Sunday, September 14, 2008

Performance Research for August: Protein Synthesis

As you know I took my PhD Preliminary Oral exam this past Friday. For those that are unfamiliar with the process, they lock you in a room with your committee for 2 hours where they can ask you any question and you present your proposed research.

Overall it went well, and I passed!! I have some revisions I need to work on to better outline the hypotheses, but that is work I will need to do at some point and the more I do up front the better it will be long term. I will submit my study this week and hopefully I will have approval and start up in mid Oct. The feedback I got was great and much appreciated.

I will be looking at several things, but overall it will be the effect of energy drinks on performance and how it relates to Metabolic Flexibility. Energy drink usage is on the rise, the media declares them to be evil and there currently is not much data to support either side.

Thanks to all for their support and understanding of my lateness on emails.

New Studies on Protein Synthesis
More brand new studies for ya! In short, more evidence to show that using a protein/carb beverage around your training time is a good thing!

Resistance exercise decreases eIF2Bepsilon phosphorylation and potentiates the feeding-induced stimulation of p70S6K1 and rpS6 in young men.

Glover EI, Oates BR, Tang JE, Moore DR, Tarnopolsky MA, Phillips SM. Department of Kinesiology, Exercise Metabolism Research Group, McMaster University, 1280 Main St. West, Hamilton, ON, Canada L8S 4K1.

We investigated the effect of resistance exercise and feeding on the activation of signaling proteins involved in translation initiation. Nine young men (23.7+/-0.41 yr; BMI=25.5+/-1.0 kg/m2; means+/-SE) were tested twice after they performed a strenuous bout of unilateral resistance exercise, such that their contralateral leg acted as a nonexercised comparator, in either the fasted and fed [1,000 kJ, each 90 min (3 doses): 10 g protein, 41 g carbohydrate, 4 g fat] states. Muscle biopsies were obtained 6 h postexercise from both legs, resulting in four experimental conditions: rest-fasted, rest-fed, exercise-fasted, and exercise-fed. Feeding increased PKB/Akt (Ser473) phosphorylation (P<0.05),>0.14). In summary, feeding resulted in phosphorylation of Akt, while resistance exercise stimulated phosphorylation of Akt, p70S6K1, rpS6, and dephosphorylation eIF2Bepsilon with a synergistic effect of feeding and exercise on p70(S6K1) and its downstream target rpS6.

Conclusion: We conclude that resistance exercise potentiates the effect of feeding on the phosphorylation and presumably activation of critical proteins involved in the regulation of muscle protein synthesis in young men.

Acute milk-based protein-CHO supplementation attenuates exercise-induced muscle damage.

Cockburn E, Hayes PR, French DN, Stevenson E, St Clair Gibson A. Division of Sports Sciences, Northumbria University, Newcastle, UK.

Exercise-induced muscle damage (EIMD) leads to the degradation of protein structures within the muscle. This may subsequently lead to decrements in muscle performance and increases in intramuscular enzymes and delayed-onset muscle soreness (DOMS). Milk, which provides protein and carbohydrate (CHO), may lead to the attenuation of protein degradation and (or) an increase in protein synthesis that would limit the consequential effects of EIMD. This study examined the effects of acute milk and milk-based protein-CHO (CHO-P) supplementation on attenuating EIMD. Four independent groups of 6 healthy males consumed water (CON), CHO sports drink, milk-based CHO-P or milk (M), post EIMD. DOMS, isokinetic muscle performance, creatine kinase (CK), and myoglobin (Mb) were assessed immediately before and 24 and 48 h after EIMD. DOMS was not significantly different (p > 0.05) between groups at any time point. Peak torque (dominant) was significantly higher (p < style="font-weight: bold;">
Conclusion: At 48 h post-EIMD, milk and milk-based protein-CHO supplementation resulted in the attenuation of decreases in isokinetic muscle performance and increases in CK and Mb.

Differential effects of resistance and endurance exercise in the fed state on signalling molecule phosphorylation and protein synthesis in human muscle.

Wilkinson SB, Phillips SM, Atherton PJ, Patel R, Yarasheski KE, Tarnopolsky MA, Rennie MJ. Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada L8S 4K1.

Resistance (RE) and endurance (EE) exercise stimulate mixed skeletal muscle protein synthesis. The phenotypes induced by RE (myofibrillar protein accretion) and EE (mitochondrial expansion) training must result from differential stimulation of myofibrillar and mitochondrial protein synthesis. We measured the synthetic rates of myofibrillar and mitochondrial proteins and the activation of signalling proteins (Akt-mTOR-p70S6K) at rest and after an acute bout of RE or EE in the untrained state and after 10 weeks of RE or EE training in young healthy men. While untrained, RE stimulated both myofibrillar and mitochondrial protein synthesis, 67% and 69% (P < p =" 0.05)." style="font-weight: bold;">Conclusion: Chronic RE or EE training modifies the protein synthetic response of functional protein fractions, with a shift toward exercise phenotype-specific responses, without an obvious explanatory change in the phosphorylation of regulatory signalling pathway proteins.

Impact of nutrient intake timing on the metabolic response to exercise.

Stephens BR, Braun B. Department of Kinesiology, Energy Metabolism Laboratory, School of Public Health and Health Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA. Effects of nutrient intake timing and exercise on carbohydrate (e.g. insulin sensitivity), protein (muscle protein synthesis), and fat (circulating triacylglycerols) metabolism are reviewed in this paper.

Conclusion:Altered nutrient intake timing relative to exercise can modulate the metabolic response, which is relevant for individuals seeking to use exercise to enhance health.