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Transcript of Copyright © 2014 American College of Sports Medicine Chapter 42: Exercise Prescription for Patients...
Copyright © 2014 American College of Sports Medicine
Chapter 42: Exercise Prescription for Patients with Osteoporosis
Copyright © 2014 American College of Sports Medicine
EpidemiologyEpidemiology
• Osteoporosis is a skeletal disorder characterized by compromised bone strength that results in an increased susceptibility to fracture.
• 200 million women worldwide currently have osteoporosis.
• Osteoporotic fractures are low-trauma fractures that occur with forces generated by a fall from a standing height or lower and are most common at the spine, hip, and wrist.
– Hip fractures are considered to be the most devastating consequences of osteoporosis.
• Costs $17 billion per year in United States
• Osteoporosis among men and women
– Although women are more susceptible, men also can have osteoporosis and often go undiagnosed.
Copyright © 2014 American College of Sports Medicine
Basic Bone Physiology Basic Bone Physiology
• Bone is a biphasic material with crystals of hydroxyapatite (calcium phosphate) and an organic collagen matrix.
– Cortical bone
– Trabecular bone
• Modeling and remodeling: affect the quantity, quality, and structure of the bone; regulated by hormonal and mechanical environments
– Osteoblasts: bone-forming cells
– Osteoclasts: bone-reabsorbing cells
Copyright © 2014 American College of Sports Medicine
FIGURE 42-1. Bone is a dynamic tissue that is vascularized and innervated. Cortical bone is dense and stiff and makes up the shaft of long bones. Cortical bone also provides a shell of protection around trabecular bone, which is more porous and flexible and is found at the ends of long bones and in vertebrae.
Copyright © 2014 American College of Sports Medicine
FIGURE 42-2. Bone remodeling is the coupled actions of osteoclasts and osteoblasts whereby a portion of older bone is resorbed by osteoclasts and replaced with newly formed bone by osteoblasts. The new bone begins as osteoid (unmineralized matrix). Eventually, the osteoid incorporates mineral.
Copyright © 2014 American College of Sports Medicine
Osteoporosis Pathophysiology Osteoporosis Pathophysiology • Skeletal fragility
– Bone quantity: amount of bone material present
• Rapid accumulation during adolescence
• Peak in second to third decade of life
• Negative bone balance: decline over time with aging where reabsorption is greater than formation rate
– Bone material quality: ability to withstand stressors
• Amount of bone in human skeleton decreases with menopause and advancing age.
• Increased mean tissue mineralization and changes in collagen properties increase fracture risk with age.
• Increased microdamage accumulation
Copyright © 2014 American College of Sports Medicine
FIGURE 42-3. Normal pattern of bone mineral accretion and loss throughout the lifespan in men and women.
Copyright © 2014 American College of Sports Medicine
Osteoporosis PathophysiologyOsteoporosis Pathophysiology
• Skeletal fragility
– Bone structure: distribution of bone material in bone space
• Structural differences in cortical bone geometry may explain some of the differences in fracture rates between men and women.
• During growth, long bones of boys have greater gains in periosteal (outer) diameter, resulting in greater overall bone size in boys that remains throughout life.
• Increased porous bone results in loss of bone strength and increased fracture risk.
– Falls
• Falls significantly increase the risk of fracture, especially when skeletal fragility exists.
• Most hip fractures occur after a sideways fall and landing on the hip.
• Hip fractures are a common occurrence because of falling.
Copyright © 2014 American College of Sports Medicine
FIGURE 42-4. Slice of trabecular bone in a normal (A) and an individual with osteoporosis (B) showing loss of trabecular connectivity and increased microdamage with ageing.
Copyright © 2014 American College of Sports Medicine
Diagnosis of Osteoporosis Diagnosis of Osteoporosis
• Measurement of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DEXA) is the primary method of diagnosis.
• World Health Organization (WHO) criteria
– Osteopenia (low bone mass): site-specific bone density between 1.0 and 2.5 standard deviations below the mean for young white adult women
– Osteoporosis: bone density that is 2.5 standard deviations or more below the mean for young white adult women
Copyright © 2014 American College of Sports Medicine
Risk Factors for Osteoporotic FractureRisk Factors for Osteoporotic Fracture• BMD
• Age
– Risk of hip fractures increases three to six times from 50 to 80 yr of age, independent of BMD status.
• Family history of fracture
• Previous fracture
• Physical inactivity
• Medication use
• Hypogonadism
• Menopause
• Hyperthyroidism and bariatric surgery risk for secondary osteoporosis
Copyright © 2014 American College of Sports Medicine
Copyright © 2014 American College of Sports Medicine
Bariatric Surgery: A Risk Factor for Osteoporosis?
Bariatric Surgery: A Risk Factor for Osteoporosis?
• With rapid and dramatic weight loss, there is an increasing concern that bariatric surgery may negatively affect the skeleton by accelerating bone loss and increasing bone fragility.
• Recent review showed that BMD loss may be as high as 15% at the hip 1 yr following gastric bypass procedures.
Copyright © 2014 American College of Sports Medicine
Clinical Management Clinical Management
• Pharmacologic therapy
– Several categories are FDA approved.
• Antiresorptive agents: act by suppressing bone resorption.
• Bisphosphonates, salmon calcitonin, hormone replacement therapy (HRT), selective estrogen receptor modulators (SERMs), and receptor activator of nuclear factor kappa-B ligand (RANKL) inhibitors
• Anabolic agents: promote bone formation
• Regulation of calcium homeostasis: parathyroid hormone (PTH)
Copyright © 2014 American College of Sports Medicine
Copyright © 2014 American College of Sports Medicine
Antiresorptive Agents and Increased Risk of Fracture
Antiresorptive Agents and Increased Risk of Fracture
• With long-term use, antiresorptive medications may lose value in preventing fracture and, in some cases, may lead to fracture.
