Post‐exercise carbohydrate and energy availability induce independent effects on skeletal muscle cell signalling and bone turnover: implications for training adaptation

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Hammond, KM, Sale, C ORCID: https://orcid.org/0000-0002-5816-4169, Fraser, W, Tang, J, Shepherd, SO, Strauss, JA, Close, GL, Cocks, M, Louis, J, Pugh, J, Stewart, C, Sharples, AP and Morton, JP, 2019. Post‐exercise carbohydrate and energy availability induce independent effects on skeletal muscle cell signalling and bone turnover: implications for training adaptation. Journal of Physiology, 597 (18), pp. 4779-4796. ISSN 0022-3751

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Official URL: http://doi.org/10.1113/jp278209

Abstract

We examined the effects of post-exercise carbohydrate (CHO) and energy availability (EA) on potent skeletal muscle cell signalling pathways (regulating mitochondrial biogenesis and lipid metabolism) and indicators of bone metabolism. In a repeated measures design, nine males completed a morning (AM) and afternoon (PM) high-intensity interval (HIT) (8 x 5-min at 85% VO2peak) running protocol (interspersed by 3.5 hours) under dietary conditions of 1) high CHO availability (HCHO: CHO ~12 g.kg-1 , EA~ 60 kcal.kg-1 FFM), 2) reduced CHO but high fat availability (LCHF: CHO ~3 g.kg-1 , EA~ 60 kcal.kg-1 FFM) or 3), reduced CHO and reduced energy availability (LCAL: CHO ~3 g.kg-1 , EA~ 20 kcal.kg-1 FFM). Muscle glycogen was reduced to ~200 mmol.kg-1 dw in all trials immediately post PM-HIT (P<0.01) and remained lower at 17-h (171, 194 and 316 mmol.kg-1 dw) post PM-HIT in LCHF and LCAL (P<0.001) compared to HCHO. Exercise induced comparable p38MAPK phosphorylation (P<0.05) immediately-post PM-HIT and similar mRNA expression (all P<0.05) of PGC-1α, p53 and CPT1 mRNA in HCHO, LCHF and LCAL. Post-exercise circulating βCTX was lower in HCHO (P<0.05) compared to LCHF and LCAL, whereas exercise-induced increases in IL-6 were larger in LCAL (P<0.05) compared to LCHF and HCHO. In conditions where glycogen concentration is maintained within 200-350 mmol.kg-1 dw, we conclude post-exercise CHO and energy restriction (i.e. <24 hours) does not potentiate cell signalling pathways that regulate hallmark adaptations associated with endurance training. In contrast, consuming CHO before, during and after HIT running attenuates bone resorption, effects that are independent of energy availability and circulating IL-6.

Item Type:	Journal article
Publication Title:	Journal of Physiology
Creators:	Hammond, K.M., Sale, C., Fraser, W., Tang, J., Shepherd, S.O., Strauss, J.A., Close, G.L., Cocks, M., Louis, J., Pugh, J., Stewart, C., Sharples, A.P. and Morton, J.P.
Publisher:	Wiley on behalf of the Physiological Society
Date:	15 September 2019
Volume:	597
Number:	18
ISSN:	0022-3751
Identifiers:	Number Type 10.1113/jp278209 DOI 1113171 Other
Divisions:	Schools > School of Science and Technology
Record created by:	Jill Tomkinson
Date Added:	15 Aug 2019 08:42
Last Modified:	31 May 2021 15:18
URI:	https://irep.ntu.ac.uk/id/eprint/37324