Assess Your Health
When you first begin a fitness program, it is a good idea to get baseline measurements of your current fitness level.
InteliHealth/Harvard Medical Content
When you first begin a fitness program, it is a good idea to get baseline measurements of your current fitness level. These can help you set goals. And, if you revisit them periodically, they can help motivate you and reinforce the rewards of becoming physically active.
You can perform some of these measurements on your own, whereas other measurements may require the skills of a trained professional. Many gyms, university fitness centers and health care providers offer these services.
Being overweight raises your risk of a number of health problems. In addition to putting extra strain on your heart, excess fat is linked to an increased risk of adult-onset diabetes, heart disease, hypertension (high blood pressure), osteoarthritis, gallstones, menstrual irregularities and several types of cancer.
Determining your body mass index
How fat is too fat? New guidelines define obesity in terms of body mass index, or BMI. To determine your BMI,
divide your weight in kilograms by your height in meters, squared. A BMI of less than 25 is ideal, 25 to 29.9 means you are overweight, and 30 or more means you are obese.
Estimating your body fat
You can use any of the following techniques to estimate your percentage of body fat:
Calipers. This tool measures your skinfold thickness at certain key areas, such as the side of your abdomen and the back of your arm. The skinfold measurements are translated into percentages. Inexpensive and portable, caliper testing is the most common and most practical method of measuring fat. It is available in many physical therapy clinics and health clubs.
Dual X-ray absorptiometry. This widely used method has replaced underwater weighing in most contemporary research studies. A type of low-intensity X-ray, dual X-ray absorptiometry assesses muscle, bone and fat, and then a computer calculates the percentages of each.
Underwater weighing. This is one of the most accurate methods of assessing body fat, but it is rarely used outside of experimental studies. Your weight underwater reflects your density. By comparing this figure with your weight on dry land, a health-care provider can determine what percentage of your weight comes from muscle and bone as opposed to fat. This method requires a large tank and a complicated apparatus that is usually found only in exercise physiology labs.
Bioelectric impedance. This technique estimates your body's composition (fat vs. lean body mass, or body-fat percentage) by measuring the amount of water in your body. Muscle has a lot of water, and fat has very little water. Thus, the rate at which the body conducts or impedes electricity can be used to estimate body fat. Electrodes attached to your hands and feet send a very low-intensity electric current through your body. The degree to which your body impedes the flow of current helps determine your body composition.
Ultrasound assessment. A portable ultrasound meter can be used to calculate the thickness of fat layers in various areas of your body, based on the length of time it takes for sound waves to pass through.
Depending on your genetic makeup and your choice of physical activities, you may be very flexible in certain areas and very tight in others. The only way to accurately evaluate your overall flexibility is to have a health-care provider, physical therapist or trainer
check the range of motion in each of your joints. This checkup will give you a clear idea of which stretching exercises you should concentrate on.
The following sit-and-reach test will help you estimate the flexibility of your hamstring muscles (which run down the back of each thigh).
- Warm up by walking or cycling for several minutes, until you're perspiring lightly.
- Place a yardstick on the floor with the zero mark closest to you. Tape the yardstick in place at the 15-inch mark.
- Sit on the floor with your feet on either side of the yardstick. Your heels should be about 12 inches apart and even with the 15-inch mark on the yardstick.
- Ask a friend to help you keep your legs straight, holding them down if necessary but not interfering with your movement.
- Place one hand directly on top of the other so your middle fingers line up, and slowly stretch forward without bouncing or jerking. Slide your fingers along the yardstick as far as possible. Stop immediately if you feel any discomfort. The higher the number you reach on the yardstick, the greater your hamstring flexibility.
Repeat the test three times. The further you can reach, the better your flexibility.
To accurately evaluate the strength of your muscles, you need to test each muscle or each muscle group separately.
If you're planning to start a resistance (strength) training exercise program, you should begin with some introductory sessions with a physical therapist or personal trainer.
To evaluate your initial level of strength, many trainers use the "one repetition maximum" method increasing weight incrementally until you determine the most weight you can lift in a single effort. (Optimum benefits occur when you use about 75% of this maximum weight, although beginners are advised to start with 50%.)
