Editor: This is the second installment of a four-part series on fitness.
KINGMAN – Elise Lau and Garrett Theel do not need to be "sold" on the value of exercise.
Elise, 14, has been a regular visitor for the past two years to the Kingman Fitness & Racquet Club, where she engages in step aerobics, rowing, treadmill and some bicycling.
"I don't get as sick as often as I used to now with exercise," she said.
"I can concentrate better on my (school) work, and my stamina is better when I run while playing soccer."
Elise said she has two running goals.
One is to run three miles in 30 minutes or less.
"I haven't run in a bit, but I also want to be able to run a mile in seven minutes," she said.
"My best time for a mile now is 8:09."
Garrett, 15, has visited the Del E.
Webb Wellness and Rehabilitation Center for about one year.
He goes three or four times per week for one hour.
"I enjoy upper and lower body workouts and some running," he said.
"My father was doing it and got me into it because I play baseball and wanted to build up for baseball season, so I began going and working out.
"It's easier to run now and it makes me feel better throughout the day."
Obesity is a common problem among teenagers who have gotten little or no exercise in their formative years, said Dr.
Paul Kalanithi, a Kingman cardiologist.
The condition often leads to heart disease, hypertension and/or diabetes.
"Heart disease develops over time and can start during the teenage years," Dr.
"In young women, lifestyle factors can increase the risks and are more common (than in male teens)."
Physical activity tends to drop as girls enter their teenage years.
Kalanithi said statistics show 14 percent of young women are inactive and 15 percent of girls ages 6-19 are overweight.
Smoking is another risk factor.
Kalanithi said 30 percent of high school students in grades 9-12 used tobacco in the year 2000 and 80 percent of smokers acquire the habit before age 18.
He recommends isotonic exercises such as bicycling, hiking, jogging, walking and swimming for teens.
But teens should avoid bodybuilding types of exercise.
"Exercising has evolved over the years," Dr.
"We used to recommend exercising two or three times per week.
But now we recommend 30 minutes of moderate exercise daily for teenagers."
Teens should be careful not to overdo any exercise regimen to avoid orthopedic problems that can include torn ligaments, he said.
Next: Fitness among adults 20-50.