[Reproducibility of strength and endurance measurements of the quadriceps in patients with COPD].

INTRODUCTION: Patients with COPD frequently have lower strength and endurance in their lower limbs compared to healthy subjects and evaluation of their quadriceps strength is recommended in practice. The handheld dynamometer has been validated and is easy to use for this measurement but its reproducibility has never been studied for endurance evaluation and only poorly for strength. The objective of this study was to estimate the inter and intra-operator reproducibility of maximal voluntary strength and endurance measurements of the quadriceps with a handheld dynamometer in patients with COPD.

METHODS: The measurements of maximal voluntary strength and endurance were performed with a single handheld dynamometer using isometric contraction. Three measurement sessions were undertaken, separated by 24hours. The intra- and interoperator reproducibility were estimated by calculation of the intraclass correlation coefficient.

RESULTS: Overall, 21 patients were included in the study. The intraclass correlation coefficient calculated for the maximal voluntary strength for intra and interoperator reliability ranged between 0.95 and 0.99. For endurance, the coefficient for intra-operator reliability was 0.81 and the two for interoperator reliability were 0.69 and 0.77.

CONCLUSION: The handheld dynamometer allows an excellent inter and intra-operator reproducibility for the measurement of quadricipital maximal voluntary strength and a correct to excellent reproducibility for the measurement of quadricipital endurance. This tool may be used for the evaluation of quadriceps strength in clinical practice in COPD patients, particularly during rehabilitation.