Alright, dudes. This one's for the ladies, but if you have a lady, pull up a chair because you need to know this stuff...particularly if you like to hit the gym with her.
Ladies, do your workouts tend to feel a little "Jeckyll and Hyde"? One week, you are smashing your HIIT workouts and lifting with increased intensity. The following week, just looking at a dumbbell ticks you off. If you are pre-menopausal, it's highly likely that your cycle is coming in to play here. I know, so fetch right? Let's talk about the two phases of your menstrual cycle and how the hormones associated with each (estrogen and progesterone) can impact performance of certain types of workouts.
Day 1-14 of your cycle is referred to as the follicular phase. During these first two weeks, estrogen levels rise, peaking at day 14 (ovulation), while progesterone levels stay constant. This is when you feel like a million bucks. The world is great, and this is the time when you will feel like an absolute beast during anaerobic training (like HIIT). Do your HIIT workouts now! At ovulation, when estrogen is at its highest, overall strength is peaked. This is the time to take advantage and have an awesome weight lifting session by upping your weights slightly (nothing extreme by any means) and going for it.
Have a good first 2 weeks? Well great, because it's about to come crashing down in the luteal phase (days 14-28). Just kidding. However, it sure doesn't feel super great. Directly after ovulation, progesterone surges and estrogen plummets. You know that song "Nasty" by Janet Jackson? Progesterone is the nasty boy in that song. Progesterone rises, moodiness and bloating due to water retention start. Cortisol levels rise and serotonin levels also drop slightly (bye bye cloud 9). Because your body uses carbohydrates to make serotonin, guess what happens when serotonin levels drop? Light bulbs with the word "CARBS" on them start going off in your brain, thus the cravings for Duncan Hines brownie mix right out of the bowl. Point is, things get a little cray cray.
Workouts during the luteal phase should be centered on aerobic activity (think steady state cardio, cardio/resistance training). This is not the time to try and PR on running, lifting, or max out on the HIIT workouts. Be good to yourself here and take it steady. You can and should work out during the second half of your cycle, but recognize that you may not be able to perform to your usual capabilities during higher intensity workouts in this phase of your cycle.
There's obviously a lot going on during your cycle internally, and please know that there is a TON of research still being conducted in terms on periodizing training plans to your period. So, while there are many other factors hat come into play for women and performance (thyroid, obesity, macronutrient imbalances), understanding the hormone fluctuations during your cycle is still a great place to start and consider when training!
Cheers to being a lady.