Ofr anabolic resistance of myofibrillar Maca root powder synthesis is exacerbated in obese inactive individuals. Rceovery that conclusion is way beyond the context of the study. Total lean fat and bone free mass by DXA Vastus lateralis muscle thickness by ultrasound fCSA by immunohistochemistry.

Protein Synthesis for Recovery -

This notion is supported by data showing that both mitochondrial and myofibrillar—MPS are increased following a REx in the untrained state Wilkinson et al.

However, following 10 weeks of RET, only myofibrillar FSR is increased. Taken together, these data suggest that with the progression of RET, and as the degree of exercise-induced muscle damage starts to diminish, the acute stimulation of MPS is directed almost exclusively to the accretion of new muscle proteins, thus explaining the correlation between acute rates of MPS and the muscle growth response during the later phase of RET Trommelen et al.

The inherent variability in the response of MPS to REx and nutrition, as well as the response of muscle hypertrophy to RET, also contributes to our inability to utilize acute metabolic data to predict an individual response to RET Figure 1.

This variability in response to exercise and nutrition is reported consistently Jackman et al. While the source of this individual variability is not fully understood at this time, genetic variability must be a contributing factor Clarkson et al.

Attempts to control prestudy activity and diet are common in these studies, yet the variability is evident. Moreover, in many studies, the population from which participants are selected is kept fairly tight. Yet, even when the range of muscle mass is restricted, there is considerable variation in the response of MPS Macnaughton et al.

The methodological conditions under which MPS is determined that may influence the measured response will be discussed below.

However, in the examples illustrated in Figure 1 , the method used to determine MPS, as well as the conditions under which it was measured, in each individual were identical within studies.

Hence, methodological issues alone do not account for all the observed variability. Inherent variability in the metabolic response to REx and nutrition contributes to uncertainty in predicting muscle growth based on measured rates of MPS in individuals.

a Individual fasted FSR at rest REST and with ingestion of 30 g protein following resistance exercise FEDEX in two groups of trained young weightlifters and b individual FSR in response to ingestion of 20 and 40 g whey protein following REx in trained young weightlifters.

a Adapted from McGlory et al. Citation: International Journal of Sport Nutrition and Exercise Metabolism 32, 1; One potential contributing factor to the variability of the response of MPS to identical REx and protein feeding conditions Figure 1 might be differences in translational capacity, that is, the total number of ribosomes capable of producing peptide chains Wen et al.

The MPS is the metabolic process from which functional proteins are produced from polypeptide chains created by ribosomes. The measurement of FSR essentially represents translational efficiency, that is, the rate of translation for a given number of ribosomes. It is clear that ribosome number, that is, translational capacity, does not change acutely following REx Brook, Wilkinson, Mitchell, et al.

Thus, translational capacity may help explain the individual variability in response of MPS to anabolic stimuli. The lack of ability to predict long-term muscle hypertrophic responses to RET with the acute measurement of MPS does not necessarily reflect the overall worth, or lack thereof, of information obtained from acute metabolic studies.

Contributing factors to the uncertain relationship between the acute MPS response to REx and nutrition, and the muscle hypertrophic response to RET, include a lack of consistency in methods utilized, as well as inherent variability resulting from the methods used Mitchell et al.

There also is heterogeneity in the response of muscle mass to RET that contributes to this disconnect. Accordingly, there are numerous reasons to suggest that the study design and methods chosen to determine hypertrophy in RET studies contributes to this quite heterogeneous response.

A full evaluation of these methods is beyond the scope of this review, so interested readers are referred to an excellent presentation of the methodology by Haun et al. Several factors related to study design and methods used to assess MPS must be considered when interpreting the relationship between the acute response of MPS- and RET-induced changes in muscle mass.

Over the past 25—30 years, the vast majority of studies investigating the response of MPS have utilized the precursor—product method with direct incorporation of the stable isotopically labeled amino acids into muscle protein to determine FSR. Accurate prediction of muscle hypertrophy during RET by determining FSR in response to REx and nutrition requires certain assumptions to be made and met.

