Although the cardio floor is a popular spot at the Sports Center at Chelsea Piers, the club also offers classes that incorporate cardio and strength training together. Photo by Fred George.

It's no surprise to fitness facility operators and fitness professionals that Americans aren't getting the cardiovascular exercise they need. After all, only 14 percent of the U.S. population belongs to a health club, and the obesity crisis continues to plague the country. Recent research studies, however, could help club owners get Americans off the couch and into their fitness facilities.

In the last year, researchers have proven that cardiovascular exercise can improve longevity. Other studies have addressed the debate about exercise intensity and frequency and about the effectiveness of blending circuit training and cardio exercise into a time-efficient workout. The findings from these recent studies may change the way clubs view their equipment, their programming and the way in which they serve their membership.

Time and Intensity

As club owners know all too well, most Americans simply aren't logging the recommended amount of physical activity — 30 minutes a day, five times a week. Only 5 percent of American adults walk 30 minutes a day, according to a study of 10,000 children, teenagers and adults published in the August 2007 issue of Medicine & Science in Sports & Exercise. The study found that 42 percent of children 6 to 11 years old get the recommended exercise per day, but as they age, their activity levels drop off dramatically.

Last month, the federal government released new activity guidelines in a 600-page report called the 2008 Physical Activity Guidelines for Americans (see related news item or more details). In the report, the U.S. Department of Health and Human Services recommends 75 minutes of vigorous exercise or 150 minutes of moderate exercise per week, which includes muscle-strengthening activities involving all the major muscle groups on two or more days per week.

The American College of Sports Medicine (ACSM) and the American Heart Association (AHA) now advise that instead of doing 30 minutes of moderate exercise five days a week, Americans should do 20 minutes of vigorous activity three times a week along with two days of strength training.

This change was unprecedented, says Wayne Wescott, senior fitness executive at the South Shore YMCA in Quincy, MA. In his opinion, the studies that have been done on frequency and duration of exercise have had a more profound effect on the fitness industry than many others.

“These recommendations are time efficient, highly effective, and there's no increased risk for injuries due to overdoing it,” he says. “While the strength training recommendations have stayed the same for 18 years, ACSM and AHA changed the frequency and duration of cardio, which makes exercise manageable for more people.”

Both of the recommendations come on the heels of studies examining the intensity and frequency of cardio exercise. One 29-week study examined the difference between doing cardio five days a week and doing three days of cardio and two days of strength. By doing cardiovascular exercise five times a week, subjects improved their cardiovascular functioning by 11 percent, while subjects that did three days of cardio and two days of strength improved by 16 percent, Wescott says.

By advising Americans to do 20 minutes of vigorous cardio three times a week along with strength training, the ACSM/AHA guidelines are moving in the right direction, he says. Americans can satisfy the requirement by doing 20 minutes of cardio, followed by 20 minutes of strength training and a few minutes of stretching, which falls easily into a personal trainer's one-hour time slot, he says.

The debate about intensity and duration of exercise has been going on for decades. Kevin Steele, a principal for Communications Consultants, Malibu, CA, says that more is better when it comes to cardio, but it's important for Americans to fit in any exercise they can.

“If they can work out for 30 minutes five times a week, that's better than 20 minutes from a caloric expenditure standpoint and long-term health,” he says. “However, [20 minutes is] better than nothing, and they'll see some improvement if they're starting from zero.”

Benefits of Circuit Training

Although the verdict is in that shorter bouts of cardiovascular activity and strength training can be effective for many Americans, recent studies have shown that adults can also benefit from concurrent training and can get their heart rate pumping through heavy resistance circuit training. These studies have validated that Americans can squeeze in a time-efficient cardio and strength workout through circuit training, something that express facilities have touted for years.

“One of the biggest barriers to exercising on a regular basis is lack of time,” says Cedric Bryant, chief science officer for the American Council on Exercise. “Being able to engage in circuit training and some cardio is a nice, time-efficient way for people to add some cardio while improving muscle.”

In a study published in the Journal of Strength and Conditioning Research, researchers found that by blending cardio and strength exercise, college athletes improved their cardiovascular and cardiorespiratory measures.

This research was backed up by a May 2007 study by the South Shore Y on the Air Force. The military professionals performed 60 minutes of cardio four days a week, yet they couldn't pass the Air Force's required 1.5-mile run test. The Y split the subjects into two groups: one that did 25 minutes of circuit training three days a week and another that engaged in an hour of cardio four to five times a week. The group that only did cardio exercise did not have any significant improvement in any of the tests, Wescott says.

“They improved their time by 15 seconds in the 1.5 mile run, which wasn't significant after 12 weeks of training,” he says. “Even though the group that did circuit training did no running at all, they improved their time by 35 seconds and improved in every single testing category.”

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