Throid and Exercise

[Lissa2112]

I am 37 years old, diagnosed with hashimoto's when I was 22.  I have been on synthroid 75mcg for the past 10 years.  At one time, I was taking too much synthroid but did not exibit the typical hyperthyroid sympyoms but a mix of symptoms..... fatigue, irritability, increased appetite and weight gain.  When my dose was adjusted, everything returned to normal,including the weight.  I exercise regularly, and always have but it seems whenever I begin a new exercise regimen, I begin to feel some of the symptoms as I had when synthroid adjustments were needed early in my treatment. ..... fatigue, muscle weakness, appetite fluctuations, weight gain, irritablility, decreased libido and restless sleep.  I have been on this new exercise regimen for 2 1/2 months now.  The first 30 days, I felt incredible but after that, I began to have a decline in the way I feel.  Is it possible that as my body adjusts to the new routine, my thyroid has to adjust as well?  It would seem to me that if it was the exercise routine, it would have effected me in the begining.... what do you think?