D-29 Free Communication/Poster - Macronutrient Metabolism I - Protein and Amino Acids: JUNE 2, 2011 1:00 PM - 6:00 PM: ROOM: Hall B
Training with low muscle glycogen concentration augments adaptation to endurance training, but the effect of glycogen status on anabolic signaling and protein synthesis following resistance exercise (REX) is unknown.
PURPOSE: To determine the effect of divergent glycogen content and subsequent post-exercise nutrition on anabolic signaling target p70S6K Thr389 during the early recovery period following REX.
METHODS: Sixteen resistance trained male subjects (∼23 yr) were randomly assigned to nutrient or placebo groups. After 48 h diet/activity control subjects reported to the laboratory the evening before an experimental trial to perform a glycogen depletion protocol where one-leg undertook cycling exercise to fatigue (LOW vs. normal [NORM]) and subjects then consumed a low carbohydrate (CHO) meal. The next day subjects completed 8 sets of 5 unilateral leg press repetitions at 80% one repetition maximum. Immediately and 2 h post-exercise subjects consumed a 500 ml bolus of protein/CHO (20 g whey + 40 g maltodextrin) or placebo drink. Muscle biopsies were obtained from v. lateralis of both legs at rest, 1 h and 4 h after REX.
RESULTS: The depletion protocol generated divergent muscle glycogen that was higher in the NORM than LOW leg in both nutrient and placebo groups at all time points (P <.05). Muscle glycogen in LOW increased between 1 and 4 h post-exercise in the nutrient (∼84 mmol·kg·dw-1, P <.05) but not placebo group. p70S6KThr389 phosphorylation in LOW increased in both nutrient (15-49 fold) and placebo (∼8 fold) groups 1 h and 4 h post-exercise compared to rest (P <.05) but was only different from rest 1 h post-exercise in NORM in the nutrient group (∼36 fold, P <.05). No differences were observed between NORM and LOW legs 1 h or 4 h post-exercise.
CONCLUSIONS: Despite disparity in muscle glycogen there were similar S6KThr389 phosphorylation responses in NORM and LOW 1 h post-exercise. Our results indicate that commencing high-intensity REX with low muscle glycogen concentration does not suppress phosphorylation of a key component in skeletal muscle translation initiation. Moreover, the possibility exists that translational signaling may be extended with post-exercise nutrient ingestion and the subsequent glycogen resynthesis with low glycogen.
This project was funded by the Australian Sports Commission.