As Medicine continues its journey to become more “evidence-based” it is humbling to realize how little we really know about prescribed treatments. A case in point: Is it good to exercise? In both health and disease? As we age? Dr. Marco Pahor and his colleagues contributed one more brick in the wall of evidence in a recent research paper in JAMA. The short answer -- probably.
Their paper (Effect of Structured Physical Activity on Prevention of Major Mobility Disability in Older Adults, JAMA
2014;311,(23):2387-2396) attempts to systematically address a fundamental
question: Does exercise help prevent or delay loss of mobility in older adults?
This was a well-designed trial. The patients represented a good cross section
of the population, geographically and ethnically. They were typical people, like those seen in
a primary care physician’s office: average age 79, obese, sedentary with
multiple chronic health conditions (e.g. hypertension, diabetes, cancer). The follow up period was adequate to detect
some longer-term impact of the intervention (average 2.6 years).
The intervention was something the average person could
reasonably replicate. Participants
walked a total of about 2 ½ hours a week, supplemented by brief sessions of
strength training (using ankle weights) and stretching of large muscle
groups. It is a program you could
actually envision a motivated patient performing. A control group was given general health
education classes (plus a little light stretching). Over 1600 patients were randomized to the two
groups.
The primary outcome measure was simple. All the participants could walk 400 meters
(about ¼ mile) upon entry to the study.
Did they maintain or lose that ability during the course of the project?
Results? At the end
of the study period, 30.1% of the exercise group lost the ability to walk 400
meters. People in the control group
(education only) lost this ability 35.5% of the time. The results were statistically
significant. So, the answer to the
question is affirmative. Exercise does
help elderly patients maintain mobility.
So do we now have evidence to support widespread
prescription of exercise to octogenarians? Nothing in medicine is so
simple. Taking nothing away from an
excellent and important study, it answers some questions, but raises others.
The impact or exercise is statistically significant, but is
it compelling enough to zealously prescribe exercise? Compliance with exercise
is not an easy task, even in the young and healthy. If you were told: “you have a 35% chance of
seeing your mobility decline in the next couple of years, but we can reduce
that risk to 30% with a long-term structured exercise program” is that a
compelling enough effect to motivate you to strap on your gym shoes? Taking the data from the study, a physician
would need to convince 23 previously sedentary people to begin an exercise
regimen, and those 23 would need to be compliant with the program, to prevent
one person from losing mobility.
The study also looked at some secondary outcome measures,
including the need for hospitalization, and the occurrence of “serious adverse
events” like heart attacks, strokes, or death.
The trend for both was negative.
Hospitalizations and adverse events increased in the exercise group, but
in neither case did the effect reach
the level of statistical significance. Had these trends been significant, it would
have created an interesting conundrum…exercise would be good for maintaining
function, but could actually increase health care costs.
In summary, this study adds to a growing literature to prove
what many might think is intuitively obvious: exercise has positive health
benefits. Enough to justify, from an
evidence based medicine perspective, a major public health investment? Enough to drive down health care costs?
Probably not.
Enough to convince you, as an individual to stay as active
as you can, for as long as you can.
Absolutely.