Postexercise muscle glycogen synthesis with glucose, galactose, and combined galactose-glucose ingestion

• Published in: American journal of physiology: endocrinology and metabolism Vol. 325; no. 6; pp. E672 - E681
• Main Authors: Podlogar, Tim, Shad, Brandon J, Seabright, Alex P, Odell, Oliver J, Lord, Samuel O, Civil, Rita, Salgueiro, Rafael B, Shepherd, Emma L, Lalor, Patricia F, Elhassan, Yasir S, Lai, Yu-Chiang, Rowlands, David S, Wallis, Gareth A
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.12.2023
• Subjects: Blood Glucose; Carbohydrates; Dietary Carbohydrates - pharmacology; Double-Blind Method; Eating - physiology; Female; Galactose; Glucose; Glycogen; Glycogens; Humans; Ingestion; Insulin; Male; Muscle, Skeletal - physiology; Muscles; Recovery; Skeletal muscle; Synthesis; exercise; nutrition; sugars; recovery
• ISSN: 0193-1849; 1522-1555
• DOI: 10.1152/ajpendo.00127.2022

Ingested galactose can enhance postexercise liver glycogen repletion when combined with glucose but effects on muscle glycogen synthesis are unknown. In this double-blind randomized study participants [7 men and 2 women; V̇o : 51.1 (8.7) mL·kg ·min ] completed three trials of exhaustive cycling exercise followed by a 4-h recovery period, during which carbohydrates were ingested at the rate of 1.2 g·kg ·h comprising glucose (GLU), galactose (GAL) or galactose + glucose (GAL + GLU; 1:2 ratio). The increase in vastus lateralis skeletal-muscle glycogen concentration during recovery was higher with GLU relative to GAL + GLU [contrast: +50 mmol·(kg DM) ; 95%CL 10, 89; = 0.021] and GAL [+46 mmol·(kg DM) ; 95%CL 8, 84; = 0.024] with no difference between GAL + GLU and GAL [-3 mmol·(kg DM) ; 95%CL -44, 37; = 0.843]. Plasma glucose concentration in GLU was not significantly different vs. GAL + GLU (+ 0.41 mmol·L ; 95%CL 0.13, 0.94) but was significantly lower than GAL (-0.75 mmol·L ; 95%CL -1.34, -0.17) and also lower in GAL vs. GAL + GLU (-1.16 mmol· ; 95%CL -1.80, -0.53). Plasma insulin was higher in GLU + GAL and GLU compared with GAL but not different between GLU + GAL and GLU. Plasma galactose concentration was higher in GAL compared with GLU (3.35 mmol·L ; 95%CL 3.07, 3.63) and GAL + GLU (3.22 mmol·L ; 95%CL 3.54, 2.90) with no difference between GLU + GAL (0.13 mmol·L ; 95%CL -0.11, 0.37) and GLU. Compared with galactose or a galactose + glucose blend, glucose feeding was more effective in postexercise muscle glycogen synthesis. Comparable muscle glycogen synthesis was observed with galactose-glucose coingestion and exclusive galactose-only ingestion. Postexercise galactose-glucose coingestion or exclusive galactose-only ingestion resulted in a lower rate of skeletal-muscle glycogen replenishment compared with exclusive glucose-only ingestion. Comparable muscle glycogen synthesis was observed with galactose-glucose coingestion and exclusive galactose-only ingestion.