As women in the sports and fitness world, sometimes it can feel like we have something to prove — that we can train, grow, and recover with the rest of 'em. But our female physiology isn't a weakness, and it certainly doesn't have to impede our training goals. Just like anything in the natural world, our bodies and hormones go through cycles, which can be monitored and adjusted to accordingly.
While we recognize that every woman is different when it comes to her period, we can use science to better guide our training choices. Let's take a closer look at how we can work with our bodies instead of against them in the gym.
First, some cycle basics
A woman's menstrual cycle has different phases; the menstrual, follicular, ovulation, and luteal phases, which is often broken down more broadly into just the follicular and luteal phases.
First comes the menstrual phase, when a woman gets her period and her levels of the hormones estrogen and progesterone drop. This typically lasts 3-7 days but can vary between individuals.
This also kicks off the follicular phase, which begins on day one of your period and continues until ovulation, a total of about 16 days. During this phase, the pituitary gland releases follicle stimulating hormone (FSH).
During the ovulation phase, luteinizing hormone (LH) is released in response to the follicular phase’s rising estrogen levels. Wondering if you’re ovulating? One sign is a slight rise in body temperature, which happens around day 14 of your cycle.
Finally, we enter the luteal phase. This is where we see a rise in progesterone and a slight bump in estrogen levels, followed by a drop in both hormones and the restart of the cycle (barring pregnancy). The luteal phase is when we experience those *lovely* PMS symptoms, like bloating, headache, weight changes, food cravings, and trouble sleeping. This phase lasts 11-17 days.
How we can work these phases into our exercise routines
For endurance workouts
In a study of sedentary women, pre-exercise heart rate was higher and peak heart rate lower during the luteal and menstrual phases, respectively.1 In this same study, VO2 max and other measures of endurance were significantly lower in the follicular and menstrual phases.1
The takeaway: try to save your higher-intensity workouts until the luteal phase is over, as this is when your heart is working slightly harder than normal; you'll reach a higher heart rate more quickly, especially when training in warmer temperatures. If you exercise according to heart rate zones, expect higher heart rates to be more of a challenge to reach during your menstrual phase. You might also see decreased endurance here, so if you're training for (or racing) an endurance event, try to opt for shorter workouts during your menstrual phase.
For strength workouts
While fluctuations of steroid hormones occur during the menstrual cycle, they have not been found to have a significant impact on muscle fatigue and strength.3 The takeaway: carry on as normal! Of course, though the science shows no significant impact on your ability to perform these sports at any phase in your cycle, only you know how your body is feeling. Consider taking a step back and opting for more recovery if you’re feeling the symptoms of PMS such as fatigue, irritability, and mood changes.
Hydration and your cycle
Fluid status will change throughout your cycle and can have an impact on your ability to exercise, especially in the heat. During the mid-luteal phase, there is a marked decrease in time to exhaustion, which is believed to be a result of increased body temperature, so pay extra attention to your water intake those days.3
Increases in fluid retention can be a secondary effect of estrogen and progesterone, peaking from ovulation through the first half of the luteal phase.3 This fluid redistributes throughout your body during the luteal phase, creating a drop in plasma volume, which can compromise the amount of oxygen delivered to the muscles.5 This drop reduces sweat rate, and since sweat helps the body cool down, it can also result in an increase in body temperature. Due to these changes, women should be more aware of their hydration and fluid intake during the mid-luteal phase, especially if in hot and humid environments.
Changes in macronutrient needs
The way our bodies metabolize macronutrients, particularly carbohydrates and protein, can change through our cycle.
In a fasted state, women were found to perform better in the follicular phase than the luteal phase. But when fueling with carbs, luteal performance caught up.2 Why the difference? Estrogen and progesterone, both of which peak during the luteal phase, have been shown to suppress gluconeogenesis, a cellular process necessary to utilize energy stores in the body. External carb sources therefore become critical for energy during exercise, especially when over 60 minutes long.4 The take-home here: female athletes preparing for an endurance event in their luteal phase should make sure they're eating adequate carbs during the event to meet increased needs2.
