Effect of treadmill exercise on circulating thyroid hormone measurements.
OBJECTIVE
Effects of exercise on circulating thyroid hormone (TH) values remain controversial. We sought to observe the effect of treadmill exercise on serum TH values in highly selected subjects.


METHODS
Twenty-six healthy male military recruits aged 23-27 (mean, 25) years were studied. All had maintained identical diet and physical activity for a week before the test. Serum samples were drawn before (baseline) and immediately, 1, 4, 24, 24 and 48 h after maximal exercise (on a treadmill, Bruce protocol). All subjects completed the protocol with normal ECG results. Specimens were analyzed to measure 3,3',5-triiodothyronine (T(3)), thyroxine (T(4)), free T(4) (FT(4)), free T(3) and thyroid-stimulating hormone (TSH) in the same assays. To determine the possible effect of hemodynamic changes, hematocrit (Hct)-adjusted data were also compared.


RESULTS
Hemoconcentration, as reflected by increased Hct, was found immediately after exercise. No significant changes of serum mean TH values before and after exercise were found except for TSH, which increased significantly immediately after exercise (1.72 vs. baseline 1.42 IU/l, p < 0.01). Values for T(3), T(4), and TSH increased significantly immediately after exercise, as compared to other postexercise values. However, the changes became insignificant after Hct adjustment. The FT(4) values showed a reciprocal increase after exercise that became significant after Hct correction. Significantly negative correlation was found between FT(4) and TSH values, but these values were still well within the normal range.


CONCLUSIONS
Maximal treadmill exercise does not greatly affect the determination of concentrations of circulating THs.
Huang
Wen-Sheng
WS
Department of Nuclear Medicine, Tri-Service General Hospital, Taipei, Taiwan, ROC. wshuang@ms22.url.com.tw
Yu
Ming-Der
MD
Lee
Meei-Shyuan
MS
Cheng
Cheng-Yi
CY
Yang
Shih-Ping
SP
Chin
Hei-Min Linda
HM
Wu
Sing-Yung
SY
D000328:Adult; D002319:Cardiovascular System / Q000378:metabolism; D004562:Electrocardiography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006400:Hematocrit; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D008889:Military Personnel; D013960:Thyroid Function Tests; D013963:Thyroid Hormones / Q000097:blood*; D013995:Time
D013963:Thyroid Hormones; D006854:Hydrocortisone