Effect of ginger extract ingestion on skeletal muscle glycogen contents and endurance exercise in male rats

[Purpose] Skeletal muscle glycogen is a determinant of endurance capacity for some athletes. Ginger is well known to possess nutritional effects, such as anti-diabetic effects. We hypothesized that ginger extract (GE) ingestion increases skeletal muscle glycogen by enhancing fat oxidation. Thus, we investigated the effect of GE ingestion on exercise capacity, skeletal muscle glycogen, and certain blood metabolites in exercised rats. [Methods] First, we evaluated the influence of GE ingestion on body weight and elevation of exercise performance in rats fed with different volumes of GE. Next, we measured the skeletal muscle glycogen content and free fatty acid (FFA) levels in GE-fed rats. Finally, we demonstrated that GE ingestion contributes to endurance capacity during intermittent exercise to exhaustion. [Results] We confirmed that GE ingestion increased exercise performance (p<0.05) and elevated the skeletal muscle glycogen content compared to the non- GE-fed (CE, control exercise) group before exercise (Soleus: p<0.01, Plantaris: p<0.01, Gastrocnemius: p<0.05). Blood FFA levels in the GE group were significantly higher than those in the CE group after exercise (p<0.05). Moreover, we demonstrated that exercise capacity was maintained in the CE group during intermittent exercise (p<0.05). [Conclusion] These findings indicate that GE ingestion increases skeletal muscle glycogen content and exercise performance through the upregulation of fat oxidation.

Early Growth and Protein-Energy Metabolism in Chicken Lines Divergently Selected on Ultimate pH

In chickens, a divergent selection on the Pectoralis major pHu allowed the creation of the pHu+ and pHu− lines, which represent a unique model for studying the biological control of carbohydrate storage in muscle. The present study aimed to describe the early mechanisms involved in the establishment of pHu+ and pHu− phenotypes. At hatching, pHu+ chicks were slightly heavier but exhibited lower plasma glucose and triglyceride and higher uric acid. After 5 days, pHu+ chicks exhibited higher breast meat yield compared to pHu− while their body weight was no different. At both ages, in vivo muscle glycogen content was lower in pHu+ than in pHu− muscles. The lower ability of pHu+ chicks to store carbohydrate in their muscle was associated with the increased expression of SLC2A1 and SLC2A3 genes coding glucose transporters 1 and 3, and of CS and LDHα coding key enzymes of oxidative and glycolytic pathways, respectively. Reduced muscle glycogen content at hatching of the pHu+ was concomitant with higher activation by phosphorylation of S6 kinase 1/ribosomal protein S6 pathway, known to activate protein synthesis in chicken muscle. In conclusion, differences observed in muscle at slaughter age in the pHu+ and pHu− lines are already present at hatching. They are associated with several changes related to both carbohydrate and protein metabolism, which are likely to affect their ability to use eggs or exogenous nutrients for muscle growth or energy storage.

Comment on: “Indirect Assessment of Skeletal Muscle Glycogen Content in Professional Soccer Players Before and After a Match Through a Non-Invasive Ultrasound Technology Nutrients 2020, 12(4), 971”

San-Millán and colleagues [...]

Reply to Comment On: “Indirect Assessment of Skeletal Muscle Glycogen Content in Professional Soccer Players before and after a Match through a Non-Invasive Ultrasound Technology Nutrients 2020, 12(4), 971”

We would like to thank Professor Niels Ørtenblad et al [...]

Muscle Regenerative Capacity May Be Reduced When Aerobic Exercise Is Initiated with Low Glycogen Content

Objectives Maintaining low muscle glycogen content during recovery from aerobic exercise with low carbohydrate, high fat feeding has been shown to reduce insulin-mediated anabolic signaling compared to high carbohydrate feeding. The effects of low muscle glycogen content on intracellular regulators of muscle mass before and after aerobic exercise with carbohydrate ingestion is unclear. This study examined the effect of initiating aerobic exercise with low muscle glycogen content on postprandial insulin-dependent muscle anabolic signaling and myogenesis. Methods Twelve men (mean ± SD, age: 21 ± 4 y; body mass: 83 ± 11 kg; VO2peak: 44 ± 3 mL/kg/min) completed 2 cycle ergometry glycogen depletion trials separated by 7 d, followed by a 24-h period of isocaloric high fat (1.5 g/kg carbohydrate, 3.0 g/kg fat) or high carbohydrate (6.0 g/kg carbohydrate, 1.0 g/kg fat) refeeding to elicit low (LOW; 217 ± 103 mmol/kg dry wt) or adequate (AD; 396 ± 70 mmol/kg dry wt) glycogen content in randomized order. Participants then performed 80 min of cycle ergometry (64 ± 3% VO2peak) while ingesting 146 g of carbohydrate. Protein signaling (Western blotting) and gene transcription (RT-qPCR) were determined from vastus lateralis biopsies obtained before glycogen depletion (baseline, BASE), and before (PRE) and after (POST) exercise. Data presented as fold change relative to BASE for LOW and AD. Results Independent of time, carbohydrate sensing p-AMPKThr172 was higher (P &lt; 0.05) in LOW compared to AD, while p-p38MAPKThr180/Tyr182 was higher (P &lt; 0.05) in LOW at POST, but not different PRE. Insulin sensitive p-AKTThr473 was higher (P &lt; 0.05) in AD compared to LOW, regardless of time. Anabolic regulators, p-mTORC1Ser2448, p-p70S6KSer424/421, and p-rpS6Ser235/236 were higher (P &lt; 0.05) POST compared to PRE and BASE, independent of group. Regulators of myogenesis, MYOD and MYOGENIN were lower (P &lt; 0.05) in LOW compared to AD, regardless of time, while PAX7 was lower (P &lt; 0.05) in LOW compared to AD at PRE, but not different POST. Conclusions Initiating aerobic exercise with low muscle glycogen content does not appear to affect downstream insulin-dependent anabolic signaling, yet reductions in myogenic regulator factors suggest muscle repair and remodeling in recovery from exercise may be impaired. Funding Sources Work supported by DHP JPC-5/MOMRP; authors’ views not official U.S. Army or DoD policy.