Creatine supplementation alters the response to a graded cycle ergometer test

To determine the effects of creatine supplementation on cardiorespiratory r esponses during a graded exercise test (GXT) 36 trained adults (20 male, 16 female; 21-27 years old) performed two maximal GXTs on a cycle ergometer. The first GXT was done in a nonsupplemented condition, and the second GXT w as done following 7 days of ingesting either 5 g creatine monohydrate, enca sed in gelatin capsules! four times daily (CS, 13 male, 6 female), or the s ame number of glucose capsules (PL, 7 male, 10 female). CS significantly (P < 0.05) improved total test time [pre-CS = 1217 (240) s, mean (std. dev). versus post-CS = 1289 (215) s], while PL administration had no effect (P > 0.05) on total test time [pre-PL=1037 (181)s versus post-PL=1037 (172)s]. I n addition, both oxygen consumption ((V)over dot(O2),) and heart rate at th e end of each of the first five GXT stages were significantly lower after C S, but were unchanged after FL. Moreover, the ventilatory threshold occurre d at a significantly greater (V)over dot(O2), for CS [pre-CS = 2.2 (0.4) l. min(-1) or 66% of peak (V)over dot(O2) versus post-CS = 2.6 (0.5) l-min(-1) or 78% of peak (V)over dot(O2); pre-PL = 2.6 (0.9) l.min(-1) or 70% peak ( V)over dot(O2), versus post-PL = 2.6 (1.1) l.min(-1) or 68% of peak (V)over dot(O2)]. Neither CS nor PL had an effect on peak (V)over dot(O2) [pre-CS= 3.4 (0.7)l.min(-1) versus post-CS = 3.3 (0.7) l.min(-1) pre-PL = 3.7 (1.1) l.min(-1) versus post-FL = 3.7 (1.1) l.min(-1)]. Apparently, CS can alter t he contributions of the different metabolic systems during the initial stag es of a GXT. Thus, the body is able to perform the sub-maximal workloads at a lower oxygen cost with a concomitant reduction in the work performed by the cardiovascular system.