Women's Pan-Power: Nature's Gift

It is widely known that, on average, men are stronger than women. This is largely due to the fact that men are typically larger and have more muscle mass. However, this difference is not as pronounced when comparing strength pound for pound, or relative to body mass.

According to the Journal of Exercise Physiology, women produce about two-thirds the amount of total strength and applied force that men produce, and they carry about two-thirds as much muscle mass. This difference is largely attributed to body size and muscle cross-sectional area.

In addition to physical differences, there are also psychological differences between men and women related to strength. Studies have shown that men with greater upper-body strength tend to favour political policies that benefit themselves and are more prone to competitiveness and hierarchical structures.

Upper-body strength

There are fundamental sex differences between men's and women's physical prowess, particularly in upper-body strength. Women's lower body strength tends to be more closely matched to men's, while their upper body strength is often just half that of men's.

In a 1993 study exploring gender differences in muscle makeup, female participants exhibited 52% of men's upper-body strength. This was attributed to their smaller muscles and a higher concentration of fatty tissues in the top half of the female body. Another study published in 1999 similarly found that women had 40% less upper-body skeletal muscle.

Even when controlling for athletic aptitude, an experiment comparing the hand grip strength of non-athletic male participants versus elite female athletes still revealed a muscle power disparity in favour of the men.

However, one study found no significant differences in elbow flexor strength gains between college-aged men and women after 10 weeks of resistance training. Both males and females significantly increased elbow flexor strength, with no significant difference between the sexes.

The sex hormone testosterone has anabolic effects, meaning it promotes muscle development. Secreted by the pituitary gland, testosterone binds to skeletal fibre cells and stimulates the growth of proteins, the building blocks of meaty muscles.

Lower-body strength

Women's lower body strength tends to be more closely matched to men's. In a 1993 study, female participants exhibited 66% of men's lower body strength. This is in contrast to upper body strength, where women exhibited 52% of men's strength.

In a 2021 study, no significant gender differences were found in lower body strength when adjusted for lean body mass. However, the study did find that men had significantly greater muscle thickness in the vastus lateralis, pectoralis major, and trapezius muscles. This suggests that differences in lower body strength may be due to variations in muscle morphology and lean body mass distribution between genders.

Another factor that may contribute to gender differences in lower body strength is hormonal differences. Testosterone, a sex hormone found in higher levels in men, has anabolic effects, promoting muscle development.

Muscle cross-sectional area

CSA refers to the area of the cross-section of a muscle perpendicular to its fibres, typically at its largest point. It is used to describe the contraction properties of pennate muscles, which can generate more force than non-pennate muscles due to their ability to pack more muscle fibres in parallel. The force generated by a muscle is proportional to its CSA, and this relationship is described by the formula:

> Total force = PCSA x Specific tension

Where specific tension is the force exerted by the muscle fibres per unit of CSA.

Studies have shown that trained individuals have a higher force-to-CSA ratio (F/CSA) than untrained individuals, regardless of sex. However, the impact of sex on F/CSA is less clear, with some studies suggesting that recreationally trained female weightlifters can produce higher F/CSA than males at lower velocities of contraction.

In addition to training status and sex, age also appears to influence the F/CSA relationship. Data suggests that F/CSA varies unpredictably across ages and may be influenced by factors other than age alone.

While CSA is a significant factor in muscular strength, it is not the only determinant. Other factors, such as muscle architecture, fibre type, and neuromuscular function, also play a role in an individual's strength capabilities.

Muscle fibres

Slow-twitch muscle fibres are the muscle cells responsible for endurance movements. They don't produce a lot of power, but they're resistant to fatigue and can contract for a long time. Slow-twitch muscle fibres help with daily movements like walking, cleaning, or sitting upright in a chair. They get most of their energy (ATP) from aerobic respiration, meaning they need oxygen to function. The oxygen makes the muscle fibres look red, which is why slow-twitch fibres are sometimes called red fibres. Type I muscle fibres have a much better blood supply and ability to receive oxygen than type II fibres. They also have a high concentration of mitochondria, which is the powerhouse of a cell where aerobic respiration takes place. Because slow-twitch muscle fibres use oxygen to produce energy, they are more resistant to fatigue. Type I muscle fibres are responsible for endurance activities such as distance running, swimming, cycling, hiking, low-to-moderate intensity dancing, and walking.

Fast-twitch muscle fibres are the muscle cells responsible for short, powerful movements. They can produce a lot more force and power for a short time, but they get fatigued quickly. Type II muscle fibres are broken down into type IIx and IIa. Type IIx fibres produce force that's much greater than type I fibres. However, they use anaerobic (without oxygen) metabolic pathways to get their energy (ATP). That means they receive less blood flow and oxygen and can only produce force for short periods of time. Type IIa muscle fibres are like a hybrid of type I and type IIx. They have elements of both fibre types. For example, they use both aerobic and anaerobic pathways and produce a medium amount of power for a medium amount of time. When your body moves, it will use slow-twitch muscle fibres first. Then, if those fibres can't produce enough force, the body will use fast-twitch type IIx and IIa fibres to get more power. So, if your fitness goals involve strength and power, you'll want to focus on training type II muscle fibres. Technically, any resistance training will train both type I and type II fibres, but training with heavier loads (at least 70% of 1RM) or lighter weights with explosive tempos are the best ways to activate and train type II fibres. These fibres also tend to achieve hypertrophy (muscle growth) easily, which can be important for bodybuilders.

The distribution of muscle fibre types depends on the primary function of the muscle in question, as well as the person's activity level, genetics, and age. For example, endurance athletes usually have a higher proportion of slow-twitch muscle fibres, while strength or power athletes usually have a higher amount of fast-twitch muscle fibres. But the exact proportion of each fibre type can range from 15 to 85% of one type or the other, and the distribution also highly depends on the muscle. There's also a theory that people who genetically have a higher percentage of slow-twitch fibres might be drawn to endurance activities, and people with more fast-twitch are drawn to power-based activities.

In summary, muscle fibres are individual muscle cells that play a crucial role in our physical capabilities and can be trained to improve performance in specific types of activities.

Physical endurance

Women are known to be particularly good at endurance running, with their running abilities declining extremely slowly into old age. They have been known to go long distances even while pregnant. For example, in 2011, Amber Miller ran the Chicago marathon and gave birth seven hours later.

Women's superior endurance is also evident in their ability to survive illnesses and cope with trauma. Women are better survivors than men, and this is true "pretty much at every age", according to Steven Austad, an international expert on ageing. Women live longer than men, and this is true all over the world and as far back as records have been kept. Globally, a million babies die on the day of their birth every year, and males are statistically at a 10% greater risk than females, even when they receive the same level of care.

Women's superior endurance may be linked to their hormones. Higher levels of oestrogen and progesterone could be protecting women by making their immune systems stronger and more flexible. This may also help maintain a healthy pregnancy. A woman's immune system is more active in the second half of her menstrual cycle, when she is able to conceive.

Women's superior endurance may also be linked to the placenta. Research from the University of Adelaide suggests that a mother's placenta may behave differently depending on the sex of the baby, doing more to maintain the pregnancy and increase immunity against infections.

Women's bodies have been shaped by evolution. For an enormous chunk of early human history, women would have travelled hundreds or thousands of miles, sometimes under extreme environmental conditions. Women would have also had to carry their children with them during these journeys.

Women's superior endurance is also evident in their ability to perform ultra-events, or very long-distance athletic events.

Frequently asked questions