Effect of Creatine Supplementation and Resistance-Exercise Training on Muscle Insulin-Like Growth Factor in Young Adults

Abstract

The purpose of this study was to compare changes in muscle insulin-like growth factor-I (IGF-I) content resulting from resistance-exercise training (RET) and creatine supplementation (CR). Male (n=24) and female (n=18) participants with minimal resistance-exercise-training experience (=1 year) who were participating in at least 30 min of structured physical activity (i.e., walking, jogging, cycling) 3-5 x/wk volunteered for the study. Participants were randomly assigned in blocks (gender) to supplement with creatine (CR: 0.25 g/kg lean-tissue mass for 7 days; 0.06 g/kg lean-tissue mass for 49 days; n=22, 12 males, 10 female) or isocaloric placebo (PL: n=20, 12 male, 8 female) and engage in a whole-body RET program for 8 wk. Eighteen participants were classified as vegetarian (lacto-ovo or vegan; CR: 5 male, 5 female; PL: 3 male, 5 female). Muscle biopsies (vastus lateralis) were taken before and after the intervention and analyzed for IGF-I using standard immunohistochemical procedures. Stained muscle cross-sections were examined microscopically and IGF-I content quantified using image-analysis software. Results showed that RET increased intramuscular IGF-I content by 67%, with greater accumulation from CR (+78%) than PL (+54%; p=.06). There were no differences in IGF-I between vegetarians and nonvegetarians. These findings indicate that creatine supplementation during resistance-exercise training increases intramuscular IGF-I concentration in healthy men and women, independent of habitual dietary routine.

Building Muscle Mass: Physiology, Nutrition, and Supplementation

“…The researchers found greater levels of mRNA for IGF-1 among subjects in the creatine supplementation group [ 170 ]. Another study demonstrating the effects of creatine supplementation coupled with resistance training on IGF-1 was led by Burke et al [ 171 ]. This randomized control study assessed the effects of creatine or placebo supplementation on muscle IGF-1 over 49 days of training in active, healthy adults.…”

Strategic creatine supplementation and resistance training in healthy older adults

“…The greater muscle benefits from post-exercise creatine supplementation may be due to an increase in skeletal muscle blood flow during resistance training, which would result in greater creatine transport and accumulation in exercising muscles. With repeated training sessions, elevated intramuscular creatine stores may effectively influence gene expression, signaling pathways (Safdar et al 2008), transcription factors (Willoughby and Rosene 2003), satellite cells (Olsen et al 2006), and anabolic hormones (i.e., insulin-like growth factor 1; Burke et al 2008;Deldicque et al 2005) involved in skeletal muscle hypertrophy.…”

Necesidades proteicas de los deportistas y pautas diétetico-nutricionales para la ganancia de masa muscular

“…En este sentido, parece ser que la suplementación con ciertos AA estaría más justi cada después del ejercicio 72 . Sólo unos pocos suplementos han demostrado amplia y claramente que pueden tener propiedades ergonutricionales; uno de ellos es la creatina 73,74 , AA que se sintetiza en el riñón y el hígado mediante la glicina y la arginina. La creatina debe indicarse en deportes con un componente explosivo, donde existe una gran intensidad en un corto espacio de tiempo, así como en los entrenamientos de hipertro a muscular 74 .…”