A Simplified Approach to Select Exercise Endurance Intensity for Interventional Studies in COPD

作者：Degani Costa Luiza H; O'Donnell Denis E; Webb Katherine; Aranda Liliane C; Carlstron Julio P; Cesar Tamires da Silva; Plachi Franciele; Berton Danilo C; Neder J Alberto; Nery Luiz E

来源：Journal of Chronic Obstructive Pulmonary Disease, 2018, 15(2): 139-147.

DOI：10.1080/15412555.2018.1428944

• exercise
• COPD
• dyspnoea
• lung function
• endurance

Time to exercise limitation (Tlim) in response to constant work rate (CWR) is sensitive to interventions in chronic obstructive pulmonary disease (CORD). This is particularly true when the pre-intervention test lasts between 3 and 8 min (Tlim(3'-8')). There is, however, no simple method to select a work rate which is consistently associated with Tlim(3'-8'), across the spectrum of CORD severity.
We assessed 59 GOLD stages II IV patients who initially cycled to Tlim at 75% peak. In case of short min, low-endurance) or long (>8 min, high-endurance) tests, patients exercised after 60 min at 50,6 or 90%, respectively (CVVR50%double left arrow 75%double right arrow 90%)
Critical mechanical constraints and limiting dyspnea at 75% were reached within the desired timeframe in 27 "mid-endurance" patients (46%). Increasing work rate intensity to 90% hastened the mechanical-ventilatory esponses leading to Tlim(3'-8'), in 23/26 (88%) "high-endurance" patients; conversely, decreasing exercise intensity to 50 % slowed those responses leading to in 5/6 (83%) "high-endurance" patients. Repeating the tests at higher (60 %) or lower (80%) intensities fail to consistently produce in "low-" and high-endurance', respectively (p > 0.05). Compared to a fixed work rate at 75aA-4 CWR50%double left arrow 75%double right arrow 90% Significantly decreased Tlim's coefficient of variation; consequently, the required N to detect 100 s or 33% improvement in Tlim decreased from 82 to 26 and 41 to 14, respectively.
This simplified approach to individualized lwork rate adjustment (CWR50%double left arrow 75%double right arrow 90%) might allow greater sensitivity in evaluating interventional efficacy in improving respiratory mechanics and exercise tolerance while simultaneously reducing sample size requirements in patients with COPD.

• 出版日期2018