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Train, eat and hydrate like a girl

25 May 2017

Stacy Sims
Dr Stacy Sims

Women are not small men – that’s the message from University of Waikato Senior Research Fellow Dr Stacy Sims.

Recently named one of the 40 most influential women by popular American outdoors magazine Outside, Dr Sims’ pioneering research into female physiology and its influence on athletic performance is changing the way female athletes train, eat and hydrate.

Dr Sims is bringing women into sport science, an area where research and data are often skewed towards men. Despite more women entering high performance sport, up until the 1980s, sport science research was based on 18 to 22-year-old men, with no recognition of the influences and differences between the outcomes of men and women. Dr Sims’ research has revealed that men and women’s unique physiology means they require different approaches to nutrition and training.

Today Dr Sims, an exercise physiologist and nutrition scientist, is based at the University of Waikato Adams Centre for High Performance in Tauranga. She helps sport coaches develop tailored training, nutrition and recovery programmes specifically for women.

After a busy day at work, she took time to talk about her research.

What drew your attention to female athletes being left out of sport science research?

As a female athlete myself, I wanted answers to questions I asked, but there didn’t seem to be any.

As an academic looking for those answers, it became apparent that science was neglecting female athletes in research and generalising results from men to women.

Your research into female athlete physiology focuses around hormone fluctuations, could you explain a little about this?

It’s no secret women have menstrual cycles. During this cycle, estrogen and progesterone go from low levels (low phase) to elevated levels (high phase) before dropping again; this drop is what causes a woman’s menstrual cycle.

Not just reproductive hormones, estrogen and progesterone impact many systems of the body: from fluid regulation to metabolism, to maintaining core body temperature and blood pressure control.

These secondary impacts are the primary reason women were left out of research studies –  it was deemed “too difficult” to control for these fluctuations. However, a well-designed study will take the two hormone phases, the low phase and the high phase, into account to be able to identify how female physiology differs under exercise stress and how to mitigate this stress to aid recovery techniques.

How do nutrition needs differ between male and female athletes?

During the high hormone phase, women have a greater capacity for burning fat and sparing glycogen, both in the liver and muscle. During this phase, research has found women should stay on top of their carbohydrate intake during exercise. An option during this high hormone phase is using glucose tablets before each high intensity interval.

During low hormone phases, when compared to her age and fitness-matched male counterpart, a woman can afford to reduce her carbohydrate intake.

So does this mean I need to eat more fat?

Actually, no - as long as your current intake is around 30% of your daily caloric intake.

How do the hydration needs of female athletes differ from males?

For too many years, high performance athletes were encouraged to drink before they were thirsty to prevent dehydration. A consequence of this approach is hyponatremia, also known as water intoxication or dangerously low blood sodium.

Hyponatremia is particularly an issue for women during their high hormone phase because it resets their body’s signals to respond to a lower plasma volume. This means their drive to drink, or their level of thirst, is dampened.

So they just don’t realise they are thirsty, even though their body might be dehydrated. Otherwise, they would go crazy with the drive to hydrate whenever they were in their high hormone phase.

This lack of thirst sensitivity only gets worse as women get older.

What are some of the misconceptions about how female athletes should eat and hydrate?

The biggest misconceptions are eating and hydrating with a one-size-fits-all approach.  For example, women do not need 90g/carbohydrate per hour of endurance exercise.

Women have a change in fluid balance, blood-sodium levels, and thirst sensation between menstrual cycle phases and should adjust accordingly.

What are common mistakes female athletes make when they are training?

Going too hard, too often and neglecting recovery, or rather using inappropriate recovery techniques.

One real misconception is in the days before a woman’s period she may feel flat, tired and unfit and will push herself harder. In reality, it is her physiology, not her fitness, that is impacting her performance.

What can non-athlete females take away from your research?

From my research, women looking to move more regularly, lead a healthy lifestyle and gain fitness can do something as simple as track their periods and alter their training and nutrition according to hormonal phases. Apps like Clue or Spot-on can help women track their cycles.

Why did you chose to come to the University of Waikato to work and continue your research?

A number of things attracted me – the new environmental chamber at Mount Maunganui and the opportunities available while being based at the Adams Centre for High Performance.

The high profile colleagues at Waikato and in New Zealand were also big draw cards.

Above all else, it’s about having fun of course!

What advice do you have for those interested in studying sport science?

Sport Science isn’t glorified personal training. It is the science of the external and internal touch points of the body.

Innovation in sport technology across wearable accessories, environmental stressors, strength and conditioning, movement patterns, and genetics all sit under the sport science umbrella.

If you have a passion for human movement and physiology, then sport science is for you.

The University of Waikato offers a Bachelor of Health, Sport and Human Performance. Applications for 2018 A semester are now open. Apply now or talk to us about your options.

After almost two decades of research into female athletes, Dr Sims released her book last year: Roar: How to Match Your Food and Fitness to Your Female Physiology for Optimum Performance. The book aims to teach the female reader everything they need to know to adapt their nutrition, hydration and training to their physiology. Check it out here.


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