6 MWT Vs S

huttle

Outcome measures of functional capacity

Content Exercise testing

Application of 6MWT

6MWT Evidence

Application of SWT

ISWT Evidence

Comparison

Exercise testingRole of Exercise Testing

Assess Exercise Capacity

Exercise Prescription

Assess Change

Exercise TestingGold Standard- Symptom Limited Graded Exercise Testing (GXT)

Laboratory based

Incremental

Symptom limited

Externally paced

Gas Exchange

Field-Based Exercise Testing 6 Minute Walk Test

Shuttle Walk Test

6 Minute Walk testBackground

Developed in 1963 by Balke to evaluate functional capacity in respiratory disease and heart failure.

Has since been used in a variety of populations including the elderly, stroke patients and spinal cord injuries.

Easy to implement, little equipment needed.

6MWTApplication

Measures the amount of distance and individual is able to walk over a period of 6 minutes on a hard, flat surface.

Self-paced. Resting allowed as necessary. Submaximal test.

Measure Heart Rate and SpO2 before test and upon completion.

6MWT Implementation:

Ideally conducted in a closed quiet hallway by a single administrator. Variables:• Test Instructions: Walk at a comfortable pace/ as quickly as

possible.• Resting Instructions (American Thoracic Society ATS)• Walkway Length: ATS recommend 30m. Others 10m/15m.• Use of Encouragement: If used the exact protocol should be

documented. • Number of Trials: Largest improvements seen over first three.

6MWT Scoring:

Range for healthy adults is 400m-600m

Clinically important difference is 54m for healthy adults (Redelmeier et al, 1997)

50m for stroke patients (Perera et al, 2006) 25m for coronary disease (Gremeaux et al, 2011). % change of clinical significance not established.

Test Evaluation Validity- Does the test measure what it is said to measure?

Reliability- If the test is repeated on the same patient by the same or different examiners will the results be similar?

Responsiveness- Is the test responsive to change? e.g.: following completion of an exercise intervention.

EvidenceSystematic review in out-patient cardiac rehabilitation

“Strong evidence suggests that the 6MWT is responsive to clinical change following cardiac rehabilitation. Intra and inter-tester reliability of the 6MWT and its validity in patients undergoing cardiac rehabilitation requires further research.”

-Bellet et al,2012

6MWT Evidence Validity-Moderate to high relationships have been reported between the

6MWT distance and peak VO2max obtained in persons with heart failure and COPD (Guyatt et al, 1985, Jaeschke et al 1993)

Reliability-Different encouragements and repeated testing produce variable results (Guyatt et al, 1984)

Responsiveness- Studies of responsiveness have shown that improvement in 6MWT distance is related to diminished breathlessness (pacemaker patients), improvements in QOL (elderly, cardiac pts) and changes in VO2 max (COPD)

Incremental Shuttle Walking TestBackground

Developed to overcome problems associated with fixed-time, self-paced walking tests.

Externally Paced

Incremental

Symptom-limited maximal test

Based on the 20m shuttle run test designed by Leger and Lambert to assess fitness in healthy adults.

ISWT Implementation 10m course marked by 2 cones set 0.5m from each end.

Walking speed set by an audio signal on a tape/cd.

Initial pace is 0.5m/sec. Walking speed increases by 0.17m/sec each minute of the test, indicated by a triple beep from the tape.

Number of shuttles increases by 1 each time the speed of walking increases.

Test ends when the patient is exhausted or too breathless to continue or when the patient is more than .5m from the cone when the turn signal sounds.

Max 12 levels. HR, SpO2, BORG Dyspea scale used in coherence with the walking test.

ISWT

EvidenceValidity

Several studies have demonstrated a strong relationship between distance walked on the ISWT and the directly determined VO2max, advocating the tests validity in:

-COPD Patients (Singh et al, 2003. Turner et al, 2004. )

-Chronic Heart Failure (Morales et al, 2000. Green et al, 2001)

-Pulmonary Fibrosis (Moloney et al, 2003)

ISWTReproducibility

Singh et al and Green et al both reported strong test-retest reproducibility when they compared distance walked during tests spaced 1 week apart.

Reliability

Strong as externally paced and audio cued.

6MWT Vs ISWT Some studies in people with COPD and CCF have demonstrated that the

6MWT overestimates disability when compared to the ISWT (Singh et al 1994, Green et al 2001, Morales et al, 2000)

Similar distances covered. Peak HR and dyspnea greater on ISWT

Conversely, Turner et al (2004) noted a strong correlation between heart rate (HR), dyspnea and distances covered in the two tests and strongly encouraged the 6MWT. This test also used encouragement.

Comparison 6MWT Vs ISWT6 Minute Walk Test Incremental Shuttle Walk Test

Self-Paced Externally Paced

Little Equipment Needed CD for incremental change

Greater Functional Exercise Prediction Greater Physiological Correlation-HR,Dyspnea

Similar distances covered Similar distances covered

ComparisonRandomised Control Trials. ? Conflicting Evidence

The shuttle walk test is simple and easy to implement in patients with chronic obstructive pulmonary disease. The encouraged 6-minute walk test produced higher post-test heart rate and greater post-test sensation of dyspnea than did the shuttle walk test. (COPD)

-Rosa et al, 2006.

The shuttle walk test is no more responsive to change than the 6-minute walk test in older people. It is limited by ceiling effects, and cannot be performed successfully by very frail older people. (Elderly population)

-Witham et al, 2012.

Conclusion Further evidence is needed for specific patient populations to establish the

true validity in all patient sub-groups.

Current evidence suggests both the 6MWT and Shuttle walk test are suitable functional capacity outcome measures for cardiopulmonary patients.

References Bellet et al, 2012. The 6-minute walk test in outpatient cardiac

rehabilitation: validity, reliability and responsiveness- a systematic review.

Guyatt et al, 1985. How should we measure function in patients with chronic heart and lung disease? J Chronic Disease.

Jaeschke et al, 1989. Measurement of health status: Ascertaining the minimal clinically important difference. Control clinical trials.

Solway et al, 2001. A qualitative systematic overview of the measurement properties of functional walk tests used in the cardiorespiratory domain. Chest.

References Singh et al, 1994. Comparison of oxygen uptake during a conventional treadmill test and

the shuttle walking test in chronic airflow limitation. Eur Resp J.

Turner SE et al, 2004. Physiologic responses to incremental and self-paced exercise in COPD. A comparison of three tests. Chest.

Moloney ED et al 2003. The Shuttle walk exercise test in idiopathic pulmonary fibrosis. Resp. Med.

Green DJ et al, 2001 A Comparison of the shuttle and 6 minute walking tests with measured peak oxygen consumption in patients with CHF. J Sci Med Sports

Morales et al, 2000. Shuttle versus six-minute walk test in the prediction of outcome in chronic heart failure. Int J Cardiol.