In a world where women are striving for equality in all aspects, it is important to make note of what makes us different. These differences are not always a negative and in some cases give our sex an advantage. In this blog we will explore how our bodies react differently and are built differently than men and what that means in terms of working out, injury and nutrition.
Due to higher estrogen levels, women have more body fat than men. The leanest female athletes, such as top marathon runners, have body fat of approximately 8 percent, compared with 4 percent for their male counterparts. In addition, women's bodies are less muscular, but their joints are more flexible, which gives them greater range of motion -- an advantage in sports such as gymnastics. The wider female pelvis also affects the alignment and movement of the extremities. Men have higher levels of testosterone, which gives them a performance advantage in other ways.
Estrogen is not a negative however. Your muscles have estrogen receptors, and, in fact, there’s good reason to believe that estrogen plays a major role in the beneficial adaptations that occur with aerobic training. When compared to sedentary men, endurance-trained men have 3-5x as many estrogen receptors in the muscles (suggesting they become more sensitive to the effects of estrogen), and it’s been found that, at least in mice, estrogen receptors on mitochondria increase the rate of glucose uptake into the muscle when activated.
Testosterone enables men to develop larger skeletal muscles as well as larger hearts. Men also have a larger proportion of Type 2 muscle fibers, which generate power, strength and speed. Testosterone also increases the production of red blood cells, which absorb oxygen, giving men an even greater aerobic advantage, reports "New York Times" writer Gina Kolata, in an interview with Dr. Mark Tarnopolsky, an exercise researcher at McMaster University in Ontario.
Women tend to have a greater proportion of Type 1 fibers (roughly 27-35% greater Type 1 fiber area relative to total fiber area) and greater capillary density. Those are two major factors. More Type 1 fibers and greater capillary density mean better tissue perfusion (ability to get more blood to the muscle to provide oxygen and clear metabolites) and greater capacity for glucose and fatty acid oxidation (because Type 1 fibers are the ones with more mitochondria and aerobic enzymes). Insulin resistance and type 2 diabetes are negatively correlated with Type 1 fiber percentage and capillary density in both lean and obese people.
Conversely, men have a higher glycolytic capacity than women. That means that they can burn through more glucose in the absence of oxygen, which lends itself to better performance for short-intense bursts of effort, but which also means more lactate accumulation and longer recovery times after all-out efforts. This is related to both the higher percentage of Type II fibers, and also higher levels of glycolytic enzymes.
Though women tend to have more fat, there are differences in where that fat is stored, and also the characteristics of that fat. For starters, men tend to have more visceral fat (fat stored around the organs in the abdominal cavity), and women tend to have more peripheral subcutaneous fat (fat stored between the muscles and the skin). This gives rise to the “apple” and “pear” shaped, or android and gynoid fat distribution patterns.
Due to some of the skeletal formation differences mentioned earlier, women are more prone to injuring joints such as the shoulders and knees. Weaker shoulder muscles and looser supporting tissues mean the joint is less stable than in men, reports writer Michael Lasalandra, in an interview with Beth Israel Deaconess Medical Center sports medicine physician Bridget Quinn. Also, the injury rate to the anterior cruciate ligament, or ACL, a major knee ligament, is significantly higher in female than in male athletes. By proper training and strengthening of supporting muscles, women can prevent such injuries.
Women have increased incidence of patellofamoral disorders, stress fractures and ACL injuries. In fact the risk of injury is 2-10 times greater than males especially with pivoting sports. ACL injury is more common due to land ion biomechanics and neuromuscular control differences. Females land with their knees in more extension and vaigus due to hip internal rotation. This picture gives a good idea of the pressure placed on the female’s lower extremities and the suceptiblility to injury. Conditioning and strength play a big role, but females in general have smaller ACL size and smaller notches. Another factor is a women’s cyclical hormone levels, placing them at a greater risk for injury during the first half of the menstrual cycle.
Perhaps one of the most important conditions that differentiate male and female athletes s susceptibility to the Female Athlete Triad, or “the triad.” The triad consists of three main symptoms including low energy availability, menstrual dysfunction and decreased bone mineral density. This was more common when skinny was in and women were afraid to put on muscle, afraid they would look to masculine or get “thick”. Strong is beautiful and in some ways our culture is starting to recognize this more and more. By regulating your caloric intake and making sure your hormones are still in healthy balance, even athletes that push to the point of no longer having a regular period can avoid the triad.
Just to reiterate, gender differences related to acute performance aren’t that huge, and are less a function of gender per se, and more a function of body composition. Of the differences that do exist, the largest contributing factors are fiber type differences and sex hormone differences. In essence, they set women up to be more metabolically suited to just about everything.
They clear VLDL and triglycerides better, have better insulin sensitivity, have a more favorable fat distribution, and burn a greater proportion of fat at any given exercise intensity, making them less fatigueable. The only place where men have the edge is in glycolytic capacity and explosive (but not maximal strength) performance (both related to Type II fiber proportion).
So what do we do with all that?
For starters, ladies, do not be afraid of carbs. Not only are they delicious and awesome, but you have better insulin sensitivity, and the more of them you eat, the more of them you burn.
Second, you do not have a harder time losing weight because you’re a woman. Yes, you’ll probably have to eat fewer calories than a man who weighs the same amount you do, but the primary factors in determining your calorie needs are body size, body composition, and activity level, with gender playing little to no role. If you’re more jacked and/or more active than a guy who weighs the same as you, then you can eat more than him. If not, you can’t.
Finally, as far as training goes, odds are pretty good that you can do more work and benefit from more work than a guy can. Your muscles are inherently more glycogen-sparing and fatigue-resistant. You can probably do more reps with a given percentage of your 1rm before fatigue sets in, and do more total work (relative to 1rm) before you hit a wall due to higher proportion of Type 1 muscle fibers, greater proportion of fat being burned instead of glycogen, and lower glycolytic capacity.
Rock on ladies!