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Exercise as it relates to Disease/The impact of exercise on the menstrual cycle

Brief background

Over the years as more women started to become involved in competitive sport it became clear there were medical issues specifically related to women. Several medical issues were regularly occurring either together or as a result of another so the female athlete triad was created, which involves eating disorders, amenorrhoea and osteoporosis.[1][2] This sheet will focus on the issue of amenorrhea in female athletes and how exercise affects it. Amenorrhea can particularly affect females involved in gymnastics, ballet and long distance running.[3]

What is amenorrhoea?

Amenorrhea or menstrual irregularity involves a delay or cessation in a regular menstrual cycle.

It can be divided into two main categories:

• Primary amenorrhea – menarche has not yet occurred by the age of 14-16

• Secondary amenorrhea – regular menstrual cycles cease for longer than six months[2][4]

Why it occurs due to exercise?

High intensity exercise can affect the body’s ability to regulate menstruation. High levels of exercise cause an abnormality in the production of gonadotrpin releasing hormone (GnRH) in the hypothalamus. GnRH is secreted in a pulse like fashion and in turn stimulates the pituitary gland to secrete luteinizing hormone (LH) and follicle stimulating hormone(FSH).[1]

Abnormal GnHR secretion is thought to be caused by either:

• The activation of the adrenal axis during exercise, which inhibits the GnRH pulse activator

• Low energy intake and high energy expenditure causing an “energy drain” [1]

These hormones regulate the ovaries and the production of oestrogen and progesterone which in turn control the menstrual cycle and other sexual characteristics during puberty.[3][5]


The menstrual cycle may also be affected by the imbalance of energy intake and expenditure that may occur with high intensity sports.[2] This imbalance may cause a reduction in metabolic rate which in turn may affect reproductive function.[3][5] A low body weight can result from an imbalance of energy intake and expenditure but potentially a psychological condition such as an eating disorder may also be a contributing cause to amenorrhoea developing.[3]

Impact of lack of regular menstruation

There are few serious short term effects of the loss of regular menstruation. Some athletes may even welcome it as the side effects of menstruation such as period pain and mood swings may not be conducive to performance. Amenorrhea causes temporary infertility as a result of a condition called anovulation which means that the ovaries are unable to produce viable eggs. However once normal menses resume fertility returns. There are however much more serious long term consequences of the loss of regular menstruation. Bone density decreases and if left untreated increases the risk of developing osteoporosis.[1] A lower bone density also increases the risk of developing stress fractures or suffering more severe bone breaks.

Recommendations/Treatment

Amenorrhoea is a serious condition that if left untreated can have long term effects after an athletes career. Ways to assist athletes in treating amenorrhoea will involve the athlete, coach and nutritionist:

• Decreasing intensity of training

• Improving diet to create an equal balance of energy intake/expenditure

• Increase of calcium intake eg 3 glasses of skim milk or if necessary calcium supplementation to improve bone density

• Estrogen replacement therapy if exercise reduction and diet improvement do not cause an change

• Once menses restart if still irregular can use oral contraceptive pill to help regulate them.[3]

Prevention is the best treatment rather than having to deal with the issue once it has occurred.

Ways to do this could be:

• Monitor athletes that may be susceptible

• Encourage athletes to keep a diary of menstrual cycles so if irregularities occur repeatedly advice can be sought

• Provide advice about the importance of proper energy balance

Further reading

• Better Health Channel , Menstruation – Amenorrhoea http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Menstruation_amenorrhoea

• Australian Sorts commission – Female athlete triad http://www.ausport.gov.au/ais/nutrition/factsheets/basics/female_athlete_triad

• The Sydney Children’s Hospital Network, -Amenorrhoea http://www.schn.health.nsw.gov.au/files/attachments/amenorrhoea_long_version.pdf

References

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1. Vereeke, R, (1998), The Female Athlete - The Triad of Disordered Eating, Amenorrhoea and Osteoporosis, Sports Medicine, Vol 26, No 2, p 63 - 71

2. Australian Sports Commission, (2010), Female Athlete Triad, http://www.ausport.gov.au/ais/nutrition/factsheets/basics/female_athlete_triad

3. Virginia Commonwealth University medical Centre, (2014), Exercise Induced Amenorrhoea, http://www.vcuhealth.org/?id=1045&sid=1

4. Better Health Channel, (2014), Menstruation - Amenorrhoea, http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Menstruation_amenorrhoea

5. The Sydney Childrens Hospital Network, (2014), Amenorrhoea, http://www.schn.health.nsw.gov.au/files/attachments/amenorrhoea_long_version.pdf

6. Loucks, A, (1990), Effects of exercise training on the menstrual cycle: existence and mechanisms, Medicine and Science in Sport and Exercise, Vol 22, No 3, p 275-280