Effects of long-term exercise training for different durations on pancreatic amylase activity and intestinal glucose transporter content in rats.

Long-term endurance training for a relatively short duration (~1 h) is reported to increase pancreatic amylase activity in rats, suggesting that chronic exercise training enhances carbohydrate digestive capacity. However, it remains unknown whether longer exercise training duration results in greater adaptation in the pancreas and small intestine. Thus, this study aimed to examine the effects of long-term endurance training for a longer duration on pancreatic amylase activity and intestinal glucose transporter content in rats. Male Sprague-Dawley rats were subjected to swimming exercise training for 1 h (Ex-1h group) or 6 h (Ex-6h group, two 3-h sessions separated by 1 h of rest) each day, 5 days a week, for 6 weeks. Sedentary rats were used as a control (Con group). Total pancreatic amylase activity in the Ex-6h group was significantly lower than that in the Con and Ex-1h groups immediately after the last training session. After 24 h of recovery, total pancreatic amylase activity was significantly higher in the Ex-1h group (~46%) than in the Con group, and a further increase was observed in the Ex-6h group (~98%). In addition, the Ex-6h group, but not the Ex-1h group, showed significantly greater intestinal sodium-dependent glucose transporter 1 (SGLT1) content compared with the Con group after 24 h of recovery. However, no significant difference was observed in glucose transporter 2 (GLUT2) content among the three groups. In conclusion, chronic endurance exercise training for a longer duration results in larger increases in pancreatic amylase activity and intestinal SGLT1 content in rats.