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Human Muscle Protein Synthetic Responses during Weight-Bearing and Non-Weight-Bearing Exercise: A Comparative Study of Exercise Modes and Recovery Nutrition.

Pasiakos SM, McClung HL, Margolis LM, Murphy NE, Lin GG, Hydren JR, Young AJ - PLoS ONE (2015)

Bottom Line: Mixed-muscle and sarcoplasmic MPS were higher in recovery for LC than CE (mode main effect, P < 0.05).No other differences or interactions (mode x drink) were observed.These data show that, although whole-body protein turnover responses to absolute VO2-matched LC and CE are the same, LC elicited a greater muscle protein synthetic response than CE.

View Article: PubMed Central - PubMed

Affiliation: Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America.

ABSTRACT
Effects of conventional endurance (CE) exercise and essential amino acid (EAA) supplementation on protein turnover are well described. Protein turnover responses to weighted endurance exercise (i.e., load carriage, LC) and EAA may differ from CE, because the mechanical forces and contractile properties of LC and CE likely differ. This study examined muscle protein synthesis (MPS) and whole-body protein turnover in response to LC and CE, with and without EAA supplementation, using stable isotope amino acid tracer infusions. Forty adults (mean ± SD, 22 ± 4 y, 80 ± 10 kg, VO 2peak 4.0 ± 0.5 L ∙ min(-1)) were randomly assigned to perform 90 min, absolute intensity-matched (2.2 ± 0.1 VO2 L ∙ m(-1)) LC (performed on a treadmill wearing a vest equal to 30% of individual body mass, mean ± SD load carried 24 ± 3 kg) or CE (cycle ergometry performed at the same absolute VO2 as LC) exercise, during which EAA (10 g EAA, 3.6 g leucine) or control (CON, non-nutritive) drinks were consumed. Mixed-muscle and myofibrillar MPS were higher during exercise for LC than CE (mode main effect, P < 0.05), independent of dietary treatment. EAA enhanced mixed-muscle and sarcoplasmic MPS during exercise, regardless of mode (drink main effect, P < 0.05). Mixed-muscle and sarcoplasmic MPS were higher in recovery for LC than CE (mode main effect, P < 0.05). No other differences or interactions (mode x drink) were observed. However, EAA attenuated whole-body protein breakdown, increased amino acid oxidation, and enhanced net protein balance in recovery compared to CON, regardless of exercise mode (P < 0.05). These data show that, although whole-body protein turnover responses to absolute VO2-matched LC and CE are the same, LC elicited a greater muscle protein synthetic response than CE.

No MeSH data available.


Related in: MedlinePlus

Experimental design.Load carriage (LC) and conventional endurance (CE) exercise muscle protein synthesis and whole-body protein turnover protocols.
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pone.0140863.g001: Experimental design.Load carriage (LC) and conventional endurance (CE) exercise muscle protein synthesis and whole-body protein turnover protocols.

Mentions: Exercise and recovery MPS responses to LC, with and without EAA supplementation, were determined using primed, constant infusions of L-[2H5]-phenylalanine (2.8 mol∙kg-1; 0.07 mol∙kg-1∙min-1). Whole-body protein turnover was assessed in recovery using primed, constant infusions of L-[1-13C]-leucine (7.6 μmol∙kg-1; 7.6 μmol·kg-1∙h-1). Volunteers received a bolus injection of 13C-bicarbonate (2.35 μmol∙kg-1) before starting the primed, constant infusion of L-[1-13C]-leucine to prime the bicarbonate pool. Baseline blood and breath samples were collected to correct for background isotopic enrichments before stable isotope infusions were initiated (Fig 1). Protein turnover studies were conducted between 0600 and 1300 h, after a 12 h fast. Isotopes were commercially available (Cambridge Isotope Laboratories, Andover, MA) and certified sterile and pyrogen free before administering.


Human Muscle Protein Synthetic Responses during Weight-Bearing and Non-Weight-Bearing Exercise: A Comparative Study of Exercise Modes and Recovery Nutrition.

Pasiakos SM, McClung HL, Margolis LM, Murphy NE, Lin GG, Hydren JR, Young AJ - PLoS ONE (2015)

Experimental design.Load carriage (LC) and conventional endurance (CE) exercise muscle protein synthesis and whole-body protein turnover protocols.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608805&req=5

pone.0140863.g001: Experimental design.Load carriage (LC) and conventional endurance (CE) exercise muscle protein synthesis and whole-body protein turnover protocols.
Mentions: Exercise and recovery MPS responses to LC, with and without EAA supplementation, were determined using primed, constant infusions of L-[2H5]-phenylalanine (2.8 mol∙kg-1; 0.07 mol∙kg-1∙min-1). Whole-body protein turnover was assessed in recovery using primed, constant infusions of L-[1-13C]-leucine (7.6 μmol∙kg-1; 7.6 μmol·kg-1∙h-1). Volunteers received a bolus injection of 13C-bicarbonate (2.35 μmol∙kg-1) before starting the primed, constant infusion of L-[1-13C]-leucine to prime the bicarbonate pool. Baseline blood and breath samples were collected to correct for background isotopic enrichments before stable isotope infusions were initiated (Fig 1). Protein turnover studies were conducted between 0600 and 1300 h, after a 12 h fast. Isotopes were commercially available (Cambridge Isotope Laboratories, Andover, MA) and certified sterile and pyrogen free before administering.

Bottom Line: Mixed-muscle and sarcoplasmic MPS were higher in recovery for LC than CE (mode main effect, P < 0.05).No other differences or interactions (mode x drink) were observed.These data show that, although whole-body protein turnover responses to absolute VO2-matched LC and CE are the same, LC elicited a greater muscle protein synthetic response than CE.

View Article: PubMed Central - PubMed

Affiliation: Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States of America.

ABSTRACT
Effects of conventional endurance (CE) exercise and essential amino acid (EAA) supplementation on protein turnover are well described. Protein turnover responses to weighted endurance exercise (i.e., load carriage, LC) and EAA may differ from CE, because the mechanical forces and contractile properties of LC and CE likely differ. This study examined muscle protein synthesis (MPS) and whole-body protein turnover in response to LC and CE, with and without EAA supplementation, using stable isotope amino acid tracer infusions. Forty adults (mean ± SD, 22 ± 4 y, 80 ± 10 kg, VO 2peak 4.0 ± 0.5 L ∙ min(-1)) were randomly assigned to perform 90 min, absolute intensity-matched (2.2 ± 0.1 VO2 L ∙ m(-1)) LC (performed on a treadmill wearing a vest equal to 30% of individual body mass, mean ± SD load carried 24 ± 3 kg) or CE (cycle ergometry performed at the same absolute VO2 as LC) exercise, during which EAA (10 g EAA, 3.6 g leucine) or control (CON, non-nutritive) drinks were consumed. Mixed-muscle and myofibrillar MPS were higher during exercise for LC than CE (mode main effect, P < 0.05), independent of dietary treatment. EAA enhanced mixed-muscle and sarcoplasmic MPS during exercise, regardless of mode (drink main effect, P < 0.05). Mixed-muscle and sarcoplasmic MPS were higher in recovery for LC than CE (mode main effect, P < 0.05). No other differences or interactions (mode x drink) were observed. However, EAA attenuated whole-body protein breakdown, increased amino acid oxidation, and enhanced net protein balance in recovery compared to CON, regardless of exercise mode (P < 0.05). These data show that, although whole-body protein turnover responses to absolute VO2-matched LC and CE are the same, LC elicited a greater muscle protein synthetic response than CE.

No MeSH data available.


Related in: MedlinePlus