Posts Tagged: Somatotypes

May 10

Obesity Lowers Male Testosterone?

Does obesity lower male testosterone levels?

From a news release

Results of a study published online ahead of print in the journal Diabetes Care, conducted by University at Buffalo endocrinologists, showed that 40 percent of obese participants involved in the Hypogonadism in Males (HIM) study had lower-than-normal testosterone readings.

The percentage rose to 50 percent among obese men with diabetes. Results also revealed that as body mass index (BMI) — a relationship of weight–to-height — increased, testosterone levels fell.

“The effect of diabetes on lowering testosterone levels was similar to that of a weight gain of approximately 20 pounds,” says Sandeep Dhindsa, MD, an endocrinology specialist in the UB Department of Medicine and first author on the study.

Correlation is not causation, but if there is actually a causal relation here, then something like this can affect the psychology and behavior of a male.

H/T FuturePundit

Jan 10

Upper Body Strength And Fighting Prowess

As a follow up to my last post on the face of a fighter, there’s a part of the paper it points out that talks about the belief that upper body strength is the or one of the most important factors for human fighting prowess. Here’s the relevant except….

Anatomical evidence supports the view that, for ancestral humans, the single most important factor driving the differential ability to inflict costs was upper-body strength. In humans, the view that upper-body strength is more relevant for fighting than lower-body strength is empirically supported by the considerable sexual dimorphism in human upper-body size and strength (for review see Lassek & Gaulin in preparation). Men, for example, have approximately 75 per cent more muscle mass than women in the arms, but only 50 per cent more muscle mass in legs. Although ancestral humans were zoologically unusual in their use of tools in some types of aggression, the force driving the weapon remains largely a function of upper-body strength (Brues 1959).

Given that upper body strength seems to be greatest with Mesomorphs, and that Somatotypes have a heredity component, it would seem that thus upper body strength will have a heredity component.

Something not surprising to me, since I’ve observed (in my personal experience) that fighters tend to run in the family.

Jan 10

Familial resemblance for physique: heritabilities for somatotype components

My personal experience suggests to me that there is a high degree of heritability for somatotypes. This study is interesting in that it tries to figure out just how heritable they are.

Primary objective: To examine familial resemblance in the Heath-Carter anthropometric somatotype in a sample of 328 participants from 103 nuclear families in Northern Ontario (Canada). Methods and procedures: The three somatotype components (endomorphy, mesomorphy, ectomorphy) were subjected to principal components analysis and the resulting first principal component (PC1) was used as an additional index of physique. The four phenotypes were adjusted for age, sex and generation effects, while each of the three somatotype components was further adjusted for the effects of the other two components using regression procedures. A familial correlation model was fit to the data and used to estimate the degree of familial resemblance in somatotype. Main outcome and results: For all somatotype variables, the most parsimonious model was one in which there was no spouse resemblance and no sex or generation effects in the familial correlations. Maximal heritabilities were 56%, 68%, 56% and 64% for endomorphy, mesomorphy, ectomorphy and PC1, respectively, indicating significant familial resemblance for the Heath-Carter anthropometric somatotype. Further, the pattern of familial correlations suggests the role of genetic factors in explaining variation in human physique. Conclusions: In general, a pattern of no spouse but significant parent-child correlations implicates the role of genes on human physique, provided that mating is random with regard to these traits.

(Emphasis mine.)