This article outlines how women could potentially optimise their training and nutrition in line with the various stages of their menstrual cycle. Originally written for coaching clients, but after many requests I have published it. The topic is huge and fascinating, and I will endeavour to update things as more research is published.
Practically, the current evidence does not warrant general guidance on modulating exercise across the menstrual cycle. As such, we recommend that a personalised approach should be taken based on each individual’s response to exercise performance across the menstrual cycle.
Considering the evidence, developing advice that addresses the higher energy expenditure and lower levels of amino acids in the luteal phase would be an advancement on the ‘one diet fits all’ current approach.
- Recent systematic review and meta-analysis The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis.
- The Curious Climber Podcast recently interviewed Dr. Stacy Sims: Women are not small men.
- Another paper I want to look at: Wilcox, A. J. (2000). The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study.
- I will be including information from Mattu, A. et al. (2019). Menstrual and oral contraceptive cycle phases do not affect submaximal and maximal exercise responses published October 2019 as soon as possible.
- I have been asked to create sections providing information for women on hormonal contraception, and also in regards to menopause. I will do.
The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis
The following systematic review and meta-analysis (78 included studies, data from 51 studies) was published 13 July 2020.
- In women, exercise performance might be reduced by a trivial amount during the early follicular phase of the menstrual cycle when compared with other phases. However, large between-study variance was identified, indicating that research design, participant characteristics and choice of outcome measure might influence any group-level effect.
- Practically, the current evidence does not warrant general guidance on modulating exercise across the menstrual cycle. As such, we recommend that a personalised approach should be taken based on each individual’s response to exercise performance across the menstrual cycle.
- The quality of evidence for this review was mostly classified as “low” quality, which can be attributed to a range of methodological issues. Future studies need to improve methodological quality and limit confounders to facilitate a deeper understanding of the effects of the menstrual cycle on exercise performance.
The results from this systematic review and meta-analysis indicate that exercise performance might be trivially reduced during the early follicular phase of the MC, compared to all other phases. Due to the trivial effect size, the large between-study variation and the number of poor-quality studies included in this review, general guidelines on exercise performance across the MC cannot be formed; rather, it is recommended that a personalised approach should be taken based on each individual’s response to exercise performance across the MC.[1:1]
A Unique Physiology
Due to a unique physiology including hormonal cycle, women require slightly different fuelling strategies during exercise, find it harder to lose body-fat, respond better or worse to training modalities, may need to consider sodium, hydration and heat management more than men, and performance may be impacted at different times of the month.
Women do generally have smaller hearts, heart volume, lungs (25-30% less capacity than men), lower diastolic pressure (artery pressure between beats), which results in 30% less cardiac output (less oxygenated blood per beat, requiring heavier breathing), lower maximum heart rate, and may be more susceptible to dehydration in hot environments.
Men have significantly higher testosterone which increases the production of red blood cells (6% more red blood cells, 10-15% more haemoglobin) which absorb and carry oxygen to working muscles. Women therefore have a 15-25% lower VO2Max (the maximum amount of oxygen the body can utilise for metabolism per minute). This means that women require a higher heart rate and more oxygen for the same workload as men.
Though women and men generally have the same muscle fibre type percentage: type I endurance (aerobic), type II power (anaerobic); women’s largest fibres tend to be type I (endurance), where men are type II (power). Men therefore have a greater glycolytic capacity, the ability to derive energy from glycogen (muscle glucose) during the absence of oxygen (high-intensity workloads). High glycolytic metabolism however leads to muscle acidity and requires longer recovery between all-out efforts. Women have greater endurance capacity, greater muscle efficiency due to lipid metabolism, and more glycogen sparring ability.
Because of this, men can generate force quicker and are more explosive. However women tend to be able to handle a higher training volume (including higher repetitions) than men. This may be related to the protective effects of estrogen (during high-hormonal phase). Women may recover faster than men after high volume training sessions, however may recover slower from explosive high-intensity sessions. Joint laxity may increase the risk of injury during progesterone elevations.
