"Runners are far ahead in aging healthfully" NY Times 12 Oct 1994

Running and the development of disability with age, "Annals of Internal 
Medicine" Vol. 121, No. 7, pp. 502-509

Background:  Musculoskeletal disability with age decreases quality of
life.  Musculoskeletal disability is often linked to osteoarthritis.
Physical activity, particularly aerobic exercise, can decrease
mortality rates.  Also, fitness and training can increase
cardiovascular reserve and bone density, and increased strength could
prevent injury.  On the other hand, vigorous physical activity could
also increase osteoarthritis and cause repetitive injury to soft
tissue, which could cause disability in the long run.

Objective:  To determine whether regular vigorous running activity is
associated with accelerated, unchanged, or postponed development of
disability with increasing age.

Kind of study:  Longitudinal observational study.

Subjects:  451 members of a 50+ runners club, 330 community controls
(50-72 years old).  Also broken down into 534 ever-runners and 247
never-runners; subjects were categorized by the groups they began in.

Measurements:  Age, sex, education level, disability score, weight, body
mass index, smoking, alcohol intake, running (minutes/wk), other vigorous
exercise (minutes/wk), running status, average years run, lifetime work
activity score, blood pressure, physical visits, medications used, medical
personal/family history.

Outcome measurements:  Using the Health Assessment Questionnaire (self-
assessment), upper and lower extremity abilities were measured.  Lower
extremity:  walking, arising from a straight chair, activity.  Upper
extremity:  hygiene, reaching, gripping objects, eating, dressing/
grooming.

Control variables:  smoking, alcohol intake, running/vigorous exercise,
medication used, personal/family history, health/arthritis.

Blindness:  none (participants did self-assessments).

Population:  men and women, 50-72 years, English predominant language,
high school graduates or higher

Statistical methods used:  chi-square, t-tests, 4 tables, 5 graphs

Stated conclusions:  Older persons who engage in vigorous running and
other aerobic activities have lower mortality and slower development
of disability than do members of the general populations.  This association
is probably related to increased aerobic activity, strength, fitness, and
increased organ reserve rather than to an effect of postponed
osteoarthritis development.

Nonresponse:  72 (16%) from runners club and 73 (22%) from community
dropped out.  Dropouts resembled those in their groups who completed
the study.

Difficulties in generalizing to the real world:  People in the club may
be healthier in general or take preventive measures before running such
as stretching or warming up, that other runners might not do.

Other problems:  Does not take into account the other kinds of vigorous
physical activity done by participants (biking, walking, tennis).