- and post-exercise lipid values at either work intensity. (MSSE Abstract 386)