Exercise Helps Obese Youths Shrink Cardiovascular Risks

ROSTOCK, Germany, Nov. 1 -- Obese youngsters in an intensive exercise regimen over six months shed not only pounds but signs of early atherosclerosis, according to researchers here.

In addition to weight loss, the 60-minute workouts three times a week quelled emerging cardiovascular risks, reported Andreas Meyer, M.D., of the University of Rostock, and colleagues, in the Nov. 1 issue of the Journal of the American College of Cardiology.

The researchers concluded that a six-month program of enhanced physical exercise can improve the endothelial function of the brachial artery, can reduce thickening of the carotid artery, and has a positive effect on blood pressure and cardiovascular risks. The findings are particularly important, they said, given the need to identify non-pharmacological interventions for improving vascular status in young people.

These results are important, they said, because treating early evidence of disease suggests that similar exercise programs might not only lower the risk of obesity-related cardiovascular risk factors, but may also hamper the progression of early-onset disease itself.

In the controlled study of 67 obese boys and girls, a baseline comparison with lean controls found that the obese children already had significantly impaired brachial artery flow-mediated vasodilation (4.09% 1.76% vs. 10.65% 1.95%, P<0.001), and increased carotid artery intima-medial thickening (0.48 0.08 mm vs. 0.37 0.05 mm, P <0.001), as well as other cardiovascular risk factors.

In the study, 33 adolescents (17 boys and 16 girls; age 13.7 2.1 years) were randomly assigned to six-months of exercise, while a control group of 34 teenagers (17 boys and 17 girls, age 14.1 2.4 years) were told to maintain current levels of physical activity.

Obesity was defined as a body mass index in excess of the 97^th percentile for the German pediatric population, generally ranging from 24 kg/m² to 35 kg/m².

Exercises for the intervention group were conducted three times a week. On Mondays, there was swimming and aqua aerobic training (60 minutes); on Wednesdays, sport games (90 minutes); and on Fridays, walking (60 minutes). All workouts were supervised by qualified coaches and physiotherapists, and exercises were progressively intensified, as tolerated.

At six months, the researchers reported significant improvements in the exercise group for carotid intima-media thickening (0.44 0.08 mm, P=0.012, - 6.3%) and flow-mediated vasodilation (7.71 2.53%, P< 0.001, +127%). Intima-media thickening improved significantly in all measured segments of the carotid artery after intervention but not in the control group.

This improvement correlated with other reduced risk factors. For example, for the intervention group, BMI changed significantly from a mean of 29.8 ( 5.93) at baseline to 27.2 ( 4.80) after six months (P <0.001), compared with no change from 31.0 ( 4.42) at baseline to 31.3 ( 4.21) for the control group.

Compared with the control group, exercise also produced a significant benefit in laboratory risk parameters, such as systolic blood pressure (128 mm Hg at baseline and 120 mm Hg six months later), fasting insulin resistance (3.94 to 3.12 pmol/L), triglycerides (1.41 to 1.04 mmol/L), as well as low-density lipoprotein/high-density lipoprotein ratio (LDL/HDL), and low-degree inflammation (C-reactive protein and fibrinogen levels).

Although the study lasted for six months, the amount of time required to produce sustained and stable changes after intervention remains unknown, Dr. Meyer said. Previous studies have shown that improvements are reversible within eight weeks of cessation of training in adults. Therefore, the researchers emphasized that the exercise program needs to be continual to maintain its benefits.

In fact, referring to a limitation of the study, the investigators wrote that consideration must be given to the influence of a high discontinuation rate in both the intervention and non-intervention groups after six months. Of 50 youngsters who started the exercise program, only 33 participated sufficiently for inclusion in the second screening protocol. Only 46 members of the obese control group could be recruited for a second risk profile evaluation.

Low motivation and perseverance might be an intrinsic problem in influencing life-style in obese children, and this fact should be taken into consideration in future studies.

Future studies will required to assess responses relating to the degree of obesity and the intensity and duration of exercise programs, they concluded.