How your menstrual cycle can impact your training and fitness

Thursday, November 23, 2017. Author Sarah Barron

How your menstrual cycle can impact your training and fitness

Ever wondered why some weeks you’re feeling super motivated in the gym, getting personal bests every training session, and completely smashing your fitness goals; while other weeks, all you want to do is crawl out of bed mid-afternoon with the sole purpose of ingesting the entire contents of your freezer’s pizza and ice-cream drawer, while binge-watching a series on Netflix?

Although this cliché is often trivialized as ‘just girl problems’, for some, the mental, metabolic and hormonal fluctuations that occur throughout the menstrual cycle can be quite debilitating. We are all too familiar with the impact of the menstrual cycle on everyday living, and now, emerging evidence suggests that dependent on the stage of the cycle, training and sporting performance can also be greatly affected.

What are the stages of the menstrual cycle?

Before delving any deeper, it’s worth taking a closer look at each stage of the menstrual cycle. The whole cycle lasts on average for 4 weeks (28 days); however, this can vary between 21-35 days depending on the individual. We can divide the menstrual cycle into four main phases: menstrual, follicular, ovulation and luteal.

Menstrual phase (day 1-5): Menstruation begins on the first day of the cycle and is marked by shedding of the uterine wall. Blood flow is usually between 10-80ml and may be accompanied by abdominal cramps which help to expel fluid. Levels of the hormones estrogen and progesterone are fairly low, and metabolism, mood, and hunger should be well balanced.

Follicular phase (day 1-14): This phase starts at the same time as menstruation, but lasts for 14 days. During this time, the pituitary gland in the brain releases a hormone (follicle-stimulating hormone [FSH]) that acts on the ovaries, causing development and maturation of an egg cell into a structure called a follicle (hence the name of this phase). The follicle releases a hormone, estrogen, which causes thickening of the uterine wall.

Ovulation phase (day 14): On roughly the 14th day of the cycle, the pituitary gland releases another hormone called luteinizing hormone (LH). LH causes the mature egg cell to be released from the ovaries and enter the Fallopian tube, which connects the ovaries to the uterus. Ovulation lasts for 12-48 hours, but a women’s ‘fertility window’ can last for up to 7 days, due to the ability of sperm to survive for several days in the female reproductive tract. When ovulation occurs, the egg breaks free from the surrounding protective follicle cells and the hormone, progesterone, is secreted.

Luteal phase (day 15-28): Progesterone levels peak and prepare the lining of the uterine wall for pregnancy. However, if fertilization doesn’t occur, progesterone and estrogen levels decrease, causing the lining of the uterus to break down and shed- marking the end of one cycle and the start of a new one.

Source:  https://en.wikipedia.org/wiki/Menstrual_cycle#/media/File:Figure_28_02_07.jpg

Source: https://en.wikipedia.org/wiki/Menstrual_cycle#/media/File:Figure_28_02_07.jpg

How do these stages affect sporting performance?

Now that we have an understanding of the stages of the menstrual cycle, let’s take a closer look at how these hormonal fluctuations may affect athletic ability. Moreover, are there styles of training that would be better suited to each stage?

Follicular phase:

As mentioned earlier, estrogen rises and peaks during the later stages of this phase.  Estrogen strengthens the effect of insulin (the hormone that causes storage of carbohydrates and synthesis of new proteins), meaning carbs are better tolerated and muscle is more easily built at this stage [1]. Why not take advantage of this and book in a high-intensity strength workout and refuel afterward with a high carbohydrate post-workout meal? If you’re hitting the weights, push yourself, but make sure to get a good warm up and cool down to prevent injury, as higher estrogen levels may also increase your tolerance to pain [2].

Ovulation phase:

Estrogen levels peak just before ovulation, meaning a rise in insulin sensitivity, carbohydrate metabolism and strength/power [3]. So, this would be the perfect time to fuel up and go for that personal best or that one rep max over in the weights area. Just make sure to warm up properly with a combination of dynamic stretching and resistance mobility work, as this estrogen peak also makes joints and ligaments more elastic and prone to injury [4]!

Luteal phase:

Levels of progesterone are maximized during this phase, before drastically falling (along with levels of estrogen). It is this sudden change in hormonal levels that is thought to underlie premenstrual syndrome (PMS), causing symptoms such as depression, fatigue, anxiety, headaches, cravings, water retention, and an increase in core body temperature. This may explain why, during this period, you lack motivation, swerve away from your diet plans and find exercise more taxing than usual. As a result of rises in body temperature during the luteal phase, metabolic output may increase by as much as 90-280 kcals per day [5]! Although this could potentially aid weight loss, the intense food cravings and quicker fatigue rates of PMS may be a limiting factor.

