THE EFFECT OF ACUTE CREATINE MONOHYDRATE LOADING ON BODY COMPOSITION, STRENGTH, AND FATIGABILITY IN WOMEN

Michaela Grace Alesi1, Benjamin E. Dalton2, Jacob M. McDougle3, Ginger Nee4, Darren G. Candow5, Abbie E. Smith-Ryan6, Robert Buresh4, Garrett M. Hester4, Trisha A. VanDusseldorp4. 1Virginia Polytechnic Institute and State University, Blacksburg, VA. 2University of Guelph, Guelph, ON. 3University of Conneticut, Storrs, CT. 4Kennesaw State University, Kennesaw, GA. 5University of Regina, Regina, SK. 6University of North Carolina, Chapel Hill, NC. BACKGROUND: Creatine monohydrate is a well-researched supplement; however, few investigations have been conducted on its effect on women, and only one study to date has factored in the phases of the menstrual cycle. Acute supplementation with creatine monohydrate during exercise has been promoted to benefit body composition and increases in strength and fatigue resistance, however, these findings are more ambiguous in women as much of the data exists from investigations of men. METHODS: Twelve recreationally trained women (22.8 ± 2.98 yrs) participated in this cross-over study, wherein they took both supplements (creatine monohydrate, CM; placebo, maltodextrin, PL) in randomized, double-blind, counterbalance order during the luteal phase of their menstrual cycle. Women were asked to perform a CM or PL loading phase of 20g per day. A 28-day washout period was allowed after the initial supplementation period. Subjects completed 5 total visits. Visit 1 included informed consent and familiarization with the fatiguing exercise protocol. Visits 2-5 comprised measures of 4-compartment body composition and fatiguing exercise on an isokinetic dynamometer. The fatiguing protocol consisted of isokinetic knee extensions at 180 deg/sec for 5 sets of 30 contractions, with 2 min of rest after each set. After each set, participants were asked their rating of perceived exertion using the Borg 1-10 scale. Fatigue index was calculated as followed: (highest peak torque-minimum peak torque)/highest peak torque × 100. Relative fatigue was calculated for each set as follows: (sum of peak toques for set 1 - sum of peak torque for set 2)/sum of peak torques for set 1 × 100. RESULTS: No significant changes for body mass (p=0.551), total body water (p=0.607), fat-free mass (p=0.789), or fat mass (p=0.943) were measured. Strength was unchanged, with no significant changes for peak torque (p=0.646). There was no change in relative fatigue (p= 0.525; p=0.525) or fatigue index (p= 0.823; p=0.149). There was no difference for rating of perceived exertion (p=0.570). CONCLUSIONS: A creatine monohydrate loading period of 20 grams per day for five days did not alter body composition, muscular strength, or fatigability in these recreationally trained women