Reliability of the Fox-walk test in patients with rheumatoid arthritis

Abstract

Purpose: The Fox-walk test is a new method used to estimate aerobic capacity outside a clinical environment, which may be useful in the implementation of daily health-enhancing physical activity. The aim of our study was to investigate the reliability of the test in people with rheumatoid arthritis (RA). Method: Fifteen participants performed the Fox-walk test three times with weekly intervals. The intraclass correlation coefficient (ICC), the standard error of measurement (SEM) and the smallest detectable change (SDC) were used to estimate the reliability. General health perception, lower limb pain and fatigue were measured to determine their potential influence on the reliability. Results: There were no systematic differences between the three test occasions (p = 0.190) and the reliability was almost perfect (ICC = 0.982). None of the covariates influenced the reliability. The SEM was 0.999 ml/kg/min or 3.4% and the SDC was 2.769 ml/kg/min or 9.4%. Conclusions: These findings demonstrate that the Fox-walk test is reliable in people with RA and enables differentiation between people with RA and monitoring progress. The validity of the test among people with RA is still to be determined.

Implications for Rehabilitation

• The Fox-walk test is a new method to estimate aerobic capacity and could be performed walking or running.

• The test is self administered without expensive equipment and is available in 150 public places in Sweden and several other European countries.

• The Fox-walk test is a reliable test for use among people with rheumatoid arthritis monitoring the progress of their physical activity.

Keywords::

• Fox-walk test
• physical activity
• physical fitness
• physiotherapy
• rheumatoid arthritis
• test-retest

Acknowledgements

We would like to thank the participants of this study for devoting their time and energy to this project. We are also grateful to physiotherapists Birgitta Nordgren and Emma Swärdh Sjöquist for providing us with the opportunity of recruiting participants via their group sessions. This study was made possible by grants from the Swedish Research Council, Combine Sweden, the Swedish Rheumatism Association and the National Postgraduate School of Health Care Sciences.

Declaration of Interest: This study was made possible by grants from the Swedish Research Council, Combine Sweden, the Swedish Rheumatism Association and the National Postgraduate School of Health Care Sciences.