Assess: What information do I need to prescribe an individualised exercise programme for pulmonary rehabilitation?

Your assessments will help you to plan your initial exercise programme for a patient during stage 2 (Prescribe) and adapt and measure progress during stages 3 (Progress) and 4 (Reassess) of the programme. You should be familiar with all the below forms of assessment and understand how you can use the insights from each one to guide your planning, adaptation and evaluation of pulmonary rehabilitation exercise programmes.

Medical Research Council (MRC) Dyspnoea Scale

Primary usage: often used to guide initial referral to pulmonary rehabilitation services; functional disability from COPD is often associated with patients who have scores of 2 or more with functional limitations.. Can be used during initial assessment and conclusion of the programme for evaluation of the progress made during the course of pulmonary rehabilitation.

The MRC Scale is a simple test of dyspnoea (breathlessness), based on the level of exertion required to elicit it. Patients are shown the scale and asked to report the grade they feel most accurately represents themselves:

Primary usage: used throughout the pulmonary rehabilitation programme to measure exercise intensity.

Primary usage: used throughout the pulmonary rehabilitation programme to measure exercise intensity (how hard a person feels their body is working during physical activity).

The Borg Breathlessness Scale and Rate of Perceived Exertion score (also known as the Modified Borg Scale, MBS or RPE scale) are two closely related subjective measurements of exertion. The scales are designed to rate exertion or breathlessness on a single scale, which is shown to the patient:

Rate of Perceived Exertion

BORG Breathlessness Scale

Crucially, the Borg and RPE scales been demonstrated to correlate with other measures of exertion (specifically heart rate and oxygen uptake) . This means that they can be used to estimate heart rate when objective measurement of heart rate or oxygen uptake is not practically possible (e.g. when a patient is exercising at home without monitoring equipment). When using the original RPE scale, you can multiply the score provided by the patient by 10 to estimate their heart rate.

Heart rate

Primary usage: used throughout the pulmonary rehabilitation programme to measure intensity of aerobic exercise, either measured directly or estimated using Borg or RPE scales. Also used to assess suitability for pulmonary rehabilitation.

A normal resting heart rate is between 60-100 beats per minute. Patients with significant bradycardia (slow heart rate) or tachycardia (fast heart rate) may require additional clinical assessment before commencing an exercise programme.

Heart rate is used for both exercise intensity and prescription due to a linear relationship between workload and maximal oxygen consumption (Vo2 max).

Target heart rate (in the form of a percentage of maximal heart rate, sometimes abbreviated to HRmax) can be a reliable way of setting and reassessing exercise intensity. Calculating a target heart rate for exercise can be done in a variety of ways.

You should have an understanding of how to calculate a target heart rate and which calculation to use depending on the patient population, including how to adjust for patients on beta blockers. The main formulas for finding a maximum heart rate are:

Once you have established a maximal heart rate, you can find a target heart rate for an exercise by using the following formula:

Target heart rate = (percentage of maximal effort required out ÷ 100) x maximal heart rate

The BACPR have also developed a number of ready reckoner tables for calculating heart rates without needing to run calculations.

Respiratory rate

Primary usage: assessing suitability for pulmonary rehabilitation

A normal resting respiratory rate is 12-16 breaths per minute. Patients with COPD often have higher respiratory rates (17-25 breaths per minute). A resting respiratory rate of more than 25 breaths per minute may indicate exacerbation of COPD, and the patient should not undertake pulmonary rehabilitation without further assessment.

Assessment can also identify if a dysfunctional breathing pattern is present, and whether or not this needs to be further assessed and treated prior to commencing the exercise programme.

Blood pressure

Primary usage: assessing suitability for pulmonary rehabilitation

A typical blood pressure range is approximately 100-140 mmHg systolic and 60-100 mmHg diastolic. Patients with uncontrolled hypertension with resting systolic blood pressure > 200 mmHg or diastolic blood pressure >120 mmHg will need additional clinical input before commencing the exercise programme.

Oxygen saturation

Primary usage: assessing suitability for pulmonary rehabilitation, potential requirement for referrals for supplemental oxygen, and monitoring the safety of patients during exercise sessions

Oxygen saturation levels must remain above safety thresholds to avoid possible complications.

During initial assessments, oxygen saturation at rest should be established to ensure the patient is safe to exercise (i.e. their saturation is above 80%). Normal oxygen saturation is above 95%; however, for those with cardiorespiratory disease, it may be lower. Patients with resting oxygen saturation at or below 92% may be considered for referral for long-term oxygen supplementation. For patients with clinical evidence of peripheral oedema, polycythaemia (haematocrit at or above 55%) or pulmonary hypertension, the threshold for considering referral for supplementary oxygen should be an oxygen saturation at or below 94%.

For healthy individuals, oxygen saturation should not change significantly during exercise. However, for patients with cardiorespiratory diseases, gaseous exchange may be compromised, leading to falls in oxygen saturation below safe levels (80%). Referral for assessment for ambulatory oxygen should be considered if oxygen saturation levels fall by at least 4% to a point below 90% during exercise.

