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by Dr. Stacy Sims
October 15, 2015
WOMEN'S CYCLING BROUGHT TO YOU BY ORBEA
When we ran Dr. Sims’ first article, “Women are not small men: How gender dictates nutritional needs during training and recovery,” the comment section blew up with great discussion and mostly questions about women post-menopause. Dr. Sims kindly follows up in this month’s column.
If there’s other topics of interest you’d like to see Dr. Sims tackle, feel free to let us know in the comments section.
The number one complaint I hear from women starting in their 40’s is that they feel as though their body has taken on a new shape of its own no matter what they do. Usual training and nutrition isn’t improving body composition nor fitness. They find they gain fat easily, and struggle to maintain or build lean mass (and power!). Sleep patterns are off, tolerance to hot conditions is decreased, and fatigue from hard training lingers longer than it should.
As women age, we face the unique challenges resulting from a radical change in hormone levels. The precursor to menopause (“peri-menopause”) begins in our forties, when estrogen and progesterone start to drop. Estrogen plays a crucial role in bone density, fat deposition, blood cholesterol and regulation of the cardiovascular system. So when estrogen levels drop, there’s a tendency to accumulate fat in your belly (which increases your risk for fatty liver and cardiovascular disease) rather than your hips and thighs; concomitantly, women become more sensitive to carbohydrate and have greater issues digesting and accessing carbs, and have greater insulin resistance to carbohydrate during normal (e.g. non-training/racing) eating.
Another aspect of hormonal change and metabolism that is often overlooked is the decline in DHEA (dehydroepindroesterone); a hormone produced by the adrenal glands and is a precursor for testosterone and estrogens. DHEA blunts the effects of cortisol (a.k.a the “belly fat” or “stress” hormone) by encouraging glucose into the muscle cells to be burned as fuel. As the levels of DHEA drop, conversion of testosterone and estrogen diminish, and you become more sensitive to glucose and more likely to store it as fat in your belly. This phenomenon isn’t just unique to perimenopause/menopause, but also occurs with high stress, so if you’re also highly stressed, the effects are worse.
Testosterone is not just important for men; it helps build and maintain muscle mass. Your testosterone levels peak in your 20s and slowly decline throughout adulthood, but while estrogen production diminishes, your ovaries and adrenal glands do continue to produce testosterone. It seems that this would create an ideal situation to build mass, but the higher protein synthesis rates in postmenopausal women is counteracted by an even higher uptick in protein breakdown. Making matters more difficult, as estrogen drops, we become less sensitive to the muscle-making stimulus we used to get from resistance training and eating protein. Neither stimulates muscle making like they used to.
Unfortunately, western medicine’s answer to mitigating these body composition changes is to prescribe hormone therapy. But, when we look closely at body composition changes of post-menopausal athletes with the addition of hormone therapy, there is minimal data to support using hormones over exercise to mitigate muscle loss and fat gain.
Hagberg et al* compared 20 sedentary, 20 active-nonathletic, and 23 endurance-trained women to determine if hormone therapy interacts with physical activity to affect body composition. All the women had total and regional body composition assessed by dual-energy x-ray absorptiometry (DEXA). And the athletes and active nonathletic women had been active for the same number of years and the same number of hours per week. Although body weight was the same for the athletes and sedentary women, the active nonathletic women weighed 3-12kg more (regardless of hormone status). The athletes, however, had less total body and abdominal fat than the other groups, and those women on hormone therapy in the active nonathletic group had less total and abdominal body fat than those not on hormones, although the athletes still fared better than their active nonathletic peers.
The caveat was the intensity of training. High-intensity exercise in postmenopausal women was associated with lower total body and abdominal percent fat values, compared with sedentary women of the same age. And women taking part in low- to moderate-intensity exercise had no difference in body compositions from those of sedentary women.
Hormone therapy had a nonsignificant association with lower percent fat values, most importantly indicating that numerous years of high-intensity endurance training had a greater effect on total and regional body fat values than hormone therapy.
