Regular exercise is your best solution for finding the Fountain of Youth. After all, age is just a number. Is eighty the new seventy? By the looks of people I see working out, it may be. Aging is inevitable, but exercise can stem or delay physical changes by the “use it or lose it” principle.
The late Dr. Fred Kasch, Professor Emeritus at San Diego State University and founder of the Adult Fitness Clinic, now known as SDSU's Center for Optimal Health and Performance, is my all-time fitness hero. A pioneer in the fitness field and a regular exerciser long before there were health clubs, Dr. Kasch jogged into his nineties. Pull-ups, to gauge his upper body strength, were part of his daily routine. He did them on a bar he had hung from a tree branch. He never used anything too fancy to perform his exercises. One of the first internationally recognized exercise physiologists, he was a pioneer, a man ahead of his time.
Dr. Kasch piloted a fitness research study of middle-aged men, following them for more than thirty-five years. Dr. Kasch found that physical declines that occur with aging and that were considered “inevitable” could be slowed with regular physical activity. The positive effects on various physiologic and musculoskeletal parameters were seen in the men who engaged in exercise programs of moderate or vigorous intensity. Important changes to the body seemed to begin at ninety minutes a week and continued up to three hundred minutes a week. The participants engaged in a variety of physical activities.
Dr. Kasch used to say, “There are many ways to Rome.” In other words, many different exercise regimens will achieve the same goal of physical conditioning. You just need to do one!
Following Dr. Kasch's sage advice, what you will find in this chapter are general principles for exercise that will enhance your bone health. Use this information to individualize your own program. It is impossible to prescribe something for you without knowledge of your starting level and a personal assessment. If you are already a regular exerciser, it is time to review your activities and make changes. You may be actually losing ground because your body gets habituated to the same exercise routine. Bone likes a variety of stimuli, so you must mix it up.
BUILD: Optimize Bone Growth (Children to Young Adults)
Depending on your age, you may remember taking a physical fitness test in grade school. I will never forget it! A classmate caught the back of my sneaker during the run and I ended up sprawled on a cinder track. I still have cinders tattooed on my right knee to remind me of that day. That memorable test, which consisted of a variety of exercises, including pull-ups, sit-ups, a shuttle run, and a six-hundred-yard run, challenged kids to be physically fit. Time has not changed those goals. Exercise early in life provides lasting benefits by establishing lifelong habits of physical activity. Start early and never stop.
“Let's Move!”
First Lady Michelle Obama has promoted her “Let's Move!” initiative for raising a healthier generation of children. It addresses all the various factors of childhood obesity, an epidemic fed by fast food, sugary drinks, too much television and computer time, too many computer games, and too little exercise.
One disease that has not been mentioned in Mrs. Obama's public health message is osteoporosis. Here's the connection: It takes movement to stimulate the mesenchymal stem cells in the bone marrow to create osteoblasts, the bone-forming cells. Inactivity creates fat cells instead! Movement directs the stem cells to operate in the correct way. The fate of these stem cells depends on it. Here is another compelling but often-overlooked reason to move!
Exercise can play an important role in building bone. Young bones respond better to exercise than adult bones, and impact exercise appears to produce the greatest bone mass. Weight-bearing exercises are the most effective. Therefore, running and jumping activities like volleyball, gymnastics, soccer, and basketball provide more impact and bone building than swimming or bicycling. Both impact and resistance exercises have been shown to increase bone mass by 3 to 5 percent and to alter bone geometry in girls and boys before adolescence.
Mechanical Strain
The “use it or lose it” principle of bone physiology is referred to as Wolff's Law. Bone microstructure is compromised by disuse and enhanced by exercise. One can find examples of this at either end of the spectrum. On the one hand, someone on bed rest will quickly lose bone along with muscle. This is the same phenomenon experienced by astronauts in space without the forces of gravity. On the other hand, a professional tennis player's racquet arm often has higher bone mass and larger muscles than his nonplaying arm.
The bone cells—osteocytes, osteoblasts, and osteoclasts—respond to physical signals. In response to increased mechanical load during exercise, the balance of bone turnover favors bone formation through increasing numbers and activity of bone-forming cells, called osteoblasts. This increases the strength of bone by adding new bone to resist the loading challenge. The mechanical signaling also influences the mesenchymal stem cells to make bone-forming cells instead of fat cells.
