Abstract :
Introduction: Exercise intolerance is typical characteristic of the subclinical hypothyroidism.
Purpose: Evaluation of heart rate responses to sub maximal exercise in subclinical hypothyroidism.
Materials and Method: Twenty three subclinical hypothyroids and thirty age, sex and BMI matched euthyroid controls were selected. Sub maximal exercise was performed using Bruce protocol using 75% target heart rate in treadmill. Heart rate recovery to sub maximal exercise was done using ECG lead II.
Results: Compared to Euthyroid controls, Subclinical Hypothyroidism (SCH) show a significant increase in warm up period heart rate. (p=0.05). There is a significant increase in the heart rate during recovery period at both 1st and 2nd minute in SCH when compared to controls. (p=0.03, 0.01), negative correlation exist between TSH level and 1st minute heart rate recovery.
Conclusion: We conclude that subjects with Subclinical hypothyroidism, shows a delayed heart rate recovery in response to a sub maximal exercise.
Keyword :
Parasympathetic tones, Basal metabolic rate, Physical Exertion, Exercise tolerance, Hypothyroidism