The mid adulthood is characterized by consistent physiological changes that occur to human body. The changes start in 40s and carry on till the end of life and the older a person grows the more significant and evident are the changes. Physical changes that occur in 40s, 50s, and 60s are markers of aging.
One of the major changes that occur after 40 is the loss of stamina. An individual becomes less endurable and cannot afford as much physical activities as he or she used to in 20s – 30s. The decrease of stamina is closely intertwined with another change that occur to human body, which is particularly significant in 50s, – the loss of muscle weight (Marner, et al., 2003). In fact, the loss of muscle weight is accompanied by the decrease of fitness and strength of human body and the transformation that occur to an individual from 40s to 60s make him or her substantially less endurable and strong.
Furthermore, the immune system starts to decline and the older a person grows the more vulnerable he or she becomes to various illnesses, including not only infectious illnesses, but also chronic diseases (Schulz & Heckhausen, 1996). The decline of the immune system decreases the resistibility of human body to negative impact of the external environment.
In addition, in 40s-50s, it is possible to trace the decline of sexual activity which gets started in 40s and keeps progressing fast in 50s. Throughout 40s – 60s, it is possible to trace less evident physiological change such as the height loss. The loss of hair is another manifestation of physical changes in the mid adulthood.
Marner, L., et al. (2003). Marked loss of myelinated nerve fibers in the human brain with age. J Comp Neurol. 462(2):144-52.
Schulz, R. & Heckhausen, J. (1996). “A life span model of successful ageing”. Am Psychol, 51 (7): 702–14.