You hear a lot of people throw different facts around about men and women, and the differences with respect to all things relating to body composition.
So what are these differences? Are they huge or not?
Let's take a look at the science!
MUSCLE MASS
Not surprisingly, women are approximately 52% as strong as men in the upper body and 66% as strong in the lower body (1).
Why are women so much weaker in the upper body than in the legs compared to men?
Because they "tend to have a lower proportion of their lean tissue distributed in the upper body" - so their muscle is mainly in the lower body.
This strength difference is due to the fact that men have larger muscle fibers (2).
Let's hear from these authors:
"The findings suggest that the sex difference in muscular strength in equally trained men and women is almost entirely accounted for by the difference in muscle size"
The authors discover that in 97% of the cases - the strength differences between a man and a women is because of the muscle size difference - meaning if a man and a woman have the same muscle mass, they will have the same strength.
And in terms of muscle fiber differences, women generally have more type 1 fibers than men; about 27-35% more type 1 fibers relative to their complete fiber area and better capillary density (3).
More type 1 fibers and a superior capillary density mean women get more blood and oxygen to their muscles, and have more room for glucose and fatty acid oxidation.
Also, more type 1 fibers seem to mean less chance of diabetes in both the obese and lean (3).
To hear from the researchers in the above citation:
"...it appears that men might be more prone to develop insulin resistance."
Women also obviously have higher estrogen levels, which really does have it's benefits!
Considering females have a greater proportion of type 1 fibers and higher estrogen, their muscles are able to handle glucose better.
This is because muscles have estrogen receptors which suck up glucose, meaning overall glucose intake is increased.
So what this means for women is......don't be scared of carbohydrates!
However, it doesn’t end there.
Female muscles also handle fat better, even when comparing female Type 1 fibers to male Type 1 fibers.
Who run the world? Girls Girls!
WOMEN USE MORE FAT AND CAN GO FOR LONGER
Furthermore, when we ignore how long either gender has been training; women do use more fat regardless of how intense the exericse is (3).
This also means they can go longer than men before fatigue kicks in.
But don't cry in your beer (or protein shake) gents - we can chew through more glucose where there's no oxygen, meaning we're better at short bursts of energy.
FAT DIFFERENCE
Any woman reading this HATES the way men seem to have less fat on average (I can feel some of you nodding your head!).
But all you ladies out there - don't bang your head against the wall yet, I have some good news!
As you've probably already worked out, men tend to store fat around their stomachs, regarded by some as the "spare tire."
This is what's called visceral fat; that stored around the organs and abdominal region (3).
Women on the other hand store fat around their arms, thighs, backside and hips.
Some women can't work out why they have very lean looking stomachs, but still seem to have what they brand "fat" legs, arms and backsides.
This is simply due to where a women's fat is distributed, and they have more of it because it's required for babies brains to feed off during pregnancy. (Some new research is out in this area - click the link for more!)
This is referred to as peripheral subcutaneous fat - fat stored between muscle and skin (3).
As you'll see below, this is why women have the "pear" shape and men the "apple".
But here's the good news on the health front for women - visceral fat (the kind in men) is unfortunetly a mean type that can increase the risk of diabetes and heart disease.
Visceral fat is broken down and pumped into the blood stream and unlike subcutaneous fat, is first sent to the liver.
Why is this bad?
Because a large amount of fatty acids delivered to your liver can decrease insulin sensitivity; paving the way for the health complications I mentioned above.
So women are less at risk of these diseases because they have less visceral fat.
SPEED BETWEEN THE SEXES
Men tend to be faster when both sexes have undergone the same level of training.
But this basically comes down to men's higher level of testosterone and thus more red blood cells - which increases the amount of oxygen delivered to the working muscles (4).
The other factor is that men have bigger hearts and are leaner (4).
So men are better equipped here, which is why 100m sprint world records will most likely always be held by a male.
But really when we look at everything - there's not a HUGE difference between both sexes.
The obvious advantage men have is larger muscle fibers, which makes them better for explosive activities but not superior when it comes to strength.
However, women do have a metabolic advantage when it comes to fat and carbohydrates, and do appear to have better insulin sensitivity!
Also, their peripheral subcutaneous fat - fat stored between muscle and skin - is superior for health.
But it's not really any harder for a women to lose weight than a man, that much is pretty clear.
However, you ladies may have the edge when it comes to training benefits; your muscles are more glycogen sparing meaning you can probably squeeze out more reps relative to your 1 Rep Max than a man can (1).
But all that being said - using your gender is really no excuse....know what results you want, and get out there and go get them!
"Stay Fit, Stay Flexed!"
REFERENCES
(1) Miller A.E.J, Macdougall J.D, Tarnopolsky M.A, Sale D.G. Gender differences in strength and muscle fiber characteristics. European Journal of Applied Physiology and Occupational Physiology. March 1993, Volume 66, Issue 3, pp 254-262.
(2) Bishop P, Cureton K, Collins M. Sex difference in muscular strength in equally-trained men and women. Ergonomics. 1987 Apr;30(4):675-87.
Author
Dayne Hudson