How accurate are portable body fat analyzers?
Answer
from Edward R. Laskowski, M.D.
 | Bod Pod |
Although technology is improving, it's difficult to get an accurate body fat measurement from most commercially available body fat analyzers.
Various types of body fat analyzers — also called impedance meters — are available to the general public. Results from portable body fat analyzers can vary depending on many factors, however, including the quality of the device and how hydrated you are when the measurement is taken.
If you're concerned about your body fat percentage, skip the body fat analyzers and ask your doctor about more accurate measurement techniques. Depending on the circumstances, options may include:
- Dual energy X-ray absorptiometry (DXA). This is a specialized X-ray exam that provides detailed information about the ratio between fat, muscle and bones in specific parts of the body.
- Air displacement plethysmography. With this technique, you're enclosed in a computerized, egg-shaped chamber (Bod Pod, others). The device measures your weight and volume to determine your body density, then uses these figures to calculate your percentage of body fat.
- Underwater weighing. During underwater weighing, also known as hydrodensitometry, you're seated on a special chair and submerged under water. Your underwater weight or body density is then used to calculate your percentage of body fat.
Keep in mind that specific body fat measurement techniques can be expensive and may not be available in all locations. Underwater weighing, for example, may be available only in specialized research facilities.
What's a normal resting heart rate?
Answer
from Edward R. Laskowski, M.D.
For an adult, a normal resting heart rate ranges from 60 to 100 beats a minute. For a well-trained athlete, a normal resting heart rate may be closer to 40 beats a minute. For healthy adults, a lower heart rate at rest generally implies more efficient heart function and better cardiovascular fitness.
To measure your heart rate, simply check your pulse. With your palm facing upward, place two fingers on the thumb side of your wrist — or place your index and third fingers on your neck to the side of your windpipe. When you feel your pulse, count the number of beats in 10 seconds. Time yourself with a timer or the second hand on a clock or watch. Multiply this number by 6 to determine how many times your heart beats in one minute.
Keep in mind that many factors can influence heart rate, including:
- Activity level
- Fitness level
- Air temperature
- Body position (standing up or lying down, for example)
- Emotions
- Body size
- Medication use
Although there's a wide range of normal, an unusually high or low heart rate may indicate an underlying problem. Consult your doctor if your resting heart rate is consistently above 100 beats a minute (tachycardia) or below 60 beats a minute (bradycardia) — especially if you have other signs or symptoms, such as fainting, dizziness or shortness of breath.
I've seen commercials for several brands of toning shoes. Can these types of shoes make my legs more toned?
Answer
from Edward R. Laskowski, M.D.
Despite the claims, there is no convincing evidence that wearing toning shoes will make your legs more toned or cause you to burn extra calories.
Toning shoes are designed to simulate walking barefoot or walking on an uneven surface. Manufacturers say the unstable design of the shoes forces wearers to use their leg muscles more — which burns more calories and tones the muscles. However, an independent study by a nonprofit fitness organization found no evidence that wearing toning shoes leads to improved muscle tone or greater energy expenditure. In addition, there are no studies that prove that they improve balance or stability to a great degree.
If you like the way toning shoes look and find them comfortable and not too unstable, there's probably no harm in trying a pair. And if you increase your activity as a result, you'll benefit your overall health.
Is it OK to exercise if I have a cold?
Answer
from Edward R. Laskowski, M.D.
Mild to moderate physical activity is usually OK if you have a garden-variety cold and no fever. Exercise may even help you feel better by opening your nasal passages and temporarily relieving nasal congestion.
As a general guide for exercise and illness, consider this:
- Exercise is usually OK if your signs and symptoms are all "above the neck" — symptoms you may have with a common cold, such as runny nose, nasal congestion, sneezing or minor sore throat. Consider reducing the intensity and length of your workout, though, or you may feel worse. Instead of going for a run, take a walk, for example.
- Don't exercise if your signs and symptoms are "below the neck" — such as chest congestion, hacking cough or upset stomach.
- Don't exercise if you have a fever, fatigue or widespread muscle aches.
Let your body be your guide. If you have a cold and feel miserable, take a break. Scaling back or taking a few days off from exercise when you're sick shouldn't affect your performance. Resume your normal workout routine gradually as you begin to feel better. And check with your doctor if you aren't sure if it's OK to exercise.
Remember if you do choose to exercise when you're sick, reduce the intensity and length of your workout. If you attempt to exercise at your normal intensity when you have more than a simple cold, you could risk more serious injury or illness.
Does exercise late in the day cause insomnia?
Answer
from Timothy Morgenthaler, M.D.
Regular exercise reduces stress and anxiety, and generally improves sleep. But for some people, exercising within five hours of bedtime may cause problems getting to sleep.
Keep in mind, everyone's different. For some people, late-day exercise isn't a problem. It may require some trial and error to see how working out affects the quality of your sleep. Without making any other changes that are likely to affect your sleep, take notes on how well you sleep after working out at different times. This can help you determine the time of day that's best for your workout and the least disruptive to your sleep.
I'm having trouble sleeping lately. Does this increase my chances of getting sick?
Answer
from Timothy Morgenthaler, M.D.
Yes, lack of sleep can affect your immune system. Studies show that people who don't get a good night's sleep or who don't get enough sleep are more likely to get sick after being exposed to a virus, such as the common cold. Lack of sleep can also affect how fast you recover if you do get sick.
During sleep, your immune system releases proteins called cytokines. These substances increase in the presence of an infection, inflammation and stress. Increased cytokines are necessary in fighting infection and regulating deeper sleep. In addition, other infection-fighting cells are reduced during periods of sleep deprivation. So, your body needs sleep to fight infectious diseases.
How much sleep do you need to bolster your immune system? The optimal amount of sleep for most adults is seven to eight hours a night. School-aged children and adolescents need nine or more hours of sleep a night.
But be careful; more sleep is not always better. For adults, sleeping more than nine to 10 hours a night has been associated with weight gain, heart problems, stroke, sleep disorders, depression and other health concerns.
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