Even during brief periods of maximal exercise, muscle glycogen makes a significant contribution to ATP production. Some studies have also examined the benefit of ingesting carbohydrate–electrolyte solutions during prolonged intermittent high intensity running in an attempt to assess the applicability to sports such as football, rugby and hockey. For several of these studies the shuttle running test (LIST) was used, which requires participants to repeatedly run, walk, jog and sprint between two lines 20 m apart in 15-min blocks of activity with 3 min recovery between each block. When continued for the full 90 min the participants cover about 12 km during which they perform 66 maximum sprints and expend in total about 1300 kcal.
These distances covered and energy expended are similar to those reported for mid-field players in professional football. In one study a group of recreational football players completed five blocks of the LIST before undertaking an endurance test. This test required the subjects to continue sprinting and jogging back and forth over the 20-m course to the point of fatigue. It was demonstrated that the players could cover more distance towards the end after drinking a carbohydrate solution.
In several studies it was confirmed that the distance covered was greater when the football players drank a carbohydrate solution than when they drank a flavoured placebo solution.