Heath & Beauty - Free Fitness Library
Bones of contention
Linda K Hall PhD
Bone health for young girls and women is a critical issue, and it is not a matter of falls, trauma, and extraordinarily force causing fractures but loss of bone through inactivity and loos of estrogen that occurs at menopause. There is more and more evidence, however, that bone health is also a matter of energy expenditure/energy supply. There is growing evidence that maintaining optimal bone health is important for you girls as well as middle-aged and post-menopausal women. Additionally, optimal bone health is strongly influenced by a well balanced regimen of exercise and diet.
Laying The Foundation
The bony skeleton is the framework to which our muscles are attached and a lever system that facilitates movement. It is also the structure that suspends our internal organs and over which our skin drapes to give form to the human body. Bone is an active living organ system that goes through a continuous cycle of cell destruction (resorption) and renewal (remodelling). Under normal conditions in the body, the two processes are balanced and fairly equal; over time, however, the destruction occurs more efficiently than the renewal and as a result both men and women suffer a decline in bony wall thickness as we age.
The goal for young girls is to optimise bone remodelling and attain a high bone mass during youth, and then through adequate nutrition and activity maintain the mass and slow the rate of bone loss as much as possible as ageing occurs. In women, the reproductive hormones that play a role in the menstrual cycle are essential for maintaining bone reformation and optimal bone density.
Menarche, the onset of the menstrual cycle, occurs at the end of puberty. While mediated by a number of things such as race, climate, genetics and socioeconomic status, in the United States the average girl begins menstrual function at around 12 years, eight months, give or take a year. Delayed onset of menarche is defined as an absence of menstrual function by age 14. Although delayed menarche can be due to a number of factors, it is often related to excessive exercise and pathologic nutritional habits such as anorexia nervosa in athletic girls.
Research has shown that young girls participating in activities which encourage a "certain amount of thinness" or a "slight" body size, such as gymnastics, ballet, distance running, figure skating, and synchronised swimming, appear to have a delayed onset of menstruation (primary amenorrhea).
Additionally, participants in these activities who have had a normal onset of menstruation at puberty may experience a cessation of menstruation (secondary amenorrhea) or longer cycles between periods (greater than 35 days, termed oligomenorrhea) during high levels of training or competition. The occurrence of these conditions appears to be more likely when body weight and appearance are considered important to performance and judgement of performance. For participants in such activities, emphasis on weigh and appearance has been shown to be a catalyst for the use of pathogenic methods (vomiting, laxatives, diuretic, etc.) to maintain "performance body weight and body shape and size."
If you are not an elite woman athlete but you do participate regularly in energy-sapping activities, are concerned about your weight enough to manage calories very closely, and are experiencing a cessation of menstruation, or an interruption of cycles, you may fit this syndrome. Current thinking among researchers is that when an athlete experiences amenorrhea, there is an energy intake/use imbalance in the body, or, to put it bluntly, the athlete is not eating enough to sustain both exercise and menstrual function. When there is a shortage of calories to meet baseline body function requirements such as menstruation (yes, it does take energy to menstruate) and exercise energy requirements, the body makes a choice. In this case, menstrual function ceases, and all of the hormones and growth functions associated with menstrual function are affected.
So what? Not having to put up with menstrual function is a benefit, isn't it? No, because the absence or disruption of menstruation, which some may view as positive, can have serious side effects on bone. Premature osteoporosis, increased stress fractures, and failure to attain peak bone mass have been observed in amenorrheic and oligomenorrheic athletes. In fact, some bone scans done on amenorrheic teenage athletes match the bone density of an 80 year old osteoporotic woman. The research is not conclusive as yet, but indications are that even when normal menstrual function returns, total bone reformation does not occur and the bone density is never optimal.
What About The Bone Health Of The Middle-Aged Woman?
As we move into our 30s and 40s, women are laying the foundation for their bony structure for later years. Having arrived in our 30s with normal menstruation, possibly having given birth to children and lived a full life, working and managing a household, what about bone health as we move into the next stage of life? Interestingly enough, women begin menopause much earlier than the first signs and symptoms demonstrate. Between the ages of 35 and 40 the ovaries and concomitant hormonal levels in the female body begin the process of menopausal onset. The amount of estrogen secretion is reduced, and while this is not evident in monthly function as yet, the impact is felt on other systems in the body as bone resorption increases and reformation decreases, causing a loss of bony skeleton. Along with the bone density changes, there are changes in the plasma levels of lipoproteins, with increases of low-density lipoproteins (the bad cholesterol) and decreases in high-density lipoproteins (the good cholesterol). In fact, the protective effect that estrogen had provided women with regard to heart disease is gone as we approach 40 years of age.
Menopause
Once menopause begins, the loss of estrogen and other hormones in the body that accelerate bone loss leading to osteoporosis which affects one in four post-menopausal women. The impact of osteoporosis takes many forms, such as a shortening of the skeletal stature, rounding of shoulders, dowager's hump, and an increase in hip and spinal column fractures. There is a rapid rise in serum cholesterol in menopausal women, increasing the risk of heart disease.
Many women do not know that heart disease is the single greatest killer of women (with a risk of four times higher than cancer) and has been since 1907. Because of this hormonal and lipid profile change with menopause, a woman's risk of heart disease quadruples. Three major studies are currently examining the importance of estrogen and progesterone replacement to bone health and lowered risk of heart disease in women. Early indications are that hormone replacement is critical in the reduction of osteoporosis and heart disease.
What To Do?
There are several things that women of all ages can do to ensure adequate
bone health throughout their lives.
1. From childhood through puberty and throughout adult life, develop
an excellent relationship with your paediatrician and family physician
and/or gynaecologist. If, for reasons other than pregnancy, an interruption
occurs in your menstrual cycle, seek the counsel of your physician.
It is important to discuss estrogen and progesterone replacement as
you approach menopause.
2. There is not time in a woman's life that exercise is contraindicated. Exercise produces optimal bone health, reduce total cholesterol, and increases high-density lipoproteins. Thus a regular exercise program is important for maintaining optimal health. Recent research indicates that weight training as a part of a regular exercise program increases bone density and muscular strength even in 90 year olds. Exercise, and particularly weight training, can improve gait and balance, leading to a decreased risk of falls and fractures and a more adequate level of muscular strength to meet the demands of daily living.
3. Maintain a healthy balance between energy intake; adequate calcium intake in the form of dairy products, fruits and vegetables; carbohydrates; and energy output. There is a growing concern that the majority of women do not meet the Recommended Daily Allowance (RDA) for calcium intake. If you have difficulty in maintaining an adequate calcium intake, call a dietician for assistance.
In essence, there is no greater wealth than health. For women, from childhood on, balance between diet and exercise is of utmost importance. For strong bones and a healthy body, proper diet and exercise, including aerobic activity and strength training, are the key to staying fit.
Linda K Hall PhD, is a consultant in leadership, management and development of educational material and programs in cardiac and pulmonary rehabilitation, fitness and wellness.
Reprinted with permission of IDEA Today