Week 12 Lecture: Nutrition in Resistance Training PDF

Week 12 lecture: Nutrition in Resistance Training Section 1 - Resistance training and protein Muscle mass and physical abilities - Genetic make up - Environment Skeletal muscle adaptations The size of human muscle is dictated by changes in rates of muscle protein synthesis and muscle protei...

Week 12 lecture: Nutrition in Resistance Training Section 1 - Resistance training and protein Muscle mass and physical abilities - Genetic make up - Environment Skeletal muscle adaptations The size of human muscle is dictated by changes in rates of muscle protein synthesis and muscle protein break down When protein is consumed, there is a significant, but transient, increase in muscle protein synthesis. In the rested, fasted state rates of protein breakdown exceed those of synthesis It is the relative contribution of these fed and fasted periods that dictate muscle mass over time Resistance training imparts a positive impact on skeletal muscle size Even a single bout of RT in the fasted state can increase MPS… but not enough to promote a positive net protein balance. Instead RT often serves to ‘potentiate’ MPS in response to consuming protein. MPS in trained and untrained athletes The effect of training age on muscle protein synthesis is an important consideration. After just 8 weeks of training, there is an attenuation of the duration (but not magnitude) of MPS. Trained vs. Untrained – Strength & Endurance Differential skeletal muscle adaptations are induced by RT when compared to endurance training. After just 10 weeks of RT, performing a single bout of RT causes myofibrillar protein synthesis but not mitochondrial. Before training, both showed significance in protein synthesis. Muscle Protein Synthesis Response to Resistance Training Considering that trained athletes have reduced MPS responses, it may be important to place greater focus on the post‐exercise period. Resistance Exercise Muscle Hypertrophy → Myofibrillar Proteins → Muscle contraction, repair, remodeling Time under tension? Volume? Fatigue? Burd et al. (2012) found greater protein synthesis with longer time under tension compared to equal volume matched training. This is likely due to greater muscle activity and the greater motor unit recruitment as greater fatigue was accumulated.  When we standardise the training by fatigue (i.e., training to muscle contractile failure), there is no difference in mixed MPS across a range of loads (e.g., 30% vs. 90%) post and greater MPS at 24 hours. Furthermore, when we standardise fatigue over 10 weeks of training, muscle hypertrophy is ~ equal irrespective of %RM Contractile failure occurs when there is significant muscle fatigue and motor unit activation. It is proposed that the manipulation of a multitude of RT variables mean a lot less for muscular hypertrophy than simply exerting a high level of effort and reaching contractile failure. However, it is plausible that there may be significant strength and muscular endurance benefits when training to failure with different loads. Therefore, when considering muscle hypertrophy not only should volume load and frequency be considered, but so should effort and proximity to contractile failure. Part 2 When people think ‘protein’… - Grow and repair What proteins actually are… - Building blocks - Signals Protein function - Regulation - kinases - Signaling - insulin - Transport - Glut 4 - Catlysis - PFK - Movement - Actin and myosin - Structure - Keratin Proteins are made from Amino Acids - Non essential amino acids - Essential amino acids Protein storage and turnover Protein is not considered a primary energy source (1 g protein= 4 kcal) During times of fasting or low energy stores it can be used Proteins in our body are in a continual state of turnover New proteins are being made‐ Protein Synthesis (MPS) Old ones are being broken down to their AA‐ Protein Degradation (MPB) Protein turnover requires energy (20% daily basal energy expenditure) Protein digestion for Protein Synthesis - Protein digested into polypeptides → - Individual amino acids → - Amino acids absorbed into blood and pass into a ‘free’ pool → - Manufactured into necessary proteins “You are what you just ate” - 12 Healthy males - Intravenous isotope tracer - 20 g intrinsically labeled casein - Arterial blood, femoral artery & venous blood, muscle biopsies for 5h post Results: When ingesting a single dose of protein, 55% of protein derived AA becomes available in the systemic circulation during 5 h post‐prandial period making these AA available for MPS The other 45% remain in the splanchnic area for gut and liver PS Protein synthetic response - PS Increases for up to 4‐5 h Protein synthetic response with RT - Increased for up to 24 h Maintenance of muscle mass Section 2 - Nutrition and resistance training Recommended Daily Intake - “An RDI is the average daily dietary intake level; sufficient to meet the nutrient requirements of nearly all (97‐98 %) healthy individuals in a group” Protein requirements for athletes - Increased synthesis of new proteins - Rebuilding and remodeling proteins damaged by exercise - Replacement of proteins broken down and oxidised for energy Dose response to protein ingestion + RE - Aim: To determine the ingested protein dose response of muscle (MPS) after resistance exercise in young healthy men.Moore et al. (2009) - Methods: 5 separate sessions - 4 x 8‐10 reps to failure - Consumed drinks containing: 0, 5, 10, 20 or 40 g of whole‐egg protein - Biopsies 1 h and 4 h post exercise Mixed muscle MPS is increased in a dose dependent manner up to 