Individuals with chronic heart failure need a "safe and effective" exercise program that could enhance their quality of life. In this study, we examined whether an experimental exercise program of autonomous walking and high-intensity Inspiratory Muscle Training (IMT) could result in better effects on respiratory muscle strength (PImax), cardiovascular endurance, quality of life, and physical activity, when compared to autonomous walking and "sham" IMT program, in adults 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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
16
The IMT intensity was set at 60% of PImax which was reassessed weekly. Frequency: 5x/week; 1x/day preferred. 6 Interval Levels: (6 efforts at 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. For the walking program, it was the same as the one for the control group.
The IMT training was 3 sets of 10 repetitions, or when the participant felt tired. Participants returned to our facility every week to reassess PImax. For the walking program, each participant was given a pedometer and a heart rate monitor to track daily step counts and heart rate. The walking program consisted of walking every day at an intensity of "somewhat hard" to "hard" on the Borg's Rating of Perceived Exertion scale. Participants began at least 10 to 15 minutes, once to twice a day, for 7 days a week, and eventually progressed to 45-50 minutes a day by the end of the six weeks, if they could tolerate.
Outpatient heart failure transitional care clinic, Presbyterian Hospital of Dallas, Texas Health Resources
Dallas, Texas, United States
School of Physical Therapy, Texas Woman's University
Dallas, Texas, United States
Change From Baseline in Mean Minnesota Living With Heart Failure Questionnaire Score
This questionnaire includes 21 questions which ask how much the heart condition affected the patient's life during the past month. Each question has 5 optional answers with the scores ranging from 0 to 5. A higher score indicates a worse outcome. The minimum overall score of the questionnaire is 0 and the maximum score is 105. A higher overall score on the Minnesota Living with Heart Failure Questionnaire indicates a worse outcome.
Time frame: Baseline and 6 weeks
Change From Baseline in Mean Score of Physical Component of the SF-36 Questionnaire
The SF-36 quality of life questionnaire (short form) was used. A higher score of the SF-36 questionnaire indicates a better outcome (i.e., lower disability). The range of overall score on the SF-36 questionnaire is from 0 to 100.
Time frame: Baseline and 6 weeks
Mean Daily Step Counts From Week 1 to Week 6
Each subject was given a pedometer to record his/her step counts every day.
Time frame: Baseline and 6 weeks
Respiratory Muscle Strength is Indicated by Maximal Inspiratory Pressure (PImax)
The inspiratory muscle strength will be measured in the unit of cmH2O by the Respiratory Muscle Pressure Meter (Micro Direct). A higher inspiratory pressure indicates a better inspiratory breathing strength.
Time frame: Baseline and 6 weeks
Six-minute Walk Test Distance
The six-minute walk test is a measure of cardiovascular endurance which measures how far a person can walk in 6 minutes. This test was conducted twice respectively at pre-training and at post-training to account for potential learning effect. A longer distance walked on the six-minute walking test indicates a better cardiovascular endurance.
Time frame: Baseline and 6 Weeks
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