Why a female athlete should track her monthly cycle
For many years female athletes have been treated like small men. Fortunately, this has changed more recently with the introduction of better female-specific clothing and equipment. There is also a greater understanding of the impact of women’s monthly cycle on training and nutrition needs. In this small series of blogs, Coach Denise looks at the factors that impact female triathletes and how these can be used to advantage within a training plan.
All female athletes will be aware that their bodies operate within a monthly cycle but not all are aware of the details of what is happening within their bodies. Knowing what is occurring, and why, can really help with understanding how to work around, and with, the monthly changes. To go back to basics, the diagram below shows the different phases within the monthly cycle. This is shown over 28 days though the exact time span can vary.
This cycle is driven by variations in hormones within the body 1 . The relative levels of the different hormones can be seen in the second picture below: Biology Of Female Reproductive System
The menstrual cycle is regulated by oestrogen levels. Levels increase in puberty and a decline in oestrogen triggers menopause. It is responsible for the growth of breast and reproductive organs in puberty and then for the tissue growth in the lining of the womb.
Progesterone is generated in the female reproductive organs and helps to prepare the body for pregnancy.
Luteinising Hormone (LH) and Follicle Stimulating Hormone (FSH) together are responsible for the development and release of an egg at ovulation.
The last 14 days of the cycle, the Luteal phase is when hormone levels are highest. While these hormones are essential for the regulation of the menstrual cycle they also have other impacts on the body.
Higher oestrogen levels in the body can reduce the amount of leucine available, which is responsible for triggering muscle building within the brain and can reduce the ability to absorb protein. At the same time, the ability to burn carbs are reduced and fatty acid availability and fat burning increase. Higher oestrogen can also lead to fluid retention as well as impact the hypothalamus leading to an increase in fatigue and lethargy.
With higher progesterone levels the body is being prepared for pregnancy. Glycogen stores are protected as they may be required for pregnancy and so they are not as available to the athlete at this time. More fluid is retained within the body and sodium excretion levels, in sweat, increase. The core body temperature also increases during this phase of the cycle and protein uptake capability is reduced. Overall, the metabolic rate just before a period can increase by 5-20%, so the base calorific demand may increase.
Looking at the above information it is clear that the female body has a lot to cope with throughout the month. Providing the body with what it needs, and when, can really help to support the system and keep the individual strong and healthy in the long term. The next blog will look at this in more detail, but the above information shows that there is an increased need for protein, from whatever source, during the high hormone phase. Increased levels of leucine in the diet will compensate for the reduction in available leucine within the body and knowing that the glycogen stores are less accessible for use in endurance training can influence the nutrition strategy within long training sessions, depending on where the female athlete is in their monthly cycle at the time.
65% of women say that their menstrual cycle affects their training, performance or well-being. Despite this only 23% of women athletes have discussed their cycle with a coach although they have discussed it with fellow women athletes 2. Something which has such a potentially large impact on training should be a topic of discussion between coach and athlete.
For all of the reasons mentioned above, an athlete needs to know just where they are in their cycle at any point in time. We all have ‘off’ days or times when training seems harder than expected. Fatigue can come from a lot of factors, work or family stress, poor sleep patterns, poor nutrition or fuelling. These factors are generally obvious and can be easily determined. If a female athlete does not know where they are in their cycle then unexpected fatigue levels can be demoralising. Knowing just where her body is in terms of her monthly cycle can help to explain fatigue when there is no other obvious cause.
Of course, everybody is different in how they experience these changes 3. Some women seem to accommodate these hormone changes with ease, while others have a much more difficult time. Stomach cramps, headaches and mood swings can make training almost impossible. Ultimately it is important to listen to your body. But understanding just what is happening can help to develop some coping strategies, adjust training to offset some of the chemical changes happening in the body and give the female athlete more control over just what is going on.
Denise has been coaching triathletes since 2019 as a coach at her local triathlon club in West Lothian. Between 2019 and 2022, Denise was the Head coach in the club, working with a team of coaches to support and develop triathletes with a wide range of capabilities, completing her BTF Triathlon Level 2 coaching qualification in 2021.
Denise joined Tri Training Harder as a coach in 2021, building on the qualifications through the experience and knowledge passed on by the coaching team.
In 2019 Denise set up and continues to run her own Jog Scotland running group, a mixed ability group of runners who meet weekly. This delivers on her passion for helping people to do much more than they think they can.
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