Although women mobilise more fat during exercise, during recovery women tend to use a higher percentage of carbohydrate, men a higher percentage of fat. Men’s post-exercise metabolism remains elevated for longer than women, and fat-loss is unfortunately harder for women.
Essential body-fat for women is 12% (men 4%), and healthy body-fat ranges for women are 12-30% (men 5-25%). Women tend to fair better on higher fat, lower carbohydrate diets, and are less hungry on higher fat diets.
Women typically present with about 10 % higher body fat compared to men and deposit it in a pattern referred to as the gynoid fat deposition, which is an accumulation of body fat below waist around the hips and thighs. Men however deposit adipose tissue in a pattern referred to as the android fat deposition which is fat accumulation in the upper body and upper abdominal areas.[2:1]
But Not So Different
Men have reported greater muscle strength and size than women, due to higher levels of anabolic hormones and greater body size. The lower blood androgen levels of women have also been hypothesised to induce less relative muscle hypertrophy in response to resistance training compared with men. However, several studies have failed to identify any difference between males and females with similar relative improvements in strength adaptations. … Men and women exhibited wide ranges of 1RM strength gains from 0 to +250% (0 to +10.2 kg). In addition, men experienced 2.5% greater gains in cross-sectional area (p ≤ 0.05) compared with women. Regardless of men having greater absolute gains in strength, relative baseline strength increases in strength measures were greater in women compared with men (+25%).
Men have more muscle than women, and several attempts have been made to determine the physiological mechanisms responsible for this phenomenon by measuring the rates of muscle protein synthesis (MPS) and breakdown (MPB) without much luck so far. … In support of the general consensus so far, they too report no difference in the rates of MPS between young men and women in the fasted state or the fed state at rest or after exercise. It therefore seems safe to say that West et al. firmly put the final nail in the coffin of the notion that rates of MPS throughout the day are different between healthy young men and women. … In summary, the answer to the question whether there are differences in muscle protein metabolism between healthy young men and women seems to be no.
We have shown that despite differences in mean testosterone level between genders, there is complete overlap of the range of concentrations seen. This shows that the recent decision of the IOC and IAAF to limit participation in elite events to women with a ‘normal’ serum testosterone is unsustainable. We have also shown that the approximate 10-kg deficit in LBM seen in elite female athletes most likely accounts for differences in performance seen between the sexes rather than the hypothesis put forward by the IOC/ IAAF that it is due to testosterone.
Women differ from men with regard to muscle and tendon, most likely because of sex differences in estrogen. The present experimental findings suggest the hypothesis that estrogen has an anabolic effect on muscle primarily by lowering the protein turnover and enhancing sensitivity to resistance training. Furthermore, estrogen may reduce the stiffness of tendons, an effect that may be modified by physical training.
In a comprehensive study with over 300 men and premenopausal women, the energy contribution of fat was significantly higher in women vs. men at all exercise intensities measured ranging from 41-61% VO2max. Studies have consistently shown that premenopausal women have a significantly greater ability to oxidize fat during exercise. Interestingly, when men were supplemented with estrogen, increases in FAox were observed along with increased cellular expression of beta-ox proteins within eight days of supplementation.
Menstrual Phases and Considerations
Estrogen secretion naturally varies in young women, increasing 10- to 100-fold over the menstrual cycle. Beyond estrogen, the menstrual cycle is characterized by significant changes in other important plasma hormones such as follicle stimulating hormone (FSH), luteinizing hormone (LH), and progesterone. 17β-estradiol levels rise from 5 pg/ml at the early follicular phase, to a peak of 200–500 pg/ml just before ovulation. Ovulation is followed by a rapid decrease in estradiol, then estradiol, and progesterone both increase in the luteal phase giving a broad secondary peak.