6MWT (6 Minute Walking Test)

Primary usage: assessing exercise capacity for aerobic exercise

Find out how to conduct the 6-Minute Walking Test here.

The 6MWT result – the 6 Minute Walking Distance (6MWD) – is used as a measure of aerobic exercise capacity. It may be used to evaluate progress by comparing scores from before and after the pulmonary rehabilitation programme.

The 6MWD can be used to calculate the intensity of prescription based on achieved distance or predicted distance for the walking programme of the aerobic exercise programme.

You can find out the maximum distance a person could walk in one minute by dividing the 6MWD by 6. This one-minute distance can then be multiplied by the percentage intensity desired and then multiplied again by the length of the bout of exercise.

For example, to programme a target distance for 10 minutes of walking at 80% intensity for someone who achieved a distance of 320m for their 6MWD:

• 320 ÷ 6 = 53.3m (one minute walking distance) 

• 53.3 x 0.8 = 42.7m (one minute walking distance at 80% intensity) 

• 42.7 x 10 = 427m (target distance for 10 minutes walking at 80% intensity) 

Using predictive distance

You can also use predictive distance formulas to estimate walking speed. However, these formulas are intended for healthy adults and are likely to be less accurate for patients with respiratory conditions.

There are gender specific equations to be used when working out predictive distance. The formulas below can be used to determine predictive distance for 6MWD, which can then be used to establish target distance for bouts of exercise using the same approach as outlined earlier in this section.
For men, the predictive formula for 6MWD is:

6MWD = (7.57 × height) – (5.02 × age) – (1.76 × weight) – 309

For women, the predictive formula for 6MWD is:

6MWD = (2.11 × height) – (2.29 × weight) – (5.78 × age) + 667

You can also use an online calculator to establish the predicted 6MWD.
You can also use predicted distance to report how much a patient has achieved compared to predicted as a percentage.

Clinical judgement is required to decide if actual or predictive distance should be used to prescribe a walking programme. As the six-minute walking test is self-paced, actual distance might underestimate exercise tolerance, whereas predictive distance may overestimate it. For this reason, due to its relationship to Vo2 peak, the ISWT allows for a more accurate prescription of walking speed.

ISWT (Incremental Shuttle Walk Test)

Primary usage: assessing exercise capacity for aerobic exercise

Find out how to conduct the Incremental Shuttle Walk Test.

The ISWT will give a result of the number of shuttles or metres achieved during the test.  This will then provide a walking speed that can be used to calculate the distance that a person could walk in 10 minutes on the flat or on a treadmill.

A ready reckoner table (adapted from materials developed by the University of Toronto) allows you to easily calculate peak walking speed based on completed levels, completed shuttles, or total distance:

For example, if someone walked between 260–330m during the ISWT, their walking speed would be 4.86km/hr. You could then use this walking speed to programme walking exercises at different intensities:

You can then multiply the walking speed per hour by the length of the bout of exercise:

ISWT results and Vo2peak/Vo2max

The ISWT result can also be used to estimate Vo2peak, which can in turn be used as an estimated Vo2max. True Vo2max testing is difficult without specialist equipment.

Vo2max may be used for aerobic exercise prescription.

The formula for estimating Vo2peak from ISWT results is:
VO2 peak(ml/kg/min) = 4.19 + (0.025 x ISWT distance in metres)

For example:

If someone achieved 190m on the ISWT
Vo2peak = 4.19+(0.025x190m)
Vo2peak = 4.19+(4.75)
Vo2peak = 8.94(ml/kg/min)

Additional details on using ISWT results to inform exercise prescriptions can be found on the “intensity” tab of this page, created by the Lung Foundation Australia.

1 Repetition Max (1RM) tests and other associated tests

Primary usage: assessing muscle strength

Find out how to conduct tests of muscle strength and estimate 1RM from sub-maximal tests.

Your exercise programme should include exercises to build both muscle strength and endurance.

To prescribe exercises at an appropriate intensity, you will need to programme exercises using percentages of 1RM (the maximum weight which the patient can lift for a single repetition for a particular exercise).

Guidance on prescription is available in the next section of these resources.

Functional assessments

Primary usage: providing additional insights into the ability of the patient to complete tasks representative of the activities of daily living

Many pulmonary rehabilitation services use simple functional tests as part of their patient assessment/reassessment process. These tests are designed to mimic everyday physical activities (such as standing up from a chair) to provide insight into the functional status of the patient. Poorer functional status (ability to complete everyday physical tasks) is associated with poorer quality of life, hospital readmission and mortality.

Functional assessments should be regarded as complementary to field walking and strength tests. There is no evidence that aerobic or strength training programmes can be reliably prescribed based solely on the results of functional assessments.

Find out more about commonly used functional assessments by clicking the links below: