Without looking at my calendar, I can predict when my period is due based solely on my capacity to exercise. I was out mountain biking with my husband a few weeks ago and my whole body felt off. Not only was I feeling exhausted, but I lacked my usual confidence on the tougher sections that typically give me thrills. A week later, my body felt better than ever. It wasn't what I had eaten during the day, nor was it a difference in my sleep or my body being run down. It was my hormones. Sound familiar?

The week I felt horrible happened to be the week before my period, the week I felt wonderful was about day four of my cycle. In between those days there is a massive shift in hormone levels in the female body. And whilst at an elite level there's an element of mindset and learning to push through those times, nothing beats understanding those changes and looking for ways to get the most out of your exercise no matter where you are in your menstrual cycle.

What exactly is changing over the course of a month? I'm going to split it up into two main phases, for simplicity.

The luteal phase (between ovulation and your period)

This is your highest hormone phase, particularly in the few days leading up to your period when both of your oestrogen and progesterone are up. If you get pre menstrual symptoms, its going to happen here and you may notice this is where you start to feel like exercise (and everything else) is hard work. The same amount of work can feel like twice the effort around this time. This can be further exacerbated if you are someone who has a heavy flow because the added blood loss can affect your iron levels, which may also make your fatigue worse. Exercise at the start of this week probably doesn't appeal that much. Although incorporating some movement that you are comfortable with can have a positive effect on cramps and help lift your mood and energy levels. Its one of those times when you probably don't feel like getting out and about and moving, but you'll feel better for doing so afterwards.

Interestingly, high levels of oestrogen change the way our metabolism works - we tend more towards fat burning than carbohydrates during this time. So if you are training or competing in an endurance event or trying to exercise for longer periods that may be OK, but you may struggle more with higher intensity exercise.

Also worth mentioning is that with your progesterone high at this time, the rate that your body is breaking down protein is elevated.

My advice: stick to lower intensity movement at this time, and make sure you've had something nourishing to eat before exercise, preferably from a good quality carbohydrate source. My go to is a piece of wholemeal toast with some peanutbutter. Its warm, comforting and is a great fuel source. And if you are wanting to work at higher intensity at this time, you may need to supplement your carbs at a slightly higher rate than you otherwise would. After exercise, reach for a protein rich snack. I personally love a smoothie with fruit and yoghurt.

The follicular phase (after your period, leading into ovulation)

Your body and mind will be in full flight. This, ladies, is the time when you will find you are able to push yourself harder, try new things and will feel like you are at your peak.

My advice: when you are feeling fabulous it can be easy to get complacent about recovery or post exercise meals. DON'T. If you want to get the most out of your favourite sport or those harder workouts, then you're going to want to replenish your carbs and protein afterwards to maximise your recovery and adaptation. If you exercise just before meal time then there's no need for a snack per se - just make sure your meal contains both carbs and protein. If you're like me, and find exercise suppresses your appetite, this is where smoothies can be amazing - making sure you add something for carbs (like fruit, other than berries or oats) and a good protein source - personally I love a plain Greek yoghurt.