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Sister, this is why some swims feel like a struggle.

YOU know those swims when you know the moment you dive in that it's going to be struggle town for the next hour? It turns out that for us, ladies there is an easy explanation and it has nothing to do with your fitness or nutrition, but all with your female physiology.

Being a girl is the best! I might be slightly bias, but I think most guys have stopped reading by now anyway! So girls, let's get into the amazing world of menstrual cycles and periods.

I have to give full credits to Dr. Stacy Sims for the knowledge I'm about the share with you. It's been so refreshing to read in an easy and understandable way why sometimes we feel invincible and other times like we've never swam a stroke in our life before.

In her book 'Roar' Dr. Stacy Sims explains the menstrual cycle following a standard 28 day duration, this of course is slightly different for everyone and by tracking your cycle you'll be able to predict the start of each phase specifically for you.

Day 1 of the cycle is the start of your period and also marks the start of your Low Hormone Phase, during the coming 12 days we feel the strongest (yes during your period) and we can train the hardest. A study done on swimmers saw the fastest times during menstruation!

Around day 12 Estrogen levels surge which causes ovulation and an egg is released. Followed by a quick dip in hormones, this will then lead into your High Hormone Phase. In this phase from day 14 - 28 Progesterone levels rise to prepare the lining of your uterus.

About 5 days out from your period Estrogen en Progesterone levels peak and this is where premenstrual syndrome (PMS) can play up. This is when your training will feel hardest and you might think you've lost your fitness and strength, now you know this is due to hormonal changes!

If the egg isn't fertilised, hormone levels drop and you shed the lining of your uterus and you're back at day 1.

With all of these amazing things happening in your body, you can only imagine this has some kind of effect on your performance in training and races. Luckily Dr. Stacy Sims has done lots of research to understand how this affects us and what we can do to work with our cycle and limit the negative effects, hallelujah!

Are you keeping track of your period?

The first thing we have to start doing (if you haven't already) is to keep track of your period and your training. Journal your training with notes on when you feel strong and when energy levels are low. If you keep track of this for a few cycles you'll be able to see some patterns and start predicting when you'll be in the low and high hormone phases of your cycle.

In the Low Hormone Phase we are strongest and this is when hard training sessions will benefit you most. It is easier for us to build muscle in this phase and you will feel more energised to smash out those extra long or extra heavy sessions. Make most of this and plan your big sessions during this time.

During your High Hormone Phase exercise will feel harder and this might show in your training stats, but the good news is that this has nothing to do with your overall fitness! Your VO2 max and lactate threshold stay the same throughout your cycle, your body is just going through a lot at the moment which takes a lot of energy out of you.

Obviously you can still train during your High Hormone Phase, but just keep in mind that if you don't feel amazing it's not because of something you've done wrong in your nutrition or you suddenly got super unfit. Understand what's going on and be kind to yourself.

Tips & tricks

  • If you feel like you need a rest, have a rest! Sometimes resting is the best thing to do for your body to get fitter and stronger.

  • Take in protein that's high in Leucine within 30 minutes of your workout to help your body recover without breaking down muscle to do so.

  • If you have carb cravings in the premenstrual part of your cycle, you probably actually need a few more carbs, so go ahead and eat some more!

  • Reduce period cramps by taking magnesium, omega-3 fatty acids and low-dose 80-milligram aspirin in the 5 to 7 days before your period starts.

  • Keep track of your period so you'll notice if anything is abnormal, missing your period is not a good thing. By keeping track you will notice abnormalities.

  • Women are not small men. Most research on training and performance is done on men, because women are too hard to study due to hormonal changes. Keep this in mind when reading training or diet tips.

This was only a brief introduction to the female physiology research outcomes by Dr. Stacy Sims. If you would like to know more, check out her book 'Roar' or visit





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