{"id":18065,"date":"2025-06-12T00:00:00","date_gmt":"2025-06-12T00:00:00","guid":{"rendered":"https:\/\/www.scienceinsport.com\/sports-nutrition\/?p=18065"},"modified":"2025-06-12T00:00:00","modified_gmt":"2025-06-12T00:00:00","slug":"having-your-period-on-race-day-does-it-matter","status":"publish","type":"post","link":"https:\/\/www.scienceinsport.com\/sports-nutrition\/having-your-period-on-race-day-does-it-matter\/","title":{"rendered":"Having your period on race day, does it matter?\u00a0"},"content":{"rendered":"

As a female endurance athlete, having your period on race day can feel a bit daunting, but the question is, should it? A lot of women (not all) can feel bombarded with numerous unpleasant symptoms such as abdominal cramps, bloating, headaches, fatigue and gastrointestinal issues.\u00a0<\/span>\u00a0<\/span><\/p>\n

Any of these alone or in combination could feel like your race day has finished before its even began. Though, a lot of these symptoms can be managed, and physiologically, will it affect how we perform? To start with, let\u2019s examine what our menstrual cycle looks like.<\/span>\u00a0<\/span><\/p>\n

Menstrual Cycle Basics<\/span>\u00a0<\/span><\/h3>\n

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Image: Hormonal fluctuations in a eumenorrheic (regular) 28-day menstrual cycle. Adapted from <\/span><\/i>McNulty et al<\/span><\/i><\/a>.<\/span><\/i>\u00a0<\/span><\/p>\n

Although some will think of the menstrual cycle as their period, this merely signifies the start of a new cycle. The term cycle refers to the fluctuation of hormones, and each phase individually could impact exercise in different ways.\u00a0<\/span>\u00a0<\/span><\/p>\n

Your menstrual cycle can be split into 6 distinct phases; early follicular, late follicular, ovulatory, early luteal, mid luteal and late luteal. In most women, this cycle will last between, <\/span>21 and 35 days,<\/span><\/a> and your period signifies the start of a new cycle rather than the end of one. During the early follicular phase when your period occurs, our hormones are fairly low and stable.\u00a0<\/span>\u00a0<\/span><\/p>\n

During the late follicular phase (just after your period), your oestrogen levels will increase as your egg matures. Once oestrogen reaches a critical point you will begin your ovulatory phase where a hormone called gonadotropin releasing hormone will cause a luteinising hormone \u2018surge\u2019. This surge signifies the release of your egg in this cycle.<\/span>\u00a0<\/span><\/p>\n

After ovulation, progesterone levels will start to rise, peaking in your mid luteal phase alongside a smaller peak in oestrogen preparing your body for a fertilised egg to be implanted in your womb. Of course, if your egg remains unfertilised, both oestrogen and progesterone will decline during the late luteal phase as your body prepares to start this cycle all over again.<\/span>\u00a0<\/span><\/p>\n

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How do these hormonal fluctuations affect exercise performance?<\/span>\u00a0<\/span><\/h3>\n

Oestrogen and progesterone have different physiological effects on our bodies, meaning there is reason to believe we should consider these hormonal changes for training and competition. The below table summarises the <\/span>possible <\/span><\/b>effects of your hormones on sporting performance.<\/span>\u00a0<\/span><\/p>\n

\u00a0<\/span>\u00a0<\/span><\/p>\n\n\n\n\n\n\n
Factor<\/span><\/b>\u00a0<\/span><\/td>\nHormonal Influence<\/span><\/b>\u00a0<\/span><\/td>\nPotential Effect on Performance\u00a0<\/span><\/b>\u00a0<\/span><\/td>\nCompensatory Consideration<\/span><\/b>\u00a0<\/span><\/td>\n<\/tr>\n
Metabolism<\/span><\/b>\u00a0<\/span><\/td>\nOestrogen <\/span>favours fat availability<\/span><\/a> in muscle with progesterone having the opposite effect, limiting fat utilisation.<\/span>\u00a0<\/span><\/td>\nAn increased preference for fat utilisation during the late follicular phase when oestrogen is high.<\/span>\u00a0<\/span><\/td>\nThe <\/span>evidence<\/span><\/a> for this is still inconclusive, and it seems the exercise demand of your training\/competition may be more influential.<\/span>\u00a0<\/span><\/td>\n<\/tr>\n
Body Temperature\u00a0<\/span><\/b>\u00a0<\/span><\/td>\nSlightly elevated during the luteal phase when progesterone is high.<\/span>\u00a0<\/span><\/td>\nCould impair longer duration exercise with basal temperature being higher leading to greater <\/span>stress<\/span><\/a> on the body trying to keep cool.<\/span>\u00a0<\/span><\/td>\nDuring the luteal phase we seem to <\/span>hold more water<\/span><\/a> which could provide a compensatory mechanism in keeping us cool.<\/span>\u00a0<\/span><\/td>\n<\/tr>\n
Recovery\u00a0<\/span><\/b>\u00a0<\/span><\/td>\nOestrogen is an anabolic hormone meaning it favours muscle building.\u00a0<\/span>\u00a0<\/span><\/td>\nCould improve <\/span>force production<\/span><\/a> when oestrogen is high. Oestrogen has also been shown to reduce<\/span> DOMS<\/span><\/a>.<\/span>\u00a0<\/span><\/td>\nThe opposite occurs when progesterone is high as it is a catabolic hormone favouring muscle breakdown. Consider eating more protein when progesterone is high.<\/span>\u00a0<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Overall, there is a fairly large body of research that has examined the effect of menstrual cycle phase on aerobic performance using measures such as endurance <\/span>exercise to exhaustion<\/span><\/a> and power output on a <\/span>treadmill<\/span><\/a> or <\/span>exercise bike. <\/span><\/a>The majority of this research as summarised in this <\/span>review<\/span><\/a>, concludes the menstrual cycle <\/span>does not<\/span><\/b> impact aerobic performance despite possible changes in metabolism.<\/span>\u00a0<\/span><\/p>\n

Further to this, it seems that your VO<\/span>2<\/span>max (your maximal oxygen uptake \u2013 a key predictor of endurance performance) and lactate threshold are also <\/span>unaffected by the menstrual cycle<\/span><\/a> meaning physiologically, you should be able to perform at your best regardless of where your race falls within your menstrual cycle!\u00a0<\/span>\u00a0<\/span><\/p>\n

So, what does it mean to have your period on race day?<\/span>\u00a0<\/span><\/h3>\n

Physiologically thinking about thermoregulation, exercise capacity and metabolism, having your period on race day is no disadvantage. This was famously proven by <\/span>Paula Radcliffe<\/span><\/a> when she broke the marathon world record in 2002 whilst on her period.<\/span>\u00a0<\/span><\/p>\n

However, there are still numerous uncomfortable or unpleasant symptoms that come with menstruation, and these could potentially still affect your performance. Managing the symptoms that affect you, is the best way to combat this.\u00a0<\/span>\u00a0<\/span><\/p>\n

There is no one-size fits all solution and which menstrual symptoms affect us will vary drastically between individuals. Monitoring your cycle and symptoms so you can have strategies ready to combat <\/span>your<\/span><\/b> specific symptoms is advisable.\u00a0<\/span>\u00a0<\/span><\/p>\n

Here are some tips for managing certain menstrual symptoms:<\/span>\u00a0<\/span><\/p>\n