It's because older hearts simply can't beat as fast as younger hearts. So the older person who's doing beats per minute is probably working harder -- at a higher percentage of maximum heart rate -- than the younger person who is at beats per minute. A new study by a group led by Catherine Proenza, PhD and Roger Bannister, PhD from the University of Colorado School of Medicine reports that one of the reasons for the age-dependent reduction in maximum heart rate is that aging depresses the spontaneous electrical activity of the heart's natural pacemaker, the sinoatrial node.
A dissertation from Eric D. Larson, a graduate from Proenza's lab in the Department of Physiology and Biophysics, is described in the article. Larson said, "I utilized a method to record ECGs from conscious mice and found that maximum heart rate was slower in older mice, just as it is in older people.
This result wasn't unexpected. But what was completely new was that the slower maxHR was because the individual pacemaker cells -- called sinoatrial myocytes, or 'SAMs' -- from old mice just couldn't beat as fast as SAMs from young mice. The researchers recorded the tiny electrical signals from the isolated cells and found that SAMs from old mice beat more slowly, even when they were fully stimulated by the fight-or-flight response which can be observed in these individual cells.
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The slower beating rate was due to a limited set of changes in the action potential waveform, the electrical signal that is generated by the cells. The changes were caused by altered behavior of some ion channels in the membranes of the older cells. Ion channels are proteins that conduct electricity across the cell membrane. Imagine a balloon with little tiny pinholes that open and close to let the air in and out; ion channels are like the pinholes.
With time, we all get visible lines on our face. It is natural for our face to lose some of its youthful fullness. We notice our skin becoming thinner and drier. Our genes largely control when these changes occur. We can influence another type of aging that affects our skin. Our environment and lifestyle choices can cause our skin to age prematurely.
CONCLUSIONS | Aging in Today's Environment | The National Academies Press
The sun plays a major role in prematurely aging our skin. Other things that we do also can age our skin more quickly than it naturally would. To help their patients prevent premature skin aging, dermatologists offer their patients the following tips. Protect your skin from the sun every day. Whether spending a day at the beach or running errands, sun protection is essential. You can protect your skin by seeking shade, covering up with clothing, and using sunscreen that is broad-spectrum, SPF 30 or higher , and water-resistant.
You should apply sunscreen every day to all skin that is not covered by clothing. Apply self-tanner rather than get a tan. Every time you get a tan, you prematurely age your skin.
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This holds true if you get a tan from the sun, a tanning bed, or other indoor tanning equipment. All emit harmful UV rays that accelerate how quickly your skin ages.
11 ways to reduce premature skin aging
If you smoke, stop. Smoking greatly speeds up how quickly skin ages. It causes wrinkles and a dull, sallow complexion. Avoid repetitive facial expressions. When you make a facial expression, you contract the underlying muscles. If you repeatedly contract the same muscles for many years, these lines become permanent. Wearing sunglasses can help reduce lines caused by squinting.
Eat a healthy, well-balanced diet. Findings from a few studies suggest that eating plenty of fresh fruits and vegetables may help prevent damage that leads to premature skin aging. Findings from research studies also suggest that a diet containing lots of sugar or other refined carbohydrates can accelerate aging. Drink less alcohol. Alcohol is rough on the skin. It dehydrates the skin, and in time, damages the skin. This can make us look older. Exercise most days of the week. Findings from a few studies suggest that moderate exercise can improve circulation and boost the immune system.
This, in turn, may give the skin a more-youthful appearance. Cleanse your skin gently. Scrubbing your skin clean can irritate your skin. Irritating your skin accelerates skin aging. Gentle washing helps to remove pollution, makeup, and other substances without irritating your skin. Wash your face twice a day and after sweating heavily. Perspiration, especially when wearing a hat or helmet, irritates the skin, so you want to wash your skin as soon as possible after sweating. Apply a facial moisturizer every day. Moisturizer traps water in our skin, giving it a more youthful appearance.