jueves, 22 de abril de 2010

Una breve reseña de un artículo sumamente interesante recien aparecido

La interacción entre ejercicio físico y factor de crecimiento IGF-I es interesantísima (un reciente estudio de investigadores del Consejo Superior de Investigaciones Científicas constata que ratones a los que se les provocan lesiones semejantes a un ictus en humanos, llegan a mejorar casi al 100% gracias a una actividad física intensa (mediada por IGF-I), pero lo que aún es más interesante, resulta que la restitución es mayor si antes ya entrenaban.

Todavía no hay estudios que lo confirmen a nivel práctico, pero los nuevos compuestos con péptidos bioactivos obtenidos del suero de la leche, podrían crear un entorno favorable (IGF-I) para que, asociado al entrenamiento, se consiguieran adaptaciones mayores al ejercicio físico.

Aquí os dejo un Artículo recién publicado que me parece fundamental

J Appl Physiol. 2010 Apr 15.
CIRCULATING BIOACTIVE AND IMMUNOREACTIVE IGF-I REMAIN STABLE DESPITE FITNESS IMPROVEMENTS AFTER 8 WEEKS OF RESISTANCE, AEROBIC AND COMBINED EXERCISE TRAINING.
Nindl BC, Alemany JA, Tuckow AP, Rarick KR, Staab JS, Kraemer WJ, Maresh CM, Spiering BA, Hatfield D, Flyvbjerg A, Frystyk JF.1United States Army Research Institute of Environmental Medicine.


Insulin-like growth factor-I (IGF-I) is regulated by a number of IGF-binding proteins (IGFBPs) and proteases that influence IGF-I bioactivity. A specific IGF-I kinase receptor activation assay (KIRA) has been developed that determines the ability of IGF-I to activate the IGF-I receptor by quantification of intracellular receptor autophosphorylation upon IGF-I binding. KIRA-assessed IGF-I bioactivity has not been utilized within the context of chronic exercise training paradigms. This study measured total and free immunoreactive IGF-I, bioactive IGF-I, and IGFBP-1, -2, and -3 pre, mid, and post in young, healthy women who were randomized into one of 4 groups: control (n = 10), resistance (n = 18), aerobic (n = 13), and combined (n = 15) exercise training. Training was on 3 alternating days a week for 8 weeks. The training programs were effective in improving physical fitness specific to the exercise mode engaged in: increases were observed for lean mass (~2%), aerobic fitness (6-7%), and upper (20-24%) and lower (15-48%) body strength (all p-values < 0.05). By contrast, no time, group or interaction effects were observed for the circulating IGF-I system as immunoreactive total (pre = 264+/-16 mug/L; mid = 268+/-17 mug/L; post = 271+/-17 mug/L), free (pre = 0.70+/-0.1 mug/L; mid = 0.63+/-0.1 mug/L; post = 0.63+/-0.2 mug/L) and bioactive (pre = 2.35+/-0.3 mug/L; mid = 2.25+/-0.3 mug/L; post = 2.33+/-0.3 mug/L) IGF-I were unchanged throughout the study. All IGFBP measures were also unchanged. We conclude that increased lean mass, aerobic fitness, and upper and lower body strength resulting from an 8-week exercise training programs can occur without concomitant increases in either circulating bioactive or immunoreactive IGF-I as well as associated IGF binding proteins. In terms of reflecting positive anabolic neuromuscular outcomes, these data support a growing consensus that locally produced IGF-I may be of greater relative importance than endocrine-derived IGF-I
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