Supervised exercise training, coupled with education and behavior change, is one of the pillars of a comprehensive pulmonary rehabilitation (PR) program for patients with chronic obstructive pulmonary disease (COPD).1 Indeed, exercise-based PR programs are safe and generally reduce daily symptoms, improve exercise tolerance, and improve quality of life in patients with COPD.2
Multiple PR guidelines provide recommendations about the mode, intensity, duration, frequency, and progression of well-known exercise-based interventions.1,3,4 Still, the duration and combination of types of exercise modalities vary to a great extent between PR programs globally,5–8 as well as exercise training intensity and progression between individual patients with COPD.9–11 This may, at least in part, explain the large variation in response to PR in patients with COPD.2,11
Stationary cycling, treadmill walking, and resistance training with handheld weights are commonly applied in North America-based PR programs,5 yet information regarding methodology is lacking. An earlier survey was conducted by the American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR) in 2012-2013 to evaluate PR exercise prescription practices.12 Findings of the 2013 survey identified PR exercise prescription practices that are consistent with national guidelines; however, wide variations in measures of intensity and method of exercise progression were reported, including what the patient can tolerate, and when the patient and staff feel the patient is ready. This study describes the results of an updated 2016 survey, compares the 2016 survey results with the 2013 survey, and discusses implications of changing trends in exercise prescription development and application in the PR setting.
A 15-question survey administered in 2013 has been previously described.12 A 22-question survey was recently developed by the authors based on the 2013 survey12 to evaluate PR exercise prescription practices in the United States (see Table 1, Table 2, and Supplemental Digital Content 1, available at: http://links.lww.com/JCRP/A167). Both surveys were developed by the authors with input from experts in PR research, exercise physiology, and program management. Survey questions asked about PR exercise prescription, methodology, exercise testing, and exercise goals. Patient education topics, oxygen titration and system used, staff clinical discipline, team makeup, patient diagnoses, program setting, and program size were also surveyed and responses are described in Supplemental Digital Content 1 (available at: http://links.lww.com/JCRP/A167). The 2016 survey was sent to all individuals listed as PR program directors in the AACVPR database. The database has a total of 1831 individual e-mail addresses. The AACVPR has identified the approximate number of PR and cardiac rehabilitation (CR) programs in the United States in a recent national search, titled “AACVPR Finding the N,” based on self-report (Kate Maude, BA, e-mail communication, April 26, 2017). The search determined that there are 237 PR centers and 1521 combined CR and PR centers in United States. The exercise prescription survey was sent via an e-mail message with invitation to complete the survey via surveymonkey.com. Data collection was voluntary. Analysis and statistical comparison of the survey results were performed using SPSS Statistics Version 24 (IBM Corp.). Chi-square analysis was performed to compare relationships between 2 variables: the survey outcome measures (eg, Do you develop an exercise prescription for your PR patients?: Yes or No) and the year of survey (2013 or 2016). Assumptions to perform a χ2 analysis were met, as variables were categorical and consisted of ≥2 categorical, independent groups. Chi-square analysis was not performed for the following survey items: If intensity is measured, check which measure is used; and If yes, describe method of exercise used during titration (Table 1) as survey response options were different across the 2013 and 2016 survey (see Supplemental Digital Content 1, available at: http://links.lww.com/JCRP/A167). P < .05 was set as significant.
EXERCISE PRESCRIPTION IN PR
Exercise prescriptions may be derived from various sources including guidelines and statements from the American College of Sports Medicine (ACSM),13 AACVPR,14 and American Thoracic Society(ATS)/European Respiratory Society (ERS)1 and combinations of PR guidelines and/or exercise methodologies developed by the PR program or health system.
Responses were returned for 371 (20.3% of requests sent) versus 380 in 2013. Survey responses regarding exercise prescription are summarized in Table 1, with a question added in 2016 in Table 2. Exercise prescription was offered to patients by >96% of respondents in both 2013 and 2016 surveys (P = .787; χ2 = 0.073). There was an increase in responses for all options describing exercise prescription methodology in the 2016 survey, with elements of the ACSM (frequency, intensity, time [duration], and type [mode]; FITT) demonstrating significant increase in use. Other components of exercise increased, but changes were not statistically significant: progression (P = .304), continuous exercise (P = .075), interval exercise (P = .188), resting intervals (P = .151), training intensity baseline and progression over time (P = .426), and supervision (P = .405). There was a significant increase in 3 methods of determining exercise goals in 2016 versus 2013: duration (P = .017), distance (P = .010), and metabolic equivalents of task (METs) (P ≤ .001). Specific methodology for assessing METs was not requested or stated. There was a similar number of respondents offering a formal exercise class in 2016 versus 2013 (P = .318).
The most frequently used measures of exercise intensity (>50% of respondents) were rating of perceived exertion (RPE), Borg 10-point dyspnea scale, 6-min walk test (6MWT), target heart rate (THR), and METs. A comparison between the 2013 and 2016 surveys was not possible, as in 2013, only one option could be selected while the 2016 survey allowed multiple options.
A new question in the 2016 survey asked about methodology used to determine progression of exercise using 1 of 11 response options versus an open-ended question used in 2013. Nearly half of the 2016 respondents reported use of RPE, Borg 10-point dyspnea scale, METs, THR, or 6MWT. The 2013 survey showed wide variability of progression methodologies, with 99 different descriptions of measures of progression. The 2016 survey lacked an open response option.
