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FOR IMMEDIATE RELEASE
JULY 17, 2007
APS Contact
Ceila Lee
(301) 634-7253
clee@the-aps.org
Exercise, Rest, Repeat: How
a Break Can Help Your Workout
Repeated sessions of exercise burn more
fat than a single, long session
BETHESDA, Md.
(July 10, 2007) — Taking a break in the middle of your workout may
metabolize more fat than exercising without stopping, according to a recent
study in Japan. Researchers conducted the first known study to compare
these two exercise methods—exercising continually in one long bout versus
breaking up the same workout with a rest period. The findings could change
the way we approach exercise. Who wouldn’t want to take a breather for
that?
“Many people believe
prolonged exercise will be optimal in order to reduce body fat, but our
study has shown that repetitions of shorter exercise may cause enhancements
of fat mobilization and utilization during and after the exercise. These
findings will be informative about the design of [future] exercise
regimens,” said lead researcher Kazushige Goto, Ph.D. “Most people are
reluctant to perform a single bout of prolonged exercise. The repeated
exercise with shorter bouts of exercise will be a great help [in keeping up
with fitness].”
This finding is part
of a study entitled Enhancement of fat metabolism by repeated bouts of
moderate endurance exercise, found in the June 2007 edition of the
Journal of Applied Physiology, which is published by the American
Physiological Society. It was conducted by Kazushige Goto, of both the
Department of Life Sciences, Graduate School of Arts and Sciences,
University of Tokyo, Komaba, Tokyo, Japan and the Institute of Sports
Medicine, Bispebjerg Hospital, Copenhagen, Denmark; Naokata Ishii, of the
Department of Life Sciences, Graduate School of Arts and Sciences,
University of Tokyo, Komaba, Tokyo, Japan; and Ayuko Mizuno and Kaoru
Takamatsu, both of the Institute of Health and Sport Sciences, University of
Tsukuba, Tsukuba, Ibaraki, Japan.
Summary of
Methodology
The researchers used
seven healthy (avg. body mass: 66.1, percentage fat: 17.6) men with an
average age of 25 who were physically active and familiar with exercise and
had them perform three separate trials:
-
one single bout of
60-min exercise followed with a 60-min recovery period (Single)
-
two bouts of 30-min
exercise with a 20-min rest after the first 30-min bout, along with a
60-min recovery period at the end (Repeated)
-
one 60-min rest period
(Control)
The men performed
each trial at the same time of day after fasting overnight. They exercised
on a single ergometer (cycling machine) at the commonly recommended exercise
prescription of 60% maximum oxygen intake. The recovery and rest periods
were conducted while the subjects sat in chairs. Blood samples were taken
every 15 minutes during the exercise and every 30 minutes during the
recovery period. Their respiratory gas and heart rates were monitored
continuously throughout the trial.
Summary of
Results
The Repeated trial
showed a greater amount of lipolysis (fat breakdown) than did the Single
trial. This Repeated trial also had a pronounced increase in free fatty
acids and glycerol (chemical compounds that are released when stored fat is
used) concentrations in the final 15 minutes of exercise, whereas these
concentrations only progressively increased throughout the Single trial.
Also, the second half of the Repeated trial showed a significantly greater
epinephrine response while also having a rapid decrease in insulin
concentration as a result of lower plasma glucose. This combination of high
epinephrine and low insulin concentration may have also increased the
lipolysis. There was also enhanced fat oxidation in the recovery period of
the Repeated trial than in the Single trial, but this result may be because
the free fatty acids concentration was already high before the recovery
period.
Conclusions
The American College
of Sports Medicine recommends moderate exercise for the duration of 45 to 60
minutes to ensure a sufficient amount of energy is depleted in obese
individuals. This has caused a greater focus on extending exercise sessions
in order to burn more fat. However, this study shows that this method may
not be the most effective way to enhance fat metabolism, as splitting up a
long bout of exercise with a rest period burns more fat than a continuous
bout of exercise. This study could help with the practical application of
implementing new exercise methods in order to better manage and control
weight in individuals in the future. However, Goto and his team of
researchers plan on conducting further studies in order to explore the
results in a variety of exercise durations as well as in different types of
individuals.
Editor's Note:
To schedule an
interview with a member of the research team, please contact Celia Lee,
American Physiological Society, (301) 634-7253 or
clee@the-aps.org.
***
Physiology
is the study of how molecules, cells, tissues and organs function to create
health or disease. The American Physiological Society has been an
integral part of this scientific discovery process since it was established
in 1887.
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