When it comes to literature about training and nutrition for cycling, there is an abundance of current research available to best guide us on how we can train and fuel effectively. However, when you dive into these studies, a majority of them use only male participants for the studies. The main reason for this is that female athletes have more variables than male athletes due to hormonal changes over the month from their menstrual cycle, and that can affect the variables within a study that need to be controlled. Essentially, it’s easier to use male subjects, but also deeply unfair. This means that scientific literature around female athletes is a lot more limited, even though there are important differences between men and women. What we’re going to try and do here, is collect the scientific literature that is available for women to help them get the best out of their training and nutrition.
I will say that there are several fantastic researchers contributing to this area of sports science for female athletes. For example, Dr Stacy Sims, Dy Nicky Keay, and a host of other researchers who are listed at the bottom of this article in the References section.
Initially, we’re going to look at the different phases/sub-phases of the menstrual cycle. We’re going to base this off of an eumenorrheic 28-day menstrual cycle (MC). This changes between individuals, so tracking your cycle and being aware of it is a useful thing to do. A healthy (eumenorrheic) MC is defined as one lasting between 21 and 35 days. The MC usually starts from around 13 years old up until perimenopause at around 45 years. Things that can change the MC are pregnancy, oral hormonal contraceptives, or menstrual and ovulatory dysfunction. It is important to note that MCs can vary from person to person so the information in this article is based on generally accepted standards but may vary between individuals.
Follicular phase
This is split into two distinct sub-phases, the Early Follicular phase and the Late Follicular phase. The Early phase covers the time when bleeding/menstruation/the period occurs. It is characterised hormonally by low levels of oestrogen (sometimes referred to as estrogen), progesterone, luteinising hormone (LH), and follicle stimulating hormone (FSH). This usually lasts for 4-6 days, and is a good indicator of whether your cycle is eumenorrheic.
The Late phase is the duration between when menstruation stops and ovulation occurs. It is characterised by increased levels of oestrogen while other hormones remain stable. This usually lasts 7-8 days.
Ovulatory phase
Ovulation is when the egg is released into the ovaries and is characterised by oestrogen decreasing slightly, progesterone increasing, a small increase in FSH and testosterone, and a large spike in LH. It generally lasts for between 3 and 4 days.
Luteal phase
The Luteal phase is split into 3 sub-phases. The Early phase sees oestrogen levels drop significantly, while progesterone levels increase more. Both LH and FSH drop and become steady. The Mid phase sees progesterone at its highest level, while oestrogen increases. The Late phase sees both oestrogen and progesterone levels drop to their lowest before the menstrual phase starts over again. Each sub-phase lasts for 4-5 days each with the total Luteal phase lasting 12-13 days generally.
Training recommendations in eumenorrheic athletes
Firstly, although we are going to look at what current literature suggests for training based on group effects and trends, many of these studies, and a recent literature review, have found that there are large individual differences from person to person. So although these guidelines and trends may be helpful to inform your training, at the end of the day you as the individual is what matters. So setting your training based on you, and only you, is key. This is why we individualise all our clients training to be specific to them.
let’s look into why training recommendations change between the phases and sub-phases. Oestrogen has a neuroexcitatory effect, essentially this increases force production via improved neuromuscular function. Progesterone has a cortical excitability inhibitory effect, meaning that strength and power production is impaired. The results of this is that during the sub-phases when oestrogen levels are highest and progesterone at its lowest, it is recommended to focus more on strength workouts. So the Late Follicular phase and Ovulatory phase are likely the best times to focus on strength work both on and off the bike. This means that the Luteal phase, primarily early and mid phases can impair strength and power performance due to progesterone levels being at their highest.
Another element potentially affected by the MC is rapid force production, think sprints and high cadence work. In a couple of studies it was found that the motor unit firing rate in several leg muscles was reduced during the early Follicular phase while it was improved during the late Luteal phase. So focussing on fast movements in the gym such as plyometrics and sprint work on the bike are potentially ideal during the late Luteal phase.
Additionally, during the Luteal phase the body’s metabolism increases, meaning the basal body temperature is greater and muscle performance over shorter duration efforts such as track races and lifting could be increased. This is because greater body temperature results in improved muscle contractility and force production, potentially why the Luteal phase was found to benefit rapid force production. However, a proper warm up can result in the same overall impact, so what this means practicality wise is that a warm up may not be as essential during the Luteal phase, and warming up properly during the rest of the MC means there is no significant difference between phases.
There have also been studies that have found that testosterone levels are higher during the Ovulatory phase. Although this requires more research to understand, the suggestion is that during this period performance levels could be enhanced as well as strength gains, especially from resistance training.
Inflammation is another factor in this process as well. During the early Follicular phase, inflammation levels are higher. What this means is that recovery from training can take longer and the rate of perceived exertion levels are sometimes higher. Nutrition and diet are some ways to combat increased inflammatory effects in the body, as is adequate sleep and proper recovery.
