β-Hydroxy-β-Methylbutyrate (HMB) Supplementation Does Not Affect Changes in Strength or Body Composition during Resistance Training in Trained Men

This investigation evaluated the effects of oral β-Hydroxy-β-Methylbutyrate (HMB) supplementation on training responses in resistance-trained male athletes who were randomly administered HMB in standard encapsulation (SH), HMB in time release capsule (TRH), or placebo (P) in a double-blind fashion. Subjects ingested 3 g · day−1 of HMB or placebo for 6 weeks. Tests were conducted pre-supplementation and following 3 and 6 weeks of supplementation. The testing battery assessed body mass, body composition (using dual energy x-ray absorptiometry), and 3-repetition maximum isoinertial strength, plus biochemical parameters, including markers of muscle damage and muscle protein turnover. While the training and dietary intervention of the investigation resulted in significant strength gains (p < .001) and an increase in total lean mass (p = .01), HMB administration had no influence on these variables. Likewise, biochemical markers of muscle protein turnover and muscle damage were also unaffected by HMB supplementation. The data indicate that 6 weeks of HMB supplementation in either SH or TRH form does not influence changes in strength and body composition in response to resistance training in strength-trained athletes.

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Resistance-training-induced adaptations in skeletal muscle protein turnover in the fed state

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y02-134 ◽

2002 ◽

Vol 80 (11) ◽

pp. 1045-1053 ◽

Cited By ~ 106

Author(s):

S M Phillips ◽

G Parise ◽

B D Roy ◽

K D Tipton ◽

R R Wolfe ◽

...

Keyword(s):

Skeletal Muscle ◽

Resistance Training ◽

Protein Turnover ◽

Acute Exercise ◽

Muscle Protein ◽

Longitudinal Design ◽

Resistance Training Program ◽

Fed State ◽

Muscle Protein Turnover ◽

Breakdown Rates

Resistance training changes the balance of muscle protein turnover, leading to gains in muscle mass. A longitudinal design was employed to assess the effect that resistance training had on muscle protein turnover in the fed state. A secondary goal was investigation of the potential interactive effects of creatine (Cr) monohydrate supple mentation on resistance-training-induced adaptations. Young (N = 19, 23.7 ± 3.2 year), untrained (UT), healthy male subjects completed an 8-week resistance-training program (6 d/week). Supplementation with Cr had no impact on any of the variables studied; hence, all subsequent data were pooled. In the UT and trained (T) state, subjects performed an acute bout of resistance exercise with a single leg (exercised, EX), while their contralateral leg acted as a nonexercised (NE) control. Following exercise, subjects were fed while receiving a primed constant infusion of [d5]- and [15N]-phenylalanine to determine the fractional synthetic and breakdown rates (FSR and FBR), respectively, of skeletal muscle proteins. Acute exercise increased FSR (UT-NE, 0.065 ± 0.025 %/h; UT-EX, 0.088 ± 0.032 %/h; P < 0.01) and FBR (UT-NE, 0.047 ± 0.023 %/h; UT-EX, 0.058 ± 0.026 %/h; P < 0.05). Net balance (BAL = FSR FBR) was positive in both legs (P < 0.05) but was significantly greater (+65%) in the EX versus the NE leg (P < 0.05). Muscle protein FSR and FBR were greater at rest following T (FSR for T-NE vs. UT-NE, +46%, P < 0.01; FBR for T-NE vs. UT-NE, +81%, P < 0.05). Resistance training attenuated the acute exercise-induced rise in FSR (T-NE vs. T-EX, +20%, P = 0.65). The present results demonstrate that resistance training resulted in an elevated resting muscle protein turnover but an attenuation of the acute response of muscle protein turnover to a single bout of resistance exercise.Key words: myofibrillar protein, hypertrophy, protein synthesis, protein breakdown.

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Dileucine ingestion is more effective than leucine in stimulating muscle protein turnover in young males: a double blind randomized controlled trial

Journal of Applied Physiology ◽

10.1152/japplphysiol.00295.2021 ◽

2021 ◽

Author(s):

Kevin J. M. Paulussen ◽

Rafael A. Alamilla ◽

Amadeo F. Salvador ◽

Colleen F. McKenna ◽

Andrew T. Askow ◽

...

Keyword(s):

Protein Synthesis ◽

Protein Turnover ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Controlled Trial ◽