In the absence of mechanical strain, the bone-breakdown cells' activity is increased while formation of new osteoblasts is decreased.
Identifying the optimal amount of mechanical loading to create the right amount of strain has been the objective of many research studies. Too much loading will lead to bone failure—fracture. Too little loading accentuates bone breakdown. Like medicine that has a “therapeutic window,” exercise has a “mechanical window.” Animal data suggest that high strain followed by rest, rather than continuous strain, may be the most beneficial exercise pattern for bone formation.
The exercises that have high strain magnitude are bone building. Examples would be jumping for the lower body and racquet sports for the upper body, and repetitive activities such as running. Interval training that consists of repetitive bursts of high intensity work alternated with periods of rest or lower activity may enhance the bone effects of running. Any physical activities incorporating increased muscle activity may be beneficial. The best window of opportunity to maximize bone mass is during the preteen to teen years.
Jump at the Bell
Short interventions using jumping show the greatest gain in bone. Simple exercise like a daily jumping program of less than three minutes classroom time, using various jumping styles, makes a difference. The jumps create a strain environment that is defined by short bursts of high impact.
In a school program, students who participated in a ten-minute circuit of varied jumping activities three times per week over seven months gained more bone than those students who did not participate. Girls in early puberty at the start of the jumping intervention program enjoyed the biggest benefit. Other high impact jumping programs compared with healthy controls show greater gain in hip and spine bone mass in prepuberty.
Lesson from Racquet Players
The effect of age at which exercise is started during growing years was shown elegantly in a study of sixty-four former nationally ranked female racquet sports players. These adult women were divided into two groups according to the age at which they started playing tennis or squash. About half began before the start of their menstrual periods, while the other group started one year or more after beginning menstruation. The players were compared with peers who did not exercise and were the same age, height, and weight.
The three groups—”young starters,” “old starters,” and “controls,”—were evaluated with bone mass measurements of both arms. The results of the middle shaft of the upper arm (humerus) were the most striking and are illustrated to show the differences. The darker lines depict the side-to-side differences (see diagram on p. 105). Young starters had more than twice as large a difference in outer cortex of the bone than the old starters (20 percent versus 9 percent).
The older bone adapts to stress by increasing the amount of tissue lining the inner cavity of the bone. The young starters showed the best results for bone density and other measures of bone strength. This is because younger bone is more adaptable to stress than older bone.
Note that the age of “old starters” is not really old. Preteen bone may be the most responsive to exercise strain. This finding is consistent in multiple studies, suggesting that intense training can boost bone mass accrual beyond that associated with normal growth. The timing is critical, since these benefits are observed only in the preteen years.
Play an Hour a Day
Children and teens should perform sixty minutes or more of moderate-to-vigorous physical activity daily. The activity can be structured or unstructured as a part of play. As children grow up, their patterns of physical activity change. They transition into more organized sports and games and are able to sustain longer periods of physical activity. In addition to team sports, it is good to encourage a variety of activities that kids can carry into their adult lives.
But are children getting enough daily activity?
Dr. Philip Nader, a pediatrician at the University of California, San Diego, followed approximately one thousand kids wearing a device that kept track of the minutes of their moderate-to-vigorous activity. Kids at age nine did well, averaging about three hours a day. But by age fifteen, they averaged only fifty minutes a day during the week and barely more than thirty minutes a day on weekends! For a gender comparison: Girls crossed below the recommended sixty minutes per day at thirteen, boys at fourteen. The negative activities for bone health add up for this age group—not enough exercise, calcium, or vitamin D. As children grow older, parents need to encourage sustained and structured activity.
College and Young Adults
Leaving home for college is a huge transition. The challenge is to continue the healthy habits started earlier. Temptations abound and you have to adjust to different foods, schedules, and activities. The “Freshman 15” for me was twenty pounds! By the end of freshman year, I could not fit into any of the clothes I took to college. I bought two pairs of jeans to hold me over until summer when more sensible eating and exercise restarted—under my mother's watchful eye, I should add.
