M. Yeung1, S. Leong1,2, B. Ong1,3, J. Soon1,4, K. Huang1,5
1Singapore Institute of Technology, Health and Social Sciences Cluster, Singapore, Singapore, 2Ng Teng Fong General Hospital, Physiotherapy, Singapore, Singapore, 3Sengkang General Hospital, Physiotherapy, Singapore, Singapore, 4Tan Tock Seng Hospital, Physiotherapy, Singapore, Singapore, 5Khoo Teck Puat Hospital, Physiotherapy, Singapore, Singapore
Background: The Incremental Shuttle Walk Test (ISWT) is used to assess maximal exercise capacity in patients with cardiopulmonary illnesses. In Singapore, ISWT predictions have been based on equations derived from non-Asian countries as no normative data and reference equation have been established locally. Hence, the primary aim of this study is to obtain normal ISWT distances of healthy adults living in Singapore.
Purpose: The study aims to investigate the ISWT performance in healthy Singaporean adults, identify predictors of ISWT distance and establish a reference equation to predict normal ISWT reference values.
Methods: A total of 132 subjects (46 males, mean age 47 years) were recruited via convenience sampling. Due to the small number of non-Chinese subjects recruited, only the data from 119 Chinese subjects (42 males, mean age 48 years) were analysed. Demographic and anthropometric data such as age, gender, height, weight, were recorded. Portable spirometry was conducted to measure % predicted Forced Expiratory Volume in 1 second (%FEV1), % predicted Forced Vital Capacity (%FVC) and % predicted FEV1/FVC (%FEV1/FVC). The subjects completed two trials of the ISWT, with the best result taken. Statistical analysis was performed using SPSS® software version 25. The dependent variable was the best ISWT distance. Independent variables were age, gender, height, weight, BMI, %FEV1, %FVC and %FEV1/FVC. Spearman correlation and multiple linear regression of all variables were utilised to study their relationship with ISWT distance. The level of statistical significance is set at p<0.05.
Results: Subjects walked an average of 587 (200 to 1020) metres in the ISWT. ISWT distance correlated (p<0.05 for all) to age (r = -0.733), gender (r = 0.232), height (r = 0.484), weight (r = 0.217) and %FEV1/FVC (r = -0.218), but not BMI (r = -0.081, p = 0.379), %FEV1 (r = -0.007, p = 0.945) and %FVC ( r = 0.140, p = 0.138). Multiple linear regression analysis showed that only age (p = 0.000) and height (p = 0.006) are significant contributors to ISWT distance and explained 62.9% of the variability. The reference equation generated for the ISWT of healthy Chinese adults is: ISWT distance = 698.783 (height) -7.813 (age) -180.623).
Conclusion(s): The ISWT performance of healthy Chinese adults in Singapore was investigated, with the predictors of ISWT distance identified as age and height. A reference equation was then established to predict distance covered in ISWT for healthy Singaporean Chinese adults, with a prediction accuracy of 62.9%.
Implications: Using age and height, the established equation can be useful in evaluating the exercise capacity in Singaporean adults in the clinical setting, especially for patients undergoing rehabilitation programmes.
Funding, acknowledgements: Singapore Institute of Technology, Health and Social Sciences Cluster.
Keywords: Incremental Shuttle Walk Test, Exercise Test, Prediction formula
Topic: Cardiorespiratory
Did this work require ethics approval? Yes
Institution: Singapore Institute of Technology
Committee: Institutional Review Board
Ethics number: 2019090
All authors, affiliations and abstracts have been published as submitted.
