This varies from person to person. There is a point in time at which hormones in a persons body begin to loose their effective functions, a period I have heard reffered to as adult puberty. In women this is marked by menopause. While you can still theoretically maintain a healthy body at this time, it becomes increasingly difficult. Maintaining a healthy diet and constant exercise are essential to achieving this. A doctor won't tell you much more than this.
There is no time when physical fitness becomes irrelevant because of age. In addition, you can maintain a reasonable level of fitness as you get older through endurance sports.
Explanation:
Resistance is the only area that is not affected by age as much as the others. This is amazing, because endurance sports are also the best way to maintain your body's fitness level as you get older. A great example is in running, it uses over 70% of the muscles in the body. Not only the legs, but also the muscles of the abdomen, trunk, shoulder and neck are involved in the running movement. This regular movement maintains the elasticity of the joints, which helps prevent problems such as arthritis. In addition, a study showed that 70-year-old runners do as well as sedentary college students, showing that there is no time in life where physical fitness becomes irrelevant because of age.
