Reliability of maximal voluntary strength and endurance measurement of the quadriceps with a hand held dynamometer in COPD patients

Abstract

COPD patients have frequently lower strength and endurance in lower limbs compared to healthy subjects. Actually, the evaluation of quadriceps is recommended in COPD. The hand held dynamometer is validated and easy to use for this evaluation. However, its reliability has never been studied for the endurance evaluation and poorly for the strength. The objective of this study was to estimate the inter-and intra-rater reliability of maximal voluntary strength (QMVS) and endurance (QE) measurement of the quadriceps with a hand held dynamometer in COPD patients. Methods: The measurement of QMVS and QE were performed with the dynamometer MicroFet 2 ™ using isometric contraction. 3 sessions of measurement were realized and separated by 24 hours. An examiner «A» made 2 consecutive sessions at D1 and D2 or D2 and D3. An examiner «B» realized a session at D1 or D3. The intra and inter-rater reliability were estimated by the calculation of the intraclass correlation coefficient (ICC). Results: 21 patients were included in the study. The patients were equally distributed between stages II to IV of the GOLD classification. ICC calculated for the QMVS for intra and inter-rater reliability ranged between 0.95 and 0.99. Concerning the endurance, ICC for intra rater reliability was 0.81. ICC for inter-rater reliability were 0.69 and 0.77. Conclusion: The dynamometer is a tool which allows an excellent inter-and intra rater reliability for the measurement of QMVS and a correct to excellent reliability for the measurement of QE. This tool is usable for the evaluation of the QMVS and the QE in COPD in clinical practice, particularly during pulmonary rehabilitation.