This is also a unique opportunity to wish you a Prosperous New Year. This is particularly striking, physically and physiologically during middle age. The testicles shrink and sperm production falls off, though not enough to totally prevent 90 year olds from fathering children. At the same time the prostate gland starts to amass dense and connective tissue that will eventually complicate urination and ejaculation. This slow decline is evident even in the brain drain which affects men the most.
Men lose brain tissue faster than women.
This is particularly greatest in the frontal lobe, which is involved in attention abstract thinking, reasoning, mental flexibility, and impulse control. Physiologically the number of special cells required for muscle growth decreases making it more difficult to replace muscle lost because of atrophy and lack of exercise. Maximal heart rate decreases at a rate of 220 minus age and the increase in peripheral vascular resistance due to non compliant vessels reduces cardiac stroke volume. However none of this these changes in men qualify as menopause due to the gradual declines in function. While a woman's ovaries shut down entirely around age 50, causing an estrogen crash that affects everything from bone cells to brain cells, men typically lose some testosterone as they age, but the decline is far more subtle and the impact in physiological terms more protracted.