Whether physically active kids maintain their higher bone mass into their twenties is not well studied. Could I have blown my good bone health in just one year at college? The University of Saskatchewan's Pediatric Bone Mineral Accrual Study follow-up suggests that the skeletal benefits accrued by physically active children are maintained into young adulthood. Children who participated in this study returned as young adults (ages twenty-three to thirty). Comparison of the active to the inactive group showed bone mineral content at multiple sites was 8 to 15 percent higher for those in the active group.
Information is not available on whether intense physical activity in growing years, followed by reduced though not entirely stopped activity, decreases the risk of fractures later in life. Nevertheless, regular physical activity provides considerable health-related benefits throughout life.
PROTECT AND CORRECT:
Maintain Bone and Counteract Bone Loss (Adults)
Preserving bone and muscle health is a challenge with increasing age. Adults can benefit from exercise as well, but it may not be reflected in bone density changes. Studies show that the decline in bone density that happens during aging can be slowed with regular physical activity. To have a significant impact on bone density, the exercise must be of a high enough intensity to promote mechanical strain. In addition, the frequency and duration of the activity play a role. Based on accumulated evidence for all types of health outcomes, at least thirty to sixty minutes of moderate-intensity exercise on most days of the week are recommended for adults.
If you are already active and meet the minimum requirements of 150 minutes every week, turn it up a notch. You can gain additional and more extensive health and fitness benefits by increasing physical activity above this amount.
Physically active people have a lower risk of hip fracture than do inactive people. Leisure time activities like gardening and household work count, too. Research studies on physical activity to prevent hip fracture show that participating in 120 to 300 minutes a week of moderate-intensity activity reduces risk.
Walking
Walking is the most common physical activity, and it confers a multitude of benefits. Walking decreases risk of hip fractures. In the Nurses' Health Study, women who did no other exercise but walked for at least four hours a week had a 41 percent lower risk of hip fractures. However, walking may increase risk of wrist fractures due to falls. Walking exercises alone appear to be insufficient for positive effects at the spine.
As part of the Tasmania Older Adult Cohort Study, men and women aged fifty to eighty used pedometers and had their bone density measured by DXA. After an average of two and a half years, positive bone density effects were seen primarily at the hip. The strongest effect was for people over the age of sixty-five. The mean number of steps in the study was about 8,500 per day and 59,500 per week. That equals approximately 3.3 miles a day and 23 miles a week.
Walk Your Way to Fitness: 10,000 Steps a Day
Grab a pedometer and get going. Your goal is to walk 10,000 steps a day. Pick up the pace. Walking ten minutes at an energetic clip equals about 1,000 steps. The point is this: Everything you do is a form of physical activity. But unless you have an active job and are constantly moving throughout the day, you may not accumulate that many steps. You may have to add some dedicated walking time to reach 10,000 steps. If you are falling just short of your daily goal, you can walk in place while you watch television.
Here's a sample log:
Here Are Some General Guidelines:
Exercise more days than not. Make an entry in your daily calendar for your exercise time—just as you would for scheduling a meeting or a date.
Vary your routine. Do a combination of cardiovascular exercises, stretching, weight training, and resistance work with cutting-edge tools like sport cords, superbands, and the TRX® suspension trainer™. Alternate days of cardio and muscle strengthening or focus on separate muscle groups, such as upper body one day, lower body the next.
Give your muscles a rest. Do two to three sets of eight to twelve repetitions with short rest in between. You should have at least forty-eight hours between workouts focused on the same muscle groups.
Keep challenging muscles. Change up your routine once your muscles become accustomed to the exercise or add more weight. Try different weight training techniques, such as kettlebells. On a treadmill, alternate between the flat level and an incline and use different speeds. When the exercises become “routine,” which is usually every six to eight weeks, change again.
Do balance and core exercises. Keep your core muscles engaged to work on improving your balance. Walk heel-to-toe. Balance on one leg. Try a workout sitting on an exercise ball instead of sitting on a bench. This works on your focused muscle group plus balance at the same time. Lift your arm weights while standing on a BOSU® Balance Trainer (a half ball that can be used on either side, the dome or the platform), a core board, or a balance platform.
Postmenopausal women must push themselves even harder. With the loss of hormones, our bodies reset. The extra push is needed not only to decrease bone loss but also to ward off extra pounds. At least an hour a day—that's sixty minutes of moderate-intensity exercise—is the prescription.
