Moderate Physical Activity Improves Thyroid Function and Reduces Autoimmunity in Korean Adults Original paper
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jorgearistotelous@hotmail.com
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Giorgos Aristotelous
What was studied?
This nationwide retrospective cohort study evaluated the relationship between physical activity (PA) intensity and thyroid function—including free thyroxine (free T4), thyroid-stimulating hormone (TSH), and thyroid peroxidase antibodies (TPOAb)—in euthyroid Korean adults using data from the Korean National Health and Nutrition Examination Survey (KNHANES) conducted between 2013 and 2015. Participants were stratified into low, moderate, or high PA groups based on metabolic equivalents (METs) using the Korean version of the International Physical Activity Questionnaire. The study aimed to determine whether PA intensity is associated with thyroid function and autoimmunity and whether it influences sensitivity to thyroid hormone (TH) and insulin.
Who was studied?
A total of 5372 euthyroid adults from the KNHANES dataset were included after excluding individuals with abnormal thyroid function, prior thyroid disease, or restricted activity. The cohort was nationally representative of the Korean population. Analyses were stratified by sex and BMI to assess potential differential effects of PA on thyroid parameters in subgroups such as females and overweight or obese individuals.
Most important findings
Moderate physical activity and thyroid function was associated with statistically significant improvements in thyroid function and markers of autoimmunity. Specifically, moderate PA correlated with increased free T4, decreased TSH, and lower TPOAb levels after adjusting for confounders. No such associations were observed in the low or high PA groups. Subgroup analyses revealed that these effects were particularly evident in females and in overweight or obese individuals. The SPISE index, reflecting insulin sensitivity, was also elevated in the moderate PA group. However, no significant differences were found in indices of TH sensitivity (TSHI or TT4RI) across PA intensities.
| Parameter | Moderate PA (vs. Low) | High PA (vs. Low) |
|---|---|---|
| Free T4 | ↑ (β ≈ 0.44–0.48; P <.05) | No significant change |
| TSH | ↓ (β ≈ –0.28 to –0.39; P <.05) | No significant change |
| TPOAb | ↓ (β ≈ –7.34 to –8.85; P <.05) | No significant change |
| SPISE (Insulin) | ↑ (β = 0.04–0.19; P <.05 females) | No consistent effect |
| TT4RI / TSHI | No significant changes | No significant changes |
Key implications
The study underscores moderate-intensity physical activity as a favorable modifiable lifestyle factor that may improve thyroid function and reduce autoimmune activity, especially in women and those with elevated BMI. Interestingly, high-intensity PA did not confer additional benefits and may be linked to adverse immunological responses, as indicated by a J-shaped association with TPOAb. These findings suggest that prescribing moderate exercise could serve as a non-pharmacologic adjunct to maintain thyroid health, especially in at-risk populations. However, due to its cross-sectional design, the study cannot confirm causality and underscores the need for longitudinal or interventional trials.