Within-and Between-Session Reliability of Ultrasound Imaging Measures in Vastus Lateralis and Gastrocnemius Medialis Muscles

Objective: To determine the within- and between-session reliability of ultrasonography and imaging analysis for measuring muscle architecture of the vastus lateralis (VL) and gastrocnemius medialis (GM) in males who play recreational sport.

Methods: Twelve (n=12) males who regularly engage in recreational sport (age: 26.83 ± 4.45 years) participated in this study. Two experimental sessions were conducted 7 days apart. Muscle thickness (MT), pennation angle (Pang) and fascicle length (Lf) for both muscles were determined. Two ultrasound images of the VL were recorded with participants lying supine with the knee at 30º flexion and a further two images were obtained following a 20 min interval. One week later, two images were recorded during the second session. This process was repeated for the GM with participants lying prone with their muscles relaxed and ankle joint in a neutral position (90Ëš).

Results: The within- and between-session minimum detectable changes were: VL MT=0.16 cm, 0.12 cm; VL Pang=0.76Ëš, 0.99Ëš; VL Lf=0.84 cm, 0.94 cm; GM MT=0.08 cm, 0.11 cm; GM Pang=0.97Ëš, 1.45Ëš; GM Lf=0.36 cm, 0.50 cm, respectively. Other reliability statistics included were intra-class correlation coefficients, coefficient of variation and typical error which also expressed high levels of reliability.

Conclusion: The findings of this study suggest that B-mode ultrasonography can be used in confidence by novice radiographers when investigating changes in muscle architecture in males who regularly engage in recreational sport. The reliability statistics reported in this study can be used by researchers for sample size estimation in future studies.