Associations between ultrasound-derived muscle morphology, adiposity, and VO_2max in young, trained runners: An...

This exploratory cross-sectional study examined how muscle thickness and echo intensity of quadriceps and calf musculature are associated with maximal oxygen consumption (VO_2max) in trained runners.

Male and female runners (n = 25; 22 ± 3.0 years; 150-300+ min running per week) participated in this study. Participants' rectus femoris, vastus intermedius, vastus lateralis, and medial gastrocnemius were imaged via B-mode ultrasound and analysed for muscle thickness, corrected echo intensity, and subcutaneous adipose tissue. Participants then completed an incremental treadmill test. Associations between muscle thickness, corrected echo intensity, and VO_2max were determined using Pearson's correlation coefficient. Multiple linear regression was used to determine whether muscle thickness, corrected echo intensity, or subcutaneous adipose tissue were predictive of VO_2max.

VO_2max was not associated with muscle thickness. VO_2max was positively associated with corrected echo intensity of the medial gastrocnemius (r = 0.413; p = 0.04). In addition, VO_2max was negatively associated with body mass index (r = -0.670), fat mass (r = -0.791), body fat percentage (r = -0.707), and subcutaneous adipose tissue of the vastus lateralis (r = -0.436; all p < 0.05). Stepwise multiple linear regression indicated corrected echo intensity of the medial gastrocnemius (F = 4.14, p = 0.047, R = 0.409, R ² = 0.167) and corrected echo intensity of the medial gastrocnemius and vastus lateralis (F = 4.79, p = 0.019, R = 0.560, R ² = 0.314) were the strongest predictors of VO_2max.

VO_2max was not associated with muscle thickness of lower extremity musculature, but was associated with subcutaneous adipose tissue, corrected echo intensity, and more favorable whole-body fat mass and deposition in young, trained runners.