Chapter 17
Being Active and Female
IN THIS CHAPTER
Discovering how female hormones impact insulin action and exercise
Being active during pregnancy and afterward, especially with gestational diabetes
Females of all ages face special challenges to blood glucose management that are directly related to changes in their hormones. Adolescent girls have raging hormones as their bodies mature that make them more insulin resistant. Women of childbearing age must manage the effects of fluctuating hormones related to monthly cycles, contraceptive use, and pregnancy. Older women deal with hormonal changes when going through menopause and lose the protective effects of estrogen on heart health.
This chapter takes you through how these changes can impact you and your body’s responses to physical activity and how to best navigate your way through them all. Knowing more about how to deal with these issues helps you get the most out of your daily movement while still managing your blood glucose effectively.
Understanding How Female Hormones Affect Insulin and Exercise
After going through puberty and before reaching menopause, females continually must factor in the effects of fluctuations in their hormones, including estrogen and progesterone. These two are the most important hormones made by the ovaries and are considered female sex hormones, but the ovaries also produce some of the more typically male hormone, testosterone. Not only do these hormonal swings affect mood and mental state (think PMS), but they can also lead to physical changes (not all of them pleasant or desirable).
Hormonal swings and insulin action
The hardest part for anyone dealing with diabetes is that female hormones influence how effectively insulin works. Changes in their levels can make blood glucose more challenging to manage during certain times of the month.
Changes in hormonal levels during a woman’s normal monthly menstrual cycle can have a large impact on insulin action and blood glucose responses. This monthly cycle has two distinct phases dictated by hormone levels:
- Follicular, which goes from the start of menses or menstruation (the “period”) up to ovulation (when eggs are released) at mid-cycle
- Luteal, spanning the time from ovulation to just before the start of the next period
Women are more insulin resistant during the luteal phase (second half of the cycle, the time after ovulation) because of the greater release of estrogen and progesterone during that time. Many women find that their blood glucose levels start to increase gradually seven to ten days before menses and then instantly decrease the day their monthly bleeding begins. If you take insulin you may have to increase your basal doses and/or your total insulin dosing to compensate for greater insulin resistance leading up to your period.
The normal menstrual cycle can last anywhere from 21 to 35 days in adult females, although the average cycle is 28 days long. It’s more variable in young teens, lasting from 21 to 45 days. Menstruation also varies from 2 to 7 days (or lasts even longer in some cases). Some women’s periods are as regular as clockwork, while others differ in timing from one month to the next.
Not all females are affected equally, with differences related to the actual increases in your female hormone levels. The higher they go, the greater the potential rise in your blood glucose when you have diabetes.
Use of oral contraceptives can alter hormonal fluctuations in women as well. Most of these contraceptive pills, injections, or patches deliver low-dose estrogen and progestin. Although this combination of hormones prevents a woman from ovulating (and getting pregnant), it may also cause her insulin action to be somewhat reduced. But at least insulin action remains more balanced over the monthly cycle with fewer swings, leading to greater predictability and easier glucose management if you use contraceptives.
Another interesting fact is that after you go through menopause, you may be more insulin resistant overall (even though your female hormones are greatly diminished). But the levels are relatively stable all the time and not changing from one day or week to the next.
Exercise responses with hormonal changes
Hormonal changes can also affect female athletes who are trying to manage their blood glucose while competing in sports and athletic events. Although very little research has looked at how menstrual cycles can affect sports performance, it appears that monthly cycles may not have much of an impact.
Women may have a higher risk of tissue injuries, especially tears of the anterior cruciate ligament (ACL) in the knee, at certain points in their menstrual cycles. According to limited research, women appear to be more likely to experience such an injury in the first half of their menstrual cycle, especially as they approach ovulation. Although more research is needed to confirm this finding, it’s potentially concerning for women athletes.
Staying Active During Pregnancy
Pregnancy typically lasts for 40 weeks, which is slightly more than nine months. Staying physically active throughout your pregnancy, if you can, is so important. Whether you had diabetes before you got pregnant or you develop it while you’re expecting, being active can lead to a better pregnancy and a healthier baby. Keeping your blood glucose in check ensures fewer problems with your pregnancy, childbirth, and the baby.
Being active does not increase the risk of having a low-birth-weight baby, a preterm delivery, or a miscarriage. On the contrary, regular exercise likely reduces your risk of having pregnancy complications, such as preeclampsia (elevations in blood pressure that require bed rest) and gestational diabetes.
Keeping insulin lower and fitness higher
During pregnancy, your higher levels of hormones spare your blood glucose for your developing baby (fetus). To do so, they make you very insulin resistant, which can make your insulin needs go up dramatically. Even if you’re regularly active, the release of the same hormones during pregnancy as during the luteal phase (second half) of your menstrual cycle ensures that your insulin requirements rise to new highs while you’re expecting.
