Reduced Volume of Inspiratory Resistance Training

Cardiovascular disease (CVD) is the leading cause of death in the US and worldwide. Although it is well-known that lifestyle changes (e.g., diet, exercise) lower blood pressure (BP) and risk for cardiovascular events, an estimated \~98% of US adults with above-normal BP do not adhere to the recommended lifestyle behaviors. Common barriers to exercise, including lethargy, low exercise self-efficacy, fear of exercise-related pain, and lack of time, make adherence to traditional exercise strategies particularly difficult. The need for novel/different forms of exercise that are i) time-efficient, ii) well-tolerated, and iii) effective has never been greater. Inspiratory muscle strength training (IMST) is a novel, time-efficient respiratory exercise, comprising just 5 sets of 6 inspiratory efforts with 1-minute rests between sets. This training takes just 5 mins/day, 5 sessions/wk, for a total weekly training time of 25-30 minutes. Distinct from other forms of traditional aerobic or high-intensity interval-type exercise, IMST is performed on a hand-held device in sitting or standing. Participants make repeated inspiratory efforts against a resistance and generate large negative pressures that are 2-4-fold greater than those generated during rest breathing, deep breathing, or high-intensity aerobic exercise. The investigators have shown that IMST performed 5 days/wk for 6 weeks, lowers SBP 9 ± 1 mmHg on average. It is well known that exercise-induced adaptations plateau over time, despite increases in volume and/or intensity. Accordingly, the goal of exercise is not only to improve health, but to maintain health adaptations long term. Importantly, the dose of exercise required to improve health/performance is higher than the dose required to maintain health/performance. Given that lack of time is the most often cited reason for adults failing to initiate exercise and stopping chronic exercise participation, it is essential that any potential participant 1) appreciate the relationship between time spent exercising and health improvements and 2) understand how much exercise is needed to preserve exercise-induced adaptations to ensure an unnecessary amount of time is devoted to exercise. The investigators have shown that 6 weeks of IMST can significantly lower BP and improve respiratory strength, however, the dose needed to preserve these adaptations is unknown. This study comprises a 6-week loading dose of IMST (5 days/week; Endpoint 1), followed by 12 weeks of IMST at a reduced dose (0, 1, or 3 days/week; Endpoint 2).