One of the principal areas of concern for exercise professionals is assessing, recognizing and explaining disease risk factors and other physiological variables for clients. From these evaluations and with the collaboration of medical professionals, personal trainers have a unique yet challenging opportunity to guide and encourage clients to make behavioral and lifestyle changes. This issue’s column serves as an informative resource for identifying the many “numbers” involved in clinical, fitness and health parameters.

Cholesterol, Triglycerides and C-Reactive Protein

Cholesterol, which is vital to the body, is used to assemble cell membranes, produce sex hormones and form bile acids (bile acids are required for the digestion of fats). When certain blood cholesterol levels are elevated, some of the excess is deposited in the arterial walls, increasing the risk of heart disease (see Table 1). Ele-vated blood triglycerides (fats) are also an underlying cause of coronary heart disease, as some fat particles can collect on arterial walls and lead to atherosclerotic plaque.

Current research additionally suggests that inflammation plays a role in the formation of atherosclerosis (American Heart Association [AHA] 2010). C-reactive protein (CRP), a substance the body produces in response to inflammation and infection, serves as a very good marker (or indicator) for heart disease risk. The blood vessel test for inflammation is called the high-sensitivity CRP, or hs-CRP, test.

Body Compostition

Body composition measurement is a key evaluation variable to monitor and assess for a client’s physical fitness and health profile. Table 2 shows recommended levels of body fat percentage by gender and age.

Body Mass Index

Body mass index (BMI)—an optional screening tool that incorporates weight and height measurements—can be used to categorize individuals as underwieght, normal weight, overweight or obese and to observe changes in body weight that may be associated with health problems (see Table 3).

Sample BMI Calculations

With the metric system, the formula for BMI is weight in kilograms (kg) divided by the square of height in meters (m):

  • weight = 120 kg; height = 193 centimeters (1.93 m)
  • calculation: 120 ÷ (1.93)2 = 32.2
  • In this example the person would be classified in the class I obesity category.

Using the inch-pound system, the BMI formula is weight in pounds (lb) divided by the square of height in inches (in), x 703:

  • weight =150 lb; height = 65 in
  • (150 ÷ {65}2) x 703 = 24.96
  • In this example, the person would be classified in the normal-weight BMI category.

Maximal Oxygen Consumption

Maximal oxygen uptake (commonly termed VO2max) is the most relevant measure of the cardiorespiratory system’s functional capacity. It is the highest rate at which oxygen can be consumed, distributed and used by the body during exercise. VO2max is commonly expressed in either relative (to body weight) terms, as milliliters of oxygen per kilogram of body weight per minute (ml O2/kg/min or ml/kg/min), or in absolute terms (liters per minute; L/min). Table 4 displays VO2max value ranges for both men and women by 10-year age stratifications.


High blood pressure, or hypertension, continues to be a clinical risk factor for cardiovascular-related diseases, such as coronary heart disease, heart attack and stroke. The classification values for the ranges of blood pressure for adults can be seen in Table 5. Note: When systolic and diastolic pressures fall into different categories, choose the higher category for classification. For example, if a client’s systolic blood pressure is 125 mm HG (millimeters of mercury) and the diastolic blood pressure is 95 mm HG, then the classification for this client is stage 1 hypertension.

Blood Glucose and Type 2 Diabetes

Blood glucose is the amount of sugar present in the blood. The three different tests that can be used to determine if a person has pre-diabetes or diabetes are the fasting blood glucose test, the oral glucose tolerance test and the A1c test (see Tables 6–8).

The A1c (the molecule’s chemical components) test is a clinical measurement of glycemic control via a process called glycosylated hemoglobin, or HbA1c. This type of test helps to detect average blood glucose concentrations over several months.

Metabolic Syndrome

Metabolic syndrome is a rather complex and progressive cluster of clinical disorders that increase the risk for cardiovascular disease and diabetes if a person has three or more of these risk factors. The National Cholesterol Education Program (NCEP), WHO and the AHA have slightly different criteria for this cluster of diseases. The NCEP data are summarized in Table 9.

Other Laboratory Tests

Clients may bring their medical reports to personal trainers for further explanation and discussion. While you can certainly use such data to build a well-rounded look at your clients’ challenges, know your professional scope of practice and encourage them to discuss specific questions about their numbers with their physician. Collaborate with the physician to construct appropriate programs for clients with specific medical challenges. Table 10 provides other selected blood variables (with normal values) and a brief description about each variable.

Practical Recommendations and Applications

Given the importance of the many clinical and physiological numbers discussed here, exercise professionals can provide education and promote action steps to improve well-being. Playing the numbers game helps trainers and instructors take a proactive and communicative approach with clients in their journey toward optimal health.

Table 1. Cholesterol, Triglyceride and hs-CRP Levels

Table 2. Body Fat Percentage Levels for Children and Adults

Table 3. International Classification of BMI Range for Women and Men

Table 4. VO2max (ml/kg/min) Classifications for Men and Women

Table 5. Blood Pressure Value for Adults

Table 6. Fasting Blood Glucose Test

Table 7. Oral Glucose Tolerance Test

Table 8. A1c Test

Table 9. Criteria for Recognizing Metabolic Syndrome

Table 10. Other Selected Blood Variables of Clinical Importance