Noah D. Patterson, Kelly E. Joniak, Sam R. Moore, Hannah E. Cabre, Alex N. Ladan, Abbie E. Smith-Ryan, FACSM. University of North Carolina at Chapel Hill, Chapel Hill, NC.

BACKGROUND: Lean mass (LM) asymmetries are strongly linked to athlete injury risk and recurrence. Although asymmetries are known to be a risk factor for injury, clinically relevant differences in LM are not clear. Dual-energy x-ray absorptiometry (DXA) is the gold standard for identifying limb differences. Custom regions of interest (ROI) can be used to further analyze region specific imbalances. The purpose of this study was to describe the use of an innovative lower limb custom ROI to increase the sensitivity for understanding leg LM asymmetries and identify meaningful thresholds among division I athletes. METHODS: Body composition of 16 male and 39 female NCAA Division I athletes (Mean Difference (MD) ± Standard Deviation (SD): Age=19.7±1.3 yrs, Ht=67.5±6.5 in, Wt=156.4±39.5 lbs, Total LM=118.7±33.9 lbs) were measured using DXA at the start of the fall semester (July-September 2022). Custom ROI of the glute, quad, and calf were created using the polygon function on both limbs. Glute ROI consisted of the tissue between the greater trochanter and iliac crest to the center of the spine. Quad ROI consisted of tissue from the greater trochanter to the tibiofemoral joint. Calf ROI consisted of tissue from the tibiofemoral joint to the talocrural joint. Absolute LM difference from right and left sides were calculated, along with regional percent difference [segment LM difference/total LM) ×100] for glute, quad, and calf, respectively. Means and quartiles were created to understand meaningful differences. RESULTS: Average LM differences between left and right sides for legs were (MD±SD): 0.54±0.40 lbs, glute: 0.09±0.43 lbs, quad: 0.13±0.53 lbs, and calf: 0.05±0.21 lbs. When accounting for total LM of the segments, average thresholds for segment differences were: 1.29±0.99% for legs, 0.17±0.94% for glute, 0.28±1.17% for quad, and 0.13±0.48% for calf. Top quartiles for leg, glute, quad, and calf LM percent differences were 2.09%, 0.61%, 1.10%, and 0.47%, respectively. CONCLUSIONS: Top quartiles may establish a threshold of concern for athletes with regional LM differences. Custom leg ROI may be used to establish significant thresholds for LM asymmetries, but more research is needed to determine injury implications. Future studies should evaluate the relationship with these thresholds with injury occurrence.

This document is currently not available here.