20 g 20 g (8.6 g EAA) (0.25 g/kg BM) = MPS maximally stimulated at 20 g What does this tell us? MPS is a saturable process in young people at doses of 20 g high quality protein per serving Protein Dose Response Relationship More recent work by McNaught et al. (2016) demonstrated that 40g protein may be beneficial when completing intense full body RT. Interestingly, there are not substantial differences in individuals with more or less muscle mass. How much? To account for differences between individuals, it has been suggested that a dose of 0.4g/kg/meal will help to optimally stimulate MPS. It is unlikely that larger amounts will add any benefit to MPS. However, changes in metabolic feedback regulation, satiety, and thermogenesis may occur! Therefore, when considering how much protein to consume, it is likely that protein beyond the rate at which it can be used for MPS (or other processes) will likely be used in ureagenesis. Timing and distribution of protein ingestion on MPS following RE Aim: To determine how quantity & timing of protein ingestion after a single bout of resistance exercise influences the muscle anabolic response throughout the day in healthy males. 20 g whey protein isolate every 3 h = optimal feeding pattern for enhanced MPS Timing of protein Resistance training increases MPS for ~48 hours and MPB for ~24. RT increases sensitivity of muscles to aminoacidemia. Meta‐analysis has shown that consuming protein in closer proximity to RT positively increases hypertrophy.  But when controlling for covariates, total protein was the strongest predictor of muscle hypertrophy and timing did not influence outcomes! Overnight recovery 16 healthy males Single bout of resistance exercise in the evening Recovery drink (20 g protein, 60 g CHO) immediately post exercise 30 min before sleep‐ 40 g casein or PLC Blood samples taken every hour during sleep Biopsies taken before and upon waking up - Effectively digested and absorbed - Increasing overnight plasma AA availability - Stimulated MPS - Improved overnight protein balance Protein timing It appears optimal to ingest protein close to training, but results may not be as drastic as once believed. Moderate doses of protein (e.g., 0.4g/kg/meal) at semi‐regular intervals may provide benefits for MPS and recovery Consuming larger doses of slow releasing proteins (e.g., 40g casein) before bed can augment muscle and strength adaptations. Part 2 Protein Quality Variation in EAA content - Whey has highest Protein quality There are differences in the protein you consume. Proteins such as whey and soy are digested rapidly, resulting in rapid aminoacidemia, and induce a larger but more transient rise in MPS. Whey vs casein vs soy protein Whey has a higher leucine content than casein (20%) – ‘leucine threshold’ Casein is digested slower than whey‐ ‘slow protein’ Whey and soy are rapidly digested‐ ‘fast protein’ Whey: Concentrate: usually contain the fat and lactose Isolate: processed to remove non‐protein components  Hydrolysate: processed to change the chemical bonds and promotes absorption Milk vs soy protein Aim: to determine the long term consequences of milk or soy protein or equivalent energy consumption on training‐induced lean mass accretion in healthy young men males - Trained 5 d/wk for 12 wk on a rotating split body resistance exercise program - Consumed fat free milk, soy or CHO immediately & 1 hour post exercise - Muscle fiber size, max strength, body composition by DEXA measured before and after training Chronic post‐exercise consumption of milk promotes greater hypertrophy than soy or CHO during the early stages of resistance training Protein quality Whole body protein synthesis is stimulated more with whey despite casein having similar levels of EAA. However, this may be related to the leucine content! When 25g of whey, or 6.25g + 5g of leucine is provided MPS is similar. When isoleucine or valine are provided MPS is not enhanced. Milk vs. beef ingestion - Increased PS post exc from milk & beef - Milk ingestion induces greater early myofibrillar protein synthetic response Supplementing with BCAA? BCAA are regularly consumed in an attempt to enhance MPS. However, Leucine, Isoleucine, and Valine share the same transporter and result in antagonism for uptake in the gut and muscle and is less effective than leucine supplementation alone!! Protein Quality To optimize MPS, protein ingestion that contains high leucine content and is rapidly digested is optimal. The difference between protein sources in their ability to stimulate MPS is likely due to a combination of both the delivery (i.e., digestion) and composition. While leucine content is important for MToRc and MPS, it appears there is a threshold for stimulation that is ~3g in young (and potentially higher in elderly). This may help explain why doses of ~0.4g/protein/kg of BM has been shown to maximise MPS. Protein and Carbohydrate Co‐ingestion - Is the insulin fairy real? Carbohydrate and protein post‐resistance training Carbohydrate is often co‐ingested with protein post‐resistance training to ‘stimulate insulin release’ beyond that seen with just protein alone.  When insulin is infused into the body at rest, MPS is increased. When insulin is infused along with protein, there is an increase in MPS and slight attenuation of MPB. However, this rise in MPS is not greater than protein alone. However, when adequate protein is consumed (~25g) with CHO following RT, there is no additional enhancements in MPS or reductions in MPB. When training athletes with frequent high‐intensity training sessions, added CHO may be of benefit.