Women’s guide to triathlon – biology

Dr Catherine Laraman takes a look at the biological differences between male and female triathletes


There are obvious biological differences between men and women that you need to consider when you’re training and racing. Hormonal changes during your periods, pregnancy and menopause – they all have an affect on your performance. The more you know about what’s happening to your body during these times, the better you’ll be able to cope with the changes says Dr Catherine Laraman.


Menstrual cycle

Your ovaries and two areas of your brain – the hypothalamus and the pituitary gland – control your menstrual cycle.?The pituitary gland produces chemicals that stimulate your ovaries to produce the two female sex hormones – oestrogen and progesterone. These hormones thicken the lining of your womb to prepare for a possible pregnancy and, when that doesn’t happen, hormone levels drop and the womb’s lining falls away, causing the blood loss that is a period.

Various changes in exercise performance during the menstrual cycle have been reported. A number of athletes have won Olympic medals while menstruating, but some athletes report poorer performance and increased fatigue. The published studies are conflicting but there’s evidence to suggest that reaction times and co-ordination may be a little poorer in the week before your period. Athletes also report that training seems harder work. It may be sensible to try to fit long endurance rides around these times.

The effects of premenstrual syndrome (PMS) on exercise performance are better known. Nearly all women are familiar with bloating, headaches, fatigue and breast tenderness in the week or so before a period, but you may also notice that training feels like ‘harder work’. In other words, you go through a few days of increased ‘perceived exertion’ during the PMS timespan.

Some literature also reports an increase in musculo-skeletal and joint injuries during this time in the menstrual cycle. This may be because the hormones released at this time relax your connective tissue – something to be aware of if you’re considering resistance training when you’re fatigued. During these more uncomfortable days, make sure you wear a really supportive bra and reduce the amount of caffeine you consume (which can exacerbate bloating, headaches and fatigue). And remember: a good session on the bike is a great way of working out a grumpy mood.

Having your period is no excuse to stop exercising. In fact, exercise can help reduce the amount of pelvic blood congestion and period pain. We also know that exercise favourably alters your body composition, making you leaner. Some women are unfortunate enough to experience chaotic or very heavy periods, and this can be made worse by the extra oestrogen produced by too many fat cells in the body.

Cutting your body fat by exercising and eating well can actually improve your periods and, for some women, improve fertility, particularly if you suffer from a condition called Polycystic Ovary Syndrome.

There are many remedies available for ‘nuisance’ periods, and many women can quickly become anaemic as a result of heavy periods. Go and see your doctor if you’re having difficulties; there are even medications which can delay your period if you really can’t face the idea of having it during Ironman week.

Of course, training can also adversely influence your menstrual health. Women who perform considerable amounts of exercise on a regular basis are at risk of losing their menstrual cycles and periods – the so-called ‘athletic amenorrhoea’.

It’s suspected that low body-fat levels and exercise-related chemicals (such as endorphins and catecholamines) disrupt the interplay of the sex hormones. This is a highly undesirable position to be in because the long-term complications of untreated athletic amenorrhoea include susceptibility to osteoporosis, raised cholesterol, and an increased risk of heart disease and premature ageing.

Diagnosis of athletic amenorrhoea requires eliminating all other possible causes, such as diseases of the reproductive system. But if you’re not pregnant and you’ve only had four or fewer periods in a year, you could be at risk and you must seek medical guidance. Treatment options include reducing the amount of exercise performed or, in severe cases, trying hormone replacement therapy.


If you find yourself in the ‘family way’, you can still continue exercising provided you were a regular exerciser before you became pregnant. Just remember that moderation is the key – keep it to a maximum of 45mins of cardiovascular exercise per day.

Pregnant women should avoid getting too hot, as this can adversely affect the developing foetus. So keep cool, drink plenty of water and avoid training on hot summer days. In the final weeks of pregnancy a hormone called relaxin causes softening of the connective tissue, making back and pelvis pains a problem, so ease right back on your training.

Non-contact sports are pretty ?risk-free during pregnancy, although in theory a tumble from a bike in late pregnancy could injure the growing baby, so road cycling is probably ?best avoided.

In the absence of any obstetric or medical complications, most women can maintain regular exercise during pregnancy. Some studies have found a greater sense of wellbeing, shorter labour and fewer obstetric interventions in physically well-conditioned women as compared with other sedentary women.

Give your body at least a couple of months to recover after the birth before you get back into structured training. Remember: many female athletes, including Ingrid Kristensen, American Susan Williams and Sonia O’Sullivan, have produced winning performances after giving birth, and credited their improved stamina to the physiological benefits of being pregnant.


The menopause can produce symptoms such as hot flushes, night sweats and vaginal dryness, as well as increasing your risk of heart disease and osteoporosis. The good news is triathlon training may help combat these physical side effects.

Research suggests that women who exercise may benefit from a temporary improvement in the incidence of hot flushes after a workout. An early evening training session may therefore help to improve sleep.

Exercise can also help offset the tendency to gain non-lean weight and lose muscle mass around the time of menopause, especially if you combine cardiovascular training with weight training. It’s also a great way to help reduce bone-mass loss (the cause of osteoporosis). Impact activity such as running and resistance training (including cycling in clipless pedals) is your best bet for reducing the bone loss that’s maximal around the time of the menopause.

There’s some evidence to suggest that calcium and vitamin D supplements can help maintain bone mass. And in terms of herbal remedies for hot flushes, Devil’s Claw and Red Clover may help some women combat symptoms and keep racing.

Dr Catherine Laraman is a GP, specialising in musculo-skeletal and sports medicine. She’s a keen triathlete and marathon runner


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