The number of respondents using a resistance training protocol increased more than 2-fold from 40.2% in 2013 to 93.5% in 2016 (P ≤ .001, χ2 = 209.9). Components of resistance training (not asked in 2013) included weight lifting (75.9%), elastic bands (69.0%), weight or resistance machines (57.1%), and resistance using one's own body weight, for example, wall push-ups (41.6%).
The content of the exercise training as part of US-based PR programs is changing over time. Indeed, the 2016 survey clearly shows that a majority of the PR programs develop an exercise prescription for their patients, using the FITT principles. Exercise intensity is measured more frequently using multiple methods, such as symptom ratings and heart rate. Interestingly, the number of PR programs that used any resistance training protocol doubled between 2013 and 2016. This suggests that more focus is placed on the training of lower-limb muscles to counteract atrophy-induced muscle weakness. Although weight lifting/resistance machines are used frequently for the resistance training (up to 75% of the PR programs), the 1-repetition maximum is only used in 5% of the PR programs. This suggests that there are still gains to be made to determine the progression of the resistance training.
Translating scientific evidence for PR into effective clinical care may challenge PR clinicians. A multidisciplinary model that supports competency in provision of supervised exercise training in a range of severities and manifestations of chronic lung disease as well as comorbidities is essential. The 2016 survey responses show a greater use of guideline-based exercise prescription methodology. The majority of programs provide both PR and CR. This may offer some advantages including shared use of gym, equipment, and possibly cross training for both PR and CR staff, which could improve both preparation and skills for caring of patients with multiple common comorbidities in the 2 settings. Both interventions have clear, distinct, and important differences that must be considered and applied to daily practice.
Limitations of the survey include low return rate and sample size and unknown characteristics of noncompleters. The exact number of PR programs in the United States is unknown, although recently estimated at 237 PR centers and 1521 combined CR and PR centers in United States (data provided by the AACVPR).
The AACVPR offers program certification that evaluates PR program quality, safety, staff competency, and exercise prescription. Nearly two-thirds of respondents reported that their PR program has been certified by the AACVPR. The AACVPR PR program certification requires that exercise prescription is based on AACVPR and/or ACSM guidelines. This requirement for national certification may influence exercise prescription practices. It is unclear why ATS/ERS PR guidelines are not included as an option and the exact influence of guidelines on exercise prescription methodology.
The American College of Chest Physicians (ACCP)/AACVPR PR evidence-based guidelines updated the graded evidence base of PR in 2007.4 The evidence base has been further strengthened by updated statements and guidelines from the ATS/ERS,1 ACSM,13 AACVPR,14 as well as multiple studies. Since publication of the 2013 survey,12 the ATS/ERS has published an updated comprehensive PR statement that updates the evidence for exercise in diverse pulmonary populations that provides detailed guidance on exercise prescription.1 The ACSM regularly publishes updated guidelines for exercise testing and prescription.13 Survey responses and approaches to exercise prescription suggest some variation in approaches to exercise prescription, with a trend toward more consistent use of ACSM and ATS/ERS guidelines. The updated 5th edition of AACVPR guidelines was released in 2019.14 Variations in responses and practices may be influenced by diverse national and international recommendations, exercise prescription requirements of the AACVPR national certification, lack of formal exercise science training for many respiratory therapy and registered nurses, programs with CR focus providing PR, and various models of PR used throughout the United States and possibly regional variations. It is unclear whether diverse practices also reflect the heterogeneity of PR patients.
All major guidelines recommend a comprehensive assessment, history and focused physical examination, and baseline exercise testing before beginning PR. Initial and ongoing assessment is key regardless of the PR setting or staff composition. Long-term adherence to exercise is a major priority in PR, particularly translating gains from PR into increased physical activity.
A comprehensive PR program results in improvement in exercise capacity, dyspnea, and quality of life. Exercise training is the core component of effective PR. Exercise recommendations are available from several US and international organizations. While there are consistencies among the various guideline recommendations of aerobic and resistance training, differences exist regarding methodology and details of exercise prescription. Exercise prescription differences may reflect variations in daily practice, background, and training of clinicians and influence from professional and scientific guidelines and organizations. It may be tempting to embrace one guideline over another. However, even multisociety international statements such as the ACCP/ATS/ERS “Diagnosis and Management of Stable Chronic Obstructive Pulmonary Disease: A Clinical Practice Guideline Update” identifies a strong level of evidence for PR-only in COPD patients with a forced expiratory volume in the first second (FEV1) of <50% predicted.15 This is inconsistent with major PR and COPD guidelines as well as current Medicare coverage of outpatient PR that identify PR for COPD with an FEV1 of <80% predicted. Clinicians should be familiar with major, evidence-based PR guidelines and use a collaborative, multidisciplinary team approach to individualized exercise training and prescription in the context of a PR program. A baseline and ongoing assessment that includes disease and symptom severity, comorbidities, and patient goals should be emphasized. This should be coupled with individual and aggregate measurement and analysis of patient-centered outcomes including exercise performance. PR should emphasize sustainable exercise that translates into both improved muscle function and increased physical activity.
Jana De Brandt was supported by funding from the Flemish government. The research of FWO aspirant Jana De Brandt is sponsored by FWO-grant #11B4718N. The authors acknowledge and thank Kate Maude of the AACVPR and Smith Bucklin Association for her considerable assistance with survey formatting, administration, data collection, aggregation, and reporting.
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