Your exercise routine should not feel like drudgery. Use of a personal trainer may help to get a program started, to keep you on track, or to provide a “tuneup” for a new routine. Another option is using an accessory such as Wii Fit™. Designed by the video gaming company Nintendo®, it may help make exercise more enjoyable. Wii Fit programs incorporate games or offer just straightforward exercises while using the Wii Balance Board. Have fun!
Bone Estrogen Strength Training (BEST) Study
Change in bone density in adults engaged in an exercise program is difficult to demonstrate in research studies. Because so many factors contribute to bone density, it is difficult to tease out the exercise component. For example, suppose that I am going to recruit you for an exercise study but I don't want you to exercise—your job is to just be a couch potato. Do you think you would change your behavior or not?
One of the most quoted studies, the Bone Estrogen Training Study (BEST), was done in the mid-1990s. More than three hundred healthy postmenopausal women, aged forty to sixty-five, were randomly assigned either to a group that was instructed to exercise or to a group that was told not to exercise. About half were taking hormone therapy and all received 800 mg of calcium supplementation. The exercise intervention was a combination of aerobic, weight bearing, and weight lifting exercises three times a week. Strength training was done using free weights and machines.
After one year, the exercisers who were taking hormone therapy improved bone density at all regions of the hip, lumbar spine, and total body. The exercisers not on hormone therapy had significant bone changes only at the trochanter region of the hip.
BEST Exercise Program for Osteoporosis Prevention:
Six BEST Strength Training Exercises
- Wall squat or Smith squat
- One-arm military press
- Leg press
- Lateral pull-down
- Seated row
- Back extension
You can find BEST demonstration videos to see how these exercises are done at http://www.citracal.com/BEST
You may incorporate these BEST exercises, with cardio activity, balance training, and core strengthening, for example, to create a program for yourself.
REVITALIZE: Function and Prevent Falls (Seniors)
Exercise! It is never too late to start. The goal at this point is not focused on bone density but instead on decreasing risks of falls and fractures. Exercise can improve strength, balance, and mobility. Muscle mass tends to decline with the passing years; strength also declines. “Sarcopenia” is the term for this gradual decrease in muscle tissue. Some of these changes may be slowed with exercise. Also, vitamin D may have a role.
Although mechanical loading increases the bone density and structure in a healthy skeleton, exercise may not be as helpful and may even be risky for someone with a fragile skeleton. This is not meant to dissuade you from exercise. However, I want you to be safe and to protect your spine. With older age and low bone density, your spine may be vulnerable to fracture.
The precaution for exercise is “go slow” and start with professional instruction. Talk with your doctor about a referral to physical therapy for evaluation and training. You may also find resources in the community. Try calling different facilities (YMCA, senior, or community centers) to inquire whether they have a trainer who works with older individuals who have osteoporosis. The evaluation and training must target balance and fall prevention. Most fractures of the hip, shoulder, and wrist, and even some spine fractures are due to falls. Keep your doctor in the loop as well.
LOADS ON YOUR SPINE
Be cautious when you have osteoporosis in your spine or have already sustained a spine fracture. Simple movements of forward bending, such as getting up from a chair, can place a large force on your spine. This puts you at risk for fracture.
Learn proper movements to lessen the loads. If you have ever gone to “back school,” the same types of principles apply. You want to maintain a neutral back and avoid bending forward. No abdominal crunches! The following figure shows the tremendous loads that are produced on the lower spine of the eleventh thoracic (T11) and second lumbar (L2) vertebral levels with common movements in comparison with relaxed standing.
Think through your daily activities and modify them to decrease your chances of a spine fracture. When you are doing your leisure time activities, avoid those with heavier loads. For instance, when gardening, avoid lifting heavy bags of compost or soil. Stand straight, kneel, or sit to avoid forward bending. Ask someone else to tug on those stubborn weeds—doing so can generate a big load. Use a long-handled, lightweight trowel or hoe (do not use a shovel or spade) or use raised planters.
You can get up, strap on your pedometer, and go walk the dog now. Just be careful to avoid getting entangled in the leash or being pulled down!
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The Bare Bones
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