With the rise in female participation in sport and gym environments, and the increased awareness of the importance for women to strength train, a conversation has started around the menstrual cycle and how it can impact women’s physical performance. For as long as women have been menstruating, periods have been stigmatised which has led to shame, embarrassment and fear for many young girls and women. In fact, a recent survey found that 70% of young women aged 12-18 years felt uncomfortable playing sport during their period, with many refusing to participate altogether. (1) Without getting into the details of how we can manipulate training variables to optimise performance throughout the cycle, it is essential that we continue to combat the stigma around menstruation to make girls and woman feel more comfortable participating in sport and training.
Understanding your cycle
A woman’s menstrual cycle is a combination of the ovarian and uterine cycles, which interact in the female reproductive system to make pregnancy possible. The overall duration of the menstrual cycle can range anywhere from 21 to 40 days. (2) It is rare for a woman to experience a textbook 28-day cycle, which further emphasises the need for an individualised approach. (3) We can divide the menstrual cycle into the follicular (or proliferative) phase, ovulation and the luteal (or secretory) phase.
- The follicular phase can last anywhere between 11 to 27 days and is the time between the first day of the period until ovulation. Following the shedding of the uterine lining, the rise in oestrogen causes the endometrium to thicken in preparation for implantation of a potentially fertilised egg. (4)
- Ovulation typically occurs mid-cycle for 24 hours in response to high levels of oestrogen causing a dramatic increase in luteinising hormone. This results in the release of the egg from the ovary. (4)
- The luteal phase typically lasts around 14 days and occurs from ovulation to the start of the next period. The follicle that contained the egg transforms into the corpus luteum, which is a temporary hormonal structure that secretes progesterone and primarily functions to prepare the uterine lining for implantation of the fertilised egg. If no fertilisation occurs, this structure starts to break down, leading to a drop in oestrogen and progesterone, causing menstruation. (4)
Not all cycles are ‘normal’
It is important to realise that not every woman has a naturally occurring cycle, either due to environmental and physiological factors or from taking exogenous hormones. Here are some key definitions that describe differences from a normal menstrual cycle:
- Anovulatory Cycle: this is a continuous menstrual cycle without ovulation (it’s like a continuous follicular phase followed by breakthrough bleeding). (5)
- Primary Amenorrhea: this is when you have never had a period (if you are 16 or older and have never had a period, it’s important to see a GP). (5)
- Secondary Amenorrhea: the absence of menstruation for 3 months in a female who previously had regular cycles or for 6 months in a female with previously irregular cycles. (5)
- Polycystic Ovarian Syndrome: this is a common condition that affects 8-13% of women of reproductive age and is commonly associated with increased levels of insulin and androgens (male-type hormones). (6)
- Functional Hypothalamic Amenorrhea: this occurs when the hypothalamus is silenced from released hormones that allow for ovulation and a normal cycle. It is generally caused by low energy intake, excessive exercise, weight loss, stress or a combination of these factors. (7)
- Perimenopause: this generally starts in a woman’s 40s and is when the ovaries begin to make less oestrogen in the transition to menopause. (8)
- Menopause: this is the natural decline in reproductive hormones during your 40s or 50s and is signalled by reaching 12 months since last menstruation. (8)
- Pill Bleed (or Withdrawal Bleed): this is not a period, is it the withdrawal of hormones in the pill and in the body. The drop in hormone levels causes the lining of the uterus to shed. (9)
Even if a woman does not have a textbook ‘normal’ cycle, it’s important for women to have an understanding of their own cycle and symptoms. This is what we term body literacy. Body literacy refers to having the self-knowledge to observe and chart signs of fertility and infertility along with a range of other health and wellness observations. (10) To make adjustments to support your training it is helpful to know the normal length of your cycle and the different phases, as well as the typical symptoms that occur each month (such as temperature changes, mood changes and hunger levels).
How do you track the menstrual cycle?
Tracking the menstrual cycle is not all about avoiding pregnancy or looking for fertile windows. The American College of Obstetricians and Gynaecologists advises health practitioners to consider the period as the ‘fifth vital sign’, as menstruation should be considered just as important as a health indicator as body temperature, pulse, breathing rate and blood pressure. (11) There are a variety of methods you can use to track your cycle, however it’s important to be aware that efficacy of these methods as a form of contraception depends greatly on consistency and ability of tracking. Apps such as Clue are useful for charting symptoms throughout the cycle, while a newly developed app WILD.AI helps by providing recommendations on training type and intensity based on the cycle and associated symptoms.
