Reply to Comment On: “Indirect Assessment of Skeletal Muscle Glycogen Content in Professional Soccer Players before and after a Match through a Non-Invasive Ultrasound Technology Nutrients 2020, 12(4), 971”

Skeletal muscle glycogen (SMG) stores in highly glycolytic activities regulate muscle contraction by controlling calcium release and uptake from sarcoplasmic reticulum, which could affect muscle contraction. Historically, the assessment of SMG was performed through invasive and non-practical muscle biopsies. In this study we have utilized a novel methodology to assess SMG through a non-invasive high-frequency ultrasound. Nine MLS professional soccer players (180.4 ± 5.9 cm; 72.4 ± 9.3 kg; 10.4% ± 0.7% body fat) participated. All followed the nutritional protocol 24 h before the official match as well as performing the same practice program the entire week leading to the match. The SMG decreased from 80 ± 8.6 to 63.9 ± 10.2; p = 0.005 on MuscleSound® score (0–100) representing a 20% ± 10.4% decrease in muscle glycogen after match. Inter-individual differences in both starting glycogen content (65–90) and in percentage decrease in glycogen after the match (between 6.2% and 44.5%). Some players may not start the match with adequate SMG while others’ SMG decreased significantly throughout the game. Adequate pre-match SMG should be achieved during half-time and game-play in order to mitigate the decrease in glycogen. Further and more ample studies are needed before the application of this technology.

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Assessment of Skeletal Muscle Glycogen Content in University Football Players before and after a Game

Medicine & Science in Sports & Exercise ◽

10.1249/01.mss.0000479081.80902.09 ◽

2015 ◽

Vol 47 ◽

pp. 867

Author(s):

Inigo San Millan ◽

John Hill

Keyword(s):

Skeletal Muscle ◽

Muscle Glycogen ◽

Glycogen Content ◽

Football Players ◽

Muscle Glycogen Content ◽

Skeletal Muscle Glycogen ◽

Before And After

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Progressive increase in human skeletal muscle AMPKα2 activity and ACC phosphorylation during exercise

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00101.2001 ◽

2002 ◽

Vol 282 (3) ◽

pp. E688-E694 ◽

Cited By ~ 95

Author(s):

T. J. Stephens ◽

Z.-P. Chen ◽

B. J. Canny ◽

B. J. Michell ◽

B. E. Kemp ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Glycogen ◽

Human Skeletal Muscle ◽

Glycogen Content ◽

Vastus Lateralis ◽

Moderate Intensity ◽

Moderate Intensity Exercise ◽

Western Blots ◽

Muscle Glycogen Content ◽

Muscle Creatine

The effect of prolonged moderate-intensity exercise on human skeletal muscle AMP-activated protein kinase (AMPK)α1 and -α2 activity and acetyl-CoA carboxylase (ACCβ) and neuronal nitric oxide synthase (nNOSμ) phosphorylation was investigated. Seven active healthy individuals cycled for 30 min at a workload requiring 62.8 ± 1.3% of peak O2consumption (V˙o 2 peak) with muscle biopsies obtained from the vastus lateralis at rest and at 5 and 30 min of exercise. AMPKα1 activity was not altered by exercise; however, AMPKα2 activity was significantly ( P < 0.05) elevated after 5 min (∼2-fold), and further elevated ( P < 0.05) after 30 min (∼3-fold) of exercise. ACCβ phosphorylation was increased ( P < 0.05) after 5 min (∼18-fold compared with rest) and increased ( P< 0.05) further after 30 min of exercise (∼36-fold compared with rest). Increases in AMPKα2 activity were significantly correlated with both increases in ACCβ phosphorylation and reductions in muscle glycogen content. Fat oxidation tended ( P = 0.058) to increase progressively during exercise. Muscle creatine phosphate was lower ( P < 0.05), and muscle creatine, calculated free AMP, and free AMP-to-ATP ratio were higher ( P < 0.05) at both 5 and 30 min of exercise compared with those at rest. At 30 min of exercise, the values of these metabolites were not significantly different from those at 5 min of exercise. Phosphorylation of nNOSμ was variable, and despite the mean doubling with exercise, statistically significance was not achieved ( P = 0.304). Western blots indicated that AMPKα2 was associated with both nNOSμ and ACCβ consistent with them both being substrates of AMPKα2 in vivo. In conclusion, AMPKα2 activity and ACCβ phosphorylation increase progressively during moderate exercise at ∼60% of V˙o 2 peak in humans, with these responses more closely coupled to muscle glycogen content than muscle AMP/ATP ratio.