Protein catabolism, the breakdown of muscles and other protein stores for cellular processes, has also been shown to beak with progesterone levels in the luteal phase, increasing protein needs during this part of a woman's cycle3. The takeaway; consider upping your protein intake during your luteal phase, especially if in a bigger or higher intensity training cycle.
Changes in iron biomarkers and performance
Despite blood loss in the menstrual phase, your cycle has little impact on performance-related iron markers like hemoglobin and hematocrit.3 This is not to say female athletes shouldn't be mindful of their potential for anemia. We recommend keeping an eye on your ferritin levels, as this biomarker will be the first to drop from insufficient iron intake.
When and how to optimize training around your cycle
For women whose performance is based on muscle output or VO2max, extra time planning your competition schedule around your cycle probably isn’t necessary.3 But women who participate in endurance exercise should consider adapting your competition schedule around your cycles, especially if in hot and humid conditions.3 The shifts in fluid, body temperature, and metabolism can make it more challenging for women to undertake big training efforts and ensure adequate recovery in the luteal phase.
Start by tracking your cycle! Doing so can help you understand when your body enters each phase, any resulting symptoms, and how to adjust accordingly. We recognize that every woman's cycle is different and a multitude of factors can play a role including the use of oral contraceptives, eating disorders, and medical conditions such as polycystic ovary syndrome (PCOS) or uterine fibroids.
IUDs can cause the lack of a monthly period. But your cycle, and the accompanying hormone changes, is still working behind the scenes! IUDs prevent pregnancy by either the hormone progestin (hormonal IUD) or with copper (non-hormonal IUD). Hormonal IUDs can also stop ovulation. Tracking your cycle can be a helpful tool for women with an IUD, but may be more challenging without a period.
Food journaling can also be helpful to assess for adequate macronutrients and fueling, especially when needs are higher. Performing sweat tests during your cycle can also be a tool to note any significant changes in fluid requirements to ensure adequate hydration and replenishing between sessions.
The bottom line
As female athletes, taking a closer loo at how our bodies change throughout our cycle can be an incredibly helpful tool. When we understand what’s going on the inside we can set ourselves up for success in reaching our health and fitness goals.
Stevie Lyn Smith, MS, RDN, CSSD, CDNStevie Lyn is a Content Strategist and Team Nutritionist at InsideTracker. As a Registered Dietitian and Ironman triathlete, she enjoys combining her passions to help educate others on how to fuel for overall health and performance. When she’s not swimming, biking, or running with her dog, you’ll find her in the kitchen working on a new recipe to improve her biomarkers.
Some other blog posts we think you'll love:
- Here's How Birth Control Can Affect Your Biomarkers
- The Health Advice We Always Hear but Continue to Ignore
- Menopause: What's Actually Happening and Why
- How to Win Your Off-Season
Bandyopadhyay A, Dalui R. Endurance Capacity and Cardiorespiratory Responses in Sedentary Females During Different Phases of Menstrual Cycle. Kathmandu University Medical Journal. 2014;10(4):25-29. doi:10.3126/kumj.v10i4.10990
Campbell S, Angus D, Febbraio M. Glucose kinetics and exercise performance during phases of the menstrual cycle: effect of glucose ingestion. American Journal of Physiology-Endocrinology and Metabolism. 2001;281(4):E817-E825. doi:10.1152/ajpendo.2001.281.4.e817
Janse de Jonge X. Effects of the Menstrual Cycle on Exercise Performance. Sports Medicine. 2003;33(11):833-851. doi:10.2165/00007256-200333110-00004
Oosthuyse, T. & Bosch, A.N. Sports Med (2010) 40: 207. https://doi-org.ezproxy.neu.edu/10.2165/11317090-000000000-00000
Sims ST, Rehrer NJ, Bell ML, Cotter JD. “Pre-exercise sodium loading aids fluid balance and endurance for women exercising in the heat.” Journal of Applied Physiology, 103: 534–541, 2007