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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

Stable isotope enrichments.Plasma 2H5-phenylalanine (A), plasma 13KIC (B), muscle intracellular 2H5-phenylalanine (C), and breath 13CO2 (D) isotopic enrichments during recovery from a 90 min, metabolically matched load carriage (LC) or conventional endurance (CE) exercise bout, with and without (control, CON) essential amino acid (EAA) supplementation. Data are mean ± SD, n = 10 per group. Drink-by-time interactions were observed, EAA different than CON, P < 0.05.
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pone.0140863.g002: Stable isotope enrichments.Plasma 2H5-phenylalanine (A), plasma 13KIC (B), muscle intracellular 2H5-phenylalanine (C), and breath 13CO2 (D) isotopic enrichments during recovery from a 90 min, metabolically matched load carriage (LC) or conventional endurance (CE) exercise bout, with and without (control, CON) essential amino acid (EAA) supplementation. Data are mean ± SD, n = 10 per group. Drink-by-time interactions were observed, EAA different than CON, P < 0.05.

Mentions: Volunteers consumed equal volumes (500 mL total, 125 mL per serving) of either the EAA or flavor-matched, non-nutritive CON drinks in 30 min intervals, beginning at the start of the exercise session and ending after completing the 90 min bout. The EAA formulation and feeding pattern (10 g EAA: 0.7 g histidine, 0.7 g isoleucine, 3.6 g leucine, 1.2 g lysine, 0.3 g methionine, 1.4 g phenylalanine, 1.0 g threonine, and 1 g valine) was based on our previous work demonstrating a MPS and whole-body protein turnover advantage of consuming small doses of leucine-enriched EAA during CE [1]. The EAA drink also provided 46 g of carbohydrate, which we recognize may contribute to our turnover outcomes. However, our intent was to test a palatable, eat-on-the move, combat ration recovery beverage item that provides not only EAA to optimize MPS and whole-body protein turnover, but also energy in the form of carbohydrate (223 kcal) to sustain activity during military operations. Furthermore, recent data suggests that adding carbohydrate to a 10g EAA solution does not enhance MPS above and beyond consuming the 10 g dose of EAA alone [18]. The phenylalanine and leucine content of the EAA drink were not enriched with small amounts of L-[2H5]-phenylalanine and L-[1-13C]-leucine, an approach commonly used when EAA (or protein) is provided as a bolus to limit the potential dilution of the tracer pool [19]. Consuming the EAA drink in four small doses (i.e., 350 mg of phenylalanine and 900 mg of leucine per serving), over 90 min period, likely minimized any isotopic dilution that may have occurred if the EAA drink was consumed as a bolus (Fig 2A–2D).


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)

Stable isotope enrichments.Plasma 2H5-phenylalanine (A), plasma 13KIC (B), muscle intracellular 2H5-phenylalanine (C), and breath 13CO2 (D) isotopic enrichments during recovery from a 90 min, metabolically matched load carriage (LC) or conventional endurance (CE) exercise bout, with and without (control, CON) essential amino acid (EAA) supplementation. Data are mean ± SD, n = 10 per group. Drink-by-time interactions were observed, EAA different than CON, P < 0.05.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0140863.g002: Stable isotope enrichments.Plasma 2H5-phenylalanine (A), plasma 13KIC (B), muscle intracellular 2H5-phenylalanine (C), and breath 13CO2 (D) isotopic enrichments during recovery from a 90 min, metabolically matched load carriage (LC) or conventional endurance (CE) exercise bout, with and without (control, CON) essential amino acid (EAA) supplementation. Data are mean ± SD, n = 10 per group. Drink-by-time interactions were observed, EAA different than CON, P < 0.05.
Mentions: Volunteers consumed equal volumes (500 mL total, 125 mL per serving) of either the EAA or flavor-matched, non-nutritive CON drinks in 30 min intervals, beginning at the start of the exercise session and ending after completing the 90 min bout. The EAA formulation and feeding pattern (10 g EAA: 0.7 g histidine, 0.7 g isoleucine, 3.6 g leucine, 1.2 g lysine, 0.3 g methionine, 1.4 g phenylalanine, 1.0 g threonine, and 1 g valine) was based on our previous work demonstrating a MPS and whole-body protein turnover advantage of consuming small doses of leucine-enriched EAA during CE [1]. The EAA drink also provided 46 g of carbohydrate, which we recognize may contribute to our turnover outcomes. However, our intent was to test a palatable, eat-on-the move, combat ration recovery beverage item that provides not only EAA to optimize MPS and whole-body protein turnover, but also energy in the form of carbohydrate (223 kcal) to sustain activity during military operations. Furthermore, recent data suggests that adding carbohydrate to a 10g EAA solution does not enhance MPS above and beyond consuming the 10 g dose of EAA alone [18]. The phenylalanine and leucine content of the EAA drink were not enriched with small amounts of L-[2H5]-phenylalanine and L-[1-13C]-leucine, an approach commonly used when EAA (or protein) is provided as a bolus to limit the potential dilution of the tracer pool [19]. Consuming the EAA drink in four small doses (i.e., 350 mg of phenylalanine and 900 mg of leucine per serving), over 90 min period, likely minimized any isotopic dilution that may have occurred if the EAA drink was consumed as a bolus (Fig 2A–2D).

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