The average menstrual cycle lasts 28 days (can range between 21-35 days) and is divided into two 14-day phases. The cycle begins the day of menstruation (Day 1).
- Follicular Phase (Days 1-14): Around day 5-6 ovaries increase the production of estrogen, there is a rise in follicle-stimulating hormone (FSH), and number of ovarian follicles are stimulated to “mature” eggs for release. Around day 12, estrogen, FSH, and luteinizing hormone (LH) spike causing ovulation and an egg is released from the fallopian tubes. Estrogen is then lowered, but will rise again if the egg is fertilised.
- Luteal Phase (Days 15-28): During this phase progesterone increases surpassing estrogen to prepare the uterus lining for egg implantation. Estrogen and progesterone peak 5 days before menstruation, and is where premenstrual syndrome (PMS) symptoms occur. If a fertilised egg is not implanted, progesterone levels fall, uterus lining is shed (Day 1), and the cycle repeats.
High / Low Hormone Phases
During the low-hormone Follicular phase, women are physiologically similar to men, but when hormones rise during the Luteal phase things are quite different.
More specifically, there were decreased levels of alanine, glutamine, lysine, glycine, serine and creatinine and increased levels of hydroxybutyrate, VLDL CH2 and acetoacetate during the luteal phase. Considering this and previous literature we concluded that the decreased levels in the luteal phase were reflective of increased utilisation. … Examination of the changes across the phases revealed that sixty-seven metabolites related to amino acid, lipid, carbohydrate, energy and vitamin metabolism significantly changed with the majority decreasing in the luteal phase.[2:2]
- High estrogen shifts the body to utilise more lipid (fat) over glycogen (carbohydrate), which means high-intensity power strength work may be hindered due to the slower rate of energy yield from lipid metabolism. More carbohydrate may need to be consumed before and during training to maintain power output. However increasing low-carbohydrate lower-intensity aerobic work during this phase may facilitate greater fat loss. In general women are likely to require less daily carbohydrate during this phase, but perhaps more targeted carbohydrate for high-intensity explosive sessions.
- High progesterone relaxes muscles, ligaments and joints, possibly decreasing muscular strength, decreases gut motility (increased constipation, heartburn), increases metabolism, hunger, core temperature, reduces the ability of aldosterone to conserve sodium, impacts the central nervous system (increased fatigue), and even increases sensitivity to carbon dioxide (shortness of breath).
Both hormones affect fluid balance with estrogen increasing the expression of vasopressin who’s role involves water retention and blood vessel constriction. Elevated levels of progesterone potently reduce the sodium-retaining activity of aldosterone, resulting in a reduction in blood volume, cardiac output, and blood pressure. When blood plasma is low, less blood is pumped with every heartbeat impacting performance. Progesterone also elevates core temperature, which along with lower blood volume can impact the ability to regulate cooling via sweating.
Training and performance may be negatively impacted and feel harder due to reduced connective tissue elasticity, central nervous system fatigue, hydration status, core temperature, and reduced sweating.
During the high-hormone phase, Carbohydrate cravings may increase as glycogen metabolism is lowered. This tends to be most noticeable during the peak hormone PMS run-up phase to menstruation. Metabolism also increases by nearly 200kcal/day during this premenstrual phase.
The uterus lining is shed by a process driven by prostaglandins which make the uterus contract often with various degrees of pain. Headaches may also occur due to blood pressure change. Spatial cognition (the ability to identify targets etc) can be also impaired. Gastrointestinal (GI) issues can occur likely related to the higher levels of prostaglandins.
After menstruation (low-hormone phase), a women’s physiology closer resembles that of a man. Research has shown that women can make greater strength gains, and produce greater force when they train during this low-hormone phase compared to the high-hormone phase.
This does not mean that women cannot train and perform during the high-hormone phase, but it highlights that peak performance will probably occur during the low-hormone phase.
