This is an excerpt from Better Body Workouts for Women by Dean Hodgkin & Caroline Pearce.
Avoiding the Female Athlete Triad
The female athlete triad describes the combination of three related aspects that lead to an unhealthy situation, namely disordered eating, amenorrhea and osteoporosis.
Disordered eating refers to the many, often unhealthy, eating routines that people, particularly women, follow in an attempt to control weight. They may have unrealistic goals that often result from perceived pressure from friends, family, society or sports coaches. Sportswomen in certain disciplines are more at risk, with dancing, swimming, gymnastics and running placing a specific emphasis on lean aesthetics. Additional common contributory factors include family issues, poor knowledge of nutrition and low self-esteem. A combination of some, or even all, of these factors can lead to extreme calorie restriction, forced vomiting and use of medication such as laxatives and diuretics. Sadly, disordered eating not only impairs your ability to work out, thus slowing your progress towards your goals, but also hurts your health status by affecting the cardiovascular, endocrine and thermoregulatory systems.
From a very basic viewpoint, insufficient calorie intake obviously leads to reduced energy stores in the body, particularly muscle glycogen. So, your ability to exercise at high intensities, a concept we've repeatedly recommended throughout this book, will be severely limited. You will also be less likely to achieve the very results you train for. Sadly, lack of sufficient calorie intake can be the precursor to the second component of the female athlete triad, amenorrhea (cessation of menstruation). This is thought to happen in two ways. First, exercise stress can potentially keep the hypothalamus from secreting the gonadotrophin-releasing hormone that stimulates the beginning of the menstrual cycle. Second, with so few fuel stores available, the body sacrifices reproduction in order to use the energy so the vital organs can continue to perform. Fortunately, simply increasing food intake will lead to a return to normal menstruation.
The final of the three components is osteoporosis, which is caused by reduced oestrogen levels associated with amenorrhea. The condition warrants greater investigation due to its prevalence within the female population worldwide. Bone growth begins in the foetus as calcium and magnesium salts are deposited and built up, a process known as ossification. Remodelling continues through life as osteoblast cells deposit mineral salts to promote new bone growth and old bone tissue gets broken down and absorbed by osteoclast cells, releasing calcium, potassium and phosphate compounds into the blood stream. In childhood, bone formation outpaces reabsorption, resulting in increased length and width of the bones, but the reverse is true in later years. Peak bone mass is achieved at around 25 years of age.
The flow of calcium in and out of the bone tissue is controlled by calcitriol, which is formed in the kidneys in a process where vitamin D (absorbed from sunlight) is a key ingredient. The parathyroid gland controls the kidney secretions so that if calcium levels in the blood fall below a certain point, more will automatically be released. This balancing act is assisted by the presence of oestrogen. The drop in oestrogen levels associated with the female athlete triad results in greater bone reabsorption and so the loss of bone density. As no obvious outward signs of bone health exist, you may not know your bones have lost density until you suffer a fracture following a relatively minor trauma. The most common fracture sites are the wrist, hip and vertebrae.
The risk of osteoporosis is increased by a number of factors:
- Family history—Daughters of mothers who have suffered the disease are likely to possess a lower bone density.
- Ethnic background—Afro-Caribbean and Hispanic people show less likelihood of suffering than European and Asian individuals.
- Age—Bone mineral density generally declines with increasing years due to the reduction in osteoblast activity.
- Medical history—Sufferers of rheumatoid arthritis, hyperthyroidism, Crohn's disease and coeliac disease all have an increased chance of osteoporosis.
- Alcohol use—The diuretic effect of drinking removes vital supplies of calcium in the urine, which slows the growth of new bone.
- Smoking habits—Smoking decreases oestrogen levels in the blood stream, leading to a reduction in the amount of calcium absorbed by the bones.
You can deploy two key strategies to reduce your chance of becoming another osteoporosis statistic. The first is to manage your diet. Foods containing calcium positively influence bone mineral density. As established earlier, low calcium intake will lead the body to reabsorb bone tissue in order to maintain adequate blood calcium levels. Low-fat dairy and leafy green vegetables provide a direct route to obtaining the calcium we need. In addition, consuming fruit and vegetables, specifically those that are more alkaline, reduces the amount of calcium lost in urine and therefore also has a positive influence on bone density. The second strategy is getting plenty of exercise. Since bone adapts to the mechanical stresses applied to it, then loading of the bones through physical activity will lead to positive changes in structure. Exercise has been shown to improve bone density at any age.
Of these two tactics, exercise carries the greatest potential to affect bone mass, as it both produces gravitational force on the skeleton and loads muscles, effects which have been proven to promote bone health. More specifically, resistance training is a vital component that must be part of your training routine. The reason strength training works is because the skeleton responds adaptively to forces applied to it. If stress is beyond a certain threshold, cell activity changes to stimulate an increase in strength of the bone. This occurs through a phenomenon known as the piezoelectric principle, a term that comes from the Greek translation of the word ‘squeeze', which helps us understand how it links to the performance of strength exercises. The tendon of a muscle exerts mechanical stress on its point of attachment to the bone, causing a charge to be released from within the collagen fibres. This voltage then attracts the oppositely charged osteoblasts that we talked about earlier, which deposit minerals at the site. The result, then, is a localised increase in bone density.
It is most important to understand that cardio training is not as effective as strength training for preventing osteoporosis. So, if your programme is geared toward improving your running, swimming or cycling performance, you really need to add regular resistance sessions. Also, the bone-loading effect is site specific, so it's vital to follow a whole-body approach to strength training.
Read more from Better Body Workouts for Women by Dean Hodgkin and Caroline Pearce.