Effects of a Walking Program and Inspiratory Muscle Training in Individuals With Chronic Heart Failure

Participants were recruited from the outpatient heart failure transitional care clinic at the Presbyterian Hospital of Dallas and other local heart failure support groups. Flyers were distributed to cardiologists, nurse practitioners, and local heart failure support groups in the Dallas/Ft Worth area. Cardiologists and nurse practitioners were aware of the scope of the study and its inclusion and exclusion criteria of research participants. Potential research participants could then call the research team for further information.

Participants came to our facility for the initial evaluation session, where a history interview was conducted to gather demographic data, such as age, gender, height, weight, race/ethnicity, and past medical/surgical history. The following baseline data were then collected: a) two trials of the six-minute walk test, b) respiratory muscle strength indicated by maximal inspiratory pressure (PImax), and two quality of life questionnaires. During the walk test, heart rate and heart rhythms were continuously monitored via a holter monitor. During the rest breaks, research participants filled out two quality of life questionnaires (SF-36, Minnesota Living with Heart Failure Questionnaire).

Each participant was randomly assigned to one of the two groups: a) the autonomous walking program with a high-intensity Inspiratory Muscle Training (IMT) program, or b) the autonomous walking program with a sham IMT. The training threshold for the experimental IMT group was trained at 60%PImax which was reassessed at weekly follow ups. The frequency of training was 5x/week (1x/day preferred) for 6 interval levels at each session (6 inspiratory efforts in each level): (1) 60s rest interval; (2) 45s rest interval; (3) 30s rest interval; (4) 15s rest interval; (5)10s rest interval; (6) 5s rest interval, trained to exhaustion. The intensity of sham IMT was set at fixed 15% PImax. Research participants were blinded to the group assignment. The time commitment for IMT was about 15-20 minutes a session per day at home. Weekly follow up was conducted at the School of Physical Therapy in Dallas to reassess PImax, collect the log of daily step count, and discuss about the walking program. Every participant was given a breathing device for inspiratory muscle training.

Each participant was given a pedometer and a heart rate monitor to track their daily step counts and heart rate during the walking session. The walking program consisted of walking daily at an intensity of "somewhat hard" to "hard" on the Borg's Rating of Perceived Exertion (RPE) scale. Participants were encouraged to walk 10 to 15 minutes, once to twice a day initially, then progressed to about 45-50 minutes a day by week six, if they could tolerate. At the end of 6 weeks, these participants returned to our facility for the final evaluation session.

Inclusion criteria

• adults with chronic heart failure (NYHA Functional Class II-III)
• BMI < 35 kg/m^2
• Age: 18 to 90 years
• walk independently with or without an assisted device
• hospital discharge for CHF within a year.

Exclusion criteria

• ECG with uncontrolled ventricular arrhythmia
• bronchiectasis
• limited walking ability due to neurologic or orthopedic impairments of the legs