KathleenMae Rogers1, Christopher J. Cleary1, & Ashley A. Herda1,2

1University of Kansas-Edwards Campus, Overland Park, Kansas; 2University of Kansas Medical Center, Kansas City, Kansas

Resistance exercise with blood flow restriction (BFR) is becoming a frequently used training implement that elicits adaptations such as hypertrophy in males yet acute changes in muscle have yet to be elucidated in females specifically. PURPOSE: The purpose of this study was to determine any acute muscle composition changes to single-leg exercise in trained females. METHODS: Fourteen healthy and active females (age: 24.9±5.8 years; BMI: 25.4±4.7 kg/m2) were assessed for baseline segmental and total body water and lean mass with multifrequency bioelectrical impedance analysis (BIA) and 1-3 repetition maximum (RM) single-leg, leg press with their dominant (Dom) and non-dominant (NonD) limbs. They revisited the laboratory and completed BIA before (Pre) and after (Post) an acute bout of resistance exercise using only their Dom limb with either traditional (TRAD: 4 sets of 8 repetitions at 75% 1-RM) or low-load plus BFR (BFR: 1 set of 30 reps and 3 sets of 15 reps at 25% 1-RM) on randomized days, 48 hours apart. Repeated measures ANOVAs were completed with a p<0.05 level of significance and when appropriate, follow up ANOVAs and t-tests with Bonferroni corrections were conducted. RESULTS: There were no significant differences in baseline evaluation of daily variation in skeletal muscle mass (p=0.701), leg lean mass (p=0.602), and water estimates for Dom (p=0.297) and NonD (p=0.185) limbs. Three-way ANOVA evaluating training condition (BFR vs. TRAD) x leg (Dom vs. NonD) x time (Pre vs. Post) indicated a 3-way interaction for both leg lean mass (p<0.001) and limb water estimates (p<0.001). Leg lean mass and water estimates increased from Pre to Post BFR (+0.11 kg; p<0.001) in Dom with no change or decreases in estimated leg lean mass (p=0.182) and limb water (p=0.102) following TRAD exercise. NonD presented greater limb water content and mirrored limb lean mass following TRAD (+0.129 L; p=0.007) despite both conditions contributing to greater Dom limb water after BFR (+0.36 L; p<0.001) and TRAD (+0.18 L; p=0.015). CONCLUSION: Results demonstrate the fluid shifts that occur following low-load exercise with BFR are more pronounced than TRAD. The lean mass estimates from segmental BIA are reflected by the limb water estimates in both limbs but more pronounced in the exercising limb resultant of water redistribution.

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