Asked 8 years, 2 months ago

Will a thyroid condition/medication affect my marathon performance?

Marathoning with a Thyroid Condition

My question concerns a possible link between my hypothyroid condition and marathon performance. My goal the past two years has been to run a Boston qualifying time of 4:00 (age 60-64). In the early 1980s, as I turned 40, I ran three sub-3:10 marathons (the master’s standard at the time) and ran Boston in 1984. After a decade off, I had no trouble running two sub-3:30 marathons (age 50-54) in 1994 and 1995 to qualify for the
100th running of the marathon in 1996.

My goal of qualifying for and running a third Boston Marathon in a third decade has proved elusive. In 2004, I started the Milwaukee Lakefront Marathon, but dropped out after 21 miles, then entered the Grand Rapids Marathon four weeks later. I posted a 4:03:58. In both cases I ran at a comfortable 9:05 pace for 12 miles, then died. The struggle in the 13th mile has become more like what I would not encounter until 16-18 miles in previous decades.

About seven years ago, I began taking a hypothyroid medication. I started with Levoxyl and switched to the generic levothyroxine in June. For all these years, the dosage has been 10 micrograms. My internist tests for TSH each year. In June 2004 it was 5.15; last June, 5.084. My question: Could my dramatic, premature falloff be linked to my hypothyroid condition? I understand the medication is used for maintenance and there shouldn’t be a wide swing even for a missed dosage (which doesn’t happen), but might there be a cumulative effect over the weeks of the longer runs and harder track workouts?

I am 63 years old, began jogging in 1978 and got serious about running and entered my first races in 1981. That year, in Chicago, I ran a 3:22 first marathon. My concession to age is running four days a week, with a base of two 4-milers and two 6-milers. For race training, one 6-miler is extended and, most weeks, the other is replaced by speed. I keep to two easy 4-milers. I crosstrain once or twice a week. My weight has edged up a little: from about 152 to about 165, but I’m no more than five pounds heavier that I was in
the mid-1990s. I take the thyroid medication with a low-dose aspirin and, during summer months, Claritin.

Some websites address general questions about hypothyroidism and running, but I have not found any that address a possible relationship between my condition and the rigors of a marathon training cycle.

Philip Lachney
Chicago, IL


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