“Only the Fit Stay Young: Changes in Women’s Bodies at 20, 30, 40, 50, 60 and 70”


The Fit Woman: she retains the strength, stamina and flexibility of her teen years. Her leanness allows the definition of her muscles to show through. Late in this decade her bone strength may reach its peak. If she continues regular weight-bearing exercises, consumes plenty of calcium-rich foods and gets adequate caloric intake, her bones will stay healthy for years to come. A lot of time spent outdoors without adequate sun protection will cause her skin to begin to freckle and develop fine lines.

The Sedentary Woman: she may look great, but physical changes are already beginning to take place that could have far-reaching effects. Her aerobic capacity begins to decline at the rate of 1 percent per year. After age 25, muscle mass can decrease by an average of 5 percent every decade. Metabolism begins to drop at a rate of 2 percent per year, which will translate into increasingly higher body-fat percentages. Any fat added now will be distributed evenly throughout her body. She will begin to experience tightness in her hips.


The Fit Woman: she looks and feels as fit as in her twenties. She’s agile and coordinated, with a lean, defined physique, thanks to well-developed muscles and below average body fat, and her aerobic capacity – the ability to transport oxygen throughout the body – is better than ever. She will, however, begin to experience an unavoidable decline in the number of fast twitch muscles, which are responsible for quick reaction time and for high-intensity activities like sprinting. If bone strength has not yet peaked, it will by age 35.

The Sedentary Woman: she will begin to feel her age in terms of muscle strength, particularly in her arms and legs. This is because her muscle fibers are starting to atrophy, and her muscle mass will continue to decline at a rate of about 6.6 percent each decade from here on out. She feels stiffer, as elastin is lost from her muscles. She could have as much as 33 percent body fat, most of it concentrated in her hips and thighs. Along with that of her active peers, her sexual responsiveness reaches a peak, but she may not have the energy to enjoy it.


The Fit Woman: she remains as energetic and flexible as ever, with excellent aerobic stamina. Because of an inevitable decline in metabolism, however, she may have a tendency to put on some fat, particularly in her hips and thighs. But her ratio of muscle to fat keeps her calorie-burning capacity up, and this, along with continued aerobic exercise, will counteract this tendency, keeping her at about 22 percent body fat. Although she experiences some compression of the vertebrae in her back, strong muscles keep her stomach relatively flat, her back supple.


The Sedentary Woman: she is by now 15 percent weaker than she was in her thirties, and the decline will be even more dramatic past age 45. Her shoulders appear narrower as muscle mass decreases in her upper back. The disks between her vertebrae begin to compress, so that with time she will be 1 to 1 ½ inches shorter, and her stomach will distend as the distance between her ribs and pelvis decreases. She has lost about 40 percent of the range of motion in her hips and may develop varicose veins.


The Fit Woman: she has maintained every aspect of fitness. Her age shows only in her percentage of body fat, which continues to increase slightly — it’s probably up to about 24 percent now. Gravity may start to take its toll on her body, and she may feel some wear and tear in her joints due to years of activity. She may want to rethink her workouts, switching to lower-impact activity — swimming or walking, for example.

The Sedentary Woman: she has poor posture due to the continued drop in flexibility and muscle strength. She slouches forward, and has a protruding stomach and overarched lower back. All the repercussions of inadequate aerobic activity begin to kick in: Her blood pressure rises; she becomes more susceptible to diabetes and heart attacks. Now body fat begins to settle around her middle, her skin wrinkles and is tugged downward by gravity.


The Fit Woman: she has strong, flexible muscles and plenty of stamina. Despite the effect menopause has on estrogen production, her bones are strong thanks in part to the weight-bearing exercises and strength training she’s done all her life (although hormone replacement may be necessary). Her target heart rate will be about 115 beats per minute (down 30 or 40 bpm from her twenties). But because aerobic exercise has kept her heart strong, she remains able to pump healthy amounts of blood. She has about 26 percent body fat.

The Sedentary Woman: she is two or three inches shorter by now and may have developed osteoperosis, partly because she has not done the weight-bearing exercise that keeps bones strong. Her breasts begin to sag in earnest and her waist widens even more. Her heart is 10 to 15 percent weaker than it was when she was 20, and measurable changes in her immune system increase her risk of developing cancer and certain infections. Wrinkles are now creases, and skin is dry.


The Fit Woman: she can work and play almost as hard as she did 30 years ago. Only a slight increase in body fat — amplified by the earth’s pull — reveals her age, along with deeper creases in her face and a drier look to her skin due to a decline in oil production that occurs after menopause.

The Sedentary Woman: she is in failing health as high blood pressure, brittle bones and unhealthy blood cholesterol levels leave her vulnerable to a host of serious diseases. Her flexibility, strength and stamina are about nil, and she may have developed the classic “dowager’s hump.” She has wrinkles in her cheeks, and her mouth turns down, so she appears as unhappy as she probably feels.

Source: Self Magazine, September 1992

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