Drag-reducing polymers increase exercise tolerance in an ischemic hind-limb rat model.

Objective: Drag-reducing polymers are long-chain, blood soluble macromolecules that can improve microcirculation invivo. This study aimed to examine the effects of drag-reducing polymers on exercise tolerance in a rat model of hind-limb ischemia. Methods: After adaptive running training, bilateral femoral artery ligation models were established in 64 Wistar rats. During an exhaustive exercise, polyethylene oxide or normal saline was intravenously injected to each group (n=32) at 4mL/h for 10min. The exhaustive exercise time was recorded, and lactic acid levels in gastrocnemius muscle and serum were measured. Serum levels of nitric oxide, creatine kinase and lactate dehydrogenase were measured as biomarkers of physical fatigue. Results: Compared with saline-treated control group, rats in polyethylene oxide-treated group had longer exhaustive exercise time (774.7171.5s vs. 687.6 +/- 166.1s, p=0.043), and lower lactic acid level in gastrocnemius muscle (p<0.01) but no significant difference in serum lactic acid level between two groups was observed (p>0.05). Nitric oxide level was higher in polyethylene oxide group than in controls (p<0.05), but no significant differences in serum creatine kinase and lactate dehydrogenase levels between two groups were observed (p>0.05). Conclusion: Drag-reducing polymers contribute to the enhancement of exercise endurance and exert anti-fatigue effect.