Progesterone in the luteal phase also decreases the body’s sensitivity to insulin and carbohydrate metabolism. Therefore, a diet higher in healthy fats and lower in carbohydrates may be more beneficial. Make sure to pack some extra snacks high in healthy fats and fiber during this phase, both to keep blood sugar levels stable and to avoid binge eating. If chocolate cravings are an issue for you, try a small bar of dark chocolate and a handful of berries!

It may also be best sticking to lower intensity training during this time, for example light cardio or a de-load/bodyweight session, especially if you are particularly susceptible to fatigue and depression during PMS. After all, it’s important to work with your body, not against it.

Menstruation:

Hormone levels, metabolism, and energy levels begin to balance out again during menstruation as the body prepares itself to begin another cycle. You might find this to be a good time to reset and evaluate your training programme, reflecting upon the variations in your strength, energy levels and motivation throughout the previous cycle

How can I optimize my workout routine according to my menstrual cycle?

Although the menstrual cycle remains a taboo subject, its impact on everyday life is very real. Female athletes face an added complication: the menstrual cycle affects strength, stamina, recovery time, body weight and mental focus - factors which all contribute to successful sporting performance.

Taking the above into consideration, your training and diet style can be timed to match your hormonal fluctuations and maximize muscle development and fat loss.

So, to summarize:

Follicular phase: A period of high estrogen, low progesterone, higher insulin sensitivity and better ability to build muscle. Carbohydrate intake can be slightly higher and resistance/strength training is most beneficial. 

Early Luteal phase: Predominance of progesterone, a lower insulin sensitivity, a higher core body temperature and faster metabolism. Intake of healthy fats can be slightly higher, with carbohydrate intake slightly lower. Interval training may be most beneficial here.

Late luteal phase: Sharp decline in both estrogen and progesterone and, in some, the onset of PMS. Low-intensity cardio or bodyweight training may be most beneficial here. Remain mindful of food cravings for sweet and starchy food.

It's also important to understand that your genes play a role in how your body responds to the stages of the menstrual cycle too. For example, changes in insulin sensitivity caused by progesterone will also be influenced by genes such as PPARG, which is involved with carb processing and insulin sensitivity. Similarly, your ability to build muscle in the follicular phase of the menstrual cycle may also be affected by genes known to impact muscle development, such as ACVR1B, IGF1 and MSTN. Knowing your genetic makeup may therefore assist you in fine-tuning any diet and training adjustments you wish to make based on your menstrual cycle.   

All this said, it’s important to take the above as a rough guide only. There are studies which suggest that there is no significant impact of menstrual cycle on athletic performance in the general population [6]. Discrepancies in these findings may reflect individual variability in the length of cycle and in the stages in which peak performance occurs. So, why not keep a diary (apps are available for this now!) to see how your mental and physical well-being changes throughout your cycle. This will allow you to be more mindful when goal-setting and ensure that you stay on track!

I hope you enjoyed my article, and I invite you to read my other FitnessGenes blogs:

The benefits of exercise on brain function and mental health

How your sleep cycle impacts your weight and your workouts

What's the difference between bodybuilding, powerlifting, and Olympic lifting?

References:
1.    D'eon, T. and Braun, B., 2002. The roles of estrogen and progesterone in regulating carbohydrate and fat utilization at rest and during exercise. Journal of women's health & gender-based medicine, 11(3), pp.225-237.
2.    Craft, R.M., 2007. Modulation of pain by estrogens. Pain, 132, pp.S3-S12.
3.    Sarwar, R., Niclos, B.B. and Rutherford, O.M., 1996. Changes in muscle strength, relaxation rate and fatiguability during the human menstrual cycle. The Journal of physiology, 493(1), pp.267-272.
4.    Wojtys, E.M., Huston, L.J., Lindenfeld, T.N., Hewett, T.E. and Greenfield, M.L.V., 1998. Association between the menstrual cycle and anterior cruciate ligament injuries in female athletes. The American journal of sports medicine, 26(5), pp.614-619.
5.    Webb, P., 1986. 24-hour energy expenditure and the menstrual cycle. The American journal of clinical nutrition, 44(5), pp.614-619.
6.    Constantini, N.W., Dubnov, G. and Lebrun, C.M., 2005. The menstrual cycle and sport performance. Clinics in sports medicine, 24(2), pp.e51-e82.

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