First, we must assume that the initial measurement of FSR is representative of every subsequent stimulation of MPS for the remainder of the RET period, that is, the responses remain unchanged throughout RET see discussion above.

Next, the measured FSR captures the true response of MPS to REx and protein ingestion. Thus, methodological choices will be critical for determining the true response of MPS. Methodological considerations influence the ability to capture the true response of MPS with measurement of the FSR in response to exercise and nutrition.

Until recently, the majority of studies measuring FSR included an infusion of a labeled amino acid and multiple muscle biopsy samples. The FSR is reported as an hourly rate of synthesis in the time between the muscle samples. An important issue for any infusion study to determine FSR is the limited time period for incorporation of the labeled amino acid.

One critical assumption is that the time between biopsies captures the true period of stimulation of MPS. Thus, regardless of the maximal magnitude of the response, if the second muscle sample is taken before the response of MPS returns to baseline, a portion of the true response of MPS may be missed and the determined FSR would be an underestimation Figure 2.

Of course, the converse would be true if the biopsy is taken too late to capture the true response. a Infusion of [ 13 C 6 ] phenylalanine and muscle samples taken at timepoints that capture the entire true response of MPS and b infusion ends and muscle samples are taken at 0 and 4 hr, but the true response of MPS remains elevated above baseline for 6 hr, so the response is underestimated.

Another factor that contributes to a mismatch between the true response of MPS to REx is the prolonged enhancement of the utilization of amino acids from protein ingestion for MPS following a REx bout Figure 3.

The REx sensitizes the muscle to the anabolic stimulation of elevated amino acid levels from protein feeding Biolo et al. It is clear that the sensitivity of muscle to amino acids remains enhanced for at least 24 hr following the exercise Burd et al. Thus, any protein containing meal consumed within this hr time period will result in a MPS response that is greater than that in response to a meal not preceded by REx.

An acute measurement of MPS based on an infusion of labeled amino acids and biopsies for only a few hours after exercise would not be capable of capturing the contribution to muscle hypertrophy resulting from all of these enhanced postprandial elevations of MPS Figure 3a.

Thus, an acute measurement limited to only a few hours after REx would not reflect the entire influence of the exercise on MPS and subsequent muscle hypertrophy further contributing to the observed mismatch between measurement of MPS and changes in muscle mass with training.

The response of MPS is enhanced following REx and this is captured by D 2 O measurement of MPS. Over the past 15 years, another method has been revisited to determine an integrated FSR in free-living participants over a time period that is not limited by an infusion, that is, the D 2 O method Figure 3.

Thus, MPS in various situations and in response to various exercise and nutrition interventions can be determined over the time course of days to weeks. The determined rate of MPS integrates the response to all physical activity and nutrient consumption during that time, including the prolonged response of MPS to subsequent meals following REx Figure 3b.

Thus, the D 2 O method could be argued to provide a more holistic assessment of MPS without the limitations inherent with the requirement for infusion of stable isotopes for measurement of MPS.

It is perhaps not particularly surprising that integrated rates of MPS over longer time periods than are possible with isotope infusion studies, as well as inclusion of habitual physical activity and enhanced periods of postprandial MPS in response to exercise hours to days earlier, are better correlated with subsequent muscle hypertrophy.

Several studies utilizing the D 2 O measurement of FSR have reported correlations of MPS with subsequent muscle hypertrophy Brook et al. Therefore, this method for assessing MPS seems to be more suitable for predicting muscle hypertrophy with RET.

The disconnect between the initial measurement of MPS and subsequent muscle hypertrophy during RET may be due to methodological choices made for measurement of changes in muscle mass in addition to MPS. Differences in study design and methods chosen to determine changes in muscle mass, in addition to inherent individual variability in the response of muscle to training Mobley et al.

Factors including training duration, sleep quality, nontraining physical activity, nutrition, and other lifestyle variables may impact the training response Haun et al.

