What’s Your CRF?: Johns Hopkins Health Alerts.
Johns Hopkins Health Alert
What’s Your CRF?
Engaging in regular physical activity has long been recognized as a key ingredient to a healthy heart. That’s because aerobic activities such as jogging, walking and bike riding can help improve blood circulation, insulin sensitivity and blood pressure, as well as assist in quitting smoking, maintaining a healthy weight, managing stress and warding off depression. Unfortunately, many people aren’t getting up and moving for their health.
The Centers for Disease Control and Prevention reports that only about 22 percent of adults participate in regular, sustained activity (defined as the recommended five times a week for a minimum of 30 minutes), and about 25 percent of adults admit to engaging in no physical activity in their downtime.
Complicating matters is that many people may be overestimating how active they really are. In one study, British researchers report that almost half of participants deemed “inactive” inaccurately labeled themselves as “active,” making it more difficult to target these individuals for lifestyle interventions.
Putting older adults at a further disadvantage, cardiorespiratory fitness (CRF) levels — essentially a measurement of your body’s ability to supply the necessary oxygen during physical activity — also tend to decrease as we age. And while CRF levels haven’t received as much attention as risk factors such as high blood pressure and high cholesterol, many experts say low CRF levels are a separate, serious risk factor for cardiovascular disease.
The numbers behind CRF. Preliminary results from the Kuopio Ischemic Heart Disease Risk Factor Study, which looked at more than 2,600 Finnish men between the ages of 42 and 60, spell out the consequences: Those people whose CRF levels decreased more than 15 percent over a decade increased their risk of heart attack by 88 percent and faced a 122 percent increased risk of dying of any cause. Previous research found significant increases in risk as well.
So how do people know if they’re “heart fit”? In a clinical setting, CRF can be measured with simple exercise stress tests. These tests are performed with the subject either walking or running on a treadmill or pedaling a special stationary bike equipped to measure exercise output. The results are expressed in METs, or metabolic equivalents.
A study published in the New England Journal of Medicine found that the minimum output needed to preserve overall heart health was 7.9 METs. Relating to real life, that’s a 50-year-old man being able to walk continuously at a speed of 4 miles per hour during the test, and 3 miles per hour for a woman.
Posted in Heart Health on October 31, 2014