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Graded reductions in pre-exercise glycogen concentration do not augment exercise-induced nuclear AMPK and PGC-1α protein content in human muscle.

Hearris, MA, Owens, DJ, Strauss, JA, Shepherd, SO, Sharples, AP, Morton, JP and Louis, JB (2020) Graded reductions in pre-exercise glycogen concentration do not augment exercise-induced nuclear AMPK and PGC-1α protein content in human muscle. Experimental Physiology. ISSN 1469-445X

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Abstract

NEW FINDINGS: What is the central question of this study? What is the absolute level of pre-exercise glycogen concentration required to augment the exercise-induced signalling response regulating mitochondrial biogenesis? What is the main finding and its importance? Commencing high-intensity endurance exercise with reduced pre-exercise muscle glycogen concentrations confers no additional benefit to the early signalling responses that regulate mitochondrial biogenesis. ABSTRACT: We examined the effects of graded muscle glycogen on the subcellular location of AMPK and PGC-1α protein content and mRNA expression of genes associated with the regulation of mitochondrial biogenesis and substrate utilisation in human skeletal muscle. In a repeated measures design, eight trained male cyclists completed acute high-intensity interval (HIT) cycling (8 × 5 min at 80% peak power output) with graded concentrations of pre-exercise muscle glycogen. Following initial glycogen depleting exercise, subjects ingested  2 g kg-1  (L-CHO), 6 g kg-1  (M-CHO) or 14 g kg-1  (H-CHO) of carbohydrate during a 36 h period, such that exercise was commenced with graded (P < 0.05) muscle glycogen concentrations (H-CHO; 531 ± 83, M-CHO; 332 ± 88, L-CHO; 208 ± 79 mmol·kg-1  dw). Exercise depleted muscle glycogen to < 300 mmol·kg-1 dw in all trials (H-CHO; 270 ± 88, M-CHO; 173 ± 74, L-CHO; 100 ± 42 mmol·kg-1 dw) and induced comparable increases in nuclear AMPK protein content (∼2 fold) and PGC-1α (∼5 fold), p53 (∼1.5 fold) and CPT-1 (∼2 fold) mRNA between trials (all P < 0.05). The magnitude of increase in PGC-1α mRNA was also positively correlated with post-exercise glycogen concentration (P < 0.05). In contrast, exercise nor carbohydrate availability affected the subcellular location of PGC-1α protein or PPAR, SCO2, SIRT1, DRP1, MFN2 or CD36 mRNA. Using a sleep-low, train-low model with a high-intensity endurance exercise stimulus, we conclude that pre-exercise muscle glycogen does not modulate skeletal muscle cell signalling. This article is protected by copyright. All rights reserved.

Item Type: Article
Uncontrolled Keywords: 0606 Physiology, 1106 Human Movement and Sports Sciences, 1116 Medical Physiology
Subjects: R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Sport & Exercise Sciences
Publisher: Wiley
Related URLs:
Date Deposited: 04 Sep 2020 12:12
Last Modified: 04 Sep 2020 12:15
DOI or Identification number: 10.1113/EP088866
URI: http://researchonline.ljmu.ac.uk/id/eprint/13577

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