When many of us were younger, there was no mention of how hormones and the menstrual cycle can affect a female’s athletic performance. Yet we could feel the effects from week to week and never knew why. Today, there has been much more research around a woman’s cycle and its impact during different stages in it for athletic performance. In fact, the time in our cycle very much correlates with differences in training and nutrition parameters in order to accommodate. Here is how the female athlete can use their monthly cycle to adjust each.

A woman’s menstrual cycle is a natural process where the body prepares for a potential pregnancy and sheds part of its uterine lining. The first day starts with the onset of a menses, the last at the onset of the next. A typical cycle lasts about 28-35 days; it is broken up into two main phases: the follicular phase (days 1-14, or the first half of the cycle), and ovulation in the middle and the luteal phase (days 14-28, or the second half of the cycle).

In this phase, estrogen and progesterone levels plummet and continue to be decreased until days 3/4. This can cause fatigue, lack of motivation, moodiness and a decrease in strength. This is very similar to the second week of the luteal phase, where it is important to make adjustments accordingly. After day 3/4 and up until day 14, estrogen starts to rise, which gives athletes the competitive advantage.

Estrogen is responsible for blood flow, muscle strength and power. The former is attributed to this hormone’s ability to increase the production of nitric oxide, responsible for vasodilation. This improves delivery of nutrients, blood flow to muscles and organs, and greater oxygen exchange. This time is ideal for adding heavier weights in the training program and including more HIIT-style workouts.

The body utilizes stored carbohydrates (better known as glycogen) more efficiently—which these types of workouts utilize more of—and is more sensitive to insulin. Before training, including easy digesting carbs such as fruits or jam and toast are the best fuel for training. Yet, the body does not require as much before during this stage as it can pull from stored carbohydrates (glycogen) and may be a little more forgiving training with lower carbohydrates. It is still more beneficial to add a source of quick carbohydrates containing 30 grams of carbohydrates before a training session.

After 60 minutes of heavy exercise, the body’s glycogen reserves start to deplete. To counteract this, including 30 grams of carbohydrates every 30 minutes thereafter will help prevent early onset fatigue. Post workout, include at least 20 grams of protein along with at least 30-60 grams of quick-digesting carbohydrates. This could be in the form of a protein shake or can be in a complex meal with whole food proteins with a big emphasis on carbohydrates, vegetables and fats. An idea for a good go-to is an egg sandwich with kale on gluten-free bread and blueberries on the side.

Also, the body is a bit more forgiving with carbohydrates during this phase due to the body’s sensitivity to insulin. Simple carbohydrates can be enjoyed after a meal or as a treat but are best paired with protein or fat.

Fat utilization does have its place in training. It is the primary fuel source for lower intensity workouts. Thus “endurance-style” workouts, such as Zone 2 of the “fat-burning” zone, are emphasized. This is due to the level of fatigue and decreased blood flow which can inhibit your aerobic capacity. Therefore, as an endurance athlete, this would be more tempo- and threshold-style workouts in a 20/80 fashion (20 percent moderate to 80 percent low intensity).

From day 21-28, progesterone and estrogen levels drop, leading to a decrease in blood flow. To counteract this, adding foods before a workout that increase blood flow, decrease fatigue and provide a source of energy to pull from will be essential. These foods contain the compound nitric oxide, such as cacao, spinach and beets. In fact, beetroot juice has been shown to improve ventilation and oxygenation of the lungs.

During this phase, body temperature increases as well as BMR. The latter may increase upwards of 40 calories to 200 calories per day. Remember progesterone is catabolic and thus the body starts to see the effects. To counteract this catabolic effect, protein intake should be increased by 10 percent and increase the carbohydrate intake around and during workouts. This can look like a banana right before training and a sports drink providing 30 grams of carbohydrates every 30-60 minutes of training after the initial 30-60 minutes. To perform any high-intensity training, the body will need extra carbohydrates and thus intra-workout carbohydrates (after about 30 minutes of work) are also emphasized. Some good sources of carbohydrates include a clean sports drink, raisins, juices or pureed fruit packs.

Post-workout, a carbohydrate containing at least 30-60 grams and a source of protein with 20-30 grams is emphasized to help with muscle recovery and glycogen storage. This is just slightly more than in the follicular phase. Carbohydrates outside of training should be more complex in nature, with fiber—such as whole grains, fruits, vegetables and legumes as the body is less insulin-sensitive—and paired with a good source of protein and fat.

This phase of the menstrual cycle applies for women in menopause. Along with the recommendations for that week, protein requirements increase, especially around training. Include at least 40 grams of protein around workouts for better muscle protein synthesis and recovery.

Hormones play a large role in the female athlete’s performance. Try incorporating some of these guidelines into your next training block.