Chronic Cardio = Infertility?

A 1984 study in the International Journal of Sports Medicine, found that 29% of female endurance athletes have amenorrhea. Which is a delay (primary) or complete absence (secondary) of the menstrual cycle.

And similarly, a 1994 study (in the same journal) found that high-mileage male runners have lower sperm counts and motility, than low-mileage runners.  Which other research suggests, is the result of a “lack of available energy”(calories) and/or an excessive training volume.

With the latter sounding more realistic, given that the excess cortisol secreted during high-mileage bouts can affect the normal release of reproductive hormones.


In fact, research has shown that the excess stress from long-distance aerobic exercise can actually decrease the size of the reproductive organs, and reduce testosterone and androgen levels in men substantially.  And other than the missed menstrual cycle, and inability to conceive, amenorrhea has been linked to bone loss and an increased susceptibilty to develop osteoporosis for women.  Who are are actualy more impacted by cortisol during exercise.

Which kind of makes you wonder why anyone would choose to purposely run long distances?

And whether that 1970’s jogging craze is pushing more women into early menopause and osteoporosis, more men into embarrassing testosterone levels, and more couples into higher rates of infertility?…

…one can only speculate.

Stay Lean!
Coach Mike


Born to Walk (or Sprint) Not Run

Chronic Cardio = Aging Muscle Fibers

Eat Less + Exercise More = Burn Less + Store More