English

Abstract

Creatine monohydrate (CrM) is considered a safe nutritional supplement. The loading phase of CrM supplementation is associated with shifts in total body water and plasma volume that may affect blood pressure. However, few studies have measured blood pressure during the loading phase of CrM supplementation. Purpose: The aim of this study was to determine if CrM supplementation in normotensive college-aged males induces a daily blood pressure increase during the supplementation-loading phase. Methods: Participants’ blood pressure, shoulder extension active range of motion (AROM), arm girth, arm volume, plasma volume, blood volume, hematocrit, and hemoglobin were measured daily for five days of supplementation (4x5gxd -1 x5d) of either CrM (n=12) or placebo (P; n=12). Results: The CrM group did not experience significant changes in systolic blood pressure (mmHg) (CrM 126.67±1.94 Day5 ; P 125.50±2.61 Day5 ) or diastolic blood pressure (mmHg) (CrM 83.83±2.19 Day5 ; P 82.33±2.07 Day5 ) compared to P. A significant T x Tx interaction (p=0.001) and Tx effect (p=0.03) support decreased AROM (cm) in the CrM group compared to P (CrM 38.3±2.19 Day 1 , CrM 34.0±2.01 Day5 ; P 41.02±2.49 Day 1 , P 43.2±2.47 Day5 ). An increase in arm volume (ml) in the CrM group (CrM 2443±99.44 Day 1 , CrM 2470±92.21 Day5 ) vs. the P group (P 2372±74.44 Day 1 , P 2374±74.61 Day5 ; p=0.026) was observed. An increase in plasma volume (%Δ from baseline) (p=0.014) (CrM 1.48±2.60 Day2 , CrM 6.03±4.03 Day5 ; P 3.25±2.74 Day2 , P 5.05±2.91 Day5 ) and a decrease in hematocrit (%) (p=0.026) (CrM 0.47±0.01 Day 1 , 0.45±0.01 Day5 ; P 0.46±0.01 Day 1 , 0.45±0.01 Day5 ) were observed. Conclusion: Findings suggest CrM supplementation in the loading phase does not affect blood pressure in normotensive college-aged males. CrM reduces shoulder extension AROM presumably due to increased tissue volume secondary to fluid shifts.