Dose–response effect of pre-exercise carbohydrates under muscle glycogen unavailability: Insights from McArdle disease
Background This study aimed to determine the effect of different carbohydrate (CHO) doses on exercise capacity in patients with McArdle disease—the paradigm of “exercise intolerance”, characterized by complete muscle glycogen unavailability—and to determine whether higher exogenous glucose levels af...
| Autores: | , , , , , , , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Fecha de publicación: | 2023 |
| País: | España |
| Institución: | Universidad Europea (UEM) |
| Repositorio: | ABACUS. Repositorio de Producción Científica |
| Idioma: | inglés |
| OAI Identifier: | oai:abacus.universidadeuropea.com:11268/12399 |
| Acceso en línea: | http://hdl.handle.net/11268/12399 |
| Access Level: | acceso abierto |
| Palabra clave: | Suplementos dietéticos Enfermedad del almacenamiento de glucógeno Nutrición Efectos fisiológicos Metabolismo Goal 3: Ensure healthy lives and promote well-being for all at all ages |
| Sumario: | Background This study aimed to determine the effect of different carbohydrate (CHO) doses on exercise capacity in patients with McArdle disease—the paradigm of “exercise intolerance”, characterized by complete muscle glycogen unavailability—and to determine whether higher exogenous glucose levels affect metabolic responses at the McArdle muscle cell (in vitro) level. Methods Patients with McArdle disease (n = 8) and healthy controls (n = 9) underwent a 12-min submaximal cycling constant-load bout followed by a maximal ramp test 15 min after ingesting a non-caloric placebo. In a randomized, double-blinded, cross-over design, patients repeated the tests after consuming either 75 g or 150 g of CHO (glucose:fructose, 2:1). Cardiorespiratory, biochemical, perceptual, and electromyographic (EMG) variables were assessed. Additionally, glucose uptake and lactate appearance were studied in vitro in wild-type and McArdle mouse myotubes cultured with increasing glucose concentrations (0.35, 1.00, 4.50, and 10.00 g/L). Results Compared with controls, patients showed the “classical” second-wind phenomenon (after prior disproportionate tachycardia, myalgia, and excess EMG activity during submaximal exercise, all p < 0.05) and an impaired endurance exercise capacity (–51% ventilatory threshold (VT) and –55% peak power output (PPO), both p < 0.001). Regardless of the CHO dose (p < 0.05 for both doses compared with the placebo), CHO intake increased blood glucose and lactate levels, decreased fat oxidation rates, and attenuated the second wind in the patients. However, only the higher dose increased VT (+27%, p = 0.010) and PPO (+18%, p = 0.007). In vitro analyses revealed no differences in lactate levels across glucose concentrations in wild-type myotubes, whereas a dose–response effect was observed in McArdle myotubes. Conclusion CHO intake exerts beneficial effects on exercise capacity in McArdle disease, a condition associated with total muscle glycogen unavailability. Some of these benefits were dose-dependent. |
|---|