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Skeletal muscle glycogen content in patients with cirrhosis

Hepatology ◽

10.1002/hep.1840200121 ◽

1994 ◽

Vol 20 (1) ◽

pp. 135-141 ◽

Cited By ~ 10

Author(s):

Oliver Selberg ◽

Eva Radoch ◽

Gerhard Franz Walter ◽

Manfred James Müller

Keyword(s):

Skeletal Muscle ◽

Muscle Glycogen ◽

Glycogen Content ◽

Muscle Glycogen Content ◽

Skeletal Muscle Glycogen

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Influence of muscle glycogen availability on ERK1/2 and Akt signaling after resistance exercise in human skeletal muscle

Journal of Applied Physiology ◽

10.1152/japplphysiol.00110.2005 ◽

2005 ◽

Vol 99 (3) ◽

pp. 950-956 ◽

Cited By ~ 98

Author(s):

Andrew Creer ◽

Philip Gallagher ◽

Dustin Slivka ◽

Bozena Jemiolo ◽

William Fink ◽

...

Keyword(s):

Skeletal Muscle ◽

Resistance Exercise ◽

Muscle Glycogen ◽

Human Skeletal Muscle ◽

Glycogen Content ◽

Vastus Lateralis ◽

Akt Signaling ◽

Cellular Growth ◽

Muscle Glycogen Content ◽

Ribosomal S6 Kinase

Two pathways that have been implicated for cellular growth and development in response to muscle contraction are the extracellular signal-regulated kinase (ERK1/2) and Akt signaling pathways. Although these pathways are readily stimulated after exercise, little is known about how nutritional status may affect stimulation of these pathways in response to resistance exercise in human skeletal muscle. To investigate this, experienced cyclists performed 30 repetitions of knee extension exercise at 70% of one repetition maximum after a low (2%) or high (77%) carbohydrate (LCHO or HCHO) diet, which resulted in low or high (∼174 or ∼591 mmol/kg dry wt) preexercise muscle glycogen content. Muscle biopsies were taken from the vastus lateralis before, ∼20 s after, and 10 min after exercise. ERK1/2 and p90 ribosomal S6 kinase phosphorylation increased ( P ≤ 0.05) 10 min after exercise, regardless of muscle glycogen availability. Akt phosphorylation was elevated ( P < 0.05) 10 min after exercise in the HCHO trial but was unaffected after exercise in the LCHO trial. Mammalian target of rapamycin phosphorylation was similar to that of Akt during each trial; however, change or lack of change was not significant. In conclusion, the ERK1/2 pathway appears to be unaffected by muscle glycogen content. However, muscle glycogen availability appears to contribute to regulation of the Akt pathway, which may influence cellular growth and adaptation in response to resistance exercise in a low-glycogen state.

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Skeletal Muscle Glycogen Content at Rest and During Endurance Exercise in Humans: A Meta-Analysis

Sports Medicine ◽

10.1007/s40279-018-0941-1 ◽

2018 ◽

Vol 48 (9) ◽

pp. 2091-2102 ◽

Cited By ~ 23

Author(s):

José L. Areta ◽

Will G. Hopkins

Keyword(s):

Skeletal Muscle ◽

Endurance Exercise ◽

Muscle Glycogen ◽

Glycogen Content ◽

Meta Analysis ◽

Muscle Glycogen Content ◽

Skeletal Muscle Glycogen ◽

Exercise In Humans

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Hepatic and skeletal muscle glycogen content in rats treated with metformin and submitted to acute exercise by swimming

Revista Brasileira de Educação Física e Esporte ◽

10.11606/1807-5509201700020355 ◽

2018 ◽

Vol 31 (2) ◽

pp. 355

Author(s):

Vitor Alexandre Pezolato ◽

Marcos Almeida Marques ◽

Fabio Marcos Abreu ◽

Nataly Mendes Silva ◽

Ronaldo Júlio Baganha ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Glycogen ◽

Acute Exercise ◽

Glycogen Content ◽

Muscle Glycogen Content ◽

Skeletal Muscle Glycogen

O objetivo deste estudo foi avaliar o comportamento das reservas glicogênicas de ratos, submetidos a uma condição de exercício agudo (50 minutos de natação na intensidade leve), após o tratamento com metformina. Quarenta ratos Wistar (180-200g) adultos foram divididos em quatro grupos (tratados ou não por quinze dias) e assim representados: Controle; Exercício agudo por natação (realizaram uma sessão de natação, sendo 50 minutos na intensidade leve); Tratado com metformina (receberam o fármaco metformina na dosagem de 1,4 mg/ml, durante o período experimental; Tratados com metformina e submetidos a condição exercício agudo por natação (receberam o fármaco metformina na dosagem de 1,4 mg/ml e realizaram uma sessão de natação, sendo 50 minutos na intensidade leve). O exercício agudo diminuiu as reservas glicogênicas, já os animais tratados com metformina, apresentaram um aumento em suas reservas glicogênicas musculares e hepáticas em relação ao grupo que realizou o exercício sem suplementação (p0,05). O tratamento com metformina promoveu melhora nas condições energéticas e menor resposta ao estresse, sugerindo ser uma importante ferramenta farmacológica para a potencialização da performance.

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