February 28 — 29, 2008 Advisory Committee Meeting
Subcommittee Report: Adverse Events
Kenneth Powell, M.D., M.P.H., led discussion on the subcommittee
report on adverse events. The subcommittee focused primarily on musculoskeletal
outcomes with a secondary focus on sudden adverse cardiac events. The group also
acknowledged issues related to heat and cold related injuries, motor vehicle
collisions, infectious diseases and other events.
Major questions addressed by the subcommittee included:
What type of activity has the lowest risk of musculoskeletal
injuries? These activities included non-contact, limited contact, contact and
collision type activities.
The interpretation of the data seems to conclude non-contact and limited
contact activities such as walking, swimming, dancing and golf had the lowest
risk of musculoskeletal injuries.
How does the dose of physical activity affect the risk of musculoskeletal
All components of dose such as frequency, duration and intensity are directly
related to risk.
What general factors influence the risks of musculoskeletal injury and
other adverse events related to physical activity?
Many, but current physical activity or fitness factors have solid evidence and
injury prevention potential.
Are people at higher risk of sudden adverse cardiac events when they are
being physically active?
Yes, but being physically active reduces risk during the activity and overall.
Dr. Powell noted that risk of adverse events is proportional to the gap between
accustomed levels of activity and activity at a particular moment. Due to the
fact that those most in need of activity are also at the greatest risk the idea
of training progression is important. During activity there is a recovery gap in
between the beginning of the activity and the time the body adapts. Breaking
these gaps into smaller periods allowing for adaptation should help avoid
breakdowns. Tissue and organ function improves after repeated cycles of
overload, recovery, and adaptation.
Data suggests walking and short bouts of activity are helpful for inactive
individuals beginning an exercise program such as walking 5 – 15 minutes 2 – 3
times per week. For subsequent increases of activity adaptation among unfit and
elderly people requires weeks of recovery. Small incremental increases should be
in the range of 5 – 15 minutes every 3 – 4 weeks. Also, increases in frequency
and duration should take place before increases in intensity.
Regarding the issue of obtaining a participation clearance from a medical or
health professional there is no empirical information that clearances are
beneficial. It is common in men over 40 years of age, women over 50 years of
age, people with chronic disease and people with risk factors for chronic
disease to consult with a health professional prior to beginning a physical
activity program. While it may be common sense to recommend consulting with a
health professional it may also be a barrier to participation by implying a
certain activity is more dangerous then being inactive. Dr. Powell discussed the
following suggested chart:
Suggested health evaluation by population group and
intensity of physical activity
||Light to moderate PA
|Children, youth and young adults
||Follow school requirements
||Follow school requirements
|People at risk
||Develop a plan with health care provider
*Assumes the increase in light to moderate intensity activity is prudent (e.g.,
5 – 15 minutes of walking 2 – 3 times per week) and increases by small amounts
at adequately spaced intervals (e.g., every 3 – 4 weeks).