Endurance training improves heart rate on‐kinetics in women with subclinical hypothyroidism : a preliminary study.

Abstract

Purpose The aim of the study was to evaluate the efect of endurance training on heart rate (HR) on-kinetics in patients with subclinical hypothyroidism (SH). Methods Eighteen women were randomly assigned to trained group (TG) or control group (CG). Both groups performed three tests at 50 W in a cycle ergometer for 6 min. HR kinetics was obtained during the tests and the mean response time

(MRT), which is equivalent to the time taken to reach 63% of the HR at steady state, was extracted. The TG was then sub- mitted to 12 weeks of endurance training (50 min, 3x/week, intensity between 70 and 85% of the maximum HR predicted

for the age). Statistical analysis was performed by the mixed analysis of variance. Results At baseline, TG and CG were similar for TSH (7.7±3.1 vs. 6.9±3.3 mUI/L, p=0.602, respectively) and FT4 (12.31±1.51 vs. 12.20±1.89 pmol/L, p=0.889, respectively). After adjustment for body mass index and age, interactions between moment (baseline or after 12 weeks) and group (trained or control) were only signifcant for MRT (TG: 39.6±10 to 28.9±8.4 s, CG: 53.6±20.3 to 55±19.7 s, p=0.001) and physical activity level (CG: 7.3±0.7 to 8±0.9, CG: 6.8±0.8 in both moments, p=0.005).

Conclusion The preliminary results suggest that 12 weeks of endurance training improve HR on-kinetics and physical activ- ity level in SH.