Staying physically active will keep you from having to raise your insulin doses as much, even during the last few months of your pregnancy, and keep you from getting out of shape. You’re likely to have a shorter time in labor if you’re fit, and who doesn’t want a faster delivery?
Being pregnant isn’t a reason to sit around and de-train for nine months. It should be your excuse to prioritize being active above all else in your daily routines — to better your health and the health of your unborn child.
If you have to stop exercising during your pregnancy for any reason, expect your insulin needs to go up dramatically, due to the combination of hormones and decreased insulin action from being inactive.
Avoiding excess weight gain by exercising
Regular exercise also keeps you from gaining too much pregnancy weight. Normal pregnancy weight gain is 25 to 35 pounds. If you’re underweight to start, you may need to gain 28 to 40 pounds during pregnancy, and if you’re overweight, only 15 to 25 pounds.
Almost half of American moms reportedly gain more than the recommended amount of weight during pregnancy, putting themselves and their babies at risk for health problems. These can include issues like elevations in blood pressure (which can lead to preeclampsia and eclampsia) during pregnancy and complications with labor and delivery (particularly when babies weigh more than 9 pounds). After pregnancy, the mother’s extra weight can make her more insulin resistant and lead to problems with lactation.
Beyond recommended amounts of weight gain, the excess is just extra body fat that you’ll have to work extra hard to take off later. Why not just prevent gaining too much in the first place by being active while pregnant? Doing so can mean having fewer stretch marks on your belly, too.
Pregnancy also increases the energy costs of doing any activity. That means you burn more calories during all your activities for nine months, particularly the weight-bearing ones. That’s like getting two workouts for the price of one when it comes to using up excess calories.
Exercising throughout pregnancy
Although being active before you get pregnant is a good idea, it’s not too late to get started if you’re already with child. In fact, all pregnant women are highly recommended to get in 30 minutes of moderate-intensity physical activity on most, if not all, days of the week.
Choosing the right activities
You have a lot of physical activities to choose from when you are pregnant and only a limited number that are better left until after your baby is born (see the following section). If you’ve been sedentary and are new to exercise when you’re pregnant, be more cautious and slowly work up to doing the recommended amounts. If you’re already active, you can generally keep doing what you’ve been doing, although you may need to lower your intensity of some of your workouts later during your pregnancy.
Physical activity recommendations for women during pregnancy include the following:
- Overall (duration, intensity, type, and frequency): 30 minutes of moderate-intensity activity (either aerobic or resistance) at least most days
- Aerobic: Walking, stationary cycling, swimming, aquatic activities, conditioning machines, prenatal exercise classes, prenatal yoga, seated exercises, and possibly jogging or running (if you’ve been highly active before pregnancy)
- Resistance: Light or moderate resistance exercises (see Chapter 11)
- Progression: If just starting out, increase the duration of moderate exercise slowly; if already more active, maintain or lower intensity during pregnancy instead of attempting to progress to higher levels
During the third trimester, consider substituting non-weight-bearing activities like aquatics and stationary cycling for running or doing excessive amounts of walking. That will be easier on your back and your leg joints.
You can continue doing both aerobic and resistance training safely. But your exercise intensity will likely need to go down, particularly in the later stages of your pregnancy.
Avoiding the wrong activities
You should avoid certain activities when pregnant — such as contact sports, sports with lots of directional changes (like racquetball), skiing (downhill or water), cycling outdoors (when balance becomes an issue), horseback riding, and scuba diving. But you can continue doing most other ones.
Don’t do any exercises lying flat on your back past the second trimester because doing so can reduce blood flow to your developing baby.
Other activities to avoid include the following:
- Any activities that increase the risk of falling or abdominal trauma
- Activities done in environmental extremes (too hot, too cold, or at high altitude)
Managing gestational diabetes
Gestational diabetes — or diabetes that develops and lasts during pregnancy only — affects as many as one in seven pregnancies. It’s diagnosed when an expecting mother’s blood glucose rises too high (usually the third trimester). It’s usually discovered with an oral glucose tolerance test (see Chapter 1 for details) at 24 to 28 weeks of pregnancy, although pregnant women who are at high risk for it may need to be tested sooner.
If you’re regularly active before becoming pregnant or start early into it, you’re less likely to experience a rise in your blood glucose during your pregnancy. You’ll also lower your risk of developing type 2 diabetes later in life if you can avoid developing gestational diabetes.
If you’re at high risk for gestational diabetes, you may be able to prevent it with lifestyle changes during pregnancy. If you do develop it, you may be able to manage it with just dietary improvements and regular physical activity, although insulin and/or oral medications may be necessary to achieve optimal blood glucose levels in some women.