The Effect of Creatine Loading on Neuromuscular Fatigue in Women
Abbreviated Journal Title
Med. Sci. Sports Exerc.
CONTRACTILE PROPERTIES; SEX; EMG; MUSCLE FATIGUE; ERGOGENIC AID; PHOSPHOCREATINE; HUMAN SKELETAL-MUSCLE; TWITCH INTERPOLATION; SEX-DIFFERENCES; ISOMETRIC; CONTRACTIONS; MUSCULAR PERFORMANCE; VOLUNTARY ACTIVATION; SUPPLEMENTATION; STRENGTH; EXERCISE; PHOSPHOCREATINE; Sport Sciences
Purpose This study aimed to examine the effects of intermittent isometric fatigue on maximal voluntary contraction (MVC) strength, percent voluntary activation (%VA), peak twitch force (PTF), peak rate of force development (PRFD), half relaxation time (HRT), and maximal compound action potential (M-wave) amplitude of the soleus and medial gastrocnemius muscles before and after creatine (Cr) loading. Methods Using a double-blinded, placebo-controlled, randomized design, 12 women were assigned to a Cr (n = 6; mean age +/- SD = 23.3 +/- 3.0 yr) or placebo (PL; n = 6; mean age +/- SD = 21.3 +/- 1.6 yr) group. Participants supplemented four times daily for 5 d with 5 g of Cr + 10 g of fructose or 10 g of fructose. At baseline and after testing, an isometric MVC and the twitch interpolation procedure were used before and after a 4-min isometric fatigue protocol of the plantarflexor muscles, which consisted of six intermittent duty cycles per minute (7-s contraction, 3-s relaxation) at 70% MVC. Results There were no interactions between the Cr and PL groups (P > 0.05) for any dependent variable. The fatigue protocol reduced voluntary strength (-17.8%, P < 0.001) and %VA (-3.7%, P = 0.005). Baseline PTF (P < 0.005) and PRFD (P < 0.001) values were less than those of all respective time points, but PTF value decreased from 3 min to 4 min and after testing (P < 0.005). HRT increased from baseline to minutes 1 and 2 and then returned to baseline at minutes 3 and 4 and after testing. The M-wave did not change (P > 0.05). Conclusions Five days of Cr loading did not influence isometric force, %VA, evoked twitch properties, or the central and peripheral aspects of fatigue measured in this study.
Medicine and Science in Sports and Exercise
"The Effect of Creatine Loading on Neuromuscular Fatigue in Women" (2014). Faculty Bibliography 2010s. 6102.