Weight-Loss Diary Stats Explained
In the debut of Shape Magazine's new Weight-Loss Diary by Jill Sherer, weight and body-fat percentage aren't the only stats listed in Jill's fitness profile. That's because those numbers are just small pieces of the health-and-fitness puzzle.
To get a more accurate view of Jill's progress, some other important measures are also included -- her estimated peak VO2, aerobic fitness level, resting blood pressure and glucose. To tell you what they all mean, we talked with Kathy Donofrio, B.S.N., M.S., the exercise physiologist who administers Jill's VO2 tests at Swedish Covenant Hospital, and Mari Egan, M.D., Jill's doctor at Evanston Northwestern Healthcare, both in Chicago.
Estimated peak VO2
This is the amount of oxygen the body uses to produce energy, which can be measured by a submaximal graded exercise test. The test monitors heart rate, blood pressure and VO2; the body's physiological response helps determine the subject's cardiovascular fitness level.
For example, if a person's estimated peak VO2 is at 40 ml/kg/min., it indicates that for every kilogram of body weight, her body is capable of utilizing 40 milliliters of oxygen per minute. Higher oxygen capacity allows for higher energy production, so the higher the VO2, the greater the person's fitness level.
What is considered a good VO2? On average, for females, a VO2 of less than 17 ml/kg/min. is considered a poor fitness level, 17-24 ml/kg/min. is considered below average, 25-34 ml/kg/min. average, 35-44 ml/kg/min. above average and greater than 45ml/kg/min. excellent fitness level. There is a ceiling to VO2, which is about 80 ml/kg/min.
Fitness level and VO2 are classified by age and gender. Males usually have a higher VO2 than females because they carry more muscle mass. And the younger a person is, the higher the VO2 because as we age, with a typical sedentary or less active lifestyle, we lose muscle mass and the ability to extract oxygen from the bloodstream. (Research shows adults that remain very active experience a decline, but a much smaller one.) Most male elite marathon runners have a VO2 between 70-80 ml/kg/min.; female elite runners have a slightly lower VO2.
Submaximal graded exercise test
This is an exercise stress test in which the subject walks on a treadmill or rides a stationary bike for 6-8 minutes during which heart rate, blood pressure and oxygen consumption are measured. The subject's physiological response to the exercise is used to determine his or her estimated peak VO2, i.e., fitness level.
Resting blood pressure
This represents the pressure in the arterial system; it should be below 140/90. The systolic pressure (140) increases with exercise and represents the pressure in the arteries when the heart contracts. The diastolic pressure (90) remains relatively unchanged during exercise and represents the pressure in the system when the heart relaxes. In general, those who are fit have lower blood pressures both at rest and during exercise.
This is a simple six-carbon sugar found naturally in fruit, honey and blood. Being overweight increases the risk for diabetes, a condition in which sugar builds up in the bloodstream (in other words, glucose increases). A glucose test can help assess diabetes risk and diagnose diabetes. Most people have glucose levels between 80-110; a reading greater than 126 after fasting, or greater than 200 on a random test, indicates the patient may have diabetes. Exercise improves glucose regulation in the body, thus decreasing diabetes risk.
This is a fatty acid that is present in the blood in two major forms, good fats (high-density lipoproteins, or HDL) and bad fats (low-density lipoproteins, or LDL). Large amounts of LDL are associated with the development of heart disease. Most of the cholesterol in your body comes from saturated and trans fats in your diet, especially meat, eggs, dairy, cakes and cookies. Too much cholesterol in your blood can raise your risk of having a heart attack or stroke.
LDLs deliver cholesterol to your body; HDLs remove cholesterol from your blood. Your risk for heart disease depends in part on the balance between the bad cholesterol (LDL) and the good cholesterol (HDL). Recent recommendations indicate that cholesterol below 200 is desirable, 200-239 is borderline and greater that 240 is high. LDL less than 100 is optimal, 100-129 near optimal, 130-159 borderline, greater than 160 high. HDL less than 40 puts you at risk, and a reading greater than 40 is desirable.