Cycling During Your Cycle

Cycling during Your Cycle

BY JULIE WALSH

A woman's monthly reproductive cycle doesn't just affect fertility. It influences mood, muscle mass, body-fat percentage, energy, metabolism, and aerobic capacity--all important factors for cycling.

World championships have been won by women during all phases of their menstrual cycles, yet many women complain of feeling tired, heavy, uncomfortable, clumsy, or weak during certain times of the month, especially just before and at the beginning of menstruation. Here's a look at what medical research and experts have to say about this complex issue, plus some tips on how to ride your best even on bad-hormone days. But first, let's see what happens in the normal menstrual cycle.

The Regular Cycle

There are two main phases of the menstrual cycle. They're separated by ovulation, the release of a mature egg into the fallopian tubes. The number of days from the first day of your period to ovulation is called the follicular phase. (It's usually 11 to 14 days.) The days after ovulation until the first day of your next period is called the luteal phase (also usually 11 to 14 days). During the follicular phase, levels of the two main sex hormones, estrogen and progesterone, are low. Around ovulation, estrogen peaks while progesterone remains low. During the luteal phase, both hormones are at high levels. The luteal phase is when many metabolic changes occur that can alter performance--for better and, possibly, for worse.

"During the luteal phase, high levels of estrogen and progesterone may facilitate more carbohydrate storage in your muscles and liver, and your metabolism shifts to burn more free fatty acids as fuel. Theoretically, for endurance cyclists, this could be a major benefit," explains Connie Lebrun, M.D., director of primary-care sports medicine at the Fowler-Kennedy Sport Medicine Clinic at the University of Western Ontario.

But research on the topic hasn't yet produced conclusive results. Some studies show improved athletic performance during the luteal phase, while others show no benefit. And surveys of female athletes reveal nothing except great individual variations.

In one of the best studies to date, Dr. Lebrun measured max VO₂ (the maximum amount of oxygen that can be consumed during all-out exertion), anaerobic capacity, high-intensity endurance and strength, and body weight and fat of 16 athletic women during both phases of their menstrual cycles. The results revealed a slight decline of max VO₂ in the luteal phase, but the decline was only of marginal statistical significance, says Dr. Lebrun. "For most women, their cycles probably won't affect performance. But for a small percentage of athletes, these cyclical changes in max VO₂ may be significant enough to alter performance."

Take Control

For now, there's no bottom line. But that doesn't mean you should let your hormones rule and stay off the saddle, sitting on your duff and feeding your fat or sugar cravings. Here are several things you can do to ride your best, no matter how bad a hormone day you're having.

Stay active. "One of the best things you can do to combat hormonal fluctuations is to get regular physical activity," says Suzanne Tanner, M.D., sports medicine physician at the University of Colorado Health Science Center in Denver. Research shows that exercise helps decrease the severity of physical changes during the menstrual cycle, and it definitely improves mood.

Log your menstrual cycle. Use a training log and add how you're feeling--physically and emotionally--along with where you are in your menstrual cycle. After a few months, review the data to see if there's a correlation between performance and cycle phase. This data can help you schedule important rides or races during the best days of the month. If you use birth control pills, you can work with your doctor to alter your cycle to be at your best for an important ride. (If you do this, however, you can't rely on the Pill for birth control during that month.)

Change your diet. Some research indicates that you can alleviate many PMS symptoms by watching what you eat. You should increase carbohydrate and fluid intake but eat less fat and protein. Also, avoid alcohol, caffeine, and excessively salty foods.

Consider the Pill. Although no drug is without side effects, the newer, low-dose estrogen and progesterone birth control pills have fewer (weight gain, lowered max VO₂) than in the past, notes Dr. Tanner. And the Pill has many advantages. "Taking a birth control pill keeps your hormones on a more even keel throughout the month," she says. It also makes your periods regular and predictable so you can plan for them. In addition, the flow is light (a major plus for long rides), and premenstrual symptoms are often minimized. The estrogen may also have other performance and health benefits, such as allowing your body to store more glycogen and reducing the risk of certain cancers. Consult your obstetrician/gynecologist to see if the Pill is appropriate for you.