An Ever Changing Period

‘I’ve lost my mojo’

‘I feel so flat’

Girls we have all said it.

We all know that at certain times of the month we are straight up knackered and at other times we are ON FIRE!

So why is this?

It’s because we are interesting and ever changing. It’s because we are beautiful and amazing. Oh and it’s also because we get PERIODS.

Yep I’m saying it. That thing that no one really acknowledges exists even though we get it EVERY bloody month from the ages of around 13 until menopause. Actual decades of our lives. That period has a big impact on us as endurance athletes. At times it can be tough to deal with, lucky we are tougher though eh? Now I am NO expert. I just figure it is worth starting a conversation about.

Maybe this will answer some questions for you.

Maybe it will explain why you might feel so fatigued even though you did exactly the same run the other day but this time it was heaps slower and it felt like your legs were made of concrete. Maybe it will help you put your finger on why sometimes you can bust out an amazingly fast run and feel like you can take on the world.

So let’s delve into the wonderful world of our menstrual cycles. Wow. I never thought I would be saying that!

Let’s say a menstrual cycle lasts 28 days. It’s broken up into roughly 2 parts around 14 days each (this only applies to women who aren’t on the contraceptive pill as that changes things again).

The first part is the Follicular Phase, as you can see from my (cough, cough yep I did ’em) drawings below, that this is the time we are most like men. When day 1 (and the bleeding come) our estrogen and progesterone levels drop. Boom! Time to go and smash out a PB or have a strong race. We access carbs well,  our core temp is normal, and we don’t have as much central nervous system fatigue. Get out and train well whilst you can! 

Fastforward to the Luteal Phase which is days 14-28. Holy changes Batman. This is when everything gets tricky for us gals. Estrogen and progesterone levels increase. Intensity sessions take longer for us to recover from. We face higher vulnerability to hyponatremia and fatigue faster in hot conditions. We also have a greater sweat rate due to vasodialation. Which, to my understanding, means that the amount of liquid we take in depends on where we are in our cycle. Estrogen also turns us into camels.. well not quite but we do have increased fluid retention, my ‘hump’ is just in another place. Estrogens’ action on the kidneys alters the way we metabolise carbs and improves glycogen sparing (glycogen sparing means your body switches over to burning fats instead of burning glycogen. When you are exercising (aerobically) your body burns glycogen. However, as you continue, your body switches to burning fat and spares your glycogen. It also increases your cortisol response.


What can we do about this to help us during that luteal phase?

Increase the amount of salt in your food.

Make sure that you are having cold things, ice cubes, ice blocks, ice packs etc to help offset your core temperature rise (when on the bike or running).

Be sure to hydrate but not by drinking plain water (that could really tip you over into hyponatremia) so you have to have a bit of sodium and carbohydrate in what you are drinking.

Put a little bit of extra carb into your training fuel so that you can hit intensities whilst in high hormone phase.

Using branch chain amino acids before and after training to help mitigate central nervous system fatigue. They’re easy to find, just check out a health store, BCAA’s should contain:  leucine, isoleucine, and valine.

I’ve only just scratched the surface BUT if you would like to know more please listen to Stacy Sims PhD podcast OR read her book: ROAR / Stacy Sims


CoachyMcCoachFace says – “Girly stuff!  yikes!” – It’s cool, I got this, I’m pretty much a Dr…
So, you get to see 3 weeks of your training plan and while it’s set as 3x 7P runs, that format only exists because society has a standard 7-day cycle by which most of us plan our lives around.  HOWEVER, perhaps we should place more emphasis on structuring your training and racing around your 28 day cycle.  Yes, the world should revolve around you!  I believe there is a very real benefit in thinking about your key training runs in that 3-week block you can see in your programme and taking into consideration how your body will respond.  If the focus is currently long aerobic base-work, and for most of you on Tarawera and UTA plans it is, maybe look to line up that super sunday with a weekend in your Follicular phase rather than having a miserable day out in your Luteal phase where fuels aren’t going in right and you can’t get that training stimulus we’re after.  Likewise as we head toward some of the sharpening stuff with key hard/fast runs some consideration should be for where you can align these runs to work best for you.  Take your 21 day programme and think about the best way to make it easier and more effective.