Objective: The aim of this study is to investigate whether there is any protective effect of a regular endurance exercise on the L-Thyroxine-induced oxidative stress in lung tissue of rats.

Materials and methods: Twenty-three male Sprague Dawley rats were divided into four groups: Control, hyperthyroidism, exercise, and hyperthyroidism plus exercise. Hyperthyroidism was induced in rats by injecting subcutaneous 250 μg L-Thyroxine / kg body weight/day. Endurance training consisted of treadmill running at a speed of 23 m/minute, 45 minute /day, 5 days a week for 8 weeks. The levels of malondialdehyde (MDA) and nitric oxide ( NO) and myeloperoxidase (MPO) activities were measured in the lung homogenates.

Results: When compared to the control group, the highest MDA and the lowest NO levels were observed in the hyperthyroidism group. In addition, the highest MPO activity was measured in the exercise group when compared with control rats. However, the differences between groups were not statistically significant for all parameters.

Conclusion: In the experiment of hyperthyroidism of training rat model; the results indicates that on the statistical value there is no significant change which is examined of either endurance training or injecting 250 μg L-Thyroxine / kg body weight parameters of MDA, NO, and MPO in lung tissue of rats with hyperthyroidism.