Key points from article :
Regular exercisers maintain their heart, lung and muscle fitness.
In their 70s, organs can be as healthy as someone 30 years younger.
Cardiovascular health was gauged with a VO2 max indoor bike test.
Biopsy taken to examine capillaries in muscle.
70 healthy participants were divided into three groups.
Ability to process oxygen declines by about 10 percent per decade after age 30.
The study was published in Journal of Applied Physiology.