Exercise and Lipids -- Does Diet Matter If They Exercise?
Exercise and Lipids -- Does Diet Matter If They Exercise?
Background The standard clinical approach for reducing cardiovascular disease risk due to dyslipidemia is to prescribe changes in diet and physical activity. The purpose of the current study was to determine if, across a range of dietary patterns, there were variable lipoprotein responses to an aerobic exercise training intervention.
Methods Subjects were participants in the STRRIDE I, a supervised exercise program in sedentary, overweight subjects randomized to 6 months of inactivity or 1 of 3 aerobic exercise programs. To characterize diet patterns observed during the study, we calculated a modified z-score that included intakes of total fat, saturated fat, trans fatty acids, cholesterol, omega-3 fatty acids, and fiber as compared with the 2006 American Heart Association diet recommendations. Linear models were used to evaluate relationships between diet patterns and exercise effects on lipoproteins/lipids.
Results Independent of diet, exercise had beneficial effects on low-density lipoprotein cholesterol particle number, low-density lipoprotein cholesterol size, high-density lipoprotein cholesterol, high-density lipoprotein cholesterol size, and triglycerides (P < .05 for all). However, having a diet pattern that closely adhered to American Heart Association recommendations was not related to changes in these or any other serum lipids or lipoproteins in any of the exercise groups.
Conclusions We found that even in sedentary individuals whose habitual diets vary in the extent of adherence to AHA dietary recommendations, a rigorous, supervised exercise intervention can achieve significant beneficial lipid effects.
Lifestyle factors, including diet and exercise, are well recognized as important modifiable determinants of risk for cardiovascular disease (CVD) and are often the first to be recommended in the outpatient setting. Plasma levels of lipids linked with elevated (low-density lipoprotein [LDL] cholesterol and triglycerides) and reduced (high-density lipoprotein [HDL] cholesterol) CVD risk are known to be responsive to changes in both diet and physical activity level. Thus, clinical advice for individuals with dyslipidemia typically includes 2 oft-repeated recommendations: (1) adopt a lipid-lowering diet pattern and (2) increase the level of physical activity. In reality, these goals are not uniformly applied or achieved. Some clinicians may choose to emphasize one treatment option more than the other or may be better at explaining one modality versus the other. Patients also differ in their likelihood of achieving these recommendations. Some may be more successful at modifying their diet patterns, whereas others encounter fewer barriers to instituting a regular exercise program.
Important advantages could result from a better understanding of diet and exercise interactions, permitting clinicians to target lifestyle recommendations to achieve the therapeutic goal while minimizing the behavioral burden on the patient. Yet, few clinical studies have carefully examined the interaction of diet intake patterns with the effects of exercise on lipid-related CVD risk. In many exercise studies, detailed diet data are simply not collected, and/or diet instructions are lacking or nonspecific. Furthermore, the intentional combination of diet and exercise interventions often obscures individual effects.
Using data from the STRRIDE I (ClinicalTrials.gov Identifier: NCT00200993) trial, we sought to determine the influence of diet patterns on lipid responses to a supervised exercise intervention targeting CVD risk. As previously described, the treatment groups were low-amount/moderate-intensity (L/M), low-amount/vigorous-intensity (L/V), and high-amount/vigorous- intensity (H/V) aerobic exercise training. All STRRIDE I subjects were instructed not to change their baseline diet composition and body mass during the trial. Diet records were carefully and consistently collected during the intervention and analyzed for nutrient composition, enabling us to explore the interaction of diet with lipid changes. We hypothesized that diet pattern effects would be small or absent in the H/V group but that diet patterns would be more influential on lipid outcomes in the L/M and L/V groups.
A secondary aim in this study was to find results applicable for clinical use by characterizing the diets by pattern, rather than considering each nutrient individually. Thus, we derived a single diet pattern z-score that characterized the degree to which the diet of each STRRIDE I subject conformed to recommendations from the American Heart Association (AHA) for CVD risk reduction. We then examined the influence of these diet pattern z-scores on lipid responses to exercise.
