Prescription for Exercise Training of patients with Pulmonary dysfunction

Prescription for Exercise Training

Exercise prescription includes mode intensity, duration, and frequency that together allow the therapist to develop a patient-specific exercise plan to increase in functional capacity.

Mode

Any type of sustained aerobic exercise can be used for pulmonary rehabilitation.

The combination of upper extremity (UE) aerobic exercise (e.g., walking, jogging, cycling) and lower extremity (LE) aerobic exercise (e.g., arm ergometry, free weights) training in a pulmonary rehabilitation program results in improved functional status compared to other exercises alone.

Intensity

Three parameters can be used to prescribe exercise intensity:

1. Exercise intensity as a percent of maximum oxygen consumption (VO2max)

Exercise intensity can be prescribed using a moderate intensity of 40% to 60% of Maximum oxygen consumption achieved on the exercise tolerance test (ETT) or are moderate to vigorous-intensity greater than 60% of the maximum oxygen consumption achieved on an ETT.

2. Exercise intensity as a percent of heart rate reserve (HRR)

1. There is a relationship between increasing workload, increasing oxygen consumption, and increasing heart rate.

2. The Target Heart Rate Range (THRR) defines a wide, safe, and effective range of exercise intensity that can be performed during pulmonary rehab sessions.

3. The target heart rate (THR) for a specific patient defines a more narrow heart rate that will be most appropriate to ensure aerobic training and patient adherence.

4. A common method to determine a patient's target heart rate range (THRR) and the target heart rate (THR) is using the heart rate reserve (HRR) method is karvonen's formula. Heart rate reserve (HRR) is the difference between the resting heart rate (HRrest) in the seated position and the maximal heart rate (HRmax) achieved on an ETT.

5. To calculate the target heart rate range(THRR), percentages (40% and 85%) of the heart rate reserve (HRR)are added to the resting heart rate (HRrest).

Karvonen's formula for determining the upper and lower limits of the target heart rate range (THRR)

Lower limit of THRR = {(HRmax – HRrest) × 0.40} + HRrest Upper limit of THRR = {(HRmax – HRrest) × 0.85} + HRrest

For Example; 

A person achieves a maximum heart rate of 165 beats per minute on an ETT. The person's resting heart rate was 85 beats/minute. 

The HRR is calculated to be 165 – 85 = 80 beats/minute.

Lower limit of THRR is 40% of 80 beats/minute (32) + resting HR (85) = 117 beats/minute.

Upper limit of THRR is 85% of 80 beats/minute (68) + resting HR (85) = 153 beats/minute.

For this person, THRR is 117 to 153 beats/minute.

3. Exercise intensity by the rating of perceived exertion (RPE) or rating of perceived Dyspnea (RPD)

• Borg's RPE is often used as the means of prescribing exercise intensity for patients with cardiovascular and pulmonary diseases.
• RPE scale allows the patients to self regulate exercise intensity based on his perception of exertion (Table 1).
• Perceived exertion ratings of 3, 4, and 5 were correlated with 60%, 72%, and 78% of maximum oxygen consumption respectively.

Table 1: Borg RPE Scale
Score	Level of Exertion
6	No exertion at all
7
8	Extremely light
9	Very light
10
11	Light
12
13	Somewhat hard
14
15	Hard
16
17	Very hard
18
19	Extremely hard
20	Maximal exertion

• Rating of perceived Dyspnea (Table 2) between 3 (moderate SOB) and 6 (between severe and very severe) defines the range within which patients with pulmonary dysfunction generally exercise. 
• A rating of to 3 corresponds approximately to 50% of maximum oxygen consumption and a rating of about 6 corresponds to approximately 80% of maximum oxygen consumption.
• Clinicians prefer to prescribe exercise intensity by using a combination of THR, RPE, and RPD.

Table 2: Rating of Perceived Dyspnea
Scale	Perceived Shortness of Breath (Dyspnea)
0	Nothing at all
0.5	Very, very slight
1	Very slight
2	Slight
3	Moderate
4	Somewhat severe
5	Severe
6
7	Very severe
8
9	Very, very severe
10	Maximal

Duration

Exercising within prescribed exercise intensity for at least 20 to 30 minutes is recommended.

Frequency

If 20 to 30 minutes of continuous aerobic exercise can be completed within the target heart rate (THR) then 3 to 5 days per week are recommended.