Engaging in physical activity can result in myriad problems for women, writes Dr Giles Warrington
OVER THE past few decades, the number of women taking part in physical activity and organised sport has increased dramatically. This has led to significant health gains for those women.
Women who regularly participate in physical activity can improve their health and self-esteem, as well as reduce the risk of degenerative diseases such as osteoporosis. In addition, they can enhance overall functionality and performance.
The scientific evidence over-whelmingly supports the notion that the potential health benefits of regular physical exercise far outweigh any potential risk, and has led many medical and scientific experts to recommend girls and women to engage in regular physical activity and sport.
The dramatic increase in participation rates in organised and, in particular, performance sports among women has led to a rise in several medical conditions which have become more prevalent as the number of female athletes has risen. In response to this, the American College of Sports Medicine in the early 1990s adopted the term "the female athlete Triad" to describe these potential medical disorders.
The female athlete Triad is a medical condition identified by the complex interaction between energy availability (with or without eating disorders), menstrual function and bone health and may manifest clinically as disordered eating, amenorrhoea and osteoporosis.
Physical signs and symptoms of those diagnosed with the female athlete Triad include general weakness and fatigue, disordered eating, cold intolerance, dry skin, dehydration, noticeable weight loss, cessation of menstrual cycle, increased incidence of stress fractures and extended healing time from injuries. Affected females may also struggle with low self-esteem, withdrawal and possibly depression.
Unless appropriately diagnosed and treated, the potential effect of each condition, in combination, may not only impact on athletic performance but also long-term health.
Researchers do not fully understand the causes of the Triad.
However, it appears that the three elements are interrelated through both the physiological and psychological mechanisms of the body associated with the stresses of intense training and competition.
Energy availability, or rather the lack of energy, appears to be a key causative factor in the development of the female athlete Triad. Energy availability, like energy balance, relates to differences between energy intake and energy expenditure.
The energy necessary for sustaining daily activity (which includes training) and normal physiological function is created through the consumption and absorption of nutrients in our diets.
For many people, the energy intake from food consumption may be in excess of daily requirement, leading to weight gain, overweight and obesity.
In the case of female athlete Triad, high daily energy expenditure from intense training combined with low energy intake, possibly associated with eating disorders but not necessarily so, will lead to low energy availability.
Despite the fact that most female athletes do not meet the diagnostic criteria for eating disorders such as anorexia nervosa or bulimia, many may still adopt what is termed "disordered eating" habits associated with restricted energy intake such as skipping meals, fasting, binge eating and even purging.
By restricting their diets, athletes worsen the problem of low energy availability, which may have a direct impact on the other two components of the Triad, namely menstrual function and bone health.
The precise causes of menstrual cycle dysfunction in female athletes may vary among individuals and is probably due to several factors.
Despite this, world-class performances and Olympic medals have been achieved by women, at different phases of the menstrual cycle.
Therefore, the general consensus among sports medicine physicians is that there is no reason for female athletes to avoid training or competition during menstruation.
Amenorrhoea is defined as the absence of menstruation and may be classified as either primary or secondary amenorrhoea.
To standardise the definition, the International Olympic Committee has defined "athletic" amenorrhoea as one menstrual period or less per year.
The primary cause of athletic amenorrhoea has now been identified as low energy availability.
This can result from either severe calorie restriction or excessive training load - or a combination of the two, which, in turn, leads to a negative energy balance.
Collectively, this stress appears to disrupt the function of key hormones principally responsible for regulating the reproductive function which in turn results in the menstrual cycle being temporarily "switched-off" to conserve energy.
It is important to note, however, that in non-athletic populations, severe dietary restriction alone is sufficient to disrupt normal reproduction function in women.
Additionally, exercise and training has no direct impact on reproductive function, only in so much that it may increase energy expenditure and therefore reduce energy availability to sustain normal physiological function.
As a result, any disruption to normal menstrual function can be prevented or reversed with appropriate energy intake and without the need to modify any training programme.
The final component of the Triad is the loss of bone mineral content, increasing bone fragility, which if left untreated will increase the risk of stress fractures and osteoporosis.
Evidence suggests there appears to be a direct relationship between menstrual function and bone health, as a number of studies have shown that female athletes suffering from amenorrhoea generally have a lower bone mineral density.
It is generally accepted that two of the key causes of such bone loss are low oestrogen levels due to amenorrhoea as a result of low energy availability and also calcium and vitamin D deficiencies, necessary for healthy bone development, caused by inadequate nutrient intake.
In terms of its prevalence, the female athlete Triad appears to be most common in sports which emphasise leanness, low body weight and fat or are scored subjectively.
A recent study assessing the incidence among female athletes from a range of sports has suggested that about 4 per cent of female athletes exhibit all three components of the female athlete Triad.
An additional 26 per cent were shown to possess at least two of the criteria.
The same study suggested that the female athlete Triad may not be exclusive to those training and competing at a high level as up to 3 per cent of non-athletic women aged between 13 and 29 were also found to possess all three elements of the Triad.
The growing evidence would suggest the Triad develops on a continuum, which underlines the importance of early detection and treatment to prevent progressing towards the extremes of the Triad.
But, like many medical conditions, prevention is better than cure.
In particular, emphasis should be placed on optimising energy availability through appropriate dietary practices and training regimen which are regularly reviewed.
Dr Giles Warrington is a sport and exercise physiologist and lecturer in the School of Health and Human Performance at Dublin City University