Physiological factors that influence your training
Female sex hormone levels are lower in the follicular phase, which means that body temperatures are lower, and women are typically more resistant to fatigue. (12) Research has shown strength levels tend to be higher in this phase and greater increases in muscle fibre diameter seen. (13) Furthermore, due to low levels of oestrogen and better insulin sensitivity, it is easier for women to tap into glycolytic stores and utilise carbohydrate for energy during exercise. (14) Carbohydrate is your main source of fuel for high intensity exercise, particularly when your body cannot utilise oxygen for fuel (e.g., at the end of a hard working set in the gym). During ovulation energy levels are typically higher due to the rise in sex and pituitary hormones. Studies have shown strength levels to peak at ovulation, however due to oestrogen levels there is a decrease in tendon and ligament stiffness which may increase risk of injury. (15,16)
Lastly, throughout the luteal phase and leading up to menses, the increase in core temperature which accompanies the rise in progesterone can lead to greater cardiovascular strain in prolonged exercise, particularly in hot and humid conditions. (17) Energy expenditure tends to increase, so more food may be required overall, and women generally conserve their glycogen stores during this time. (18) Lastly, reaction time and coordination may be lower due to the higher levels of oestrogen and progesterone. (19)
What if I’m on the oral contraceptive pill (OCP)?
Examining the effects of the OCP on performance and training is a whole other article in itself. However, one of the main considerations when taking the OCP is that it can mask irregularities that would normally be evident if the natural cycle was occurring. (20) Menstrual cycle irregularities are one of the early indicators of low energy availability or relative energy deficiency so it’s important to that energy intake is adequate when taking the OCP. (21)
Can I track my cycle if I use an intrauterine device (IUD)?
Given that you can still get a period and ovulate when using hormonal and non-hormonal IUDs, you can absolutely make adjustments to your training based on the cycle. The same rules apply – track your cycle length and symptoms and try to get an understanding of the length of your follicular and luteal phases to better optimise timing of de-load and peak weeks in training.
Putting it all together
The menstrual cycle is complex, leading to a variety of physiological fluctuations that influence temperature, mood, fatigue and hunger levels. You don’t need to overcomplicate the process, rather follow a few practical recommendations as best as you can.
- Utilise autoregulation in training, rather than percentage-based prescriptions, to allow training adjustments based on real-time psychological and physiological feedback.
- Aim for your hardest week of strength training to occur in your late follicular phase before ovulation. Use the rise in hormones and the feel-good benefits of ovulation to your advantage.
- Get in your higher intensity conditioning work in your follicular phase when hormone levels are low. This ties in well with your body’s ability to better utilise carbohydrates.
- Keep your lower intensity conditioning work for your luteal phase when your body is preferentially utilising fat for fuel and when your energy and motivation may be a little lower.
- The rise in core temperature that occurs for women due to increasing levels of progesterone can affect sleep and recovery. In the week leading up to your period, it’s important to keep the bedroom cool and utilise strategies to avoid overheating at night to better optimise recovery from training.
- Let your symptoms guide you. If you get bad back pain just before or during your period, maybe that’s a day to skip out on lifting and choose to do some active recovery or gentle stretching instead.
- Lastly, get in touch with a coach who can guide you through the process!
There is a significant amount of variability between women in regard to cycle length, function and symptoms that are experienced throughout the cycle. As such, training and nutrition strategies should be adjusted accordingly. It’s also essential that there is an open line of communication between the coach and client to allow for changes to be made and to keep an eye on warning signs of menstrual irregularities or loss of the period altogether. It’s time for women to start working with their hormones, not against them. Use these hormonal perturbations to your advantage to optimise your training, health and performance.
Written by Performance Coach Katie Crombie
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- Hinde, N. Huffington Post [Internet]. United Kingdom: HuffPost UK [updated 2016 August 16; cited 2016 August 16]. Available from: https://www.huffingtonpost.co.uk/entry/period-stigma-report-bodyform-most-girls-avoid-sport-while-on- period_uk_57b2f9eae4b0730aab6465c5
- NHS. UK: National Health Service, c2019 [cited 2021 August 6]. Available from: https://www.nhs.uk/conditions/periods/fertility-in-the-menstrual-cycle/
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- Jean Hailes. Australia: Jean Hailes for Women’s Health, c2021 [cited 2021 August 6]. Available from https://www.jeanhailes.org.au/health-a-z/menopause
- Wright KP, Johnson JV. Evaluation of extended and continuous use oral contraceptives. Ther Clin Risk Manag. 2008 Oct;4(5):905-11. doi: 10.2147/tcrm.s2143. PMID: 19209272; PMCID: PMC2621397.
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