The effects of three years of exercise training on plasma lipids and interacting physiological variables in initially fit middle-aged men

Abstract

The purpose of this investigation was to determine the effects of three years of running and/or jogging on plasma lipid levels and interacting variables in a group of middle-aged men already engaged in a long-term training program. The specific problems were to determine: (1) If cholesterol, triglycerides, HDL-C, and/or HDL-C/cholesterol changed over time in a group of middle-aged men. (2) If interacting variables (as established from the CHD literature) of % BF, weight, training mileage, and/or VO(,2) max changed over time in the group of middle-aged men. The subjects for this investigation were 30 middle-aged males who were training a minimum of six miles per week initially. The subjects were tested physiologically in 1978, 1980, and 1981. The subjects continued their training program throughout the study periods. Yearly data collected included: % BF, weight, VO(,2) max, training mileage per year, cholesterol, triglycerides, HDL-C, and HDL-C/cholesterol. All data were analyzed retrospectively for the purposes of this study. Pearson correlation coefficients were calculated for all variables of interest to determine the degree of association between two variables. A one way MANOVA with repeated measures was utilized to analyze the data. The hypothesis of no difference between the subject's criterion responses over time was tested at the 0.05 level. When the null hypothesis was rejected, simultaneous confidence intervals (SCI) were used to determine which dependent variables contributed to the rejection. The results of this investigation showed significant interrelationships between the dependent variables. The profile of the vector of means for the criterion variables changed significantly over time. The changes in weight, mileage, cholesterol, triglycerides, HDL-C, and HDL-C/cholesterol did not contribute to the overall time effect. The significant increases in % BF and decrease in VO(,2) max, as determined by SCI, contributed to the overall year effect. On the basis of the collected data limitations of this study, the following conclusions can be made: (1) A low-risk profile for CHD development can be maintained in initially fit middle-aged men by engaging in a consistent long-term jogging and/or running program. (2) Moderate increases in % BF and decreases in VO(,2) max can occur over time in a continuous jogging and/or running program without resulting unfavorable changes in plasma lipids or lipoproteins.