Reduced variability of endurance time in new protocols for exercise tests in COPD

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T1 - Reduced variability of endurance time in new protocols for exercise tests in COPD

AU - Tufvesson, Ellen

AU - Radner, Finn

AU - Papapostolou, Georgia

AU - Jarenbäck, Linnea

AU - Jönsson, Saga

AU - Nihlén, Ulf

AU - Ankerst, Jaro

AU - Tunsäter, Alf

AU - Peterson, Stefan

AU - Bjermer, Leif

AU - Eriksson, Göran

PY - 2020

Y1 - 2020

N2 - Purpose: For exercise testing of COPD patients, a standard endurance test (ET) with constant workload is recommended. The test suffers from large inter-individual variability and need for large sample sizes in order to evaluate treatment effects. Methods: A new protocol for ET in COPD was designed. In contrast to the standard ET, the new ET involved an increasing workload in order to reduce the standard deviation of endurance time. Two new ETs were compared with the standard ET. In Study A, the new ET started at 75% of the patient’s maximum workload (WMAX) and increased stepwise with 3%/2 min until exhaustion. Study B started at 70% of WMAX and increased linearly with 1%/ min. Results: In Study A, that included 15 patients, the standard deviation and range for endurance time and work capacity were narrower for the new versus the standard ET. However, the higher mean workload at end and the low mean work capacity relative to the standard ET indicated that the stepwise increase was too aggressive. In Study B, that included 18 patients, with a modified protocol, the averages for endurance time, workload at end and work capacity were similar for new and standard ET, while the standard deviations and ranges for endurance time and work capacity were kept more narrow in the new ET. The variances for endurance time were not equal between the standard ET and the two new ETs (p<0.05 for both according to Levene’s test). Conclusion: The new ET reduced the number of patients with extreme endurance times (short and long) compared to the standard test. The new test showed a significant lower variance for endurance time, which potentially can lead to fewer patients needed in com-parative studies. The overall best results were observed with a low linear increase during endurance.

AB - Purpose: For exercise testing of COPD patients, a standard endurance test (ET) with constant workload is recommended. The test suffers from large inter-individual variability and need for large sample sizes in order to evaluate treatment effects. Methods: A new protocol for ET in COPD was designed. In contrast to the standard ET, the new ET involved an increasing workload in order to reduce the standard deviation of endurance time. Two new ETs were compared with the standard ET. In Study A, the new ET started at 75% of the patient’s maximum workload (WMAX) and increased stepwise with 3%/2 min until exhaustion. Study B started at 70% of WMAX and increased linearly with 1%/ min. Results: In Study A, that included 15 patients, the standard deviation and range for endurance time and work capacity were narrower for the new versus the standard ET. However, the higher mean workload at end and the low mean work capacity relative to the standard ET indicated that the stepwise increase was too aggressive. In Study B, that included 18 patients, with a modified protocol, the averages for endurance time, workload at end and work capacity were similar for new and standard ET, while the standard deviations and ranges for endurance time and work capacity were kept more narrow in the new ET. The variances for endurance time were not equal between the standard ET and the two new ETs (p<0.05 for both according to Levene’s test). Conclusion: The new ET reduced the number of patients with extreme endurance times (short and long) compared to the standard test. The new test showed a significant lower variance for endurance time, which potentially can lead to fewer patients needed in com-parative studies. The overall best results were observed with a low linear increase during endurance.

KW - Constant endurance test

KW - COPD

KW - Endurance time

KW - Exercise testing

U2 - 10.2147/COPD.S268894

DO - 10.2147/COPD.S268894

M3 - Article

C2 - 33239872

AN - SCOPUS:85096376273

VL - 15

SP - 3003

EP - 3012

JO - The International Journal of Chronic Obstructive Pulmonary Disease

JF - The International Journal of Chronic Obstructive Pulmonary Disease

SN - 1178-2005

ER -