Exercise Reverses Unhealthy Effects Of Inactivity

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Exercise Reverses Unhealthy Effects Of Inactivity

http://www.medicalnewstoday.com/medicalnews.php?newsid=44476

Many of the detrimental effects of physical inactivity can be

reversed, and in some cases improved, by a similar period of moderate

exercise, Duke University Medical Center researchers have found in a

new analysis of data from the first randomized clinical trial to

evaluate the effects of exercise in sedentary overweight men and

women.

Just as important, the trial participants who exhibited the greatest

decline in physical status during inactivity benefited the most from

exercise training, according to the researchers.

These findings linking the ability of exercise training to reverse

the negative effects of inactivity can be attributed to the exercise

alone, because the participants did not alter their diets during the

trial, the researchers said.

" Continuing to lead an inactive lifestyle leads to a gradual decline

in many important markers for cardiovascular health, " said

Robbins, an exercise physiologist at Duke, who presented the results

of the study June 2, 2006, at the annual meeting of the American

College of Sports Medicine in Denver.

" The good news is that a small amount of physical activity can make a

big difference in reducing the risks for developing such conditions

as heart disease, stroke or diabetes, " she said. " Our findings

demonstrate that while the cost of choosing a sedentary lifestyle can

be high, switching to an active way of life can be beneficial at any

time. "

The current study stemmed from a recently completed trial known as

STRRIDE (Studies of a Targeted Risk Reduction Intervention through

Defined Exercise). The trial, funded by a $4.3 million grant from the

National Heart, Lung and Blood Institute, investigated the effects of

exercise on sedentary overweight adults at risk for developing heart

disease, diabetes, or both.

The STRRIDE trial, in which the intervention ran for six months,

randomly assigned 334 participants into three different exercise

groups and one control group.

" At the end of the trial, we were surprised to see that many markers

of cardiovascular health declined in participants in the control

group, who did not exercise, " Robbins said. " Our Duke group decided

to see if these negative effects could be reversed after the

participants spent the same amount of time in an exercise program. "

Of the 61 STRRIDE participants randomly assigned to the control group

53 agreed to the take part in the new study, which ran an additional

six months. The researchers measured 17 biological factors known to

increase cardiovascular risk, including waist size, physical fitness,

visceral fat levels, body mass index, cholesterol levels, insulin

sensitivity and indicators of metabolic syndrome, a precursor of

diabetes.

" In the new analysis, we found that waist size, time to exhaustion,

visceral fat and metabolic syndrome scores deteriorated significantly

during the six-month period of inactivity during the original STRRIDE

trial, " Robbins said. " However, after six months of exercise training

in the study, 13 of the 17 variables had either reverted to original

baseline levels or even improved. "

According to Robbins, only a moderate amount of exercise is needed to

counteract the detrimental effects of inactivity in these

individuals. The STRRIDE trial measured three levels of physical

activity: the equivalents of 12 miles of walking per week, 12 miles

of jogging per week or 20 miles of jogging per week. Participants

worked out on treadmills, elliptical trainers or cycle ergometers in

a supervised setting.

" When looking at the group as a whole, we found it wasn't the

participants with the highest intensity of exercise who accounted for

the combined beneficial effects, " Robbins said. " That should be

reassuring for people to know they don't have to do a high-intensity

workout to get these benefits of exercise. "

A previous analysis by the Duke group of the same STRRIDE

participants, reported in 2005, found another unhealthy effect of

physical inactivity: inactive participants gained an average of 2

pounds in six months.

" At that rate, it can be assumed that this group of inactive people

would gain 20 pounds in five years, " Robbins said. " This means this

population of sedentary people needed to exercise just to maintain

their current weight. However, our earlier studies have shown that

people who exercise can derive many of the cardiovascular risk

benefits even in the absence of weight loss. "

The STRRIDE trial was led by Duke cardiologist Kraus, M.D.

The Duke team is currently enrolling patients in STRRIDE II, in which

the team will study the effects of weight training, aerobic training,

and aerobic and weight training combined on cardiovascular health.