Intra- and inter-rater reliabilities for novel muscle thickness assessment during Co-contraction with dual-rehabilitative ultrasound imaging.

Objectives: This study aimed to investigate the intra- and inter-rater reliabilities of dual-rehabilitative ultrasound imaging (D-RUSI) for the simultaneous measurement of the thickness of the tibialis anterior (TA) and gastrocnemius (GCM) muscles in healthy young adults.

Design: A single-group repeated-measures reliability study.

Setting: Rehabilitative ultrasound imaging analysis laboratory.

Participants: Thirty-six healthy participants (23 males; age = 26.36 ± 5.57 years).

Main Outcome Measures: D-RUSI was used for the simultaneous measurement of the muscle thickness of the TA and GCM at rest and during maximum voluntary contraction. Two examiners acquired data from all participants during three separate testing sessions.

Results: In the results for the intra-examiner reliability of the TA and GCM muscle thickness for two sessions, all ICC values (95% CI) were good to very good, ranging from 0.72 to 0.95 (SEM 0.01-0.05 mm, MDC 0.02-0.13 mm, respectively). In the results for the inter-examiner reliability of the TA and GCM muscle thickness for three sessions, all ICC values (95% CI) were good to very good, ranging from 0.78 to 0.97 (SEM 0.01-0.10 mm, MDC 0.02-0.15 mm, respectively).

Conclusions: These results suggest the potential usefulness of D-RUSI measurements for making management decisions related to muscle function, including muscle co-contraction.