Proper control of many of these factors is virtually impossible in most RET study situations. This variability is further complicated by the various permutations possible with various combinations of these factors Haun et al.

Perhaps a more prosaic factor contributing to the disconnect between the acute response of MPS and subsequent muscle hypertrophy with RET relates to the inherent limitations of methods used to measure changes in muscle mass in humans.

Reported changes in muscle mass with RET are heavily dependent on the method chosen to assess those changes. Hence, the critical reader should consider the limitations of these methods when evaluating any particular training study.

Changes in muscle mass may be measured on one or more of several levels, that is, biochemical, ultrastructural, histological, and gross anatomical levels. When multiple methods from these levels of hypertrophy are used, the agreement between methods is often poor Haun et al.

Moreover, as detailed above, there are different types of hypertrophy that must be considered in combination with the method chosen to assess changes in muscle mass.

Three types of hypertrophy have been proposed: connective tissue, sarcoplasmic, and myofibrillar. For example, there is evidence that hypertrophy measured at the early stage of a RET program may result from edema-induced, that is, muscle swelling and sarcoplasmic hypertrophy Damas, Phillips, Libardi, et al.

This means that if muscle hypertrophy is based on dual-energy X-ray absorptiometry or other methods without consideration of changes in intramuscular fluid, overestimations of true hypertrophy will be made. Clearly, changes in muscle mass with fluid infiltration are not related to MPS.

These methodological factors should be considered when assessing the relationship between the acute response of MPS to changes in muscle mass with RET. Based on our critical evaluation of existing evidence, we can make three practical implications. In this review, we have attempted to provide an evidence-based critical evaluation for the use of results from acute metabolic studies to predict changes in muscle mass with RET.

This lack of predictive power is especially true if the individual is beginning an unaccustomed exercise program. Nevertheless, this discrepancy should not be used to determine the value of studies measuring MPS in response to REx and protein nutrition.

There are multiple examples of studies in which the acute response of MPS does predict the average hypertrophy on a group level Hartman et al. Moreover, measurement of the acute response of MPS to REx and nutrition interventions can provide valuable information.

Regardless of training status, the acute response of MPS is indicative of protein turnover and muscle remodeling critical for recovery from exercise and adaptation to training. The measurement of integrated MPS that includes the enhanced postprandial response of MPS to protein ingestion in free-living individuals certainly may provide predictive information about subsequent muscle growth, albeit not in individuals undergoing unaccustomed exercise.

Moreover, the acute measurement of MPS also provides more sensitivity than chronic training studies over a much shorter time frame and can thus be viewed as a good starting point for determining nutritional recommendations.

Given the nature of measurement of FSR, if a difference is detected in an acute study, for example, between different protein sources, then we can conclude with high confidence that the measured difference is physiologically relevant, at least qualitatively.

In this regard, the protein source that engenders the greater FSR may be considered the higher quality protein source irrespective of whether chronic studies are able to detect differences in muscle hypertrophy under comparable conditions of protein source manipulation.

Thus, we can use that information to inform subsequent RET studies. Finally, the acute measurement of MPS in response to exercise and nutrition offers valuable mechanistic information.

In fact, delineation of mechanisms of muscle protein metabolism was the aim of many of the seminal studies that are now used to contribute to the development of recommendations Biolo et al. Thus, whereas practitioners should be aware of the potential pitfalls with reliance on acute metabolic studies for making nutritional recommendations for athletes and exercisers, with proper interpretation a great deal of valuable information may be gleaned from these studies.

Acute measurement of MPS in response to various nutrition and exercise interventions should be viewed as yet another tool in the toolbox for use by practitioners and others. Balagopal , P. Skeletal muscle myosin heavy-chain synthesis rate in healthy humans.

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Ingestion of whey hydrolysate, casein, or soy protein isolate: Effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. Resistance training alters the response of fed state mixed muscle protein synthesis in young men.

