Out There: Where’s The Chocolate?

PMS does have an effect on running performance, writes Susan Lacke.

Last night, I couldn’t stop craving chocolate. This was no ordinary “boy, I could really go for a Hershey’s Kiss” type of craving, mind you. It was a full-on assault of my kitchen cabinets, searching for something —anything!—that contained chocolate. After 20 minutes (and one minor temper tantrum) I finally located a lone packet of hot chocolate mix in the back of the pantry.

Nevermind that the contents were over a year old, or that it was a sunny, 107-degree day; that cup of hot cocoa was the best I’ve ever had. I actually cried tears of joy—though in my defense, there was also a very touching commercial for dog food on television at the time.

Go ahead and call me a cliché. I freely admit it—once a month, I turn into every bad stereotype of PMS. Insatiable cravings for chocolate? Check. Tired? You know it. Bloated? Like a pregnant hippo. Easily irritated? Go bleep yourself, buddy.

Though the body certainly means well—a regular cycle is actually a sign of good health—I think most women would agree the monthly theatrics are a bit much, especially when training for a race.

Most women don’t require bed rest to survive the menstrual cycle, but the idea is certainly more tempting than a 10-mile run. Speed work is hard enough as it is without a water-filled innertube sloshing around your waist. When I tell my cranky legs to shut up mid-run, they usually get with the program, but if I apply that same tactic to my uterus, it just laughs condescendingly and stubs a lit cigarette into my belly button.

One recent day when PMS and training coincided, a male running partner asked why I was struggling to keep up with him on the intervals. Not wanting to go into details with a dude, I muttered something about “lady troubles.”

“Aww, shuddup, Lacke,” he replied. “You women and your ‘lady troubles.’ That didn’t work to get out of gym class when you were in middle school, and it won’t work now.”

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After threatening to introduce my foot to his rear-end (see above re: “easily irritated”) he apologized. I accepted, but only after he bought me a chocolate milkshake.

The conversation got me thinking, though—how much does PMS really affect run performance? Could it be possible that I use “lady troubles” as a convenient excuse for a bad run?

To find out, I asked Stacy Sims, PhD, an exercise physiology researcher at the Stanford School of Medicine. Sims has dedicated her career to understanding how women work—specifically, how the ebb and flow of hormones during a woman’s monthly cycle impact athletic performance. Her work has led to several new breakthroughs in women’s training philosophies and sports nutrition, including a hydration line for Osmo Nutrition.

According to Sims, the fluctuations of hormones (specifically, estrogen and progesterone) affect more than just the reproductive cycle. During the same time women experience bloating, strange cravings, and general angst at the world, they’re also experiencing high hormone levels, causing symptoms that affect their athletic performance:

— A drop in plasma volume, meaning less total blood for circulation and thermoregulation.

— Increased core temperature—when combined with the drop in plasma volume, heat tolerance and time to fatigue decreases significantly.

— A change in metabolism to spare glycogen, meaning a runner can’t reach her reserves to hit higher intensities as well as she normally could.

— An overall increase in central nervous system fatigue.

“See? It’s not a lousy day!”  Sims yelled excitedly. “It’s physiology, not fitness!”

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Are you listening, men and gym teachers?

These symptoms aren’t as obvious as other PMS symptoms (I’m talking to you, water retention), which is why most women don’t even consider their hormones are to blame for a bad day. If they’re like me, they just let their emotions get the best of them: I’m so slow, and why am I so fat, and where the hell is the chocolate?

But there’s good news, too: after a woman has her period, her hormones drop to a very low level, causing an increase in performance. So fear not, sisters—next week will be better. In the meantime, it’s OK to dig out the stretchy shorts, adjust your mile splits and cut yourself some slack.

And while you’re at it, replenish the chocolate supply, too.

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About The Author:

Susan Lacke does 5Ks, Ironman Triathlons, and everything in between to justify her love for cupcakes (yes, she eats that many). In addition to writing for Competitor, she serves as Resident Triathlete for No Meat Athlete, a website dedicated to vegetarian endurance athletes. Susan lives and trains in Phoenix, Arizona with three animals: A labrador, a cattle dog, and a freakishly tall triathlete boyfriend. She claims to be of sound mind, though this has yet to be substantiated by a medical expert. Follow her on Twitter: @SusanLacke