Effects of Resistance and Aerobic Exercise on Cardiovascular Health
Effects of Resistance and Aerobic Exercise on Cardiovascular Health
This study will investigate the separate and combined effects of aerobic and resistance
 training on cardiovascular risk factors in overweight men and women with mild to moderate
 dyslipidemia.
BACKGROUND:

 Substantial evidence supports a favorable relationship between cardiovascular fitness,
 physical activity, and cardiovascular health. In particular, it is well established that
 increased levels of physical activity result in favorable improvements in lipid and
 carbohydrate metabolism. There is also evidence that increased physical activity and
 cardiovascular fitness have beneficial effects on cardiovascular health, independent of the
 effects on specific cardiovascular risk factors. One hypothesis proposes that the beneficial
 effects of regular exercise in humans is mediated through peripheral mechanisms, in
 particular through the chronic adaptations in skeletal muscle to habitual exercise. The
 exercise exposure required to achieve health benefits is poorly defined and the mechanisms
 through which these beneficial adaptations occur are poorly understood. This study will
 investigate the peripheral biological mechanisms through which chronic physical activity
 alters carbohydrate metabolism and lipid metabolism, resulting in improvements in these
 parameters of cardiovascular health and fitness.

 DESIGN NARRATIVE:

 In Studies of a Targeted Risk Reduction Intervention through Defined Exercise II (STRRIDE
 II), participants will be randomly assigned to one of four exercise training regimens after a
 4-month sedentary control period. After an initial ramp period of up to 2 months,
 participants will be asked to train for 6 months in a given exercise program. The programs
 differ either in the dose of aerobic exercise or in the mode (e.g., aerobic exercise,
 resistance exercise, or a combination). Parameters reflecting changes in carbohydrate and
 lipid metabolism will be studied at an integrative physiologic level and with measurable
 biological endpoints in peripheral skeletal muscle (capillary surface area). It is proposed
 that the elucidation of the peripheral mechanisms mediating the favorable responses in
 carbohydrate and lipid metabolism to chronic physical activity will lead to better
 understanding of the health benefits conferred by physical activity and cardiovascular
 fitness. This may also point the way toward better exercise recommendations for clients with
 significant cardiovascular risk factors. The purpose of this study is to investigate the
 peripheral biological mechanisms through which chronic physical activity will alter
 carbohydrate metabolism and lipid metabolism that results in improvement in parameters of
 cardiovascular health and fitness. The driving hypothesis is that the health benefits derived
 from habitual exercise are primarily mediated through adaptations occurring in skeletal
 muscle. The mechanism of change in skeletal muscle differs by the mode of exercise training.
 It is hypothesized that the health benefits of aerobic exercise are mediated primarily by
 qualitative changes in skeletal muscles (alterations in exposed capillary surface area in
 skeletal muscle induced by exercise training) and that the health benefits of resistance
 exercise are mediated primarily by quantitative changes in skeletal muscles (alterations in
 fiber area in skeletal muscle induced by exercise training). The investigators will use
 combination exercise regimens in moderately obese patients with mild to moderate lipid
 metabolic abnormalities in order to investigate whether induced alterations in skeletal
 muscle fiber area, metabolic capacity, and capillary surface area account for favorable
 alterations in insulin sensitivity, glucose metabolism, lipoprotein levels, and lipid
 metabolism.
Inclusion Criteria:

 -  Sedentary (exercises fewer than two times per week)

 -  Overweight or mildly obese (body mass index [BMI] of 25 to 35 kg/m2) with mild to
 moderate lipid abnormalities (either LDL cholesterol 130 to 190 mg/dl or HDL
 cholesterol less than 40 mg/dl for men or 5 less than 45 mg/dl for women)

 Exclusion Criteria:

 -  Diabetes

 -  Hypertension

 -  Other metabolic or musculoskeletal diseases

 -  Current use of or intent to diet

 -  Use of confounding medication

 -  Overt presence of coronary heart disease

 -  Unwilling to be randomized to any group