Effects of Resistance and Aerobic Exercise on Cardiovascular Health
Condition: Cardiovascular Diseases; Heart Diseases; Obesity; Hyperlipidemia; Insulin Resistance; Metabolic Syndrome X
MeSH terms: Cardiovascular Diseases; Heart Diseases; Metabolic Syndrome; Insulin Resistance; Hyperlipidemias
Study type: Interventional
Phase: Phase 2

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): Resistance Training; Aerobic Exercise; Combo; Continued Sedentary lifestyle
Intervention type(s): Behavioral; Behavioral; Behavioral; Behavioral
Intervention description(s): Lifting weights 3 times per week; 8 different exercise each time; for each exercise, do three sets = lifting an appropriate weight between 8-12 for each set; rest 45 seconds (at least) between sets; Exercise at 75% of maximal capacity for approximately 2 hours per week; Lift weights (as described in RT group) and do aerobic exercise (as described in Aerobic group; No changes
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Prevention