Enlargement of glycogen store in rat liver and muscle by fructose-diet intake and exercise training

Murakami, Taro, Yoshiharu Shimomura, Noriaki Fujitsuka, Masahiro Sokabe, Koji Okamura, and Shuichi Sakamoto. Enlargement of glycogen store in rat liver and muscle by fructose-diet intake and exercise training. J. Appl. Physiol. 82(3): 772–775, 1997.—This study investigated the effect of long-term intake of a fructose diet and exercise training on glycogen content in liver and skeletal muscle in female rats. Thirty-six rats (8 wk old) were divided into two dietary groups and were fed with a control (chow) diet or fructose diet (containing 20% fructose) for 12 wk. During this period, one-half of the rats in each dietary group were trained by using a motor-driven treadmill (running speed of 25 m/min and duration of 90 min/day, 5 days/wk). The liver glycogen was increased by intake of a fructose diet and exercise training, and the content was in the following order: control-diet and sedentary rats < fructose-diet and sedentary rats ≤ control-diet and trained rats < fructose-diet and trained rats in the ratio of 1:3.4:3.6:5.0. The glycogen content in gastrocnemius muscle showed the same trend as that in liver; the ratio was 1:1.3:1.3:1.6. These results indicate that both long-term intake of the fructose diet and exercise training synergistically increased glycogen in both tissues.