Examination of Changes in Echo Intensity Following Resistance Exercise among Various Regions of Interest

Aim: Within the resistance exercise literature, echo intensity (EI) is often quantified using different regions of interest (ROI). Purpose: To compare changes in the EI of images of the biceps muscle using different ROI immediately following exercise as well as 24 and 48 h following exercise. Methods: Twenty seven non-resistance trained individuals visited the laboratory 4 times. One arm was assigned to the experimental condition, and the other was a non-exercise control. During visit 1, paperwork and strength were measured. During visit, 2 participant's muscles were imaged before performing biceps curls. Additional muscle images were taken immediately after exercise, as well as 24 and 48 h post. EI was measured using three different ROI: 1) Trace around the entire muscle; 2) Small box placed in the middle of the muscle (2 × 2cm); and 3) Maximal rectangular box. Results are displayed as means (95%CI). Results: There was no condition (experimental vs. control) x time (pre, post, 24h and 48h) x box size (small, large, full trace) interaction (p = 0·592). However, there was a main effect for box size (p < 0·001). EI values were higher with the small box [28·2 (23·3, 33·1) AU] compared to the large box [26·8 (22·3, 31·2) AU, p = 0·016] and compared to the full trace [24·2 (20·3, 28·0) AU p < 0·001)]. In addition, EI values were higher with the large box compared to the full trace technique (p = 0·001). Conclusion: Similar changes in EI are detected when using different commonly used ROI for analysing EI. However, when larger ROI are examined, EI values appear to be lower.