It may be strange to lump these concepts together, but they interplay quite a bit. Let’s start with sleep. In normal cycling pre-menopausal women, the increased melatonin production in the low hormone phase is responsible for the body temperature decline which allows us to sleep, but in the high hormone phases, progesterone interferes with the release and effectiveness of melatonin, which is part of the reason we have more disrupted sleep and a higher core body temperature in the high hormone phase. When we hit peri and post-menopause, there are a combination of factors that disrupt sleep and body temperature. The estrogen withdrawal causes a decrease in melatonin production as well as causes central-nervous system (CNS) changes to reduce our ability to handle temperature changes. The beginning of the cascade of CNS effects is increased bursts of gonadotrophin-releasing hormone (GnRH). This increased GnRh stimulates the hypothalamus to increase vasodilation; which in turn dumps too much heat, and causes a rebound constriction/shivering (notice sometimes when you try to go to sleep, you are super warm, then all of a sudden shivering?). With increased circulating brain concentrations of nor-epinephrine, we also experience a reduced capacity to drop core temperature for optimal sleep.
Hormonal havoc can make it harder for menopausal women to tolerate the heat, especially during exertion where they are quicker to heat up and less able to cool down than their younger peers. To complicate things further, the biological safeguards that protect us from overheating can be a little sluggish to kick in. Case in point, one recent study compared** the sweat rate, sweat volume, sweat sodium content, and level of thirst among three groups of women—premenopausal (average age 22), peri-menopausal (average age 46) and post-menopausal (average age 52)—as they exercised on a treadmill. The pre-menopausal had the highest sweat rates and the postmenopausal women the lowest levels of thirst, which makes sense, since they weren’t sweating as much. However, the post-menopausal women are also more likely to be cooking inside, so ideally should start sweating earlier and getting the cues to drink sooner.
1) Blood vessels are less compliant (meaning blood pressure changes are slower)
2) There is less core temperature flux tolerance (meaning you can’t handle hot very well)
3) Menopausal women sweat later in activity and vasodilate longer (i.e. your body tries to get rid of heat by sending more blood to the skin instead of relying on sweating to cool you off for a longer period of time)
4) There is greater sensitivity to carbohydrate (more blood sugar swings and less need for carbohydrate overall)
5) The body uses protein less effectively (meaning that the type and quality of protein you eat and when you eat it becomes very important for building lean mass and holding onto it)
6) Less power production and muscle synthesis (thus train for power, not for endurance!- on the bike and in the gym!)
For 1 and 2: Cooling post exercise is a great way to facilitate blood flow for recovery. Using cool towels or cool water immersion to get a bit of skin constriction- pushing the blood back into central circulation. During exercise, consume cool foods and fluid (if possible).
For 3: Focus on hydration- food in the pocket, hydration in the bottle. Using the pre-hydration technique before racing or training in hot weather will help.
4: Aim for 40-50g carbohydrate per hour; not 60-90g. Upping your calorie needs with mixed macronutrient foods
5: Take 15g whey isolate or 9g branch chained amino acids 30 minutes before training; and definitely 25g mixed whey isolate and casein within 30 minutes post exercise. (NOT soy as there is not enough leucine for post-menopausal women to promote muscle synthesis; it takes 50g soy to match the bioavailability of 25g whey. High stress exercise, age-changes in protein synthesis and post-exercise recovery all change amino acid and protein metabolism in your muscles and increase the metabolism of leucine. Specifically, the damage in the muscle tissue stimulates the breakdown of branched chain amino acids and total muscle cell breakdown. To recover, you need to take in high enough amounts of leucine to shut down all these breakdown processes The more leucine you get into your system, the faster the tissue levels rise, the more quickly your muscles get the signal to repair and grow.)
6: Focus on power training- the speed and strength of muscle contractions tends to diminish with age; thus power and speed becomes an essential aspect of the post-menopausal woman’s training arsenal.
7: For sleep- 30 minutes before bed, drink 4oz COLD tart cherry juice (this will help drop your core temperature and the tart cherry will help your body produce more melatonin, naturally).
*Hagberg JM1, Zmuda JM, McCole SD, Rodgers KS, Wilund KR, Moore GE. Determinants of body composition in postmenopausal women. J Gerontol A Biol Sci Med Sci. 2000 Oct;55(10):M607-12
**Amabebe E, Omorodion SI, Ozoene JO et al. Sweating and thirst perception in premenopausal, perimenopausal, and postmenopausal women during moderate exercise. J Exp Inter Med 2013; 3(4):279-284.