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

• SF-36 Quality of Life questionnaire [ Time Frame: 6-week training ] [ Designated as safety issue: No ]
  The SF-36 quality of life questionnaire (short form) will be used.
  
  
• Minnesota Living with Heart Failure Questionnaire [ Time Frame: 6-week training ] [ Designated as safety issue: No ]
  This questionnaire includes 21 questions which ask how much the heart condition affected the patient's life during the past month (4 weeks).
  
  

• Heart rate variability [ Time Frame: 6-week training ] [ Designated as safety issue: No ]
  Heart rate and heart rhythm will be recorded via a holter monitor during some testings: comfortable walking speed test, grip strength test, single limb stance test, and resting in supine (5 min) and in standing (5 min) conditions. Data will be analyzed later.
  
  
• Physical Activity [ Time Frame: 6-week training ] [ Designated as safety issue: No ]
  Each subject will be given a pedometer to record his/her step counts every day. They will also wear a heart rate monitor while they walk and record their steps and average heart rate in the walking log. In addition, each subject will wear an accelerometer for the first week and the last week during the study period for validation purpose.
  
  
• respiratory muscle strength [ Time Frame: 6-week training ] [ Designated as safety issue: No ]
  The inspiratory muscle strength will be measured in the unit of cmH2O by the Respiratory Muscle meter (Micro Direct).
  
  
• Six-minute walk test distance [ Time Frame: 6-week training ] [ Designated as safety issue: No ]
  The six-minute walk test is a measure of cardiovascular endurance which measures how far a person can walk in 6 minutes. This test will be conducted twice respectively at pre-training and also post-training to account for potential learning effect.
  
  

Participants will be recruited from the outpatient heart failure clinic and in-patient heart failure unit at the Presbyterian Hospital of Dallas and other local heart failure support groups. Flyers will be distributed to cardiologists, nurse practitioners, a research nurse, and local heart failure support groups. Cardiologists and nurse practitioners are 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. Potential participants will be screened for their respiratory muscle strength (indicated by the maximal inspiratory pressure (PImax) via a pressure meter). If they show a certain degree of respiratory muscle weakness, they will be eligible to participate in the study. This screening can be done at the outpatient clinic of the Presbyterian Hospital of Dallas or at our facility.

Participants will come to our facility for the first initial evaluation session where a history interview will be conducted to gather demographic data such as age, gender, height, weight, race/ethnicity and past medical/surgical history. We will collect baseline data for the following: a) two trials of 6 minute walk test, b) respiratory muscle strength, c) comfortable walking speed, d) grip strength, and e) single limb stance time. During these testings, their heart rate and heart rhythms will be continuously recorded via a holter monitor. Then, their heart rate variability can be analyzed later. During the rest breaks, Participants will fill out two quality of life questionnaires (SF-36, Minnesota Living with Heart Failure Questionnaire.) After rest breaks, participants will then repeat the six-minute walk test.

Each participant will be randomly assigned to one of two groups: a) a walking group with a high-intensity Inspiratory Muscle Training (IMT) program, OR a walking program with a sham IMT program. The Sham group will be trained at a low intensity and low repetitions. The training threshold for the Experimental IMT group will be set at 60% of PImax (high-intensity respiratory muscle training). The PImax will be adjusted weekly with a nose clip used to ensure participant breathes completely through the mouth. Frequency of training: 5x/week; 1x/day preferred. 6 Interval Levels: (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 sham IMT intensity will be set at fixed 15% PImax. Research participants will be blinded to the group assigned. The time commitment for their IMT training is about 15-20 minutes per training session at home. Weekly follow up on their maximal inspiratory pressure will be done at the School of Physical Therapy at Dallas Center for 15 to 20 minutes, then they will train at a new IMT training intensity on the breathing device. Researchers will also make a copy of their weekly step counts log.

Each participant will be given a pedometer, an accelerometer, and a heart rate monitor so they can track their step counts and heart rate during the study. The walking program will consist of walking every day at an intensity of "hard" to "somewhat hard" on the Rating of Perceived Exertion (RPE) scale. Participants will begin walking at least 15 minutes twice a day and eventually progress to 45-50 minutes a day by the end of the six weeks.

At the end of 6 weeks, participants will come to our facility to repeat those initial tests and to fill out the two quality of life questionnaires again.