Body Composition And Muscle Function: Examining Leg Lean Mass and its Relation to Muscle Function in Healthy Athletes and Athletes with Previous Anterior Cruciate Ligament Injury

Abstract

Literature to date has primarily reported examining athletes’ muscle function and lower extremity lean muscle mass independently. Additionally, few studies have examined the relationship between asymmetries in contralateral lean mass and muscle function, despite the utility that examining this association may have for lower extremity injury risk assessment. To address these limitations, our laboratory recently developed and demonstrated the accuracy of a lateral scanning method to examine upper-leg compartmental (i.e., ipsilateral) lean mass using the gold standard body composition assessment method dual X-ray absorptiometry (DXA). However, validation of this method has only been conducted on one DXA scanner model, the GE Lunar iDXA. Therefore, evaluating this novel scanning method’s accuracy on a DXA scanner made by a different manufacturer is important and may allow for this method’s more widespread use in the sport performance and rehabilitation settings. Further, no studies have examined lateral view DXA-measured upper-leg compartmental lean mass in relation to isokinetic peak torque and jump mechanography-measured force production in healthy athletes and athletes with prior anterior cruciate ligament (ACL) injury and reconstruction. This assessment is warranted to examine how lean mass influences muscle function and how this relationship changes as a result of prior ACL injury. Thus, conducting studies which fill the preceding literature gaps is important. This dissertation's purpose was to: (a) examine the lateral segmentation method’s measurement accuracy on another DXA scanner model, the Hologic Horizon A; and (b) evaluate DXA-measured leg lean mass’s relationship with strength and force production in healthy athletes and previously ACL-injured athletes.