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Skeletal muscle is a highly plastic tissue that responds to stimuli such as mechanical overload/resistance training (RT) or disuse/unloading. It has been demonstrated that individuals who perform RT, undergo detraining, and then re-engage in RT experience more skeletal muscle hypertrophy upon retraining than on the initial block of RT despite returning to baseline size with detraining. What is not known, however, is whether training status affects the progression of disuse-induced atrophy. Therefore, the purpose of this study was to examine the effects of 2-weeks of lower limb immobilization on lower body strength and vastus lateralis (VL) thickness in a cohort of young, healthy previously trained (T) or training naïve (UT) men and women. In this study, 21 young healthy men and women (n= 10 T; n= 11 UT) underwent 2-weeks of left leg immobilization via a locking leg brace and crutches. Data were collected at baseline (PRE), and after the 2-week immobilization period (POST). Muscle thickness was assessed via ultrasound of the VL, while lower limb strength was determined via three repetition maximums (3RMs) of the hex bar deadlift and the seated leg press. Data were checked for normality by a Shapiro-Wilk test and analyzed via two-way ANOVAs to compare lower body strength and VL thickness pre-and post-immobilization. A two-way ANOVA for hex bar deadlift 3 RMs did not show a training status x time interaction (P= 0.566), but did reveal main effects of training status and time (P< 0.005) with T being greater than UT at both time points (P< 0.001) and T decreasing from PRE to POST (P< 0.034). A …