Measuring Muscle Strength for People With Chronic Obstructive Pulmonary Disease: Retest Reliability of Hand-Held Dynamometry

O’Shea SD, Taylor NF, Paratz JD. Measuring muscle strength for people with chronic obstructive pulmonary disease: retest reliability of hand-held dynamometry.ObjectiveTo evaluate the retest reliability and quantify the degree of measurement error when measuring isometric muscle strength with a hand-held dynamometer for people with chronic obstructive pulmonary disease (COPD).DesignRetest reliability of hand-held dynamometry for 4 muscle groups was assessed on 2 occasions separated by a 2-week interval.SettingCommunity rehabilitation center.ParticipantsEight men and 4 women (mean age ± standard deviation, 71.4±10.3y) with moderately severe COPD (percentage of predicted forced expiratory volume in 1 second, 41.5%±17.7%).InterventionsNot applicable.Main Outcome MeasuresMuscle strength (in kilograms). Statistical analysis was conducted by calculating intraclass correlation coefficients and 95% confidence intervals for both group and individual scores.ResultsAll reliability coefficients were greater than .79. Muscle strength would need to increase by between 4% and 18% in groups of people with COPD and between 34% and 58% in a person with COPD to be 95% confident of detecting real changes.ConclusionsHand-held dynamometry is suitable for monitoring change in muscle strength and testing hypotheses for groups of people with COPD. However, hand-held dynamometry is not likely to detect changes in muscle strength for a person with COPD.