Abstract and Introduction
Abstract
Background The standard clinical approach for reducing cardiovascular disease risk due to dyslipidemia is to prescribe changes in diet and physical activity. The purpose of the current study was to determine if, across a range of dietary patterns, there were variable lipoprotein responses to an aerobic exercise training intervention.
Methods Subjects were participants in the STRRIDE I, a supervised exercise program in sedentary, overweight subjects randomized to 6 months of inactivity or 1 of 3 aerobic exercise programs. To characterize diet patterns observed during the study, we calculated a modified z-score that included intakes of total fat, saturated fat, trans fatty acids, cholesterol, omega-3 fatty acids, and fiber as compared with the 2006 American Heart Association diet recommendations. Linear models were used to evaluate relationships between diet patterns and exercise effects on lipoproteins/lipids.
Results Independent of diet, exercise had beneficial effects on low-density lipoprotein cholesterol particle number, low-density lipoprotein cholesterol size, high-density lipoprotein cholesterol, high-density lipoprotein cholesterol size, and triglycerides (P < .05 for all). However, having a diet pattern that closely adhered to American Heart Association recommendations was not related to changes in these or any other serum lipids or lipoproteins in any of the exercise groups.
Conclusions We found that even in sedentary individuals whose habitual diets vary in the extent of adherence to AHA dietary recommendations, a rigorous, supervised exercise intervention can achieve significant beneficial lipid effects.
Introduction
Lifestyle factors, including diet and exercise, are well recognized as important modifiable determinants of risk for cardiovascular disease (CVD) and are often the first to be recommended in the outpatient setting. Plasma levels of lipids linked with elevated (low-density lipoprotein [LDL] cholesterol and triglycerides) and reduced (high-density lipoprotein [HDL] cholesterol) CVD risk are known to be responsive to changes in both diet and physical activity level. Thus, clinical advice for individuals with dyslipidemia typically includes 2 oft-repeated recommendations: (1) adopt a lipid-lowering diet pattern and (2) increase the level of physical activity. In reality, these goals are not uniformly applied or achieved. Some clinicians may choose to emphasize one treatment option more than the other or may be better at explaining one modality versus the other. Patients also differ in their likelihood of achieving these recommendations. Some may be more successful at modifying their diet patterns, whereas others encounter fewer barriers to instituting a regular exercise program.
Important advantages could result from a better understanding of diet and exercise interactions, permitting clinicians to target lifestyle recommendations to achieve the therapeutic goal while minimizing the behavioral burden on the patient. Yet, few clinical studies have carefully examined the interaction of diet intake patterns with the effects of exercise on lipid-related CVD risk. In many exercise studies, detailed diet data are simply not collected, and/or diet instructions are lacking or nonspecific. Furthermore, the intentional combination of diet and exercise interventions often obscures individual effects.
Using data from the STRRIDE I (ClinicalTrials.gov Identifier: NCT00200993) trial, we sought to determine the influence of diet patterns on lipid responses to a supervised exercise intervention targeting CVD risk. As previously described, the treatment groups were low-amount/moderate-intensity (L/M), low-amount/vigorous-intensity (L/V), and high-amount/vigorous- intensity (H/V) aerobic exercise training. All STRRIDE I subjects were instructed not to change their baseline diet composition and body mass during the trial. Diet records were carefully and consistently collected during the intervention and analyzed for nutrient composition, enabling us to explore the interaction of diet with lipid changes. We hypothesized that diet pattern effects would be small or absent in the H/V group but that diet patterns would be more influential on lipid outcomes in the L/M and L/V groups.
A secondary aim in this study was to find results applicable for clinical use by characterizing the diets by pattern, rather than considering each nutrient individually. Thus, we derived a single diet pattern z-score that characterized the degree to which the diet of each STRRIDE I subject conformed to recommendations from the American Heart Association (AHA) for CVD risk reduction. We then examined the influence of these diet pattern z-scores on lipid responses to exercise.
