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 hours following exercise.

Methods

27 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 hours post. EI was measured using three different ROI: 1) Trace around the entire muscle; 2) Small box placed in the middle of the muscle (2x2cm); 3) Maximal rectangular box. Results are displayed as means (95%CI).

Results

There was no condition (experimental vs. control) x time (pre, post, 24h, 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 analyzing EI. However, when larger ROI are examined, EI values appear to be lower.