The menstrual cycle and exercise performance
The effects of the menstrual cycle on female exercise performance are currently not very well researched, and so we don’t yet fully understand all of the impacts. However, we do know that the menstrual cycle can impact women physiologically and psychologically at certain stages.
To give you an idea of just some of the effects, the menstrual cycle;
- influences carbohydrate and fat usage
- affects how the body stores glycogen and how quickly it replenishes it (glycogen is the storage form of glucose in the body)
- increases cardiovascular strain around post ovulation (for example, you might experience an increased heart rate and feel like you are working harder at the same given rate)
- reduces the ability to balance (neuromuscular)
The menstrual cycle also affects weight. Weight fluctuations are common, and this comes from increased water, electrolyte, and glycogen retention, which means many females feel 'fuller' around their period. This can have phycological implications, and this is also why stepping on the scales doesn’t give a true reflection of body composition (i.e. it doesn’t differentiate between fat and muscle).
Having an understanding of how the body and mind can be affected by hormonal changes of the menstrual cycle may help to better structure training, and may also help you to be more compassionate to yourself when your energy levels may not be as high as they might normally be.
In a nutshell, the menstrual cycle is made of two phases, the follicular and the luteal phase (and ovulation in the middle). Other hormones are involved, but the two main hormones are oestrogen and progesterone. The luteal phase is known as the 'high hormone' phase.
It has been reported that there are some differences between the follicular and luteal phase with carbohydrate and fat utilisation. There seems to be greater carbohydrate utilisation than fat in the follicular phase (when hormones are lower), which means that you may feel that you have more energy during this time and get more out of your training (although this may not be the case for all females).
During the late luteal phase when oestrogen levels are high, females seem to use more fat as fuel and tend to conserve carbohydrate stores. This may make high-intensity sessions more challenging. During this high hormone phase, you may find that you need to do a less intense session than normal. During the late luteal phase, you may also experience decreased reaction times, and increased perception of exertion (e.g. the session feels more difficult). Additionally, during the luteal phase, muscle breakdown is higher which has implications for ensuring that protein intake is sufficient. Ensuring that you have a portion of protein at each meal and at key times - such as the meal before training and the meal after - will help you to meet your requirements.
Dietary iron also needs to be considered. Adult females aged 19-50 have greater iron requirements compared to men, but when menstrual bleeding is heavy, iron requirements can be elevated to maintain health and performance. Iron-rich foods include lean meats, pulses (peas, beans, lentils), fortified cereals, and dark green leafy vegetables. As the iron from plant-based foods is less well absorbed than animal-based food sources, having vitamin C rich foods with meals can help with the absorption. Peppers, tomatoes, citrus fruits, or a glass of fresh orange juice are rich in vitamin C. Also, having large amounts of tea and coffee can make it harder for the body to absorb iron, and so avoiding these drinks around mealtimes can help.
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