you might be interested in some new research on training and the ageing athlete in the latest edition of the Clinical Journal of Sports Medicine.
Cardiovascular Aging and Exercise in Healthy Older Adults.
Conclusions: Lack of physical activity is a major risk factor for the epidemic of chronic disease and disability facing an aging population. Many age-associated changes in cardiovascular function result from physical inactivity. The benefits of regular exercise include prevention of cardiovascular events, disability, and cognitive impairment. Age is not a contraindication to exercise, which can usually be initiated safely in older persons.
Is Regular Exercise a Friend or Foe of the Aging Immune System? A Systematic Review
Conclusions: Overall, in healthy older adults, regular, particularly aerobic, exercise appears to be a friend of the immune system, helping to offset diminished adaptive responses and chronic inflammation. The possibility exists that particularly strenuous exercise may cause acute immunologic changes, such as diminished NK cell activity, which could predispose to infection in certain individuals. However, given the possible benefits of regular exercise on the immune system and the many definite benefits on other systems, the evidence presented here should not dissuade practitioners from suggesting regular exercise to otherwise healthy older adults.