Respiratory Muscle Training to Improve Cerebrovascular and Immune Function

Obesity, a growing global epidemic in America, is linked to cerebrovascular dysfunction and increases the risk of stroke, the nation's fourth leading cause of death. Cerebrovascular dysfunction is defined by impaired cerebrovascular reactivity and reduced cerebral autoregulation. Inspiratory muscle strength training (IMST) has proven to be a time-efficient, effective, low-cost, and highly feasible intervention for improving peripheral vascular function.

Given the link between the peripheral vasculature and cerebrovasculature systems, it is highly plausible that IMST may improve cerebrovasculature function. Emerging data show that in adults with elevated blood pressure, IMST improves cerebrovascular function. Thus, the study team will examine whether 8 weeks of IMST improves cerebrovascular function in otherwise healthy young adults with obesity.

Aim 1 will test the hypothesis that IMST will favorably increase cerebrovascular reactivity and improve cerebral autoregulation. Obesity-induced cerebrovascular dysfunction may be driven by chronic low-grade inflammation resulting from excessive sympathetic signaling. Additionally, inflammation is associated with reduced immune function. In adults with obesity, the systemic immune-inflammation index is elevated and positively associated with all-cause mortality. Emerging studies show IMST has the potential to reduce sympathetic activity and improve inflammation status.

Aim 2 will test the hypothesis that IMST will reduce inflammation and improve immune function in otherwise healthy young adults with obesity. It is hypothesized that IMST will improve cerebrovascular reactivity and autoregulation, suggesting improved cerebrovascular health. Additionally, IMST will reduce the systemic immune-inflammation index and improve immune function in otherwise healthy young adults with obesity. This project explores the potential of IMST as a time-efficient and cost-effective intervention to improve cerebrovascular function and mitigate inflammation-related immune dysfunction in adults with obesity, potentially enhancing healthspan and lifespan. These findings could inform public health initiatives targeting approximately 40% of American adults with obesity, improving overall cerebrovascular function in the short term and reducing stroke incidence later in life.

Inclusion criteria

• Body mass index greater than or equal to 30 kg/m2
• Waist circumference greater or equal to 88 cm for females and greater than or equal to 102 cm for males

Exclusion criteria

• Not weight stable (<5% change in body mass over the past six months)
• Overt cardiovascular, neurological, renal, liver, and/or metabolic illness (e.g., diabetes mellitus)
• Current, or history of uncontrolled, Stage 2 hypertension (blood pressure >140 / 90 mmHg; anti-hypertensive medications are permitted)
• Diagnosed obstructive sleep apnea
• Previous bariatric surgery
• Diagnosis or signs (e.g., values below the lower limit of normal) of overt airway disease(s)
• Current or recent (regular use within the past 6 months) use of tobacco or nicotine products (e.g., cigarettes, vaping)
• Pregnant (self-reported and confirmed via urine pregnancy test), lactating (self-reported), or post-menopausal (self-reported) females
• Prisoners

Per the POWERbreathe® company:

• Patients who have undergone recent abdominal surgery and those with abdominal hernia.
• Asthma patients who have a very low symptom perception and suffer from frequent, severe exacerbations or with an abnormally low perception of dyspnea.
• If a patient is suffering from a ruptured eardrum or any other condition of the ear.
• Patients with marked elevated left ventricular end-diastolic volume and pressure.
• Patients with worsening heart failure signs and symptoms after training. If an individual is suffering from a cold, sinusitis or respiratory tract infection, it is advised that they do not use the POWERbreathe device.