Commentaries on Viewpoint: What is the relationship between acute measure of muscle protein synthesis and changes in muscle mass?

ViewpointCommentaries on Viewpoint: What is the relationship between acute measure of muscle protein synthesis and changes in muscle mass?Published Online:15 Feb 2015https://doi.org/10.1152/japplphysiol.01069.2014MoreSectionsPDF (57 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations COMMENTARY RESPONSE TO VIEWPOINT: “WHAT IS THE RELATIONSHIP BETWEEN ACUTE MEASURES OF MUSCLE PROTEIN SYNTHESIS AND CHANGES IN MUSCLE MASS?”Philip J. Atherton, B.E. Phillips, M.S. Brook, D.J. Wilkinson, and K. Smith.Author AffiliationsMRC/ARUK Centre of Excellence for Musculoskeletal Ageing Research School of Medicine University of Nottingham, UK.T.E. Etheridge.Author AffiliationsDepartment of Sport and Health Sciences College of Life and Environmental Sciences University of Exeter, UK.to the editor: Mitchell et al. (3) critique putative links between acute muscle protein synthesis (MPS) and ensuing hypertrophy after resistance exercise (RE) training (RT). Just two papers have addressed this longitudinally. The first reports that young but not older individuals exhibit acute (fasted mixed muscle MPS, 24 h post-RE) increases in MPS (2); yet hypertrophy gains, assessed by DXA and fiber area, were equal. Similarly, poor quantitative MPS linkages were reported 1–6 h post-RE (myofibrillar muscle, fed state) with ensuing hypertrophy (4), i.e., two study's suggesting bona fide dissociation. However, for (2), prior reports of age-related temporal differences in acute MPS responses to RE (1) and lack of intra/inter age group correlations (2) mitigate such resounding conclusions. Also, in (4), RE was under fed state conditions; this is significant because consumption of protein feeds extends (not amplifies) elevations in MPS post-RE (5). Therefore, MPS responses 1–6 h post-RE were chiefly predominated by feeding, i.e., the coupling of which to RE may not aptly reflect interindividual variation (5), e.g., due to isolated mechano-auto/paracrine responses to RE. Yet, acute MPS can/does inform on group interventions for RT-induced muscle hypertrophy, signifying it a practicable, informative end-point. But, could quantitative relationships still exist and what defines “acute” post-RE MPS? Fasted/fed? Immediately (<6 h?)/later (>24?) What muscle fraction(s)? Is there an applicable “snapshot”? Without defining acute this is indiscernible. The authors justifiably raise potential technical, temporal, methodological confounder(s). Because hypertrophy is a heterogeneous and temporally dynamic process we hypothesize that (coupled to not isolating/fractionating/holistically capturing “acute” MPS) interindividual trajectories and plateauing hypertrophy in the face of fixed study end-points are the major barriers to defining quantitative links between acute MPS and RT-induced hypertrophy.REFERENCES1. Drummond MJ, Dreyer HC, Pennings B, Fry CS, Dhanani S, Dillon EL, Sheffield-Moore M, Volpi E, Rasmussen BB. Skeletal muscle protein anabolic response to resistance exercise and essential amino acids is delayed with aging. J Appl Physiol 104: 1452–1461, 2008.Link | ISI | Google Scholar2. Mayhew DL, Kim JS, Cross JM, Ferrando AA, Bamman MM. Translational signaling responses preceding resistance training-mediated myofiber hypertrophy in young and old humans. J Appl Physiol 107: 1655–1662, 2009.Link | ISI | Google Scholar3. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between the acute muscle protein synthetic response and changes in muscle mass? J Appl Physiol; doi: 10.1152/japplphysiol.00609.2014.Link | ISI | Google Scholar4. Mitchell CJ, Churchward-Venne TA, Parise G, Bellamy L, Baker SK, Smith K, Atherton PJ, Phillips SM. Acute post-exercise myofibrillar protein synthesis is not correlated with resistance training-induced muscle hypertrophy in young men. PLoS One 9: e89431, 2014.Crossref | PubMed | ISI | Google Scholar5. Moore DR, Tang JE, Burd NA, Rerecich T, Tarnopolsky MA, Phillips SM. Differential stimulation of myofibrillar and sarcoplasmic protein synthesis with protein ingestion at rest and after resistance exercise. J Physiol 587: 897–2009, 2009.Crossref | PubMed | ISI | Google ScholarREFERENCES1. Drummond MJ, Dreyer HC, Pennings B, Fry CS, Dhanani S, Dillon EL, Sheffield-Moore M, Volpi E, Rasmussen BB. Skeletal muscle protein anabolic response to resistance exercise and essential amino acids is delayed with aging. J Appl Physiol 104: 1452–1461, 2008.Link | ISI | Google Scholar2. Mayhew DL, Kim JS, Cross JM, Ferrando AA, Bamman MM. Translational signaling responses preceding resistance training-mediated myofiber hypertrophy in young and old humans. J Appl Physiol 107: 1655–1662, 2009.Link | ISI | Google Scholar3. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between the acute muscle protein synthetic response and changes in muscle mass? J Appl Physiol; doi: 10.1152/japplphysiol.00609.2014.Link | ISI | Google Scholar4. Mitchell CJ, Churchward-Venne TA, Parise G, Bellamy L, Baker SK, Smith K, Atherton PJ, Phillips SM. Acute post-exercise myofibrillar protein synthesis is not correlated with resistance training-induced muscle hypertrophy in young men. PLoS One 9: e89431, 2014.Crossref | PubMed | ISI | Google Scholar5. Moore DR, Tang JE, Burd NA, Rerecich T, Tarnopolsky MA, Phillips SM. Differential stimulation of myofibrillar and sarcoplasmic protein synthesis with protein ingestion at rest and after resistance exercise. J Physiol 587: 897–2009, 2009.Crossref | PubMed | ISI | Google ScholarCOMMENT VIEWPOINT: “WHAT IS THE RELATIONSHIP BETWEEN ACUTE MEASURES OF MUSCLE PROTEIN SYNTHESIS AND CHANGES IN MUSCLE MASS?”Benjamin F. Miller and Karyn L. Hamilton.Author AffiliationsTranslational Research on Aging and Chronic Disease Laboratory Department of Health and Exercise Science Colorado State University.to the editor: Mitchell et al. (4) state that acute measurements of muscle protein synthesis may not necessarily reflect the magnitude of hypertrophy during long-term training studies, which we agree with. Two points deserve further comment: 1) magnitude of muscle protein synthesis does not necessarily equate with hypertrophy, but rather remodeling, and 2) limitations of acute measurements are a primary reason some in the field advocate for long-term measurements of synthesis. Regarding the first point, as the authors mention, synthesis is more commonly measured than breakdown and is likely the driving factor behind phenotypic change. However, it is still important to consider that breakdown can change the outcomes. If a high rate of synthesis is accompanied by equal or slightly lower rates of degradation, one would have hypertrophy, whereas the other may not. Importantly though, both are indicative of remodeling. This concept is clear when one studies endurance exercise where there is a high degree of protein remodeling, and phenotypic change, without hypertrophy (5). Regarding our second point, we have advocated for the use of deuterium oxide to measure long-term changes in protein synthesis (1, 3) because of the limitations of acute protein synthesis measurements (4). We have even emphasized this point in a previous “Viewpoint” (2). Although acute measurements of protein synthesis have value, the overall outcome of a long-term treatment or intervention should be assessed by long-term measurement techniques to understand the integrated responses over time. We hope that others, like Mitchell et al., continue to recognize this important point.REFERENCES1. Miller BF, Drake JC, Naylor B, Price JC, Hamilton KL. The measurement of protein synthesis for assessing proteostasis in studies of slowed aging. Ageing Res Rev 18: 106–111, 2014.Crossref | ISI | Google Scholar2. Miller BF, Hamilton KL, Cuthbertson DJ, Smith K, Williams J, Mittendorfer B, Greenhaff P, Atherton P. Commentaries on Viewpoint: The curious case of anabolic resistance: old wives' tales or new fables? J Appl Physiol 112: 1236, 2012.Link | ISI | Google Scholar3. Miller BF, Hamilton KL. A perspective on the determination of mitochondrial biogenesis. Am J Physiol Endocrinol Metab 302: E496–E499, 2012.Link | ISI | Google Scholar4. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between the acute muscle protein synthetic response and changes in muscle mass? J Appl Physiol; doi: 10.1152/japplphysiol.00609.2014.Link | ISI | Google Scholar5. Scalzo RL, Peltonen GL, Binns SE, Shankaran M, Giordano GR, Hartley DA, Klochak AL, Lonac MC, Paris HLR, Szallar SE, Wood LM, Peelor FF, Holmes WE, Hellerstein MK, Bell C, Hamilton KL, Miller BF. Greater muscle protein synthesis and mitochondrial biogenesis in males compared with females during sprint interval training. FASEB J 28: 2705–2714, 2014.Crossref | PubMed | ISI | Google ScholarREFERENCES1. Miller BF, Drake JC, Naylor B, Price JC, Hamilton KL. The measurement of protein synthesis for assessing proteostasis in studies of slowed aging. Ageing Res Rev 18: 106–111, 2014.Crossref | ISI | Google Scholar2. Miller BF, Hamilton KL, Cuthbertson DJ, Smith K, Williams J, Mittendorfer B, Greenhaff P, Atherton P. Commentaries on Viewpoint: The curious case of anabolic resistance: old wives' tales or new fables? J Appl Physiol 112: 1236, 2012.Link | ISI | Google Scholar3. Miller BF, Hamilton KL. A perspective on the determination of mitochondrial biogenesis. Am J Physiol Endocrinol Metab 302: E496–E499, 2012.Link | ISI | Google Scholar4. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between the acute muscle protein synthetic response and changes in muscle mass? J Appl Physiol; doi: 10.1152/japplphysiol.00609.2014.Link | ISI | Google Scholar5. Scalzo RL, Peltonen GL, Binns SE, Shankaran M, Giordano GR, Hartley DA, Klochak AL, Lonac MC, Paris HLR, Szallar SE, Wood LM, Peelor FF, Holmes WE, Hellerstein MK, Bell C, Hamilton KL, Miller BF. Greater muscle protein synthesis and mitochondrial biogenesis in males compared with females during sprint interval training. FASEB J 28: 2705–2714, 2014.Crossref | PubMed | ISI | Google ScholarTHE POSTEXERCISE INCREASE IN MUSCLE PROTEIN SYNTHESIS RATE IS INDICATIVE OF SKELETAL MUSCLE RECONDITIONING RATHER THAN MUSCLE HYPERTROPHY PER SENicholas A. Burd, Joseph W. Beals, and Stephan van Vliet.Author AffiliationsDepartment of Kinesiology and Community Health University of Illinois at Urbana-Champaign.Luc J.C. van Loon.Author AffiliationsMaastricht University.to the editor: We regard the acute muscle protein synthetic response to exercise as an indicator of skeletal muscle reconditioning rather than predictive for muscle hypertrophy. For example, a single bout of endurance-type exercise also acutely increases muscle protein fractional synthetic rate (FSR) (1–3). The increase in the muscle protein synthetic response to endurance type exercise is generally not accompanied by substantial gains in muscle mass and, as such, is far from predictive for muscle hypertrophy in healthy, lean individuals. Instead, the postexercise increase in muscle protein synthesis is rather representative of muscle reconditioning, comprising muscle repair and remodeling. Consequently, the postexercise increase in muscle protein FSR should not be regarded as a marker for exercise training induced hypertrophy but rather as an indicator of skeletal muscle reconditioning, which comes in many different forms and measures. The muscle protein synthetic response to a single bout of resistance type exercise training may provide some insight in the extent of muscle hypertrophy observed during more prolonged resistance type exercise training but does not provide a quantitative estimation of hypertrophy in the individual (4).REFERENCES1. Beelen M, Zorenc A, Pennings B, Senden JM, Kuipers H, van Loon LJ. Impact of protein coingestion on muscle protein synthesis during continuous endurance type exercise. Am J Physiol Endocrinol Metab 300: E945–E954, 2011.Link | ISI | Google Scholar2. Carraro F, Stuart CA, Hartl WH, Rosenblatt J, Wolfe RR. Effect of exercise and recovery on muscle protein synthesis in human subjects. Am J Physiol Endocrinol Metab 259: E470–E476, 1990.Link | ISI | Google Scholar3. Harber MP, Konopka AR, Jemiolo B, Trappe SW, Trappe TA, Reidy PT. Muscle protein synthesis and gene expression during recovery from aerobic exercise in the fasted and fed states. Am J Physiol Regul Integr Comp Physiol 299: R1254–R1262, 2010.Link | ISI | Google Scholar4. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between the acute muscle protein synthetic response and changes in muscle mass? J Appl Physiol; doi: 10.1152/japplphysiol.00609.2014.Link | ISI | Google ScholarREFERENCES1. Beelen M, Zorenc A, Pennings B, Senden JM, Kuipers H, van Loon LJ. Impact of protein coingestion on muscle protein synthesis during continuous endurance type exercise. Am J Physiol Endocrinol Metab 300: E945–E954, 2011.Link | ISI | Google Scholar2. Carraro F, Stuart CA, Hartl WH, Rosenblatt J, Wolfe RR. Effect of exercise and recovery on muscle protein synthesis in human subjects. Am J Physiol Endocrinol Metab 259: E470–E476, 1990.Link | ISI | Google Scholar3. Harber MP, Konopka AR, Jemiolo B, Trappe SW, Trappe TA, Reidy PT. Muscle protein synthesis and gene expression during recovery from aerobic exercise in the fasted and fed states. Am J Physiol Regul Integr Comp Physiol 299: R1254–R1262, 2010.Link | ISI | Google Scholar4. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between the acute muscle protein synthetic response and changes in muscle mass? J Appl Physiol; doi: 10.1152/japplphysiol.00609.2014.Link | ISI | Google ScholarCOMMENT ON VIEWPOINT: WHAT IS THE RELATIONSHIP BETWEEN ACUTE MEASURES OF MUSCLE PROTEIN SYNTHESIS AND CHANGES IN MUSCLE MASS?Lindsay S. Macnaughton, Sophie L. Wardle, and Kevin D. Tipton.Author AffiliationsHealth and Exercise Sciences Research Group University of Stirling Stirling, Scotland.to the editor: Mitchell and colleagues (2) present a nicely balanced viewpoint regarding the discordance between acute measurements of muscle protein synthesis (MPS) and long-term muscle mass gains in response to exercise training and nutrition. Individual genetic and other physiological characteristics, as well as methodological limitations of the endpoint measures, are correctly identified as contributing factors to the hypertrophic variability inherent in these types of training studies (1). However, the practicalities of controlling long-term training studies themselves are not addressed.Consideration is warranted for the difficulties in controlling extended-duration intervention studies to generate appropriately valid and reliable results. Changes and variability in diet, timing of exercise in relation to meal ingestion, sleep patterns, daily stress, and compliance with the training regimen will contribute to the considerable intrinsic variability of measured changes in muscle mass (3). Small differences between interventions may easily be missed when these confounding factors are coupled with the variations outlined in the Viewpoint. Acute measurements are much easier to control and differences between interventions often can be easily detected. Therefore, any disconnect between acute metabolic studies and long-term changes in muscle mass do not necessarily reflect the worth of the metabolic studies.There is no question that acute measurements of MPS alone should not be used to predict the training response of any given individual. However, with appropriate appreciation for their limitations, these methods can play a valuable role in acquiring information to help determine appropriate training and nutrition interventions for various populations.REFERENCES1. Hartman JW, Tang JE, Wilkinson SB, Tarnopolsky MA, Lawrence RL, Fullerton AV, Phillips SM. Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass accretion than does consumption of soy or carbohydrate in young, novice, male weightlifters. Am J Clin Nutr 86: 373–381, 2007.Crossref | PubMed | ISI | Google Scholar2. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between the acute muscle protein synthetic response and changes in muscle mass? J Appl Physiol; doi:10.1152/japplphysiol.00609.2014.Link | ISI | Google Scholar3. Tipton KD. Efficacy and consequences of very-high-protein diets for athletes and exercisers. Proc Nutr Soc 70: 205–214, 2011.Crossref | ISI | Google ScholarREFERENCES1. Hartman JW, Tang JE, Wilkinson SB, Tarnopolsky MA, Lawrence RL, Fullerton AV, Phillips SM. Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass accretion than does consumption of soy or carbohydrate in young, novice, male weightlifters. Am J Clin Nutr 86: 373–381, 2007.Crossref | PubMed | ISI | Google Scholar2. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between the acute muscle protein synthetic response and changes in muscle mass? J Appl Physiol; doi:10.1152/japplphysiol.00609.2014.Link | ISI | Google Scholar3. Tipton KD. Efficacy and consequences of very-high-protein diets for athletes and exercisers. Proc Nutr Soc 70: 205–214, 2011.Crossref | ISI | Google ScholarCOMMENTARY RESPONSE TO VIEWPOINT: “WHAT IS THE RELATIONSHIP BETWEEN ACUTE MEASURES OF MUSCLE PROTEIN SYNTHESIS AND CHANGES IN MUSCLE MASS?”Andrew J. Murton.Author AffiliationsSchool of Biosciences The University of Nottingham, UK.F.B. Stephens and R. Billeter.Author AffiliationsMRC/ARUK Centre for Musculoskeletal Ageing Research School of Life Sciences The University of Nottingham Medical School, UK.B.T. Wall.Author AffiliationsDepartment of Sport and Health Sciences College of Life and Environmental Sciences University of Exeter, UK.to the editor: The authors raise several insightful points while describing the discordance they observe between acute measures of postexercise muscle protein synthesis (MPS) and the subsequent resistance exercise (RE) training-induced muscle hypertrophy (1, 2). Although the authors suggest that intersubject variability in the MPS response to RE is a likely major contributory factor, the impact of recruiting individuals naive to the mode of RE be of RE in individuals to in myofibrillar signaling (5), and of the protein response (4), that are to MPS we have observed that 24 h after a of the in muscle on and between individuals (3). we observed a in the of gene with MPS which could in the variability observed by the the response to a of RE was and was not by of muscle (3). these suggest when to changes in MPS to gains in muscle have a of to RE may a more Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between acute of muscle protein synthesis response and changes in muscle J Appl Physiol; doi:10.1152/japplphysiol.00609.2014.Link | ISI | Google Scholar2. Mitchell CJ, Churchward-Venne TA, Parise G, Bellamy L, Baker SK, Smith K, Atherton PJ, Phillips SM. Acute post-exercise myofibrillar protein synthesis is not correlated with resistance training-induced muscle hypertrophy in young men. PLoS One 9: e89431, 2014.Crossref | PubMed | ISI | Google Scholar3. Stephens F, K, Greenhaff in human skeletal muscle at the of resistance exercise training. J Appl Physiol | ISI | Google Scholar4. Parise G, Tarnopolsky The protein response is a Am J Physiol Regul Integr Comp Physiol | ISI | Google Scholar5. Cross JM, Bamman MM. Differential responses in old young of muscle after resistance Physiol 2010.Link | ISI | Google ScholarREFERENCES1. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between acute of muscle protein synthesis response and changes in muscle J Appl Physiol; doi:10.1152/japplphysiol.00609.2014.Link | ISI | Google Scholar2. Mitchell CJ, Churchward-Venne TA, Parise G, Bellamy L, Baker SK, Smith K, Atherton PJ, Phillips SM. Acute post-exercise myofibrillar protein synthesis is not correlated with resistance training-induced muscle hypertrophy in young men. PLoS One 9: e89431, 2014.Crossref | PubMed | ISI | Google Scholar3. Stephens F, K, Greenhaff in human skeletal muscle at the of resistance exercise training. J Appl Physiol | ISI | Google Scholar4. Parise G, Tarnopolsky The protein response is a Am J Physiol Regul Integr Comp Physiol | ISI | Google Scholar5. Cross JM, Bamman MM. Differential responses in old young of muscle after resistance Physiol 2010.Link | ISI | Google MEASURES OF MUSCLE PROTEIN and A. and Research Group School of Exercise Science for Sport and Exercise Sciences University the editor: The by Mitchell and colleagues (4) a that acute responses to interventions are not the for training-induced changes in outcomes. Skeletal muscle with the to the type and of protein in response to of the and (3). is to but a variation in the degree of between is the responses after interventions (2). The state that an genetic and are potential for after resistance training (RT). to that is the that may of the variability in the muscle hypertrophic the acute response to a single bout of resistance exercise is with the subsequent accretion of lean mass after (1). Although this postexercise measures of could be a valid of an to after acute measures of MPS still provide important insight to the in response to it is clear that training studies with responses of and are to provide insight as to interventions in responses between Bellamy LM, S, A, Mitchell CJ, Phillips Baker S, Parise The acute response and skeletal muscle hypertrophy resistance training. PLoS One 9: 2014.Crossref | PubMed | ISI | Google Scholar2. C, T, and in the of to exercise. Physiol 2011.Crossref | PubMed | ISI | Google Scholar3. M, MJ, of exercise. 2014.Crossref | PubMed | ISI | Google Scholar4. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between the acute muscle protein synthetic response and changes in muscle mass? J Appl Physiol; doi: 10.1152/japplphysiol.00609.2014.Link | ISI | Google ScholarREFERENCES1. Bellamy LM, S, A, Mitchell CJ, Phillips Baker S, Parise The acute response and skeletal muscle hypertrophy resistance training. PLoS One 9: 2014.Crossref | PubMed | ISI | Google Scholar2. C, T, and in the of to exercise. Physiol 2011.Crossref | PubMed | ISI | Google Scholar3. M, MJ, of exercise. 2014.Crossref | PubMed | ISI | Google Scholar4. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between the acute muscle protein synthetic response and changes in muscle mass? J Appl Physiol; doi: 10.1152/japplphysiol.00609.2014.Link | ISI | Google AND THE OF PROTEIN S. and the editor: Mitchell and colleagues their for a lack of between acute and muscle protein synthesis (MPS) with their and The for such a lack is in of these However, while in and the hypertrophy after or of resistance training was between and the in after was our the was because in the was during the while in and it was not. it is the as between MPS response after acute and are to because they can increase more than in than a do not have because of their is in the The of increases with the increase of because more is during when muscle are and protein protein and protein which during postexercise repair in protein This is by the by the (2). of protein synthesis by field (1) that muscle by should have MPS stimulation of protein and synthesis in human FASEB J | ISI | Google Scholar2. Fry CS, JM, KL, Drummond MJ, Volpi E, Rasmussen BB. is not for muscle protein synthesis exercise. J Appl Physiol 2012.Link | ISI | Google Scholar3. RL, R. The relationship between protein synthesis and in J | ISI | Google Scholar4. L, in A J Scholar5. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between acute of muscle protein synthesis response and changes in muscle mass? J Appl Physiol; doi: 10.1152/japplphysiol.00609.2014.Link | ISI | Google ScholarREFERENCES1. stimulation of protein and synthesis in human FASEB J | ISI | Google Scholar2. Fry CS, JM, KL, Drummond MJ, Volpi E, Rasmussen BB. is not for muscle protein synthesis exercise. J Appl Physiol 2012.Link | ISI | Google Scholar3. RL, R. The relationship between protein synthesis and in J | ISI | Google Scholar4. L, in A J Scholar5. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between acute of muscle protein synthesis response and changes in muscle mass? J Appl Physiol; doi: 10.1152/japplphysiol.00609.2014.Link | ISI | Google of Medicine School of the editor: Mitchell and colleagues have identified an important can a single measurement of protein synthesis be to provide changes in muscle Muscle mass is often used as a for muscle protein but muscle muscle muscle muscle in or type and to (3). For of muscle mass in exercise of with or without of muscle by an increase in protein synthesis muscle protein no is without measurement of protein of or used to measure or skeletal muscle protein in (2). rates of protein synthesis and are often by the rate of protein the of from muscle (4). This does not both synthesis and information to be from the The rate of protein is greater than the rate of protein synthesis of muscle hypertrophy or If the of protein synthesis is to provide an of changes in muscle protein we suggest that the of the of in a of muscle as for assessing the of on muscle hypertrophy Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. What is the relationship between the acute muscle protein synthetic response and changes in muscle mass? J Appl Physiol; doi: 10.1152/japplphysiol.00609.2014.Link | ISI | Google Scholar2. PJ, DL, P, muscle protein breakdown in with type | PubMed | ISI | Google Scholar3. J, J, resistance muscle protein of the by in muscle | PubMed | ISI | Google Scholar4. J, Exercise in muscle protein and 2009.Crossref | PubMed | ISI | Google Scholar5. J, J, of protein muscle in 2007.Crossref | ISI | Google ScholarREFERENCES1. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. What is the relationship between the acute muscle protein synthetic response and changes in muscle mass? J Appl Physiol; doi: 10.1152/japplphysiol.00609.2014.Link | ISI | Google Scholar2. PJ, DL, P, muscle protein breakdown in with type | PubMed | ISI | Google Scholar3. J, J, resistance muscle protein of the by in muscle | PubMed | ISI | Google Scholar4. J, Exercise in muscle protein and 2009.Crossref | PubMed | ISI | Google Scholar5. J, J, of protein muscle in 2007.Crossref | ISI | Google OF IN AND MUSCLE University.to the editor: Muscle a is with an of to muscle and skeletal This is the dynamic between muscle protein synthesis and (1). Muscle hypertrophy when protein synthesis protein Although the authors (2) agree with the of acute measurements in of and they advocate the for long-term studies to understand the due to hypertrophy is a process muscle and metabolic many have observed other such as genetic and and training to the hypertrophic response to a training both the rate and the in lean muscle and are also to play in hypertrophic process (3). some of these have on remodeling, and fluid A greater in (4). A in responses to and exercise training is reported (5). was reported to have on and and (3). the of such it is appropriate to long-term of exercise training on muscle hypertrophy.REFERENCES1. M, resistance exercise of and muscle J Appl Physiol | ISI | Google Scholar2. Mitchell CJ, Churchward-Venne TA, Cameron-Smith D, Phillips SM. Viewpoint: What is the relationship between acute measures of muscle protein synthesis and changes in muscle mass? 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Rev | ISI | Google PDF to responses to acute exercise and their for in skeletal muscle to exercise and P. | in muscle protein synthesis for muscle in in the of muscle protein | of and skeletal muscle in and | the of protein synthesis during skeletal muscle hypertrophy induced by | of and of in | the of Exercise and of and exercise muscle protein synthesis in in young Kevin J. S. J. P. P. and J. van | of of in Skeletal Muscle in muscle protein synthesis and biogenesis anabolic resistance to exercise in | The of for athletes and and | metabolic and temporal of muscle hypertrophy in response to resistance | of Sport of different types of on muscle protein synthesis in on a and on Viewpoint: What is the relationship between the acute muscle protein synthetic response and changes in muscle J. A. and Stuart | of from this the in