Prescribed walking
can improve physical fitness
Newswise — Exercise counseling
with a prescription for walking at either hard intensity or
high frequency produces improvements in cardiorespiratory
fitness, according to a study in the November 14 issue of
Archives of Internal Medicine,
one of the JAMA/Archives journals.
The health benefits of
regular physical activity have been well established. But
most U.S. adults are not sufficiently active regularly, and
26 percent are not active at all, according to background
information in the article. The exercise prescription needed
to improve cardiovascular disease risk factors in
free-living sedentary adults remains unclear.
Glen E. Duncan, Ph.D.,
R.C.E.P.S.M., of the University of Washington, Seattle, and
colleagues conducted a randomized trial to examine the
effects of exercise counseling prescriptions, varied in
intensity and frequency. A total of 492 sedentary adults
(177 men, 315 women) were randomized to one of four exercise
counseling conditions, or to a physician advice comparison
group. The duration of exercise (30 minutes) and type of
exercise (walking) were the same in the four counseling
groups, while exercise intensity and frequency was
manipulated to form four prescriptions:
• Moderate intensity (ModI)-low frequency (LowF)
• Moderate intensity-high frequency (HiF)
• Hard intensity (HardI)-low frequency
• Hard intensity-high frequency
Intensity was defined by percentage of maximal heart rate
(HR) reserve – 45-55 percent for ModI, and 65-75 percent for
HardI. LowF was defined as three to four sessions per week,
while HiF was five to seven sessions per week. Comparison
group participants received physician advice and written
materials regarding recommended levels of exercise for
health. The researchers measured changes in
cardiorespiratory fitness (maximum oxygen consumption),
high-density lipoprotein cholesterol (HDL-C), and the ratio
of total cholesterol to HDL-C.
“At six months, the
HardI-HiF, HardI-low frequency, and moderate intensity-HiF
conditions demonstrated significant increases in maximum
oxygen consumption, but only the HardI-HiF condition showed
significant improvements in HDL-C level, total cholesterol-HDL-C
ratio, and maximum oxygen consumption, compared with
physician advice” the authors write.
“At 24 months, the
increases in maximum oxygen consumption remained
significantly higher than baseline in the HardI-HiF, HardI-low
frequency, and moderate intensity-HiF conditions and in the
HardI-HiF group compared with physician advice, but no
significant effects on HDL-C or total cholesterol-HDL-C
ratio were observed,” they continue.
“The findings demonstrate
that significant improvements in cardiorespiratory fitness
can be achieved and maintained over 24 months via exercise
counseling with a prescription for walking 30 minutes per
day, either at a ModI five to seven days per week, or at a
HardI three to four days per week,” the authors conclude.
“Additional benefits, including larger changes in fitness
and increases in HDL-C level, may be achieved by prescribing
either more exercise or the combination of HardI plus HiF
exercise.”