+++ New Paper - Divergent skeletal muscle metabolite exchange in insulin-like growth factor-1-stimulated myotubes and resistance-exercised human muscle

Skeletal muscle hypertrophy requires increased nutrient uptake, yet global metabolite exchange during growth remains poorly understood. We profiled metabolite uptake and release in IGF-1-stimulated C2C12 myotubes and in human skeletal muscle 24 h after resistance exercise. In vitro, IGF-1 promoted uptake of serine, arginine, and pyridoxamine while increasing lactate release, consistent with anabolic metabolic reprogramming. In contrast, human muscle 24 h after exercise showed no significant net essential amino acid uptake in the postabsorptive state. Instead, modest changes suggested increased peptide turnover and lipid release, although these did not remain significant after multiple-testing correction. Together, these findings indicate that while IGF-1 drives anabolic nutrient uptake in vitro, human muscle 24 h after resistance exercise exhibits limited substrate accumulation and biomass accretion in the absence of exogenous nutrient availability.

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Reference:
Tim Havers, Moritz Eggelbusch, Marius Meinhold, Kira Sing, Rainer Okrojek, Anna Artati, Michael Witting, Dominik Lutter, Claire V. Kieker, Collin Starke, Tushar More, Karsten Hiller, Flemming Dela, Martin Schönfelder, André Kafka, Stephan Geisler, Henning Wackerhage: Divergent skeletal muscle metabolite exchange in insulin-like growth factor-1-stimulated myotubes and resistance-exercised human muscle. Experimental Physiology, 02 July 2026, https://physoc.onlinelibrary.wiley.com/doi/10.1113/EP094096