The body changes with age and many organs and systems in the body that function perfectly when we are young begin to falter with age. Most of those involved in bodybuilding and fitness activities are aware that testosterone levels drop in many men starting about age 40. Indeed, testosterone levels decline an average of 1 to 2% a year after that. Along with this gradual decline in testosterone levels comes various symptoms related to the lower T levels. These can include adverse mood changes, including depression; a change of body composition that favors increased body fat with a loss of muscle mass; and sexual problems that may include erectile dysfunction or ED. Testosterone does promote optimal erectile response because it promotes the local production of nitric oxide within the spongy tissues of the penis. And testosterone plays a larger role in sexual response through promoting increased libido or sexual drive. But having an increased sex drive does little good if there isn't much you can do about it, such as if your penis plays dead no matter how turned on you are. Whether such a scenario occurs is largely related to existing health conditions. For example, it is now known that your erectile response is often a reflection of the state of your cardiovascular health. This isn't hard to understand since getting an erection depends on having a certain degree of blood flow within the penis. Adverse cardiovascular conditions, such as atherosclerosis, which involves a narrowing of arteries, can impede blood flow within the penis and thus adversely affect the ability to achieve erections. Poorly controlled diabetes can result in impotence through two mechanisms: lack of optimal blood flow within the penis, and damage to nerves that play major roles in promoting erectile response.
Indeed, experiencing erectile function is now considered an early warning sign of impending cardiovascular disease, a sort of physiological "canary in the coal mine," that warns of the necessity to begin measures that protect cardiovascular health. But there are other causes of ED that are not related to cardiovascular problems, although blood circulation within the penis always plays some role in ED. One study showed that two-thirds of men who were clinically shown to have coronary artery disease had ED 39 months prior to that diagnosis. Another study of men without cardiovascular disease nonetheless showed reduced blood flow-mediated dilation, which reflects the ability of blood vessels to rapidly expand. This dilation was reduced to half the normal rate in men with ED. That is a reflection of poor nitric oxide or NO status. NO is produced in the endothelium or the lining of blood vessels when the amino acid arginine interacts with an enzyme that exists in the endothelium called nitric oxide synthase. That enzyme immediately converts arginine into NO, and when that happens, the blood vessel dilates. Such dilation of blood vessels or specifically arteries is required for penile erection. Why wouldn't . . .