Stacy T. Sims, MSC, PhD is a female athlete performance physiologist with one passion: helping women to understand and become empowered by their unique physiology. An easy task? When, according to Stacy herself, only -4% of sports science research even includes women, we’d say no.
Let Sims run you through the basics of a key topic in her work: how to workout through your cycle. According to Stacy, your period should enhance physical performance, stamina and recovery — not harm it. Here’s what we’ve learned from her so far…
Q: Fitness studies are almost all based on data from men only.
why is this important for women to understand?
Only -4% of sport science research (to include sport nutrition) includes female participants. The research has been generalized from primarily white cis men 18-22 years old and these insights are applied to women of all ages (and men of older ages, too), without really questioning if this generalization is viable.
Most of the time, the research design is through a male lens, not accounting for the different hormone profiles of women (menstrual cycle phases, oral contraceptives, IUD, implants, peri-menopause, post menopause). We know that female sex hormones directly affect training adaptations, recovery, nutritional needs and responses, just to name a few.
There are some sex differences from birth that influence our bodies’ fueling mechanisms (biological women are primed to use free fatty acids, sparing carbohydrates) and female sex hormones also influence how our bodies respond to training adaptations, as well as nutrition.
For example, women do better in a fed state for training and adapting to training, whereas men can get away with fasted training to improve their training adaptations.
Supplements are another massive area that has been under-studied in women. A recent meta-analysis of popular supplements concluded that there is no robust research to support anything except for protein and caffeine supplementation, and the caffeine effects are more genetic, not sex-response.
To reach a woman’s performance potential, we have to look at the individual in the moment, as there is a lack of robust research to support the current protocols and guidelines used for training and nutrition plans.
Q: Women have often been taught to power through a consistent, daily fitness schedule. But that doesn’t take into account our unique hormone changes and monthly cycle. What’s your perspective on this?
This is absolutely a disservice to women. When we look outside of sport science research, the endocrine, cardiovascular, metabolic, and psychological literature shows that shifts in menstrual cycle hormones affects stress resilience and the ability to take on stress.
Training and adapting to training is a massive stress on the body. By being consistent day in and day out — in intensity, duration, nutrition — women are missing the mark, often working against their own physiology, which can slow results and predispose us to injury and illness.
+ In the low hormone phase of the natural menstrual cycle, women are the most resilient to stress. We see this in the immune system where innate and acquired immunity are the primary responses to attack and kill off invading pathogens. After ovulation, progesterone suppresses these immune responses, thus the body relies heavily on pro-inflammatory responses.
+ From a cardiovascular aspect, during the low hormone phase there is an increase in heart rate variability (coupled with a lower resting heart and respiratory rate), but after ovulation, progesterone affects the autonomic nervous system, increasing resting heart and respiratory rates, and decreasing heart rate variability.
+ From a psychological perspective, women have better cognition, reaction, decision timing, and better sleep architecture through the low hormone phases, all those patterns can change during the luteal/high hormone phase. When we layer on newer training research, we see that women respond better to strength and strength adaptations when loaded in the low hormone phase, and reduce the intensities and loading in the late luteal phase.
Note that training is different from performance. A woman can nail any performance on any day of the menstrual cycle, as her prep leading up to the event supersedes hormonal nuances on the day.
With training, a woman can track and leverage her own hormone patterns to hit it hard when the hormones are low, then transition to a more steady state, moderate intensity around ovulation, and dial it back to recovery, technique, and reaction drills in the 5ish days leading up to her period.
+ On using hormonal contraceptives: The use of hormonal contraceptives creates a different pattern of stress resilience and recommended training: the first 5 days of the active pill of combined oral contraceptives is akin to the low hormone phase of the natural cycle, but the subsequent 2 weeks of active pills are different in that for each day of high intensity, more recovery is needed until the second day of the placebo pill during the withdrawal bleed, when the hormone levels have washed out, and the body is able to take on stress.
Q: Can you outline some of the fitness guidance women should be aware of around the 4 phases of their cycles?
First and foremost, every woman should track her cycle to identify her own unique patterns. Some women feel bulletproof in the few days leading up to their period, others feel absolutely flat. Same thing around ovulation and the transition from late luteal to bleeding phases.
If a woman knows that, say, on day 11 of her cycle she always feels flat, regardless of how she slept/ate/recovered, it takes away the negative self talk and allows her to dial in her training, taking it easier on day 11 and then hitting it hard again when she feels awesome (day 12 or 13-ish).
How To Workout Through The 4 Phases of Your Cycle
+ Follicular: Your energy/mood/body may be most resilient to stress and can take on high loads of intensity and recover really well. Energy and mood is high, ability to take on new skills is high.
Fitness/movement guidance: High intensity, new classes/new moves, high quality lifting.
+ Ovulation: Your energy/mood/body may feel flat right at the estrogen surge, then feel bulletproof after, whereas other women don’t have any flatness. This is why tracking for your own individual pattern is so important.
Fitness/movement guidance: Always listen to your body.
If you feel flat, you can try a couple of 20-second high intensity efforts. These will help increase energy by releasing a surge of growth hormone and anti-inflammatory responses post-exercise.
If you feel bulletproof, take advantage of the estrogen surge and hit it hard with resistance training. Estrogen is a woman’s testosterone when it comes to anabolism/building tissue.
+ Luteal: In the early luteal phase (right after ovulation until 5 or so days before the period starts) women will feel moderate to high energy, but may find recovery a bit harder.
In the late luteal phase (5 days before the period starts), the body is in the process of transitioning from high to low hormones, with an accompanying inflammatory response. This can lower energy, mood, reduce quality sleep, and women may feel bloated and lethargic. Although some women find the day before their period starts as a bulletproof day, again this depends on how fast the hormones drop and why it is important to know your own patterns.
Fitness/movement guidance: In the early luteal phase, work more in the steady state/moderate intensity zone — chippers and AMRAP workouts, hypertrophic type training for strength.
In the late luteal phase, this is the time to absorb all the hard training from the weeks before, looking to do recovery modalities, low intensity, and technique work (running drills, swim drills, technique under the bar/lifting technique) and reaction time drills.
+ Menstrual: The first 3 days are variable. Some women are unfazed and have lots of energy because of the dropped hormones (see follicular phase, as the menstrual phase is part of the follicular phase). Others may experience severe cramping, heavy bleeding, and discomfort.
Fitness/movement guidance: For those who are unfazed, this is the time to hit it hard again. The body is very capable of taking on high loads and recovering well.
For those women who have severe cramping, heavy bleeding, and the thought of hard work is too much, any movement is good. We often recommend short Tabata-type intervals to garner a growth hormone and anti-inflammatory response from the exercise, which then helps with cramping discomfort.
Note, if she suffers from heavy menstrual bleeding, this is a clinical condition that can be helped, and should be helped as it is not normal to be severely incapacitated by your period.
Want more advice on this topic? First, Know The Four Phases Of Your Monthly Cycle. Next, Take The Period Quiz, an in-depth assessment of your period health. Learn from from Alisa Vitti on Fitness and Your Cycle.