Effects of physical activity on body composition and fatigue perception in patients on thyrotropin-suppressive...

Subclinical thyrotoxicosis (scTox) may be associated with alterations in body composition and fatigue that can be possibly reversed with physical activity. The aim of the present study was to evaluate whether the systematic practice of physical activity improves lower extremity muscle mass and fatigue perception in patients with scTox.

We studied 36 patients (2 men) with median age of 48.0 (43.0-51.0) years, body mass index of 27.4 (22.1-30.2) kg/m(2), thyrotropin <0.4 mU/L, and free thyroxine between 0.8 and 1.9 ng/dL and 48 control subjects (C group; 7 men). Patients were randomly divided in two groups according to the adherence to the exercise training: scTox-Tr (n = 19)-patients who adhered to the exercise intervention and scTox-Sed (n = 17)--patients who did not adhere to it. The C group did not participate in the randomization. The exercise training was supervised by a physical education instructor, and it was composed of 60 minutes of aerobic activity and stretching exercises, twice a week, during 12 weeks. In both groups, body composition was assessed (anthropometric method), and the Chalder Fatigue Scale was determined at baseline and after 3 months of intervention (scTox-Tr group) or observation (scTox-Sed group).

At baseline, patients with scTox had lower muscle mass and mid-thigh girth and more fatigue on the Chalder Fatigue Scale than euthyroid control subjects. The scTox-Tr group had an increase in muscle mass, reduction in the variables reflecting whole body fat, and lesser perception of fatigue during the exercise training period (p ≤ 0.05 for these parameters at the start and end of the exercise training period).

scTox is associated with lower muscle mass and mid-thigh girth and more fatigue. Physical activity training can partially ameliorate these characteristics. More studies are needed to determine what training program would be optimum, both in terms of beneficial effects and for avoiding potential adverse responses.