Practical Actions for the High-Hormone Phase
Though there are unique differences between women and men, and those differences may impact performance at times, in regards to nutrition I believe there is not a large difference in application.
However I will highlight some useful actions below.
- Be mindful of how you may feel during the high-hormone phase, however use this as a means to be kind and forgiving to yourself, not as an excuse to forgo training or pushing yourself. Quite simply training may feel harder, power and strength may be decreased. Understand this and program your training with this in mind. Importantly, your mind is your greatest performance limiter, so do not believe you are slow, weak, and less powerful just because you are in the high-hormone phase. Again just be aware, and approach yourself with less self-criticism if your performance is less than what you expect. With all this in mind, simply program your max strength and power sessions to be during your low-hormone phase, use the low hormone phase to really push yourself.
- Menstrual cramps may be reduced by consuming magnesium glycinate or malate (200-400mg) and Omega-3 rich foods (oily fish, fish oil, algae oil) along with a low-dose aspirin (80mg) every day for the 5-7 days leading up to menstruation. Aspirin specifically suppresses prostaglandins.
- Make sure you hydrate appropriately before your sessions especially if doing so in the in the heat.
- Cravings may be reduced by consuming a few squares of dark chocolate (darker the better, e.g., 80%) daily.
- Within your typical daily protein spread, consume one protein meal (~30g) immediately after training to facilitate muscle recovery. However this is my general recommendation at all times, and worth keeping as a default action.
- Keeping protein constant, daily carbohydrate consumption can lower and fat intake can increase to match energy requirements.
- It may be worthwhile programming more long low-intensity duration cardio sessions during your high-hormone phase. By doing endurance-type training without consuming carbohydrate immediately before will facilitate the opportunity to burn more fat during your session.
- Consume 30-60g of carbohydrate ~30 minutes before power strength sessions, with 30-60g every hour of training. Since GI symptoms may be higher during the high-hormone phase, your choice of carbohydrate may be better suited to be lower in fibre. This does not mean eat lots of refined carbohydrates, but rather just be mindful that digestion may be impacted.
- If you have a heavy bleeding during menstruation, please consult your GP to test for iron levels. This is more important as an athlete and even more so if you do not eat animal products.
Timing Training Around Cycle
Some women may gain significant weight during the Luteal Phase going into menstruation. This is however mostly water weight. It appears this is related to higher sustained levels of aldosterone. Aldosterone results in sodium retention and potassium excretion in the urine.
Whenever you retain sodium you retain water.
Whereas potassium pulls water into your cells, resulting in a more muscular look, sodium pulls water out of your cells resulting in an often swollen, puffy appearance and possibly feelings of bloating.
As a climber, this could have quite an impact on your performance.
The following can potentially mitigate this, and should be implemented as soon as you notice unfavourable weight gain. Over time you could possibly preempt this and start sooner.
- Decrease sodium intake: reduce processed foods and heavy salting of meals
- Increase potassium rich foods: fruits, vegetables, legumes, potatoes
- Daily supplementation: 200-400mg Magnesium (glycinate or malate), 40-50mg B6 (pyridoxal 5-phosphate)
- A mild diuretic: dandelion tea or dandelion root tea may help reduce excess water
This study is the first to systematically investigate the basis of the somatic symptoms that are associated with fluid retention in women with PMS. These women, who were selected using stringent criteria, reveal that their fluid retention-related symptoms, namely, ankle edema, bloatedness, and breast swelling, during the LL [late luteal] phase of their menstrual cycles, are associated with elevated levels of plasma aldosterone and PRA [plasma renin activity]. The present study shows that women with PMS have exaggerated increases in PRA and plasma aldosterone levels during the LL phase of their menstrual cycles compared with those of healthy control subjects. Although the plasma levels of estrogen and progesterone were comparable, a delay in their physiological withdrawal (withdrawal phase) was evident in the women with PMS during the LL menstrual phase. This was associated with low plasma levels of LH and FSH.
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