Ever noticed how some days your runs feel easy and you fly through them, whereas other days that same easy pace feels like a struggle, your legs feel heavy and you just can’t hold the speed? Whilst there’s many components which influence how hard our training feels, such as nutrition/fuelling, sleep, stress and what the rest of your training load looks like, your hormones could also play a factor. When talking about the menstrual cycle, we often focus on the actual menstrual bleed, the period. However, when it comes to how we feel and perform, the rest of the cycle matters too. There is some interest in potentially adapting your training according to your hormonal fluctuations, to optimise performance, also known as ‘cycle syncing’.
During the first half of the menstrual cycle, the Follicular Phase, oestrogen levels rise and it becomes the predominant hormone. Oestrogen gives us energy, and is an anabolic hormone, having positive effects on muscle strength and ability to recover. During the follicular phase, there is a shift towards carbohydrate metabolism and there becomes more anaerobic capacity, which theoretically makes it an optimal time to do high intensity training. Some studies also show higher utilisation of carbohydrate stores from glycogen in muscles and liver, which may improve endurance capabilities.
The second half of the menstrual cycle, following ovulation, is known as the Luteal Phase. During the luteal phase, progesterone rise and becomes the predominant hormone. Compared to oestrogen, progesterone is a more catabolic hormone, switching our metabolic processes towards breaking down building blocks of energy (such as glycogen, fat and even muscle stores) to free up energy supply for a potential implantation of an embryo. There are some studies suggesting exercise capacity including vo2 max, heart rate and RPE may be affected by this. Progesterone also can increase the core body temperature which may compromise sleep quality. These factors may limit prolonged exercise capacity and reduce endurance capabilities. During the luteal phase, despite perhaps feeling more fatigued and lower in energy, basal metabolic rate actually increases up to 300 calories per day, with a metabolic shift towards fat oxidation, to spare glycogen stores. You may want to factor this into your run fuelling, with increased or more regular energy intake during runs, and ensuring adequate protein intake before and after, to compensate for the catabolic effects of progesterone.
The actual published scientific data on these theories is premature and at times contradicting. Further studies are required to fully understand the impact of the menstrual cycle on metabolism and exercise performance. Whilst we shouldn’t necessarily be overhauling our training to sync with our menstrual cycles, I do think having an awareness of how your hormones may be affecting you and your training is useful. If you notice changes throughout your cycle, having an appreciation of the hormonal fluctuations may allow you to cut yourself some slack and take things slightly easier, or other times, utilise your hormones being on side, speed up, and push yourself towards that PB!
How to optimise your Runna plan around your cycle
We should use our menstrual cycle as our superpower, you are likely to find that you can be more physically active and train at a greater intensity at certain times of the month - period tracking is a great way to understand when this is for you as it’s very individual from person to person. At points in your cycle when you feel most energised, aim to get the most quality out of your training. If you are feeling fatigued at points in your cycle, don’t be afraid to let your body rest as reducing intensity is important to allow your body to absorb the good training and get the benefits.
Rearranging your week to include more rest or easy miles over the course of a few days will allow you to feel fresher and more recovered to tackle more intense running such as a speed session or long run to when you feel more energised.
If you need to change or skip a run then please do. Be kind to yourself and listen to your body. No one run will make or break your training plan and you certainly won’t lose any fitness after missing a couple of sessions.
You can focus on lower intensity movement by increasing pilates, mobility and strength within the Runna app. Active recovery, gentle cardio, pilates and stretching are often a great natural way to alleviate PMS symptoms and maintain fitness. You can add these additional workouts into your schedule by selecting ‘manage plan’.
We would always encourage you to appreciate how hormones fluctuate throughout training and work with this, rather than against. Adapting your training around your cycle will allow you to optimise your training.
