β-GPA and metformin differentially alter myotube morphology. A, B) β-GPA increased myotube length and reduced myotube diameter each day throughout differentiation. Scale bar = 100 μm. C) TEM (scale bar = 1 μm revealed 48 h β-GPA treatment led to 16.5% reduction in mean cell volume, but this was not significant (P=0.139). D, E) Metformin treatment increased myotube diameter at 48 h, with no significant difference in length or diameter at any other time point. F) TEM (scale bar = 1 μm) complemented these findings, revealing a 52.5% increase in cell size. n=36; *P≤0.05, ** P≤0.01.