VALIDITY AND RELIABILITY

OF THE INCREMENTAL

SHUTTLE WALK TEST AND

SIX-MINUTE WALK TEST IN

CHRONIC HEART FAILURE

*PhD Student, Glasgow Caledonian University, Glasgow /

Cardiac Rehabilitation Physiotherapist, NHS Ayrshire & Arran

(aynsley.cowie@aaaht.scot.nhs.uk) TITLE OF PRESENTATION

Mr John SmithSchools and Colleges Liaison

Cowie, A.*, Thow, M.K.,

Granat, M., Mitchell, S.L.

Background Valid - measures what it’s supposed to measure

Reliable - gives consistent results repeatedly

PeakVO2 (peak oxygen uptake) from cardiopulmonary exercise test

(CPET) = most accurate measure of exercise capacity

(gold standard)

CPET: incremental cycling / treadmill protocol to symptom-limited

peak BUT time-consuming, costly, and often poorly tolerated

(clinically inaccessible)

Incremental Shuttle Walk Test (ISWT) and self-paced 6-minute Walk

Test (6MWT) = popular clinical substitutes; simplistic, inexpensive,

familiar

6MWT (Butland et al, 1982)

self-paced over known distance for

6 minutes (with rests as required)

many trials in CHF* inconsistently

confirming validity and reliability

* = chronic heart failure

ISWT (Singh et al, 1992)

externally-paced, progressive

walking speed (around cones)

governed by audio signal

less evidence to support use -

very few trials in CHF

Trials comparing tests in CHF:

ISWT more valid

Reliability confirmed though lack

of consensus regards pre-test

familiarisation / practice walk?

(Green et al, 2001; Morales et al, 1999;

Pulz et al, 2008)

10m

Background

To examine:

Validity of the ISWT and 6MWT (in relation to

symptom-limited treadmill CPET)

Test-retest reliability of each walking test

Whether familiarisation has any effect on walking

test reliability

Aims

Power calculation: n=22 (80% power) (Green et al, 2001)

Recruited from CHF nurses, and cardiology clinics

EXCLUSION CRITERIA

Contraindications to exercise

testing (ACSM, 2006)

Local NHS Ayrshire & Arran

treadmill testing protocol

(exclusions) adhered to

INCLUSION CRITERIA

Left ventricular dysfunction

Clinically stable for at least

one month (ACPICR, 2006)

Optimised cardiac

medication doses

Sample

n=22 familiarised with either

ISWT or 6MWT (randomly assigned)

1 x treadmill CPET, STEEP protocol (Northridge et al, 1990)

3 x ISWT and 3 x 6MWT (familiarised test first)

Data from 1st

walking test

compared to data

from CPET

Data over 3

attempts of each

walking test

examined

Reliability data of those

familiarised compared

to those not

VALIDITY OF EACH

WALKING TEST

RELIABILITY OF EACH

WALKING TEST

EFFECT OF

FAMILIARISATION

ON RELIABILITY

OUTCOMES:

peakVO2 (ml.kg-1.min-1)

walking test distance (m) Methodology

Cosmed K4b2

27 participants

recruited initially

n=22 completed

study with no

adverse events

Results

CHARACTERISTICS VALUES

n n=22

Mean age (years) 64 Age

range (years) 51-76 Gender

(males / females) 19 / 3

NYHA class: II / III 13 / 9

Aetiology of heart failure:

- idiopathic 0

- ischaemic 14

- other 8

Baseline ECG:

sinus rhythm / atrial fibrillation 17 / 5

Validity

Neither walking

test stressed

participants to the

level of CPET

Mean peakVO2*:

CPET - 16.99

ISWT - 13.43

6MWT - 14.39

(* = ml.kg-1.min-1)

6MWTISWTCPET

25

20

15

10

Pe

akV

O2

(m

l.kg

-1.m

in-1

)

CPET PeakVO2 Versus

Walking Test PeakVO2

6MWT distance has stronger relationship with CPET

peakVO2 - though both relationships significant (p<0.05)

**regression correlation, †closer to 1.0 = stronger relationship

Validity

COMPARISON** r VALUE† p VALUE

6MWT distance v. CPET pVO2 r = 0.62 p = 0.001

ISWT distance v. CPET pVO2 r = 0.48 p = 0.001

CPET PeakVO2 Versus

Walking Test Distance

*Two-way ANOVA

†intra-class correlation

co-efficient (closer to 1.0

= stronger relationship)

Reliability & Familiarisation

ICC† (p VALUE)

ALL PARTICIPANTS THOSE FAMILIARISED

6MWT 0.74 (p=0.97) 0.58 (p=0.45)

ISWT 0.84 (p=0.15) 0.86 (p=0.29)

ISWT showed better reliability - enhanced by

familiarisation

Reliability of 6MWT reduced with familiarisation

All reliability analyses non-significant (p>0.05)

WALKING

TEST

PeakVO2 Data Over 3 Attempts of Each Walking Test

Neither walking test stressed participants to the level of CPET

6MWT distance is a more valid representation of exercise

capacity than ISWT distance

ISWT demonstrated greater reliability - and reliability improved

with familiarisation

Familiarisation increased variation in 6MWT data, reducing its

reliability

As reliability is a pre-condition of validity, the ISWT may be the

more valid test for clinical practice in CHF

Conclusions

American College of Sports Medicine, 2006. Guidelines for exercise testing and

prescription. 7th Edition. Baltimore, Maryland: Lippincott Williams & Wilkins;

Association of Chartered Physiotherapists in Cardiac Rehabilitation (2006)

Standards for the exercise component of the phase III cardiac rehabilitation.

London: ACPICR.

Butland, R.J., Pang, J. & Gross, E.R. (1982) Two-, Six- and 12-minute Walking Tests

in Respiratory Disease. BMJ, 284,1607-8.

Green, D., Watts, K., Rankin, S., Wong, P. & O’Driscoll, J., 2001. A Comparison of

the Shuttle and 6-Minute Walking Tests with Peak Oxygen Consumption in

Heart Failure. Journal of Science and Medicine in Sport, 4(3),292-300.

References

Morales, F.J., Martinez, A., Mendez, M., Agarrado, A., Ortega, F., Fernandez

Guerra, J. et al (1999) A Shuttle Walk Test for Assessment of Functional Capacity

in Chronic Heart Failure. American Heart Journal, 138,291-8.

Northridge, D., Grant, S., Ford, I., Christie, J., McLenachan, J., Connelly, D. et al.

1990. Novel Exercise Protocol Suitable for Use on a Treadmill or a Bicycle

Ergometer. British Heart Journal, 64,313-316.

Pulz C, Diniz RV, Tebexreni AS. Incremental shuttle and six-minute walking tests

in the assessment of functional capacity in chronic heart failure. Canadian

Journal of Cardiology 2008;24:131-5.

Singh, S.J., Morgan, M.D.L., Scott, S., Walters, D., & Hardman, A.E., 1992.

Development of a Shuttle Walking Test of Disability in Patients with Chronic

Airways Obstruction. Thorax, 1019-24.

References