Abstract
M.Phil.
Numerous studies have demonstrated the favourable effects of aerobic training on blood lipid profiles. However, few studies have generated conclusive data on the effects of dynamic resistance training (DRT) on blood lipid profiles.
In order to evaluate the effect of DRT on lipoprotein-lipid profiles, a group of 28 sedentary but healthy males (mean age 28 years and 7 months) were matched and randomly assigned into a control/non-exercising (n = 15) or an experimental (n = 13) group. To control for variations in lipoprotein-lipid profiles, the present investigation recorded dietary intake and smoking behaviour in an attempt to account for any changes in lipoprotein-lipid profiles over the eight-week period.
The experimental group (EG) exercised using DRT for a period of eight weeks and was monitored for changes in lipoprotein-lipid profiles. The control group (CG) took part in no structured exercise throughout the eight-week period. The experimental training programme consisted of nine exercises (dumbbell (D/B) shoulder shrugs, D/B lateral shoulder raises, seated chest press, latissimus dorsi pulldowns, seated pulley rows, biceps curls, triceps extensions, crunchies and unilateral leg press). These exercises were performed at 60% of one repetition maximum (1-RM) and were performed three times per week on non-consecutive days. Serum was analyzed for total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C). In addition to this, the TC: HDL-C and LDL-C: HDL-C ratios were calculated.
The Independent t-Test and the Paired t-Test were utilized to determine the significance (at a 95% confidence level (p ¡Ü 0.05)) of the lipoprotein-lipid profile changes from pre- to post-test. These student t-Tests demonstrated no statistically significant changes in TC, TG, LDL-C, HDL-C, TC: HDL-C ratios and LDL-C: HDL-C ratios in the EG.
However, the present investigation did demonstrate the following changes: a 0.50% decrease in TC, a 1.74% increase in TG, a 2.95% decrease in LDL-C, a 4.61% increase in HDL-C, a 4.12% decrease in the TC: HDL-C ratio and a 5.96% decrease in the LDL-C: HDL-C ratio.
The lack of statistically significant changes in the individual lipoprotein-lipid parameters could not have been affected by diet, cigarettes smoked daily, aerobic fitness and/or body mass, since these parameters did not change significantly from pre- to post-test. Specifically, both the EG and CG demonstrated no statistically significant changes in intake in total calories consumed, carbohydrates, proteins, fats (monounsaturated, polyunsaturated and saturated fatty acids), cholesterol and fibre.
Although the present investigation findings suggest that this study¡¯s eight-week combination of dose, workload, number of repetitions and order and number of exercises may not have been sufficient to elicit significant improvements in lipoprotein-lipid parameters in this population of sedentary but healthy males, it is the opinion of the author that DRT should be included with aerobic modes of exercise. DRT should be used in conjunction with aerobic modes of exercise for its additional benefits. Such additional benefits include inter alia: increased strength, increased lean tissue mass, increased maintenance of metabolically active tissue in the elderly and increased muscle control.
Prof. J.M. Loots
Mr. L. Lategan