Young Men ◽

Double Blind ◽

Muscle Protein Turnover ◽

Breakdown Rates ◽

Over Time

Leucine is regarded as an anabolic trigger for the mTORC1 pathway and the stimulation muscle protein synthesis rates. More recently, there has been an interest in underpinning the relevance of BCAA-containing dipeptides and their intact absorption into circulation to regulate muscle anabolic responses. We investigated the effects of dileucine and leucine ingestion on postprandial muscle protein turnover. Ten healthy young men (age: 23±3 y) consumed either 2 g of leucine (LEU) or 2 g of dileucine (DILEU) in a randomized crossover design. The participants underwent repeated blood and muscle biopsy sampling during primed continuous infusions of L-[ring-13C6]phenylalanine and L-[15N]phenylalanine to determine myofibrillar protein synthesis (MPS) and mixed muscle protein breakdown rates (MPB), respectively. LEU and DILEU similarly increased plasma leucine net area under the curve (AUC; P = 0.396). DILEU increased plasma dileucine AUC to a greater extent than LEU (P = 0.013). Phosphorylation of Akt (P = 0.002), rpS6 (P <0.001) and p70S6K (P < 0.001) increased over time in both LEU and DILEU conditions. Phosphorylation of 4E-BP1 (P = 0.229) and eEF2 (P = 0.999) did not change over time irrespective of condition. Cumulative (0-180 min) MPS increased in DILEU (0.075±0.032 %⋅hour-1), but not in LEU (0.047±0.029 %⋅hour-1; P=0.023). MPB did not differ between LEU (0.043±0.030 %⋅h-1) and DILEU conditions (0.051±0.027 %⋅hour-1; P = 0.659). Our results showed that dileucine ingestion elevated plasma dileucine concentrations and muscle protein turnover by stimulating MPS in young men.

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Effects of dietary energy levels on Pectoralis major mixed muscle protein turnover and body composition in two broiler lines housed in different grow‐out environments

Journal of Animal Physiology and Animal Nutrition ◽

10.1111/jpn.13467 ◽

2021 ◽

Author(s):

Pramir Maharjan ◽

Garret Mullenix ◽

Katie Hilton ◽

Jordan Weil ◽

Antonio Beitia ◽

...

Keyword(s):

Body Composition ◽

Protein Turnover ◽

Muscle Protein ◽

Energy Levels ◽

Pectoralis Major ◽

Dietary Energy ◽

Muscle Protein Turnover

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Non-protein energy source in parenterally fed weanling rats influences growth, body composition, and skeletal muscle protein turnover

Clinical Nutrition ◽

10.1016/0261-5614(89)90025-3 ◽

1989 ◽

Vol 8 (1) ◽

pp. 49-55

Author(s):

S.A. Ash ◽

G.E. Griffin ◽

M.J. Stock

Keyword(s):

Energy Source ◽

Skeletal Muscle ◽

Body Composition ◽

Protein Turnover ◽

Muscle Protein ◽

Skeletal Muscle Protein ◽

Muscle Protein Turnover ◽

Protein Energy ◽

Weanling Rats

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Post-absorptive muscle protein turnover affects resistance training hypertrophy

European Journal of Applied Physiology ◽

10.1007/s00421-017-3566-4 ◽

2017 ◽

Vol 117 (5) ◽

pp. 853-866 ◽

Cited By ~ 17

Author(s):

Paul T. Reidy ◽

Michael S. Borack ◽

Melissa M. Markofski ◽

Jared M. Dickinson ◽

Christopher S. Fry ◽

...

Keyword(s):

Resistance Training ◽

Protein Turnover ◽

Muscle Protein ◽

Muscle Protein Turnover

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Skeletal and cardiac muscle protein turnover during cold acclimation in young rats

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.2000.278.3.r705 ◽

2000 ◽

Vol 278 (3) ◽

pp. R705-R711 ◽

Cited By ~ 8

Author(s):

T. A. McAllister ◽

J. R. Thompson ◽

S. E. Samuels

Keyword(s):

Skeletal Muscle ◽

Protein Synthesis ◽

Cardiac Muscle ◽

Cold Acclimation ◽

Protein Turnover ◽

Muscle Protein ◽

Muscle Protein Turnover ◽

Protein Mass ◽

The Absolute

The effect of long-term cold exposure on skeletal and cardiac muscle protein turnover was investigated in young growing animals. Two groups of 36 male 28-day-old rats were maintained at either 5°C (cold) or 25°C (control). Rates of protein synthesis and degradation were measured in vivo on days 5, 10, 15, and 20. Protein mass by day 20 was ∼28% lower in skeletal muscle (gastrocnemius and soleus) and ∼24% higher in heart in cold compared with control rats ( P < 0.05). In skeletal muscle, the fractional rates of protein synthesis ( k syn) and degradation ( k deg) were not significantly different between cold and control rats, although k syn was lower (approximately −26%) in cold rats on day 5; consequent to the lower protein mass, the absolute rates of protein synthesis (approximately −21%; P < 0.05) and degradation (approximately −13%; P < 0.1) were lower in cold compared with control rats. In heart, overall, k syn(approximately +12%; P < 0.1) and k deg(approximately +22%; P < 0.05) were higher in cold compared with control rats; consequently, the absolute rates of synthesis (approximately +44%) and degradation (approximately +54%) were higher in cold compared with control rats ( P < 0.05). Plasma triiodothyronine concentration was higher ( P < 0.05) in cold compared with control rats. These data indicate that long-term cold acclimation in skeletal muscle is associated with the establishment of a new homeostasis in protein turnover with decreased protein mass and normal fractional rates of protein turnover. In heart, unlike skeletal muscle, rates of protein turnover did not appear to immediately return to normal as increased rates of protein turnover were observed beyond day 5. These data also indicate that increased rates of protein turnover in skeletal muscle are unlikely to contribute to increased metabolic heat production during cold acclimation.

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