Originally Posted by
ftwelder
I don't feel the same this year. I have been steady with good efforts on the spin bike and lot's of physical work but my legs feel like they are starving. After a ride I am more tired than usual. I use a heart rate monitor and even modest efforts seem to drain me quickly. I raced a lot of BMX all through the years and have maxed my heart out thousands of times but I don't feel comfortable doing that any more. My legs still bulk up so they are feeling the effort.
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Yes, that can be a heart problem -- but it is equally likely (maybe more so) to be something else such as a hypoactive thyroid, anemia, rhabdo..., etc...
I would suggest, if you have not already done so, check with an internist (or somebody similar) for a complete workup. (CMP, CBC, TSH, etc...) If you felt fine and strong and now you feel tired and weak, it is an indication that something is not quite right inside -- but the possible causes of that can be myriad.
An internist, endocrinologist or a (good) general practitioner can run the tests to find the problem.