Anyone who’s lived a day in his life (or played summer football in a city park or worked out at a vibrant gym) has noticed that different races have different musculature and athletic talent. Blacks are the most ripped, and often the biggest, particularly in the deltoids and lats. They respond the fastest to resistance training and are amazingly agile on their feet, (something you have to marvel at the first time a black guy with the ball makes a cut around you).
Whites are the most varied, ranging from nerd skinny to hulking well-marbled powerlifter. Few whites can get as defined as blacks, so you really become aware of those white guys who do manage to carve their abs and delts well past the norm for their race. Whites also have wider waists than blacks, and tend to stockiness, although this is far from a universal white trait.
Asians are the slightest and the least toned, and are less varied in appearance than either blacks or whites, (although asian sub-groups, like Koreans, who hit the gym hard can become quite strong in compound movements like the squat that leverage their naturally lower center of gravity and shorter limbs).
Hispanics (or amerindians, if you prefer) resemble their asian progenitors in muscle tone, but not in gracility. And depending on how you define “hispanic”, their physical variance is either very large (think Spanish-Cuban vs Mestizo) or very small (the round mamacita millions).
All these racial differences in physique are far more noticeable in younger men (and women) than in older representatives, owing primarily to the fact that most people of any race get fatter and looser with age, the biological upkeep of their sexual dimorphism becoming less relevant beyond reproductive age, and this symptom of aging is greatly exacerbated by the Western obesity plague, especially in black women who get so enormously fat soon after leaving high school that you’d need a team of archaeologists to excavate evidence of their buried female form.
So, you’d have to be blind or a self-deluding status whoring SWPL leftoid to not notice these differences.
For a while, curious noticers wondering what accounted for their observations would assume that testosterone had something to do with it. After all, T and T mimics are injected by bodybuilders to build huge blocks of muscle. Naturally, one infers that the less muscular-looking races (if not necessarily the less strong) have lower levels of testosterone in their blood.