Födointagets betydelse för muskelglykogeninlagringen efter arbete hos häst och människa

Sammanfattning: Glycogen is the storage form of glucose and is used by the skeletal musculature as energy both for intense and endurance events. The glycogen content in the horse's middle gluteal muscle is more than 600 mmol/kg dry weight, and almost 400 mmol/kg dry weight in the human's Vastus lateralis. In some special occasions, for example in competitions with several moments on following days, there is a need of a fast muscle glycogen resynthesis. The feed intake is of importance for the velocity of the resynthesis. A diet rich on carbohydrates with high glycemic index will speed up the process of glycogen accumulation by increasing concentration of glucose in the blood and make it more accessible to the muscles. In human studies it has been shown to be favourable for the glycogen resynthesis to intake feed immediately after exercise. No corresponding study seems to have been done in horses. The muscle glycogen accumulation rate in horse is slower than the accumulation in human. If the diet is rich in carbohydrates it will take about 24 hours after exercise to restore the glycogen concentration in humans, and at least 72 hours in horses. The resynthesis of glycogen in the muscles seems to be of a lower priority in the early recovery period in horse than in human. No clear explanation to this has been found, but there are some theories. One reason seems to be the horse's inability to use fat instead of carbohydrates as energy for the muscles in the early recovery period. Other explanations is that the horse has a lower concentration of the protein glucose transporter type 4 (GLUT-4) and a lower activity of glycogen synthase in the muscles than human. The horse also has a higher content and consumption of muscle glycogen during similar exercise load which may be another reason for the longer build up-time.