Reliability and Validity of Upper Limb Muscle Strength Measurements by Handheld Dynamometer in Patients With Chronic Obstructive Pulmonary Disease

Background and Purpose International respiratory societies recommend upper limb muscle strengthening in patients with chronic obstructive pulmonary disease (COPD). To design an adapted and effective muscle strengthening program, it is necessary to assess the muscle strength of muscle groups involved. The objective of this study was to assess the reliability and validity of measuring the maximum voluntary isometric strength of shoulder abductors, elbow flexors, and extensors using a handheld dynamometer. Methods Maximum voluntary isometric strength was measured using a handheld dynamometer, and the one repetition maximum test was performed using dumbbells. Three separate 24‐h measurement sessions were conducted: the first 2 sessions (Day 0 and Day 1) by a physiotherapist and the third session (Day 2) by another physiotherapist. Results Fifty‐seven COPD patients (age: 65.7 ± 8.5; FEV1: 45.3 ± 18.9%) were included and 54 were analyzed across three measurement sessions. We found an excellent correlation for intra‐rater measurements ( p < 0.001; shoulder abductors: r = 0.84, elbow flexors: r = 0.94, elbow extensors: r = 0.89) and good to excellent correlation for inter‐rater measurements (Day 0/Day 2: p < 0.01; shoulder abductors: r = 0.76, elbow flexors: r = 0.89, elbow extensors: r = 0.87; Day 1/Day 2: shoulder abductors: p < 0.01; r = 0.90, elbow flexors: r = 0.91 elbow extensors: r = 0.93). Poor to good concordances were observed between the maximum voluntary isometric strength and the one repetition maximum test for intra‐rater measurements. Discussion Handheld dynamometer is a reliable and valid tool for assessing upper limb muscle strength in clinical practice for COPD patients. Trial Registration ClinicalTrials.gov Identifier: NCT04341753