Artery Function Responses to Heat Therapy and Exercise Training
Condition: Endothelial Dysfunction
Study type: Interventional

Summary: 
      This study will explore the effects of 8 weeks of local leg heat therapy, exercise training,
      or both on measures of vascular function, cardiorespiratory fitness, and muscle strength in
      young, healthy individuals. Participants will be allocated into either a control group that
      will maintain their regular physical activity habits; or into one of three training groups:
      heat therapy will involve lower limb warm water immersion, exercise training will involve
      moderate-intensity cycling, and combined training will involve both performed in sequential
      order.
    

Detailed description: 
      A between-groups interventional design will be used in a cohort of 80 young, healthy males
      and females 18-35 years old. Interested individuals will be invited to the lab for a
      screening and familiarization visit (1 hr), in which participants will be introduced to
      various lab testing protocols to ensure proper performance and tolerance during experimental
      data collection sessions. Participants will be randomized into one of four groups for an
      8-week intervention period: (1) no training (CON), (2) lower limb heat therapy (HEAT), (3)
      moderate intensity cycling training (EX), or (4) combined training (HEATEX). CON will involve
      maintenance of regular physical activity habits. HEAT will involve 45 minutes of lower limb
      hot water immersion (42 °C) using a custom-made heating apparatus 3x/week. EX will involve of
      45 minutes of cycling on an ergometer at 40-59% VO2reserve 3x/week. HEATEX will require
      participants to perform 3x/week of exercise training and heat therapy consecutively and in
      that order, such that each session is 90 minutes in duration. In total, all groups except CON
      will be expected to complete 24 intervention sessions. Vascular function will be
      characterized by measures of endothelial function, arterial stiffness, arterial structure,
      central hemodynamics, arterial blood flow and shear, and endothelial cell nitric oxide
      production. Muscle and metabolic adaptations will be characterized by measures of
      cardiorespiratory fitness, body composition, muscle strength and thickness, and fasting
      glucose and insulin. Inflammatory profile will be characterized by concentrations of
      interleukins, heat shock proteins, and cortisol. Thermal physiological adaptations will be
      characterized by measures of core and skin temperature and sweat rate. Perceptual responses
      will be characterized by measures of thermal comfort and sensation, calmness, alertness,
      mood, affect, and ratings of perceived exertion. Intervention adherence will be tracked
      throughout the intervention period. For the acute investigation (3-hr visit), outcome
      measures will be assessed before and immediately following the first and last training
      session. For the chronic investigation (2-hr visit), outcome measures will be assessed at
      weeks 0, 2, 4, 6, and 8 of the intervention period.
    

Intervention name(s): Heat therapy; Exercise training
Intervention type(s): Other; Other
Intervention description(s): Lower limb warm water immersion (42 degrees C); Moderate-intensity cycling exercise (~40-59% VO2 reserve)
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: heat therapy; exercise training; endothelial function