Can changes in echo intensity be used to detect the presence of acute muscle swelling?

The purpose of this study was to examine acute changes in muscle thickness (MTH) and echo-intensity (EI), following four sets of biceps curls, when it is known that the change in MTH is due entirely to swelling.

Forty-nine resistance-trained men and women participated in this study. Individuals in the experimental group (n  =  23) visited the lab on two separate occasions. During the first visit, paperwork and one repetition maximum (1RM) strength were measured. During the second visit (3-5 d after visit 1), individuals performed four sets of biceps curls to failure using 70% of their 1RM. MTH and EI measurements were taken before and immediately following exercise using B-mode ultrasound. The ultrasound probe was equipped with a level to minimize the influence of probe tilt on the EI measurement. A time-matched control group (n  =  26) was included to account for measurement error for both MTH and EI. Results are presented as means (95% CI).

For MTH there was a group (Experimental versus Control) by time (Pre-Post) interaction (p   <  0.001). MTH increased in the experimental group (mean value change  =  0.44 (0.33-0.54) cm), but not in the control group (mean value change  =  -0.015 (-0.03-0.01) cm). For EI, there was no group by time interaction (p   =.074). In addition, there were no main effects for group (p   =  0.254) or time (p   =  0.314). The mean difference in the change in EI between groups was  -2.99 (-6.25-3.03) arbitrary units.

EI cannot be used to detect exercise induced changes in muscle thickness.