Finally we have a mental aspect of things, discomfort. Some women experience significant discomfort during the early Follicular phase during menstruation, while some experience cramps during Ovulation. This is why it is important to take these recommendations and apply them to you as an individual. You theoretically may perform better during the Ovulatory phase, but if you suffer from cramps during that phase and not during the Luteal phase, that can impair performance significantly. Additionally, I have worked with many female athletes over the years, and for some they find they perform better during menstruation, going pretty much against what all the literature suggests.
This really does highlight why at the end of the day, you need to know yourself well, and why we work with every athlete on a case by case basis. Based on current literature, trends suggest that you should structure your training with more strength based workouts being conducted during the late Follicular phase along with endurance work, and fast power production and sub-maximal work being done during the Luteal phases. But setting the tougher sessions around when you feel best as an individual is key. If you feel best during the early follicular phase, do key sessions then. If you feel best during the late Luteal phase, do them then. If you feel lethargic around the Ovulatory phase, reduce training intensity and duration, perhaps focus on lower intensity sub-Lactate Threshold 1 riding. Tracking MC along with training data and RPE/perceptions can give you a clearer picture and help identify trends and patterns, and if you feel comfortable doing so, talk with your coach about this.
Nutrition recommendations in eumenorrheic athletes
During the early Follicular phase, the body is shedding the lining of the uterus, and protein requirements are increased significantly due to the need to synthesise more tissue. There is also an increase in inflammation in the body. Fuelling recommendations here are based around an increased need for protein after exercise and during the day, while increasing the levels of antioxidant rich foods (fruits, berries, turmeric, oily fish) can help to reduce the inflammation and see elements of discomfort.
In the late Follicular phase, substrate metabolism is weighted more towards utilising carbohydrates with several studies finding that during sub maximal exercise, there was a greater percentage of energy derived from carbohydrates for women during the follicular phase (Ashley et al., 2000). What this potentially means is that greater carbohydrate supplementation is required before, during, and after exercise. Generally, the guidelines are given for around 60g/hour, but women tend to use fats more than carbohydrates compared to men anyway. So perhaps, during sub-max exercise, 60g/hour is useful, while at higher intensity you will want to experiment with what your gut can tolerate carbohydrates wise. As for recommended carb intake for female athletes, ideally you want to tailor to different training days. An easy day should be 2.5-3g/kg, with this increasing to 3.5-7g/kg based on hour long intervals, 2 hour moderate paced, 3-5 hours endurance, or 5+ hours heavy endurance.
As we move into the Luteal phases, substrate utilisation switches and the body becomes better at using fats than carbohydrates. Again several studies have found that fat oxidation levels were higher during the Luteal phases than the Follicular phases. This could mean that the overall requirement for exogenous carbohydrates is reduced, so maybe 40-50g/hour is more suitable at sub/max intensities. However, the Luteal phase is also characterised by an increase in metabolism, and some studies have shown that increased carbohydrate ingestions can increase serotonin in females during the Luteal phase, assisting with mood and effort perception. So if energy requirements are higher, that may negate the reduced carb needs, and improving mood could result in improved training capacity and recovery. Additionally, protein requirements are higher as the progesterone breaks down more protein to help rebuild the uterus lining, so consuming a higher amount of protein throughout the day is essential, especially post exercise, ideally 25-35g, and 1.7-2.4 grams of protein per kilogram of body weight per day.
Additionally, several of these studies have found that once you get to more maximal intensities, then the hormone levels don’t have so much of an impact on substrate utilisation, and fueling for the work required is where it’s at. So with that in mind, for a tough session with efforts above Critical Power, consume enough carbs before and during regardless of MC phase. For sub-max workouts, tailor carb intake a bit around the MC. When you feel you have more discomfort or cramps, increase anti-oxidant rich foods.
The biggest factor to consider overall though when it comes to nutrition is Energy Availability, which covers both overall calorie intake as well as enough carbs to fuel workouts. There are far more studies into energy availability in female athletes now especially in weight restricted sports such as Ballet, Gymnastics, Running and Cycling. Poor energy availability can result in Relative Energy Deficiency in Sports (RED-S). It can be experienced in one of two ways, the first is intentional, when we reduce energy intake to try and control body composition, and the other is unintentional, when we increase activity levels without properly fuelling the work. In fact, a study by Shriver et al., (2013) found that 91% of the female college athlete study participants did not fuel adequately. Negative side effects vary from feeling fatigued and less energised, to advanced reduction in bone mineral density, loss or dysfunction of periods, and in extreme cases infertility. An irregular cycle or loss of menstruation can be a sign of RED-S and should be addressed immediately.
For an athlete, what this means is that you should be consuming at least 45kcal/kg of fat free mass as your basal calorie intake. Below this means you are not fuelling your body adequately alongside your training. Remember, the energy we use during training is not the only energy we use during the day. We use energy to sleep, live, digest, walk to the fridge, and to recover after exercise as we rebuild tissue damaged by training to experience training adaptation. This is why for female athletes it is important to ensure you eat enough when your metabolism fluctuates, and listen to your body when it feels hungry. This is also a reason why fasted and low-carb training are not recommended for women, as the risks of low energy availability are higher and the proposed mechanisms for enhanced training gains are not scientifically supported in women compared to men for fasted training.
