Effect of inspiratory muscle training on blood pressure with inspiratory loading

Abstract

Aims: Stimulation of the respiratory muscle group III/IV muscle afferents via inspiratory loading (IL) augments the blood pressure response during exercise. However, it is unknown if inspiratory muscle training (IMT) will ameliorate this response. We hypothesized that 8 weeks of IMT will attenuate the IL-induced increase in blood pressure during exercise in healthy adults. Methods: Ten adults were recruited and randomized to the IMT (n=5) or sham group (n=5). Participants performed 8 weeks of IMT twice a day, 7 days a week at 50% (IMT) or 10% (sham) maximum inspiratory pressure (MIP). On separate visits, participants performed an incremental cycling test to volitional fatigue and a 10 min cycling exercise bout at 40% peak oxygen uptake before and following IMT. The exercise bout consisted of 5 min of spontaneous breathing followed by 5 min of voluntary hyperventilation (i.e. breathing frequency of 40 breaths per min with 50% duty cycle) with IL (30% MIP). Systolic and diastolic blood pressure (SBP and DBP, respectively) were measured using manual sphygmomanometry. Mean arterial pressure (MAP) was calculated as (SBP-DBP)/3+DBP. Results: After 8 weeks, MIP increased in the IMT (Pre: 86±18; Post: 112±26 mmHg, p=0.02), but not the sham group (Pre: 124±49; Post: 127±51 mmHg, p>0.05). Pre-IMT, the IL resulted in increased MAP in both groups during exercise (ΔMAP, IMT: 11±3; sham: 12±6 mmHg) (both, p 0.05). Conclusions: These data suggest that IMT may not modify the cardiovascular response with IL in healthy adults.