The Endurance Shuttle Walk: A New Field Test for the Assessment of Endurance Capacity in Chronic Obstructive Pulmonary Disease

Abstract

Background-The purpose of this study was to develop an externally controlled, constant paced field walking test to assess endurance capacity in patients with chronic obstructive pulmonary disease (COPD). There were four objectives: (1) to develop a protocol; (2) to compare treadmill and shuttle walk tests of endurance capacity; (3) to examine the repeatability of the endurance shuttle walk test; and (4) to compare the sensitivity to pulmonary rehabilitation of endurance and incremental shuttle walk tests. Methods-The test was designed to complement the incremental shuttle walk test (ISWT) using the same 10 m shuttle course and an audio signal to control pace. The intensity of the field endurance test was related to a percentage of each patient's maximum field exercise performance assessed by the ISWT. A number of cassette tapes were prerecorded with a range of audio signal frequencies to dictate walking speeds between 1.80 and 6.00 km/h. In the first limb of the study 10 patients with COPD (mean (SD) forced expiratory volume in one second (FEV 1) 1.0 (0.36) l, 35% predicted) performed three endurance shuttle walk tests (ESWTs) and three treadmill endurance tests. The walking speeds were calculated to elicit 75%, 85%, and 95% of each patient's maximum ISWT performance for the field tests and measured peak oxygen consumption for the treadmill tests. In a separate group of patients the repeatability of the ESWT at an intensity of 85% of the ISWT performance was evaluated. Finally, the ESWT (at the 85% intensity) and the ISWT were performed at the start of a five week control period and at the start and end of a seven week pulmonary rehabilitation programme in 21 patients with COPD (mean FEV 1 0.80 (0.18) l). Results-The mean (SE) times achieved during the ESWT were 13.1 (2.3), 10.2 (2.5), and 5.3 (1.7) min for the walks at 75%, 85%, and 95% intensities, respectively. Patients tended to walk for longer on the treadmill than during the field tests at all intensities, but there were no significant diVerences between the end of test heart rates or Borg ratings of breathlessness or perceived exertion. Following one practice ESWT at the 85% intensity, the mean diVerence and limits of agreement (2SD) between tests 2 and 3 was +15 (42) s (p>0.05). There was no significant change in performance on either test following the five week control period prior to rehabilitation. Following rehabilitation the ESWT duration increased by 160 (24)% and the ISWT distance increased by 32 (11)% (eVect sizes 2.90 and 0.41, respectively). Conclusions-The ESWT was simple to perform, acceptable to all patients, and exhibited good repeatability after one practice walk. The test showed major improvement following rehabilitation and was more sensitive to change than the field test of maximal capacity.

Effects of Formoterol Inhaled Dry Powder on Exercise Performance in Chronic Obstructive Pulmonary Disease: A Single-Center, Randomized, Double-Blind, Placebo-Controlled, Crossover Study

“…23 The well-known possibility of improving SWT performance after 2 months of pulmonary rehabilitation and maintaining the improvement for 10 months indicates that HRQL may improve with rehabilitation programs. 24,25 Our findings add to existing literature by showing that no statistically significant correlation exists between the effects of treatment with formoterol on airway patency and exercise performance. Thus, the observed significant improvement in expiratory flows after formoterol treatment did not support the seemingly obvious explanation of formoterol-induced lengthening of maximal walked distance.…”

Recommendations on the use of exercise testing in clinical practice

“…The endurance SWT (ESWT) seems more sensitive to change after a course of rehabilitation than the ISWT. REVILL et al [285] secured a mean increase in duration of 160%, compared with the ISWT change of 32%.…”

Prospective validation of the endurance shuttle walking test in the context of bronchodilation in COPD

“…As such, measuring the endurance to constant load exercise has been an important objective of several clinical trials evaluating the impact of pharmacological or rehabilitative interventions in COPD [3][4][5]. In this context, the endurance shuttle walking test (ESWT) is gaining acceptance due to its minimal requirement for equipment, low cost and ease of administration [6], and to its responsiveness and sensitivity to interventions, at least in single centre studies [7][8][9][10][11][12]. With the advancement of portable cardiopulmonary monitoring, it is also possible to obtain a thorough physiological assessment during the ESWT.…”

“…However, some methodological aspects of the ESWT deserve further evaluation. The reproducibility of the ESWT time has been reported in only one study [12], involving a limited sample size and without measurement of cardiopulmonary variables during the test. Another issue is the interpretation of changes in ESWT performance after an intervention.…”