Danish researchers recently conducted a study where they found that an exercise regimen that focuses on intensity rather than duration of activity can significantly lower the risk for the constellation of cardiovascular risk factors known as metabolic syndrome.
For instance, brisk walking halved the risk that metabolic syndrome would develop over a 10-year period, according to Eva Prescott, MD, DSc, and colleagues from Bispebjerg University in Copenhagen.
In contrast, leisurely walking, even for more than an hour each day, had no preventive effects, the researchers reported online in BMJ Open.
Previous cross-sectional studies have suggested that physical activity can reduce the risks for components of metabolic syndrome such as obesity and insulin resistance, but longitudinal studies have had conflicting results.
To clarify this, Prescott and colleagues conducted a study that included both cross-sectional and longitudinal analyses using data from the Copenhagen City Heart Study.
For the cross-sectional analysis, they included 10,135 individuals evaluated between 1991 and 1994, while the longitudinal analysis included 3,992 seen between 2001 and 2003.
Each participant reported on physical activity, smoking, alcohol use, and demographic factors.
Metabolic syndrome was defined as having at least three of the following: central obesity, high triglycerides, low levels of HDL cholesterol, hypertension, and elevated plasma glucose.
In the cross-sectional analysis, participants who reported having higher levels of physical activity were younger, averaging 48 years old for men and 51 for women, and had an overall more favorable cardiovascular risk profile than those who were sedentary.
A total of 21 percent of women were classified as having metabolic syndrome at baseline, as were 27 percent of men.
Significant differences were seen, however, in rates of metabolic syndrome according to the degree of physical activity.
For example, the rate for sedentary men was 37 percent, falling to 14 percent for high levels of exercise, while the corresponding rates for women were 31 percent and 11 percent, respectively.
In this analysis, the baseline risk for having metabolic syndrome was lower for fast-paced walking in both men and women.
Risk also was reduced for jogging in men and women, but the adjusted risk for increased duration of walking was not significantly reduced.
Heart rate was reduced from 76 beats per minute among sedentary men to 66 for those with high activity and from 75 to 69 among sedentary and active women, respectively.
Those differences in heart rate reflected greater cardiorespiratory fitness, according to the researchers.
After 10 years, an additional 15 percent of participants had developed metabolic syndrome. Among those who were sedentary, the incidence was 19 percent compared with 12 percent of those who reported moderate to high physical activity.
In the longitudinal analysis, along with brisk walking speed, jogging also was associated with an adjusted lower risk for developing metabolic syndrome, as was an overall high level of physical activity.
The researchers noted that the duration of walking did not appear to lower the risk, but acknowledged that spending more time walking, even if at a slower pace, could still have health benefits.
“If results can be corroborated by intervention studies showing beneficial cardiovascular effects of increased walking speed, this may represent a low-cost intervention with minimal side effects and numerous significant health benefits,” Prescott and colleagues concluded.