We’re all familiar with the menstrual cycle, but fewer of us are aware of how our hormones fluctuate across the cycle, and what that could mean for our training and nutrition. This month, we look at how understanding women’s physiology can help us optimise our performance, whether you’re new to fitness or an experienced athlete.

The idea of women taking a cycle-based approach to their activities, workouts and food has been growing in popularity in recent years. Sometimes called cycle synching, the strategy marks an exciting development in health research and practice: while fitness and diet knowledge previously considered commonplace has been derived from studies done almost exclusively on men (hello keto diet!), more research is now being done to understand how women’s physiology impacts a woman’s own training and nutritional needs, performance and success.

Cycle synching is not an exact science, nor will every menstruating woman experience her cycle and its shifts in the same way. Our sensitivities to hormones will be different, other health conditions have an impact, and sleep and stress also play a huge role in how we feel. However, the below is useful as a guide – and, if you’re interested, you can start tracking your cycle, which will help you become more aware of shifts in mood, energy, hunger and recovery, and you can tailor your training and nutrition accordingly.

Please note that the learnings discussed below refer to menstruating women with regular periods who have not entered perimenopause, who are not pregnant, and who are not using hormonal forms of birth control.

Many women’s cycles will differ in length from one another, and their own will vary in length across their menstruating years. For the purposes of this article, we’ll use a 28-day cycle as the standard example. The basic principles are the same, and the more you track your own cycle, the more aware you will become of how these principles inform your individual experience and physiology.

The menstrual cycle is split into two distinct halves, follicular and luteal, which are separated by the event of ovulation; and each of these halves can themselves be characterised by two different phases, marked by shifts in hormone levels. When looking at the impact of your cycle on performance, the essential hormones to remember are oestrogen, progesterone and testosterone. Testosterone levels in most women remain low through the cycle, with a brief but noticeable rise around ovulation – so we’ll come back to that one later.

In the follicular phase, days one to five are early follicular, or your bleed days (menses), and are marked by low levels of both oestrogen and progesterone; days six to 12 are late follicular, where oestrogen is high and progesterone remains low. After ovulation, around day 16, the luteal phase begins. In the luteal phase, days 16 to 23 are mid-luteal, with high levels of both oestrogen and progesterone; days 24 to 28 are late luteal, in which both oestrogen and progesterone levels have once again dropped, signalling to your body that it’s time to shed its uterine lining, thereby recommencing the menstrual cycle.

Today we will look at the first half of the cycle, the follicular phase, and examine how hormone levels might impact performance, and how cycle synching your training and nutrition could help optimise your workouts and recovery.

Day 1, or the start of menses, is when oestrogen and progesterone are at their lowest levels for the entire cycle. The onset of menses is typically characterised by lower energy levels and fatigue, thanks to rock-bottom oestrogen, the likelihood that your iron stores are depleted, and the tendency for you to be experiencing some cramping and pain.

For days one to three of your period, if you tend to experience low energy and cramps, you may choose to opt out of high-intensity workouts like HIIT and boxing. However, studies show that moderate-intensity exercise can help alleviate symptoms, so if you routinely suffer from cramps, headaches, fogginess or depression during your period, a moderate workout could be a great way to offset premenstrual symptoms. Yoga, swimming, an easy run or that Zumba class are all good options. If you prefer strength training, consider backing off the heavy weights and using the time to really focus on form. Not all women suffer from low energy and painful periods however, and studies show that hormonal fluctuations during menses don’t have a significant impact on muscle fatigue or strength, so do what feels right for your body.

Oestrogen starts to increase from day one, which it continues to do, rapidly, until its peak at ovulation. Around days three to six, many women will start to notice its impact – your physical and mental energy levels will surge, your brain will be sharper, and motivation gets a big boost. If you typically struggle for the first few days of your period, take advantage of the renewed energy you’ll now be feeling to get back into your activities and workouts.

You may also start feeling a lot stronger during workouts in this phase, thanks to the combination of rising oestrogen and low progesterone. This will continue into ovulation, and it’s a great time to turn up the intensity in your training with things like HIIT, weight training and circuits.

In the late follicular phase, oestrogen is climbing to its highest level and, with progesterone still staying low, you are likely to be feeling better now than at any other point in your cycle. The boost in energy, motivation, confidence and optimism that you noticed in the early follicular phase are likely to be even higher now, and you are more likely to be open to new ideas, new activities and new ways of looking at things. This would be the perfect time to try a new fitness class, learn a new form of exercise, or commit to more days in the gym.

Many women also find that they can push their limits more easily during this time. You’re more likely to be able to train longer, harder and at higher intensities, so it’s a great time to aim for new personal bests, particularly in traditional strength-focussed workouts, as oestrogen affects the quality of skeletal muscle, allowing muscle fibres to generate greater force, contributing to strength gains.

In more good news, studies suggest that a woman’s body is more adaptive to training during the follicular phase, that her pain tolerance is higher, her quality of sleep better and her recovery time faster. This is the case as oestrogen rises through the follicular part of the cycle, peaking in the late follicular phase. Oestrogen is shown to offer protection against exercise-induced muscle damage and reduce inflammatory responses, so you may find that you’re able to hit the gym more frequently and with less downtime needed between sessions for recovery.

Injury incident rates suggest that there may be a slightly increased risk of injury in the late follicular phase and during ovulation, particularly muscle and tendon injury. This is due to the effect of oestrogen on connective tissue laxity, making joints less stable and more prone to injury. Don’t avoid exercise, but be aware of the possibility of injury, and prepare your body for your workouts with adequate warmups and mobility exercises.

Ovulation marks the end of the follicular phase, and the start of the luteal phase. Oestrogen plummets at ovulation and levels of progesterone start to rise, and women who are sensitive to hormonal fluctuations may experience a short burst of PMS-like symptoms, though this experience will be shorter and less intense than true PMS. Progesterone also typically has a dampening effect, so you may find that your motivation and enthusiasm start to wane as you progress from ovulation into the luteal phase. However, research shows that handgrip and quad strength both increase at ovulation, so it would be a good time to take advantage of this in your own sport.

Specific nutritional needs are less important here compared to the luteal phase, but maintain a baseline intake of protein, carbs, fats and fluids, as well as adequate rest and sleep, and a variety of colourful fruit and vegetables to hit your general micronutrient needs.

If you have heavy periods or are concerned about iron levels, consult your doctor to understand whether you could benefit from iron supplements. Otherwise, focus on including more food sources of iron in your diet, such as beef, oysters, salmon, tofu and leafy green vegetables.

Keeping track of your cycle can help you understand how your body experiences the menstrual cycle, and the impact that your hormonal fluctuations may be having on you. Of course, every woman’s cycle is different, and a host of other factors can impact mood, energy, strength and health across the cycle, but if you are tracking, you’ll have a much better sense of what’s going on with your body.

With the proliferation of health and performance apps, there are plenty of resources available to help you track your cycle. Apps like Clue, Fitr, CycleMapping and Flo all do a good job (some require a monthly subscription), and a number of wearables have integrated cycle tracking functionalities, such as Whoop and Garmin. But there’s nothing wrong with a notebook and pen, or a good spreadsheet! Once you’ve tracked three cycles, you should start to notice trends which appear for you, and as you continue to monitor your symptoms, you will probably become more sensitive to the changes that your body is going through, and so also your changing needs.

Look out for our next article, in which we will explore the luteal phase of your cycle and its characteristics, and how you can adapt your training and nutrition in days 16 to 28 for optimal performance.