ROAR, Revised Edition

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What It Means to Be “Like a Girl”

All the Physiological Stuff That Makes Females Unique

You “throw like a girl.” You “run like a girl.” The “like a girl” insult has been so ubiquitous, such a strong underlying current in our culture, that in 2015, Always, one of the biggest makers of feminine hygiene products, stole the show during the Super Bowl with a 60-second ad spot that challenged the culture to dismantle the phrase with its Like A Girl campaign, which turns the insult into an inspirational compliment. You saw what it can mean to compete like a girl in the introduction—how women can dominate their sport.

Look, I’m not one to sugarcoat anything, so I’ll give it to you straight. Yes, in head-to-head objective physical performance comparisons, females may have some disadvantages compared to males. We also have some distinct advantages, but you never hear about those. So let’s set the stage here with a complete look at your female physiology in action.

Sugar and Spice and Everything Nice: What We’re Really Made Of

No surprise: Women tend to be smaller and lighter and have a higher portion of body fat (hello breasts, hips, and all things childbearing!) than men. But dig a little deeper, and the comparisons become more interesting and revealing.

First, let’s talk about body mass and how it’s distributed. Our mass is the stuff we’re made of, which everyone commonly refers to as weight—the number you see on the scale. That’s not exactly accurate. For one, technically, weight is determined by gravitational pull, so you’d weigh less on the moon and far more on Jupiter, but that’s being picky. The more important factor is that the number you see on the scale—your weight—fluctuates widely depending on fluid intake, what you’ve eaten during the day, salt intake, and how much glycogen you’re storing in your muscles. (For every 1 gram of glycogen, you store 3 grams of water; as you get fitter, you become better at glycogen storage. So before a big event, you can gain 5 or more pounds that you will blow through during your event—but you haven’t gained or lost any fat.) Body mass, by contrast, is the actual stuff you’re made of—bone, muscle, fat, and organs—that requires tissue loss or gain and is harder to change.

We’ll cover bones in Chapter 9, because a strong skeleton is essential for vibrant living, and women’s bones are vulnerable to getting brittle. For now, however, let’s focus on muscle and fat.

When researchers take core needles and pull out a column of muscle tissue from the designated muscle of interest (usually the shoulder, biceps, or quadriceps) of men and women, the findings might surprise you: There’s not much difference. Men and women generally have the same muscle composition as far as the percentage of type I endurance (aerobic) fibers and type II power (anaerobic) fibers. What is different is that the largest fibers in women’s bodies tend to be type I endurance fibers, while in men the type II power fibers take up the lion’s share of real estate.

That fiber type difference makes a difference when you’re looking at pure strength between the sexes. In head-to-head strength comparisons, women fall a bit short. Studies show that, generally, the strength of women is typically reported in the range of 40 to 75 percent of that of men, with women about 52 percent as strong as men in their upper bodies and 66 percent as strong as men in their lower bodies. In well-muscled women, those strength differences evaporate a bit. When you look at sheer strength relative to lean body mass, a trained woman’s strength shoots up to 70 and 80 percent as strong as men in the arms and legs respectively. Still less powerful, but definitely closer. We also tend to carry more of our lean muscle tissue below the waist, with much of our power coming from our hips and legs.

Then there’s fat, which many athletes I work with still consider a four-letter word, even though you can’t train, race, or even live without it. Most of us have been conditioned to think of any fat under our skin as unwanted. But that’s far from the truth. That’s our storage fat. Those are energy reserves we accumulate. That fat also acts as padding and generates key hormones such as adiponectin that regulate insulin (the hormone that helps your body use and store blood sugar). We need some storage fat to perform our best. Most of the fat you don’t see in the mirror is essential body fat, which is in your nerves, bone marrow, and organs. Essential fat in men is about 4 percent, but in women, it is about 12 percent (because we are designed to reproduce!). As a woman, your breasts are also largely fatty tissue.

How much fat either men or women carry depends largely on lifestyle, but you can’t dismiss the fact that there are also very distinct body types. For instance, there are people who are endomorphs. They tend to be larger, and they carry more body fat. On the other end of the scale are the ectomorphs, who are naturally slimmer. And in the middle are mesomorphs, who tend to be medium built and naturally muscular. You can also be a blend of the two; for example, a mesomorph with endomorph tendencies. How active you are and the type of activity you do can impact the dominance of one body type over another. Your physical activity directly affects your body fat levels and distribution.

We’ll delve into the topic of body composition in great depth in Chapter 5, but generally speaking, healthy body fat ranges span from 12 to 30 percent in women and 5 to 25 percent in men.

In the athletic world, muscle is usually prized, while fat is shunned. As I see it, however, what you’re made of is important, but more important is the impact of what you’re made of on what you do and/or want to do. Take two cyclists, for instance. A man may have big pectorals (pecs) and biceps, but those heavy upper-body muscles will only weigh him down when faced with a 10 percent climb. A woman who is lighter in the torso but still powerful in the hips and legs will have a far easier time pedaling her way up the mountain.

Likewise, women often dominate in the sport of open-water swimming. When you look at the records, female swimmers often perform on par with or better than their male counterparts, especially as the swims get longer. Research investigating the sex difference in performance for successful women and men crossing the Catalina Channel—an arduous 20-mile swim from the Southern California coast to Catalina Island—reports that the fastest woman ever was about 22 minutes faster than the fastest man ever. And though the three fastest women ever were about 20 minutes faster than the three fastest men ever, the overall difference in performance didn’t reach statistical significance. But the women appear to be continuously narrowing the performance gap.

And let’s not forget that in 2013 Diana Nyad became the first person ever to swim the 110.86 miles between Cuba and Florida without the use of a shark cage for protection in a mind-boggling 52 hours and 54 minutes. Fat is more buoyant than muscle, so that extra padding may be a distinct advantage in the open water.

Women on the Run: Our Capacity for Cardio and Endurance

Whether you run marathons, cycle Gran Fondos, compete in triathlons, or just exercise to stay fit and healthy, training works similarly for both sexes. As you train longer and harder, you get fitter. Your body can deliver and use more oxygen (that’s your max VO2); you can push the pace to a higher point before your muscles beg for mercy (that’s your lactate threshold talking); you become stronger and better at burning fat; and your performance improves.

But that open-water swimming example aside, pound for pound, men still generally outrun, outwalk, and outcycle us. Research published in 2022 reported that the performance gap was relatively small at very short distances, but widened as the events got longer (to a point; we’ll discuss ultraendurance in a bit). So women were 8.6 percent slower in the 60 meter, 9.6 percent slower in the 100 meter, 11 percent slower in the 200 meter, and 11.7 percent slower in the 400 meter. After that point, there’s a relatively consistent 10 to 12 percent discrepancy in endurance performance.

Why? Well, for the same reason that a Prius will have to pull some wily moves if it wants to race against a Mustang—we start with a smaller engine. As a woman, you have a smaller heart (26 percent lighter than the male heart), smaller heart volume, smaller lungs (10 to 12 percent less volume than men), and lower diastolic pressure (the pressure in the arteries when the heart is resting between beats and the ventricles fill with blood), which predisposes us to have lower maximum heart rates and greater problems with dehydration in the heat. This also means we pump out less oxygenated blood with every beat—about 20 percent less cardiac output than men.