Measuring upper-body strength. The following push-up self-test will give you a rough estimate of your upper-body strength:
- Position yourself over the floor with your arms extended and your hands flat on the floor.
- If you're a man, your legs should be straight behind you, with your weight balanced on your hands and feet.
- If you're a woman, bend your knees slightly until they touch the ground, so your weight is balanced on your hands and knees.
- Lower your chest until it touches the floor. Exhale while pushing back up. (Don't hold your breath.) Fully straighten your arms at the end of each push-up.
- Do as many push-ups as you can, counting as you go, until you need to stop and rest.
The more push-ups you can do without having to stop, the better your upper-body strength. Repeating this test over time may be a helpful way to monitor your progress.
There are three relatively easy ways to measure how hard you're working (your level of exertion) during a bout of exercise:
Although your main focus should be on just getting out there and being active, it is important to make sure that you use this time efficiently. If you don't exercise vigorously enough, the exercise won't be as beneficial. On the other hand, if you exercise too vigorously, you risk injury and increase your odds of giving up.
The talk test is a simple, although hard to quantify, way to make sure you aren't working too hard. During exercise, you should experience some heavy breathing, but you should still be able to speak without excessive effort. If you are unable to speak during exercise, your level of exertion may be so high that you cannot get enough oxygen to your working muscles.
To optimize the benefits of aerobic exercise, it is ideal to keep your heart rate between 50 percent and 85% of your estimated maximum heart rate. Maximum heart rate is calculated as 220 your age. For example, if you're 45, your maximum heart rate is 220 45, or 175 beats per minute. Fifty percent of this maximum heart rate is 87.5 beats per minute, which you would round up to 88 beats per minute; 85% is 149 beats per minute.
Measure your pulse either on your neck or on your wrist. Be sure not to use your thumb, because your thumb has a pulse of its own. And don't press too hard on your neck; this may give you a distorted heart rate count. Count the beats for 15 seconds and multiply by four.
The chart below illustrates the ideal range of heart rate for people of various ages. Exercising at a rate below 50% of maximum heart rate is not as beneficial as staying above that point, unless you have cardiopulmonary problems. A rate above 85% may overwork your heart. Exercise at this level is self-limiting; you will become fatigued and will be forced to slow down your pace.
Ideal heart rate during aerobic exercise
100 to 170 beats per minute
98 to 166 beats per minute
95 to 162 beats per minute
93 to 157 beats per minute
90 to 153 beats per minute
88 to 149 beats per minute
85 to 145 beats per minute
83 to 140 beats per minute
80 to 136 beats per minute
78 to 132 beats per minute
75 to 128 beats per minute
73 to 123 beats per minute
70 to 119 beats per minute
68 to 115 beats per minute
The Perceived Rate of Exertion Scale entails simply asking yourself how hard you feel you're working. As with the talk test, this measure is harder to quantify than your heart rate, but it provides a helpful reminder to tune into your body and notice how you're feeling.
The scale ranges from 6 (no activity) through 20 (an all-out effort). In general, for aerobic exercise, you should aim for somewhere between 12 and 14. You can also use this scale to track your progress. You may initially rate a particular exercise at 15, and then after a month feel that it has dropped to 13.
Becoming more familiar with how you feel at different intensity levels can help you plan your exercise session and vary your routine. This can improve your performance, move you past any plateau and decrease any feelings of boredom.
As you become more fit, your heart begins to work more efficiently, pumping more blood through your body with fewer beats. One way to track your improvement is to measure changes in your resting heart rate. Start by recording your heart rate first thing in the morning for three consecutive days. Average the three measurements. Periodically, repeat this three-day measurement, and see if your average resting heart rate decreases over time. Eventually, you may also notice that your heart rate returns close to this baseline more quickly after exercise. This is another indication that your heart is working more efficiently.
If your resting heart rate begins to increase and you notice a decrease in performance, you may be overtraining. Reassess your fitness regimen and consider decreasing the intensity, frequency or duration of your workout. You may benefit from a few much-needed days off.
Last updated July 01, 2009
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