The Impact of Physical Activity on Thyroid Health: Insights From Representative Data in Korea.

Context: Thyroid hormones are essential for energy metabolism related to thermogenesis and oxygen consumption.

Objective: This study evaluated the potential association of thyroid function including thyroid peroxidase antibodies (TPOAb) with physical activity in nationally representative data.

Design/setting/participants: This retrospective cohort study used data from the Korean National Health and Nutrition Examination Survey between 2013 and 2015. Physical activity (PA) was assessed using metabolic equivalents based on the validated Korean version of the International Physical Activity Questionnaire Short Form. PA level was categorized into 3 groups of high, moderate, and low. Participants with abnormal thyroid function test, restricted activity, or previous history of thyroid disease were excluded in the study.

Results: A total of 5372 participants was finally selected. The free T4 level was lowest in the low PA group, while TSH was not significantly different among the groups. TPOAb titers increased in the following order: moderate PA, low PA, and high PA. After adjustment for confounding factors, moderate PA was associated with a high T4 level and a decrease in TSH and TPOAb with significance. However, there were no significant changes in free T4, TSH, or TPOAb titer in the high PA group. In a subanalysis, females with moderate PA showed a significant decrease in TSH and TPOAb. In both males and females, insulin sensitivity was increased with moderate PA. In obese participants, TSH negatively correlated with PA, and free T4 levels decreased in the low PA. The sensitivity to thyroid hormone did not differ in our study.

Conclusion: The present study found an association between thyroid function and moderate PA. Therefore, moderate-intensity PA should be recommended to improve thyroid function.