DR. KATHLEEN LENINGER, PT & DPT.
Back in the day, I was a fast runner. I have a distinct memory of going to Penn Relays as a junior, so excited to run the 4×400 (I was the anchor) and that morning I woke up with my period. At that point in my life, I got my period every few months but most of my teammates hadn’t had their period in over a year! I wanted that. It was such a badge of honor and I was so embarrassed to be the only fast girl who got her period in the season. Years later I learned that it is called amenorrhea and that nothing about it is cool.
Secondary functional hypothalamic amenorrhea (amenorrhea which is not caused by disease or other pathology) is an issue that runners deal with often. I often hear “when my miles are high I stop getting my period.” This is not a cause and effect thing. Estrogen is needed to have a normal period, but estrogen is also used for other things in the body, such as muscle contraction, muscle injury repair, and T3 production (which is needed to increase calcium to your bones). Chances are that if you don’t have enough estrogen to have a period, the other parts of your system aren’t working correctly either.
A study recently published by the American College of Sports Medicine looked at hormone levels, energy availability, reaction time, bone health, and muscular endurance in elite athletes who are eumenorrheic (normal period) v.s. amenorrheic (absence of 3 cycles in a row). There were 14 that were amenorrheic and 16 that were eumenorrheic. The amenorrheic subjects had higher levels of cortisol (stress hormone). Lower levels of fat were found in amenorrheic athletes, but they also had less energy availability, blood calcium levels, T3, and estrogen. During the strength test, everyone if the eumenorrheic athletes had a stronger knee contraction and a longer contractile hold. So the athletes with less body fat and lower weight were also weaker!
The old theory is that lighter = faster but we now know that is not always the case (if ever). You need to get enough nutrients to make the energy to burn, hormones to signal body function, protein to build muscle, and calcium to build bone! That is a full-time job for your body before you even start running.
If you are experiencing amenorrhea or have a history of it, a comprehensive medical workup and functional evaluation will be very helpful to improve your running health as well as your physical health!
*Source: Tornberg, A et.al. Reduced Neuromuscular Performance in Amenorrheic Elite Endurance Athletes. Mexican College of Sports Medicine. July 2017. 2478-2485.