Exercise in cold water instead of warm water may
increase people's appetites, making it harder for
them to lose extra pounds, a University of Florida
Results indicate people may consume more calories
after exercising in cold water, according to Lesley
White, a UF researcher who designed the study to better
understand why aquatic exercise is often less successful
than equal amounts of jogging or cycling for people
who want to lose weight.
"It's possible that individuals who exercise in
cooler water may have an exaggerated energy intake
following exercise, which may be a reason why they
don't lose as much weight," said White, an assistant
professor in the College of Health and Human Performance.
"So it may not be the exercise itself that causes
the problem because you can match the exercise energy
expenditure; rather it's the increased eating after
the exercise is over."
White said her research is not meant to suggest
that swimming or aquatic exercise is ineffective for
building physical fitness. In fact, water exercise
is suggested for people who are overweight because
the buoyancy given by the water makes exercising easier
for people with joint or balance problems.
"Water exercise is an excellent activity for many
people, particularly those with joint disorders, thermal
regulatory problems and balance or coordination difficulties,"
she said. "However, an earlier study reported that
women who swam did not lose as much weight as those
who jogged or cycled."
For her study, published in February in the International
Journal of Sport Nutrition and Exercise Metabolism,
White tracked the energy used by 11 UF students as
they rode a stationary bicycle submerged in water
for 45 minutes. The students exercised in cold water
of 68 degrees Fahrenheit and warm water of 91.4 degrees
Fahrenheit. The same students, ages 21 to 31, also
spent 45 minutes resting. The study found the students
used a similar amount of energy during the exercises,
517 calories in the cold water and 505 in the warm
water. Students expended 123 calories while resting.
After each exercise session and the rest period,
the students were allowed into a room to measure their
blood pressure and heart rates. They were left to
rest for one hour in the same room and had free access
to a standard assortment of food of known caloric
values. However, the students didn't know their caloric
intake was going to be measured.
"We found that during the recovery period when the
subjects had access to an assortment of foods that
significantly more calories were eaten after exercise
in cold water compared to exercise in warm water or
at rest," White said.
Caloric intake after exercise in cold water was
44 percent higher than exercise in warm water and
41 percent higher than in the resting periods. The
students consumed a mean 877 calories after exercise
in cold water, 608 calories after exercise in warm
water and 618 after resting periods.
"This is a preliminary study, which suggests that
environmental conditions during exercise may influence
post-exercise appetite," White said. Individuals should
consider the kinds of foods they eat after exercise,
White suggested that body temperature might have
some influence over post-exercise appetite.
A previous study by her colleague Dr. Rudolph Dressendorfer
indicated that body temperature at the end of exercise
can affect post-exercise appetite.
"Aquatic exercise is widely used in weight-loss
programs, especially for those people with orthopedic
concerns," said Dressendorfer, an adjunct professor
with the faculty of physical education and recreation
at the University of Alberta and a physical therapist.
"The practical implication of this study is that cold
water temperature could frustrate weight loss by increasing
caloric intake. This study also provides some theoretical
insight to the mechanism of appetite after exercise."