Influence of muscle depth and thickness on ultrasound echo intensity of the vastus lateralis.

BACKGROUND

Ultrasonography is used to evaluate muscle quality (i.e. echo intensity [EI]), but an attenuation of ultrasound waves occurs in deeper tissues, potentially affecting these measures.

PURPOSE

To determine whether muscle thickness (MT) affects EI and if EI varies between the superficial and deep portions of the muscle.

MATERIALS AND METHODS

MT, EI, subcutaneous adipose tissue thickness (SAT), tissue depth (DIS), and EI of the overall (EI) as well as deep (EI) and superficial (EI) portions of the vastus lateralis (VL) were assessed in 33 resistance-trained males using ultrasonography. The difference (EI) between EI and EI was calculated. Mean differences between EI, EI and EI were analyzed using a repeated-measures analysis of variance (ANOVA). Relationships between measures of muscle depth/ thickness and EI were examined using Pearson's .

RESULTS

EI was greater than EI ( < 0.001) and EI ( < 0.001). MT was negatively correlated with EI ( < 0.001) and positively correlated with EI ( < 0.001). SAT was not correlated with any EI measure, but DIS was positively correlated with EI ( < 0.001).

CONCLUSION

EI of the VL is heterogeneous, as the deeper portion produces lower values than the superficial portion. Thicker muscles present lower EI but have greater discrepancies in EI between the superficial and deep portions. Although SAT was not correlated with EI, DIS was related to EI, demonstrating that the combination of MT and SAT should be considered when evaluating muscle quality. Future research is necessary to determine if changes in EI following resistance training are driven by increases in MT.