6. Peak VO2 ≤75% predicted with peak respiratory exchange ratio≥1.0 CPET Normal Values for Peak VO2* Criteria (ml/kg/min) 7. No chronic nitrate therapy or not using intermittent sublingual nitroglycerin (requirement for >1 SL nitroglycerin per week) within last 7 days 8. No daily use of phosphodiesterase 5 inhibitors or soluble guanylyl cyclase activators and willing to withhold prn use of phosphodiesterase 5 inhibitors for duration of study 9. Ambulatory (not wheelchair / scooter dependent) 10. Body size allows wearing of the accelerometer belt as confirmed by ability to comfortably fasten the test belt provided for the screening process (belt designed to fit persons with BMI 20-40 kg/m2 but belt may fit some persons outside this range) 11. Willingness to wear the accelerometer belt for the duration of the trial 12. Willingness to provide informed consent