P19 Reliability of tests of muscle strength and voluntary activation: a narrative review
Nuzzo JL, Taylor JL[1, 2], and Gandevia SC
- Neuroscience Research Australia, Randwick, NSW, Australia
- School of Medical and Health Sciences, Edith Cowan University, Perth, WA, Australia
The number of research trials that report measures of muscle strength and voluntary activation continues to increase. In this narrative review of 104 studies, we report on the intra- and inter-rater reliability of common tests of upper- and lower-limb muscle strength and voluntary activation in various samples. Tests of isometric strength (grip strength, mid-thigh pull, knee extension, elbow flexion), isokinetic strength (knee extension and elbow flexion at 60°/sec), and isoinertial strength (bench press, chest press, lat pulldown, biceps curl, squat, leg press, knee extension) exhibit good intra-rater reliability (intraclass correlation coefficients, ICC ≥ 0.90). Their reliability is not influenced by sex, age, motor impairment, resistance training experience, or limb tested. However, some tests of isoinertial strength exhibit systematic bias – an increase in group means (up to 5 – 10%) at retest. The number of studies on inter-rater reliability of strength tests has been limited, but the existing evidence suggests two different raters can obtain similar scores on these tests, particularly for grip strength (ICC ≥ 0.90). Tests of voluntary activation from both peripheral electrical stimulation and transcranial magnetic stimulation exhibit good intra-rater reliability. They are free from systematic bias (≤ 1% change at retest), and ICCs are usually > 0.80. To our knowledge, the inter-rater reliability of tests of voluntary activation has not been examined. In conclusion, tests of muscle strength and voluntary activation of upper- and lower-limb muscles are reliable across test modalities and subject samples.