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Sports Medicine, 48, 53 — Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise. Exercise-induced changes in protein metabolism. Acta Physiologica Scandinavica, 3 , — Exercise, protein metabolism, and muscle growth. Dietary protein is important for the remodeling of skeletal muscle after not only resistance exercise but also after high-intensity sprint exercise 68 , steady-state endurance exercise 69 , and combinations thereof i.

Unlike resistance exercise, which provides a predominantly muscle-specific stimulus 72 , endurance exercise can increase whole body oxidative disposal of amino acids that must ultimately be replaced via dietary sources This may contribute to the increased protein requirements of endurance athletes 74 , Studies from the same laboratory utilizing identical tracer methodology have demonstrated that the ingestion of 0 g ~0.

Although the relative differences in myofibrillar protein synthetic rates between 0 g protein and a moderate relative intake i.

Therefore, while the consumption of ~ 0. Both young and old adults are capable of mounting an enhanced muscle protein synthetic response after resistance exercise in the fasted state 78 , 79 , which is consistent with the ability to increase muscle mass with this type of training across the lifespan In potential support, it has been shown that the ingestion of 40 g ~0.

However, the relative dose may not be substantially greater than younger adults as 30 g ~0. The studies examining the post-exercise ingested protein dose-response utilized high quality i.

In contrast, proteins that contain lower quantities of the branched-chain amino acids e. For example, it has been reported that the post-exercise stimulation of mixed muscle protein synthesis over 5 h 90 , and myofibrillar protein synthesis over 3—5 h 34 of recovery is similar with the ingestion of ~20 g of a mixed protein i.

Early studies investigating the nutritional regulation of muscle protein synthesis have primarily provided dietary protein in beverage form. However, recent focus has been placed on the importance of studying whole foods e.

In this event, it is unclear if consuming a greater protein intake to account for any attenuated hyperaminoacidemia from solid food ingestion may be required to maximize post-exercise muscle protein synthesis.

However, digestion rate may not be the only or even primary variable that influences the anabolic potential of whole food as minced beef has been demonstrated to induce a more rapid postprandial aminoacademia than skim milk but a lower early i.

Other studies have also demonstrated whole milk as more anabolic than skim milk 93 and skim milk more anabolic than soy juice 8 during post-exercise recovery.

Finally, we recently demonstrated that whole egg supports a greater post-exercise myofibrillar protein synthetic response than an isonitrogenous quantity of egg white protein, which was supported by a greater lysosomal targeting of the mechanistic target of rapamycin mTOR as the potential underlying physiological mechanism 94 , This could suggest there may be circumstances whereby whole, nutrient-dense foods may require a lower relative intake to maximize post-exercise anabolism than other isolated protein sources.

Although additional research is warranted to define the anabolic potential of whole food and its associated dose-response relationship to post-exercise anabolism, a target of ~0. Although it is generally accepted that daily protein requirements are elevated in strength athletes 96 , habitual intakes of populations engaged in chronic resistance training generally far exceed most recommendations i.

Habitually high protein diets increase the capacity for protein catabolism and amino acid oxidation as a means to manage this excess macronutrient load From an acute feeding standpoint, rodent models have demonstrated that adaptation to a high protein intake is accompanied by a greater splanchnic extraction of dietary nitrogen, which results in an attenuated post-prandial delivery to and deposition of dietary nitrogen in peripheral tissues In this way, the gut may act as a buffer to ensure amino acid delivery to peripheral tissues including muscle is relatively constant regardless of habitual dietary protein intake.

This has some support in humans as there is reduced dietary amino acid availability after consumption of 25 g of milk protein when adapted to a moderate 1. Collectively these data could suggest that individuals habituated to lower protein diet approximating the recommended dietary allowance RDA; 0.

However, the threshold at which this greater acute requirement may manifest could be relatively high e. Muscle protein synthesis is an energetically expensive process and is down-regulated during periods of cellular energy stress, such as during a diet-induced negative energy balance 49 , The post-exercise stimulation of myofibrillar protein synthesis with dietary protein ingestion is not affected by low levels of muscle glycogen , highlighting that acute energy restriction does not constrain post-exercise muscle remodeling with exogenous amino acid ingestion.

