Effect of Fructose Ingestion after Exhausted Treadmill Exercise on Glycogen Repletion in Rats

Journal of Exercise Nutrition & Biochemistry 1999;3(2):63-74.

Abstract

S
tored glycogen is one of the important energy source during endurance exercise thus glycogen repletion, when exhausted, should be considered in most of athletes. At this point of view, using SD rats, glycogen repletion after exhausted exercise was investigated. Forty-eight male SD rats run on the treadmill until exhausted(7˚ incline, 35m/min). When exhausted, they were given ad-libitum either fructose (5%/100㎖, experimental group; Exe) or water (control group: Con) as a placebo for 60min or 120min. Rats were decapitated at pre-exercise, exhausted, 60min, and 120min of recovery, respectively. Serum glucose, lactate, insulin, FFA, muscle glycogen and liver glycogen was analyzed. Glucose concentration in Exe was significantly higher than Con (p<.05) during recovery periods. Lactate and insulin concentrations were not affected to both experimental substrates. FFA concentration was decreased at 120min of recovery in Exe but was continuously increased in Con. Muscle glycogen concentration was significantly repleted by fructose ingestion compared to water ingestion. Liver glycogen was, also, significantly repleted in Exe and its ratio of repletion was faster than muscle glycogen. These results suggested that, like other carbohydrate solutions such as glucose, sucrose, and maltodextrine and so forth, fructose ingestion after exhausted exercise has beneficial effect for depleted glycogen repletion compared to water ingestion.