Hearris, MA, Hammond, KM, Seaborne, RA, Stocks, B, Shepherd, SO, Philp, A, Sharples, AP ORCID: https://orcid.org/0000-0003-1526-9400, Morton, JP and Louis, JB (2019) Graded reductions in pre-exercise muscle glycogen impair exercise capacity but do not augment cell skeletal muscle signalling: implication for CHO periodisation. Journal of Applied Physiology, 126 (6). pp. 1587-1597.

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Abstract

We examined the effects of graded muscle glycogen on exercise capacity and modulation of skeletal muscle signalling pathways associated with the regulation of mitochondrial biogenesis. In a repeated measures design, eight males completed a sleep-low, train-low model comprising an evening glycogen depleting cycling protocol followed by an exhaustive exercise capacity test (8 x 3 min at 80% PPO, followed by 1 min efforts at 80% PPO until exhaustion) the subsequent morning. Following glycogen depleting exercise, subjects ingested a total of 0 g kg-1 (L-CHO), 3.6 g kg-1 (M-CHO) or 7.6 g kg-1 (H-CHO) of carbohydrate during a 6 h period prior to sleeping, such that exercise was commenced the next morning with graded (P < 0.05) muscle glycogen concentrations (Mean ± SD) (L-CHO: 88 ± 43, M-CHO: 185 ± 62, H-CHO: 278 ± 47 mmol kg-1 dw). Despite differences (P < 0.05) in exercise capacity at 80% PPO between trials (L-CHO: 18 ± 7, M-CHO: 36 ± 3, H-CHO: 44 ± 9 min) exercise induced comparable AMPKThr172 phosphorylation ( 4 fold) and PGC-1α mRNA expression ( 5 fold) post- and 3 h post-exercise, respectively. In contrast, exercise nor CHO availability affected the phosphorylation of p38MAPKThr180/Tyr182, CaMKIIThr268 or mRNA expression of p53, Tfam, CPT-1, CD36 or PDK4. Data demonstrate that when exercise is commenced with muscle glycogen below 300 mmol kg-1 dw, further graded reductions of 100 mmol kg-1 dw impair exercise capacity but do not augment skeletal muscle cell signaling.

Item Type: Article
Additional Information: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via American Physiological Society at http://dx.doi.org/10.1152/japplphysiol.00913.2018 - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: exercise capacity, mitochondrial biogenesis, muscle glycogen, train low, sleep low
Subjects: R Medicine > R Medicine (General)
Divisions: Faculty of Medicine and Health Sciences > Institute for Science and Technology in Medicine
Depositing User: Symplectic
Date Deposited: 06 Jun 2019 09:28
Last Modified: 06 Jun 2019 09:36
URI: http://eprints.keele.ac.uk/id/eprint/6448

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