In contrast, more chronic periods of negative energy balance i. In addition, after a 5-day moderate protein i. Although the maximal absolute protein intake was lower than previous dose-response studies during energy balance i. While it is possible that maximal rates of myofibrillar protein synthesis may generally be constrained during chronic diet-induced negative energy balance, the lack of a plateau and the relatively modest increase in myofibrillar protein synthesis with 30 g of protein could also suggest that the protein intake required to maximize post-exercise myofibrillar protein synthesis is slightly greater during a period of energy restriction.

This would generally be in line with the observations that high daily dietary protein intakes i. Additional benefits for higher protein intakes during negative energy balance could be increased satiety and post-prandial thermogenesis , both of which would help support weight loss goals.

Therefore, although it has been suggested that 0. Beyond traditional derangements in glucose metabolism, it is becoming appreciated that excess body fat may also be an independent factor contributing to the dysregulation of muscle protein synthesis in obese populations For example, obesity has been associated with a blunted myofibrillar protein synthetic response to dietary protein ingestion i.

In addition, this anabolic resistance, which is not reported in relatively active obese individuals i. Thus, inasmuch as this anabolic resistance extends to the post-exercise sensitivity to dietary amino acids, it could be argued that obese individuals may require a greater relative protein intake than their lean counterparts when normalized to the metabolically active lean body mass.

However, studies used in the present analysis that yielded a relative protein intake of ~0. Therefore, providing recommendations relative to total body mass would result in a greater dose per kg lean body mass in obese individuals i.

A single bout of resistance exercise can increase muscle protein synthesis for up to 24—48 h with the duration for which it is elevated influenced by training history of the athlete 13 , and the specific exercise stimulus 11 , which ultimately factor into the general inability of single acute i.

However, individuals who are able to support greater rates of myofibrillar protein synthesis over this 24—48 h post-exercise recovery period have been shown to experience greater training-induced gains in muscle hypertrophy Dietary protein consumed at any point during this prolonged 24—48 h recovery period would ultimately contribute to the remodeling of skeletal muscle.

Outside of the response after a single meal, the pattern and distribution of dietary protein ingestion has been shown to influence muscle protein synthesis over 12—24 h both at rest and after resistance exercise 28 , , For example, the repeated ingestion of 20 g of whey protein ~0.

This has led to the suggesting that 4—5 meal occasions, which is the typical feeding frequency already adopted by many elite athletes 24 , would be the most favorable and metabolically efficient means to consume one's daily protein intake if the goal is to maximize skeletal muscle remodeling while simultaneously minimizing irreversible amino acid oxidative catabolism 28 , Both of these estimates are within the range of intakes suggested to maximize lean mass growth with training and are in line with current sports science consensus recommendations for daily protein intake The present review puts forth the argument that protein recommendations should be normalized to the body weight of an individual for a greater ease of translation of the dose that maximizes muscle protein synthesis and minimizes amino acid oxidation during the recovery from resistance exercise.

Based on re-analysis of previously published literature, an intake of ~0. The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Kirsten E. Bell, Christopher Séguin, Protein Synthesis for Recovery Parise, Prtoein K. Baker, Stuart Proten. Resistance exercise RE and aerobic exercise are recommended for older adults for fitness and strength. High-intensity interval exercise HIIT is an understudied but potent potential alternative to aerobic exercise. Sean is a Allergy-safe diets for athletes and researcher Synhtesis experience Protein Synthesis for Recovery ySnthesis, field research, and data analytics. When trying to optimize muscle growthprotein intake is essential. But Protein Synthesis for Recovery are limited by how much protein Progein can synthesize to repair and grow your muscles. This brings into question the importance of protein timing and amounts and how to best stimulate muscles to grow. Manufacturers of sports supplements and protein powders often claim that their products can increase muscle protein synthesis MPS. While this suggests that sports supplements somehow facilitate changes in muscle mass, the process is more complicated than that. Muscle growth is ultimately achieved with the combination of resistance training and protein intake.