The World’s First Women-Specific Sports Hydration Line
Women’s different hydration needs have historically been ignored because research on women in sports has lagged. Until now.

Heading out the door? Read this article on the new Outside+ app available now on iOS devices for members! Download the app.
Dr. Stacy Sims, Osmo Co-Founder and Chief Research Officer, MSc, PhD, Exercise Physiologist-Nutrition Scientist, CISSN, Stanford University professor and pro elite cyclist, today released the world’s first women-specific sports hydration line.
It’s not a gimmick—there is real science behind Sims launch.
Sims, whom we wrote about earlier this year when she launched Osmo, says that the estrogen and progesterone in women’s bodies impact their performance as athletes. So she created three Osmo products formulated specifically for women to help them improve power output and endurance, avoid premenstrual performance decline, and optimize training adaptations
If you’re a dude who can’t handle reference to a woman’s menstrual cycle, stop reading now, because it turns out that a lot of the differences in what men and women when they exercise is directly related to that time of the moth.
If you’re a guy who likes to run, bike, ski or recreate with your female partner—whether wife, daughter or girlfriend—read on. And get your credit card out.
Women’s different hydration needs haven’t been recognized until now because while women’s participation in sports has increased significantly over the last several decades, research on women in sports has lagged. Until very recently, most of the data collected in case studies regarding nutrition and training were conducted largely on men. Women were deemed “too difficult” to be included because of female hormone fluctuations.
Women have an altered energy metabolism during exercise, which impacts how they recover. Their recovery window is smaller and they have a predisposition to become overtrained if they go for too much intensity at different parts of their periods.
During the menstrual cycle, women have two hormone phases: high and low. During the low hormone phase, women’s carbohydrate metabolism and recovery are closer to men’s and they are able to complete high-intensity workouts.
During the high hormone phase, estrogen reduces the availability of carbohydrate and increases the amount of fat used for fuel; thus women have problems hitting intensities. Elevated progesterone increases women’s core temperature by ~0.5’C, it increases their total body sodium losses, and increases women’s muscle breakdown—at the same time, reducing a woman’s ability to synthesize muscle. The combination of elevated estrogen and progesterone drops a woman’s available plasma volume by ~8%, and with concurrent shifts in baseline thresholds, makes females more predisposed to hyponatremia, abnormally low blood sodium.
Finally, the recovery window for men and women is different. Women have 30 minutes for acute recovery and only 3 hours to eat a balanced meal for glycogen recovery. So—your girlfriend, wife or daughter may not just being unjustifiably moody when you take her on that five hour mountain-bike ride. She may not have the juice because her hormones are wreaking havoc with her ability to perform.
To address women’s physiological realities, Sims developed and tested three formulas that Osmo launched on its website today. Preload Hydration for Women counteracts a hormone induced drop in body water, increases power and endurance, reduces muscle fatigue and improves recovery. (Available October 2013, $25.) Active Hydration for women increases Power Output, improves Endurance, and helps women avoid premenstrual-related performance decline. (40-serving container, available now, $20.) Acute Recovery promotes muscle synthesis, reduces hormonal influences on recovery, and optimizes training adaptations. (16-serving container, available now, $35.) And if this sounds good, check out the parallel formulas Sims created for men.