Menopause
Menopause is when the female body becomes unable to reproduce due to many changes within the body physically and hormonally. However it is defined by several different stages leading up to this. Firstly, we have perimenopause, the period of time leading up to menopause occurring and when hormones start to change significantly. This can happen 8-10 years before menopause. Oestrogen decreases overall, and can also become more irregular during the MC. Menopause itself occurs when a period has not been present for an entire year as oestrogen levels are so low that an egg cannot be produced. Both these stages come with a host of side effects that vary between individuals and can cause varying levels of discomfort and effects on exercise performance. What this can mean is that nutrition and training has to become less rigidly structured and requires more flexibility and adjustment due to how you feel and the swings in hormones during your MC. Once everything has stabilised post menopause, it becomes a little easier to plan consistently.
Due to the decrease in oestrogen as well as an increase in both muscle catabolism and reduction in bone mineral density, there is an increased need for power and strength workouts both on and off the bike. Ensuring muscle function and power is maintained means that including more intervals and high capacity efforts into your training is essential. Additionally, resistance training is a highly important factor as this can reduce both the rate of muscle and bone mineral density decline.
In terms of nutrition, protein requirements are one area that increases significantly, with the ideal target being more like 2.2-2.4g/kg FFM as well as consuming branched chain amino acids (BCAAs), especially Leucine, during training sessions. The amount you require after exercise also increases from 20-30g (25-35g during Luteal Phase), to around 40-45g with regular 20-30g intake throughout the day.
Oral contraceptive
The Oral Contraceptive Pill (OCP) has two distinct effects, to reduce natural levels of oestrogen and progesterone during certain MC phases, while supplements exogenous levels of those hormones during other MC phases to prevent pregnancy from occurring. The issue is that this change in the regular eumenorrheic cycle can affect performance. A full meta-analysis and systematic review found that OCP use did result in a slightly inferior exercise performance when compared to naturally menstruating women, but again the results varied and the guidance was to individualise your approach. For some women the OCP may impair exercise performance, while for others they may feel no ill effects at all. But it is important to consider the pros and cons for both exercise and also day to day life.
Summary
Hopefully this article has given you a heap of information to help you make informed choices about your training and nutrition around the menstrual cycle and menopause. Although scientific literature does offer some general rules and guidelines around training and nutrition around the MC, it is a research area that is ever expanding with new knowledge coming to light every year. It is also hugely important to consider that individuals will not always experience their MC the same way. This means understanding your own cycle, how you feel during it, and what works for you, should always be the priority. Tracking your cycle, and your training/racing results and perceptions is really important to work out trends and correlations for you as an individual.
The big takeaway though – maintain energy availability, train strength and power, fuel for the work required, and listen to your body.
References
Ashley, C. D., Bishop, P., Smith, J. F., Reneau, P., & Perkins, C. (2000). Menstrual Phase Effects on Fat and Carbohydrate Oxidation During Prolonged Exercise in Active Females. Journal of Exercise Physiology Online, 3(4).
Carmichael, M. A., Thomson, R. L., Moran, L. J., & Wycherley, T. P. (2021). The impact of menstrual cycle phase on athletes’ performance: a narrative review. International journal of environmental research and public health, 18(4), 1667.
Zderic, T. W., Coggan, A. R., & Ruby, B. C. (2001). Glucose kinetics and substrate oxidation during exercise in the follicular and luteal phases. Journal of applied physiology, 90(2), 447-453.
Elliott-Sale, K. J., McNulty, K. L., Ansdell, P., Goodall, S., Hicks, K. M., Thomas, K., … & Dolan, E. (2020). The effects of oral contraceptives on exercise performance in women: a systematic review and meta-analysis. Sports Medicine, 50(10), 1785-1812.
McNulty, K. L., Elliott-Sale, K. J., Dolan, E., Swinton, P. A., Ansdell, P., Goodall, S., … & Hicks, K. M. (2020). The effects of menstrual cycle phase on exercise performance in eumenorrheic women: a systematic review and meta-analysis. Sports Medicine, 50, 1813-1827.
Burke, L. M., & Dziedzic, C. E. (2013). 2 Carbohydrates Requirements for the Female Athlete. Nutrition and the Female Athlete: From Research to Practice, 25.
Wohlgemuth, K. J., Arieta, L. R., Brewer, G. J., Hoselton, A. L., Gould, L. M., & Smith-Ryan, A. E. (2021). Sex differences and considerations for female specific nutritional strategies: a narrative review. Journal of the International Society of Sports Nutrition, 18(1), 27.
Shriver, L. H., Betts, N. M., & Wollenberg, G. (2013). Dietary intakes and eating habits of college athletes: are female college athletes following the current sports nutrition standards?. Journal of American College Health, 61(1), 10-16.
I wanted to try and cover as many aspects and areas of it possible and summarise as much of the available literature as it can be quite an arduous task trawling through papers for the relevant info
) males who just want to (very basically?) understand females better!
