As I write in Running for Women, there are obvious differences between women and men in anatomy, physiology, hormones, and metabolism. So why do all trainers, coaches, and running books take a one-sex-fits-all approach to training? As an active female, here are seven things you need to know to capitalize on being an active woman.
Estrogen is the single biggest thing that differentiates you from that guy running next to you in a race or grunting near the barbell rack in the gym. It’s a powerful hormone, influencing many aspects of a woman’s physiology, from metabolism to glycogen storage and lung function to bone health. A runner-friendly hormone, times of the month when estrogen is high (just before ovulation at end of follicular phase of your menstrual cycle and middle of luteal phase) are good times to focus on hard workouts and races.
Many female runners who train hard and have a low body fat percentage often experience irregular or even absent menstrual cycles, which reduces estrogen levels. High training volumes, low body weight, and endurance sports like distance running increase the incidence of menstrual irregularities. Any disruption to your menstrual cycle can decrease your bone mineral density, increasing the risk for osteoporosis and stress fractures. Estrogen is extremely important in facilitating the absorption of calcium into bones. Female runners with irregular or absent menstruation have significantly lower bone density than those with regular menstruation and even compared to non-athletes. If you’re at risk for a stress fracture because of a loss of estrogen, you need to do everything you can to strengthen your bones and prevent a stress fracture, including adequate intake of calcium and vitamin D and strength training. You may also want to take oral contraceptives, which supply you with estrogen.
Perhaps the most significant effect of estrogen is a shift in your metabolism during cardio exercise to a greater reliance on fat and less on carbohydrate. Because humans’ carbohydrate stores are limited, this metabolic shift gives female runners an advantage for very long endurance activities, during which there is a greater need to conserve carbohydrate and a greater use of fat because of the slower pace. Focus on endurance training at times of the month when estrogen is high.
Body temperature changes rhythmically throughout the menstrual cycle, peaking during the luteal phase in response to the surge in progesterone. Progesterone acts on the brain’s hypothalamus (the temperature control center), which increases set-point temperature. A higher body temperature during the luteal phase makes it harder to run in the heat during this phase, as runners don’t begin sweating to dissipate heat until they have reached a higher body temperature. So avoid long races in the heat during the luteal phase of your cycle.
Since muscular strength and power are proportional to muscle size, you can’t get as strong or as powerful as your boyfriend or hubby since men typically have bigger muscles and more testosterone to make those muscles even bigger. But you can cheat the system a bit if you alter your training based on your hormones and capitalize on being a woman. Although you’re not any stronger at certain times of the month than you are at any other, your menstrual cycle can influence how you respond to your workouts. For example, a study in International Journal of Sports Medicine found that weight training with 3 sets of 12 reps every second day during the follicular phase of the menstrual cycle and once per week during the luteal phase increased maximal quadriceps strength by 32.6 percent compared to just 13.1 percent by training once every third day over the whole menstrual cycle. It appears that doing more training in the estrogen-dominant follicular phase and less training in the progesterone-dominant luteal phase leads to greater strength gains. Estrogen rocks!
For most female runners, running through the first two trimesters is completely healthy. Frequent complaints of pregnancy, including nausea, heartburn, insomnia, varicose veins, and leg cramps are reduced in women who remain active during their pregnancy. Exercise during pregnancy has also been associated with a reduced risk of developing certain obstetrical complications, including preeclampsia, pregnancy-induced hypertension, and gestational diabetes. There are a few medical conditions that may prohibit you from running and racing while pregnant: significant heart and lung disease, persistent bleeding in the second and third trimesters, and ruptured membranes.
If you bleed a lot during menstruation, your blood’s hemoglobin concentration may decrease, which can negatively impact your ability to transport oxygen in your blood. Since iron is an important component of hemoglobin, iron loss often accompanies a lot of bleeding. If this happens, you may need to supplement your normal diet with iron. Many female runners exhibit athletic anemia (low blood iron levels due to physical activity), especially if they lose a lot of blood during menstruation. Athletic anemia is very common among female runners, especially those training at altitude.
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