Overweight Older Women have Less Leg
Strength, Power
Newswise, September 20, 2011--A new study
from the University of New Hampshire finds
that the leg strength and power of
overweight older women is significantly less
than that of normal-weight older women,
increasing their risk for disability and
loss of independence.
With more Americans aging and becoming
overweight or obese, the study, published
recently in the Journal of
Electromyography and Kinesiology,
dispels the popular image of the bird-thin
elder being at greatest risk of becoming
disabled due to loss of muscle mass.
“That’s the chorus that’s been sung for the
last 20 years,” says lead author Dain
LaRoche, assistant professor of kinesiology
at UNH. “But with two-thirds of Americans
overweight or obese and the elderly
population expected to double by year 2030,
we are going to see a large portion of
people who are disabled due to the
concurrent gaining of weight and loss of
strength.”
Working with two undergraduate students,
Rachel Kralian and Erica Millet (both class
of 2010), LaRoche sought to measure the
impact of excess weight on subjects’ leg
strength, walking speed, and power, the
factors that affect activities of daily
living like rising from a chair or climbing
stairs.
They found very little difference in the
absolute strength of the overweight and
normal-weight participants, but when their
strength-to-weight ratio was calculated, the
overweight women had an average of 24
percent lower strength than the
normal-weight study participants.
“The deficits were even worse when you
looked at power,” says LaRoche, adding that
power – the rate at which strength is
applied – is more closely related to
physical functions and fall risk than
strength. The overweight women demonstrated
38 percent less power than the normal weight
women. Walking speed was significantly
slower – about 20 percent – for the
overweight participants, as well.
“Everything pointed to the fact that it was
the extra fat that these people were
carrying that was really limiting their
mobility,” he says. “Being of a normal body
weight lets you perform activities of daily
living and live on your own longer.”
Based on these findings, LaRoche suggests
that normal-weight adults should work to
maintain their weight and strength as they
age. Older adults who are overweight can
improve their strength-to-weight ratio by
either losing weight or gaining strength.
Perhaps surprisingly, data suggest the
latter is the easier route. While most
people are not successful at losing weight,
“even the oldest old people can have
dramatic increases in strength,” says
LaRoche, citing an earlier study he did
(read about it here:http://www.unh.edu/news/cj_nr/2008/oct/bp23strength.cfm).
The key to building strength is to fatigue
the muscle with eight to fifteen
repetitions, an aspect many new to weight
training overlook.
LaRoche has been researching effects of
strength and exercise on elderly populations
for several years, but this is his first
foray into the effects of obesity on this
population. “I never intended to study
overweight and obese elders, but it became
obvious to me that being overweight is a
growing and problematic concern,” he says.
A summary of the study, called “Fat mass
limits lower-extremity relative strength and
maximal walking performance in older women,”
is available here:http://www.ncbi.nlm.nih.gov/pubmed/21824789.
LaRoche was supported by the National
Institute on Aging.
The University of New Hampshire, founded in
1866, is a world-class public research
university with the feel of a New England
liberal arts college. A land, sea, and
space-grant university, UNH is the state's
flagship public institution, enrolling
12,200 undergraduate and 2,300 graduate
students.
