There are training days where everything clicks. You’re destroying sets and slaying goals – at the end, walking out of the gym with a spring in your step. Then there are those other days. You’re out of sync and barely reaching the ends of your reps. After you’re all done, you feel like you were hit by a bus – repeatedly.

Why do you rock certain days and struggle through others? Maybe it’s how much you prepare, maybe it’s how things went at work, maybe it’s something else entirely. But what if there was another explanation? Even better, what if you could flip the situation and take advantage of it?

And what if it had everything to do with your menstrual cycle?

Fortunately, sports medicine physicians and dietitians have been uncovering a close connection between an athlete’s menstrual cycle and how her body responds to training. By understanding how the different phases of your cycle affect your hormone levels, you can time your diet and training accordingly and tap into the greatest physical and mental benefits of exercise.

So what happens during these phases? How do you know what part of the cycle you’re in? How do you hack it? And why didn’t we discover this sooner? To start, let’s go back to health class.

Learn how being more knowledgeable about your menstrual cycle can actually enhance athletic performance.

How your menstrual cycle can impact exercise and athletic training

There are two main phases of the menstrual cycle: the follicular phase and the luteal phase.

What is the follicular phase? The follicular phase happens during the first half of your cycle. What is the luteal phase? The luteal phase is the second half of your cycle. These two halves feature distinctly different hormone levels, with lower levels during the follicular phase and higher levels during the luteal phase.

Researchers and physicians are discovering that these hormone levels have a big impact on muscle development and how an athlete’s body uses energy.

The follicular phase and athletic performance

With a lower level of hormones during the first phase of your menstrual cycle, your body is primed to maximize hard training efforts. This means your body is better able to access stored carbohydrates, making this an ideal time for high-intensity training. It’s also easier to build and maintain muscle, which means this is also a great time to emphasize muscle-building exercises.

The follicular phase starts with day one of your cycle. You’ve recently lost some blood, so your body has a greater need for iron. Also, due to the shedding of the uterine lining during this time, there are a few days of increased inflammation. But during this lower hormone phase, hydration is easier, and you have a more even, cooler body temperature.

The luteal phase and athletic performance

During the back half of your menstrual cycle, your body is preparing for your next period or pregnancy, if you happened to conceive during this cycle. This means your hormones are running at a higher level, due to an increase in estrogen and progesterone. More hormones means a decrease in anabolic, or muscle-building, capacity. This means that it’s time to take it easier, focusing on lower-intensity workouts with more recovery time.

Also, rather than being able to easily access stored carbohydrates, your increase in hormones has that energy locked up tight. Now, your body needs fuel from extra carbs and calories from the outside (that is, your plate). Plus, your body also needs more water during the luteal phase – more hormones means a greater risk of dehydration.

Why women’s athletic research is catching up – the role of hormones

Let’s address the big question in the room. Why haven’t we discovered this sooner? It all comes down to the primary focus of early sports medicine science: male athletes. As a result, many of the results from past nutrition and training research apply perfectly to men, but not so much for women.

Fortunately, as the field has become more diverse, more recent women’s sports medicine research has produced a wealth of information on how the female bodies interact with activity and nutrition. And it shouldn’t come as much of a surprise that the more we study, the more we discover just how distinct and different a woman’s needs really are.

Even more importantly, we’re finding that those needs aren’t particularly constant from week to week. A woman’s hormones – affected by age, maturity and pregnancy history – set the pace for her reproductive system and physical performance.

We’re finding that hormone levels can influence everything from a woman’s susceptibility to certain injuries to how your body processes food and even how flexible your joints are. Of course, as physicians and dietitians, we’re just starting to scratch the surface – plenty more research needs to be done in a lot of areas. However, there’s a lot you can do with what we know now to hack your menstrual cycle and make it work for you.

Getting to know your cycle by tracking your period

Of course, the first step of taking advantage of your menstrual cycle’s phases is actually knowing when they are. Fortunately, there are many tracking apps out there on both Apple iOS and Android. Here are some popular apps:

You can also track your cycle through your Garmin, Apple Watch or Fitbit – both provide tools within their respective apps.

Exercise and nutrition tips for the two phases of your menstrual cycle

Once you start to see patterns emerge from the app that you choose, you can start to train and eat according to the phase that you’re in.

The follicular phase

  • Go for it – As we mentioned earlier, this is the phase where your body is better able to use the energy from stored carbohydrates. Feel free to attack higher-intensity workouts that build fitness, as well as focus on resistance training to build muscle.
  • Iron woman – At this phase, your body is craving iron. Familiar sources like red meat, dark chicken meat and shellfish should be on the menu. However, don’t forget that whole grains and legumes like beans, peas, chickpeas, lentils and soybeans can also deliver the iron you need.
  • Get fishy – In addition, eating foods high in omega-3 fatty acids will help fight increased inflammation. Think salmon, mackerel, tuna, herring and sardines, along with nuts, seeds and plant oils. As with iron, you can use supplements to get what you need, but getting these nutrients from food is best.
  • Relax with the water – Your body has an excellent handle on staying cool and hydrated during this phase. Definitely make sure you’re getting enough water, but don’t make it a massive priority.

The luteal phase

  • Tread lightly – Your body is in prep mode, so it’s not a great time to go hard on your training. Switch up to low-intensity workouts with more recovery time than usual. You can try pushing the intensity, but listen if your body is begging you to stop.
  • Eat up – This is when you need to get your fuel from carbohydrates both before and during workouts.
  • Listen to your body – During these weeks, you will probably feel hungrier than usual. This is completely normal. In fact, your body uses up 5-10% more calories during this premenstrual phase. Don’t fight it and listen when your body is telling you to eat.
  • Be “water aware” – It can be more difficult to stay hydrated during the luteal phase, so keep water at hand, especially during and after workouts.

Working with a sports dietitian

As physicians and dietitians at TRIA, we use this knowledge every day to help women improve their performance and prevent injury. We find that once women realize this close connection between their menstrual cycle and athletic performance, they understand that their period doesn’t have to be a negative thing. Once you know how your body functions, you can work with it and not against it. And that’s incredibly empowering.

Of course, every woman has a different situation with different needs. That’s why it’s a good idea for active females – exercise newbies and junkies alike – to make an appointment with a sports dietitian. During a visit, we can talk about your current training routine, diet and health history. Then, we can create a game plan that addresses your specific needs, helping you to be at your very best.

Even better, you don’t need a referral to meet with a dietitian. To make an appointment with a dietitian, give us a call. To make an appointment with a sports medicine physician or another expert on our Women’s Sports Medicine team, call or make an orthopedic appointment online.