Frykholm E1, Gephine S2, Saey D2, van Hees H3, Lemson A3, Klijn P4,5, Maltais F2, Nyberg A1
1Umeå University, Department of Community Medicine and Rehabilitation, Umeå, Sweden, 2Université Laval, Institut Universitaire de Cardiologie et de Pneumologie, Quebec City, Canada, 3Radboud University Medical Centre, Department of Pulmonary Diseases, Nijmegen, Netherlands, 4Merem Pulmonary Rehabilitation Centre, Department of Pulmonology, Hilversum, Netherlands, 5Amsterdam University Medical Center, Department of Pulmonary Medicine, Amsterdam, Netherlands
Background: Impaired limb muscle function as evidenced by a reduction in strength and/or endurance of the quadriceps is a common secondary consequence of chronic obstructive pulmonary disease (COPD), intimately associated with important clinical outcomes such as reduced quality of life, exercise intolerance, greater healthcare utilization, and premature mortality. Therefore, it is highly recommended to assess quadriceps function in clinical practice. Isometric contractions have been recommended for the assessment of quadriceps strength but despite its clinical relevance, there is no consensus on how to measure quadriceps muscle endurance in people with COPD. Moreover, the reliability and feasibility of available measurement strategies for such assessments are only partly known.
Purpose: The aim was therefore to determine test-retest reliability and feasibility of isokinetic, isometric, and isotonic protocols to assess quadriceps muscle endurance in people with COPD.
Methods: Fifty-nine participants (FEV1 of predicted 55±18%, age 67±8 years) were included and tested in an interday multicenter test-retest design with test occasions separated by 5-9 days. Quadriceps muscle endurance was assessed using isokinetic, isometric and isotonic knee extension protocols controlled by a computerized dynamometer. Relative reliability was determined by intra-class correlation coefficient (ICC) using two-way mixed effects, absolute agreement, single measurement and absolute reliability by standard error of measurement (SEM).
Results: Isokinetic measurements demonstrated very high relative reliability (ICC: [95% confidence interval] 0.98 [0.94-0.99]), and isometric and isotonic demonstrated high relative reliability (0.89 [0.79-0.94], and 0.89 [0.82-0.94], respectively). Mean values across test-retest occasions were 2122 joules, 49 seconds, and 29 repetitions, for isokinetic, isometric and isotonic measurements, respectively. Corresponding SEM values were 136 joules, 7 seconds, and 5 repetitions. All three measurement strategies were feasible with an average time consumption of less than 10 minutes and no major adverse events.
Conclusion(s): The results indicate that isokinetic, isotonic and isometric measurements of quadriceps muscle endurance are reliable and feasible in people with COPD. However, the isokinetic protocol seems to be superior with a higher relative reliability and a lower absolute reliability.
Implications: In the search for reliable measurement strategies that could be used by physiotherapists to measure quadriceps muscle endurance in people with COPD, these findings indicate that this decision can be made based on the equipment available to the clinician and the needed level of precision. This since, both isokinetic, isometric as well as isotonic protocols were found to be highly reliable as well as clinically feasible. The limited time consumption per test ( 10 minutes) and the absence of adverse events indicate that protocols are clinically feasible.
Keywords: intra-rater agreement, reproducibility, lower limb muscle endurance
Funding acknowledgements: The Swedish Research Council, The Swedish Heart and Lung Association, The Canadian Lung association, Stichting Gooiskinderziekenhuis Huizen.
Purpose: The aim was therefore to determine test-retest reliability and feasibility of isokinetic, isometric, and isotonic protocols to assess quadriceps muscle endurance in people with COPD.
Methods: Fifty-nine participants (FEV1 of predicted 55±18%, age 67±8 years) were included and tested in an interday multicenter test-retest design with test occasions separated by 5-9 days. Quadriceps muscle endurance was assessed using isokinetic, isometric and isotonic knee extension protocols controlled by a computerized dynamometer. Relative reliability was determined by intra-class correlation coefficient (ICC) using two-way mixed effects, absolute agreement, single measurement and absolute reliability by standard error of measurement (SEM).
Results: Isokinetic measurements demonstrated very high relative reliability (ICC: [95% confidence interval] 0.98 [0.94-0.99]), and isometric and isotonic demonstrated high relative reliability (0.89 [0.79-0.94], and 0.89 [0.82-0.94], respectively). Mean values across test-retest occasions were 2122 joules, 49 seconds, and 29 repetitions, for isokinetic, isometric and isotonic measurements, respectively. Corresponding SEM values were 136 joules, 7 seconds, and 5 repetitions. All three measurement strategies were feasible with an average time consumption of less than 10 minutes and no major adverse events.
Conclusion(s): The results indicate that isokinetic, isotonic and isometric measurements of quadriceps muscle endurance are reliable and feasible in people with COPD. However, the isokinetic protocol seems to be superior with a higher relative reliability and a lower absolute reliability.
Implications: In the search for reliable measurement strategies that could be used by physiotherapists to measure quadriceps muscle endurance in people with COPD, these findings indicate that this decision can be made based on the equipment available to the clinician and the needed level of precision. This since, both isokinetic, isometric as well as isotonic protocols were found to be highly reliable as well as clinically feasible. The limited time consumption per test ( 10 minutes) and the absence of adverse events indicate that protocols are clinically feasible.
Keywords: intra-rater agreement, reproducibility, lower limb muscle endurance
Funding acknowledgements: The Swedish Research Council, The Swedish Heart and Lung Association, The Canadian Lung association, Stichting Gooiskinderziekenhuis Huizen.
Topic: Outcome measurement
Ethics approval required: Yes
Institution: Umeå University, Laval University, CMO Arnhem/Nijmegen
Ethics committee: Respective medical ethics committee
Ethics number: DNR: 2015-426-31M, 2016-379-32M, CER: 21322, CMO: NL59926.091.16
All authors, affiliations and abstracts have been published as submitted.
