Available data beginning at age 18 years through age 80 indicate that males and African Americans have more skeletal muscle mass than females and other ethnic groups across the entire age range, even adjusting for weight and height [41] .
In the Health, Aging, and Body Composition Study black subjects had greater appendicular lean mass and strength, but also lower muscle quality than whites [20].
Skeletal muscle is a highly heritable quantitative trait, with heritability estimates ranging 30–85% for muscle strength and 50–80% for lean mass.
Genetics impacts all areas of fitness and performance, including muscles and strength. From sprinters who have genes allowing them to develop more fast-twitch muscle fiber to endurance runners with genetics dictating muscle contraction speeds, genes determine our abilities to some degree.
South Asians are able to mount an anabolic response to resistance exercise training of a similar magnitude as White Europeans with similar increases in muscle mass and strength.
Asians had more upper-body subcutaneous fat than did whites. The magnitude of differences between the two races was greater in females than in males. Prediction equations developed for each sex and race, based on BMI alone, gave SEEs ranging from 4.4% to 5.7%.
Proposed explanations for South Asian low lean mass range from the long-term impacts of climatic adaptations, through dietary changes with the transition to agriculture and/or the adoption of vegetarianism, to the more recent impacts of severe 19th century famines, which were exacerbated by colonial policies.
The Genetics of Defined Muscles
Part of how muscular you look comes down to genes, notes Westcott. "Some people are born with long muscles and short tendons," he says. And this is ideal for that super-defined look.
Body composition differs between men and women, with women having proportionally more fat mass and men more muscle mass.
By combining data from 24 separate studies, the study concludes that genetic differences are responsible for 72% of the variation in outcomes for people using an identical strength training regimen. Genetic variants are linked to 44% of the differences seen following cardiovascular fitness exercises.
Generally, people of West African origin have more fast twitch muscles which allow intense bursts of power. This is why running backs, defensive linemen, and receivers are almost all black.
Most people feel as though they look more like their biological mom or biological dad. They may even think they act more like one than the other. And while it is true that you get half of your genes from each parent, the genes from your father are more dominant, especially when it comes to your health.
"The genes responsible for making muscle cluster on the X chromosome," says David Bainbridge, Ph. D., author of The X in Sex: How the X Chromosome Controls Our Lives. That means Mom may be responsible for your innate ability (or inability) to build massive lats.
The skeletal muscle index (SMI, kg/m2) was highest in Germans, whereas in BIVA, the Mexican group had the longest vector, and the Japanese group had the lowest phase angle and the highest extracellular/total body water ratio.
The relationship between BMI and percentage of body fat depends on age and sex, and differs across ethnic groups. Most Asian ethnicities have higher average body fat percentage than Whites of the same age and BMI. As a consequence, Asians may be predisposed to a greater risk of clinical events, despite similar BMI.
Bodybuilding, Strength Training, and DNA
It's obvious that our genes play a role in fitness. Long before we understood so much about DNA, good genetics, and health, it was clear that some people just build muscle more easily. Bodybuilders work hard to get chiseled bodies, but many also have a boost from their genetics.
Females have 37-68% of muscle strength of males in general. The difference on muscle strength between females and males is more on upper body, and less on lower body. Females are relatively stronger on their legs than arms and shoulders.
Muscular forearms are also among the most important muscles women like the most in men. Strong arms come with an all-around package of good back and shoulder muscles that women love. In fact, many females like men flaunt their forearm veins and stuff.
Research also shows that to maximize your attractiveness to women, guys only need to gain about 20 to 30 pounds of muscle and reduce their body fat percentage to 8 to 12%. Read this article to learn exactly what kind of body women do and don't find attractive, and how to get the kind of body they want.
Functionally, a lean body is more efficient as you can move better and faster. However, a bulk body is necessary if you wish to enter professional bodybuilding or appear a certain way.
Bigger muscles aren't always better and bulking up may not have much to do with being healthy says UK based celeb trainer Nick Orton. Getting big doesn't keep your from being fit or damaging your health. If you think being bulky and healthy are one and the same thing, you might be wrong.
In South Asians, because our genes lead to more visceral fat storage in our midsections, our BMI cutoffs are much lower. A BMI of 18-22.9 is considered normal for most South Asians while a BMI of 23-24.9 is considered overweight and a BMI of 25 or over is considered obese.
Many South Asians can still appear “thin” but actually have a high percentage of visceral fat—and therefore present with conditions like Type 2 Diabetes at a lower BMI than other ethnicities.
Results The male groups of North Asian type were endomorphic mesomorph and the South Asian types were balanced mesomorph, while the East Asian types differed greatly from each other.