The truth about female physiology

For too long, female cyclists have been urged to follow the same training principles as their male counterparts. Here, Dr Stacy Sims explains to Deena Blacking why female physiology demands a different approach

Women are not small men. This is the watchword of Dr Stacy Sims, a world-leading physiologist who specialises in female nutrition, training and wellbeing. A former bike racer for UCI Team Tibco and a proud applied scientist, Sims has been in high-performance environments for decades. Her work has been tried and tested by the world’s top performing female athletes, including 2019 USA national road champion Ruth Winder. 

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In 2016, Sims published Roar, a training guide that lifts the lid on female physiology’s best kept secrets. The book was widely hailed as a game-changer in understanding female physiology as pertains to sport. Sims agreed to speak to CW to help us bust the most prevalent myths while providing the corrective truth and, for good measure, throwing in some ‘biohacking’ tips for improving performance.

MYTH: Always train three weeks on, one week off

Three weeks on, one week off - a build phase followed by a shorter deload period. Online or paperback, this is the most common structure for training plans. The idea behind it is simple: progressively push the body until it is ‘overloaded’, then pull back and give yourself a chance to recover before you go again.

It may follow a three-one pattern - shorter or longer depending on how you respond to training. If everyone’s doing it, and has been doing it for so long, it must work, right? Wrong, at least if you’re female.

TRUTH: Match your training to your hormone cycles

Hormones influence how we adapt to training. For females, this includes how we build muscle, how we adapt to intensity, and how we metabolise carbohydrates. When hormones are high, they can limit the body’s ability to perform and respond to training stimulus. By contrast, the beginning of a natural cycle - when hormones are low - is often the ideal time to train hard and build muscle.

Sims is emphatic: “Know that you have this window of advantage in the low hormone phase,” and adds that the oral contraceptive can disturb the levels of naturally occurring hormones, and understanding this is important.

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Armed with this information, females need to track their cycles so they can match training intensity to hormone levels. “Put in the high-intensity session when your body can handle it,” Sims advises. “Get the really strong power and training stress when your body is in a low hormone phase. Work on technique in the high hormone days before your period - that’s your deload week.”

Whether you are a male or a female - male sex hormones can also fluctuate significantly - effective training demands that you pay attention to what your body is doing and how you are feeling so you can match your training to your physiology.

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Founded in 1891, Cycling Weekly and its team of expert journalists brings cyclists in-depth reviews, extensive coverage of both professional and domestic racing, as well as fitness advice and 'brew a cuppa and put your feet up' features. Cycling Weekly serves its audience across a range of platforms, from good old-fashioned print to online journalism, and video.