• Long-term bisphosphonate use remains controversial.
– Fractures appear to occur infrequently
– Lack of strong evidence
– FDA has issued warning regarding possible risk
Copyright © 2014 American College of Sports Medicine
Lifestyle ModificationsLifestyle Modifications
• Adequate calcium (1,000–1,500 mg · d–1) intake
• Adequate vitamin D (600-800 IU · d–1) intake
• Regular exercise
– Exercise is the only lifestyle modification that can simultaneously ameliorate low BMD, augment muscle mass, promote strength gain, and improve dynamic balance — all of which are independent risk factors for fracture.
• Smoking cessation
• Avoidance of excessive alcohol intake
• Visual correction to decrease fall risk
Copyright © 2014 American College of Sports Medicine
Exercise and Osteoporosis Exercise and Osteoporosis
• Physiologic response of bone to exercise
– Acute physiologic response
• Exercise causes compression, tension, or torsion of bone tissue and ultimately deformation, which is the basis for chronic adaptations.
– Chronic physiologic response
• Changes via modeling/remodeling take up to several months.
• Maintenance of bone tissue quality through targeted remodeling
Copyright © 2014 American College of Sports Medicine
Exercise and OsteoporosisExercise and Osteoporosis
• Osteogenic activities
– Response is site specific.
– Loading/stress should be designed to affect the location in which osteoporosis is identified (e.g., spine, hip).
– Rest is important for proper bone adaptation or response.
Copyright © 2014 American College of Sports Medicine
Exercise and OsteoporosisExercise and Osteoporosis• Exercise during youth: building a strong skeleton
– Exercise in youth is deemed very important for adult bone health.
– Period of maximal velocity of height growth may be most important period of bone mineral accumulation.
– Studies suggest that the bone response to loading is optimized in prepuberty and early puberty.
• Exercise prescription for optimizing bone development in youth
– ACSM Position Stand on Physical Activity and Bone Health: 10–20 min, 3 d · wk–1 of impact activities such as plyometrics, jumping, moderate-intensity resistance training, and participation in sports that involve running and jumping (soccer, basketball)
– Ten jumps, three times per day has also been shown to significantly increase bone mineral density in the proximal femur and intertrochanteric regions.
Copyright © 2014 American College of Sports Medicine
Exercise and OsteoporosisExercise and Osteoporosis
• Exercise during adulthood: maintaining a strong skeleton
– Goal of exercise in adulthood is to gain bone strength and to offset bone loss observed during this time in life.
– Not as much research in men as women but appears men can also retard the BMD loss associated with aging.
• Exercise prescription to preserve bone health during adulthood
– ACSM Position Stand on Physical Activity and Bone Health: 30–60 min · d–1 of a combination of moderate-to-high intensity weight-bearing endurance activities (three to five times per week), resistance exercise (two to three times per week), and jumping activities
Copyright © 2014 American College of Sports Medicine
Exercise for the Elderly and Individuals with Osteoporosis
Exercise for the Elderly and Individuals with Osteoporosis
• Exercise testing for those with osteoporosis
– Not contraindicated
– Use of cycle ergometry may be indicated in patients with severe vertebral osteoporosis if walking is painful.
– Vertebral compression fractures compromise ventilatory capacity and may affect balance during treadmill walking.
– May have increased false-negative test rate because of inability to exercise to significant level of stress
– Maximal muscle strength testing may be contraindicated in those with severe osteoporosis because of risk for fracture.
Copyright © 2014 American College of Sports Medicine
Exercise Prescription for Individuals with Osteoporosis
Exercise Prescription for Individuals with Osteoporosis
• Should consult with patient’s physician first
• Pain may limit exercise program options
• Pain management may be an important part of the care
• ACSM position statement on physical activity and bone health: “Exercise programs for elderly men and women should include not only weight-bearing endurance and resistance activities aimed at preserving bone mass but also activities designed to improve balance and prevent falls.”
Copyright © 2014 American College of Sports Medicine
Exercise Prescription for Individuals with Osteoporosis
Exercise Prescription for Individuals with Osteoporosis
• Contraindicated exercise for individuals with osteroporosis
– Contraindicated because they can generate large forces on relatively weak bone
• Twisting movements (e.g., golf swing)
• Dynamic abdominal exercises (e.g., sit-ups)
• Excessive trunk flexion
• Exercises that involve abrupt or explosive loading
• High-impact loading
Copyright © 2014 American College of Sports Medicine
Exercise Prescription for Individuals with Osteoporosis
Exercise Prescription for Individuals with Osteoporosis
• Flexibility training for individuals with osteoporosis
– Increased flexibility can be of benefit (especially with posture).
– Many commonly prescribed exercises for increasing flexibility involve spinal flexion and should be avoided.
– Slow and controlled movements should be the rule.
– Avoid ballistic-type stretching.
Copyright © 2014 American College of Sports Medicine
Exercise Prescription for Individuals with Osteoporosis
Exercise Prescription for Individuals with Osteoporosis
• Aerobic training for individuals with osteoporosis
– Goals
• Increase aerobic fitness
• Decrease cardiovascular disease risk factors
• Help maintain bone strength
• Improve balance
– Perform 3-5 d · wk–1 at an intensity of 40%–59% of VO2 reserve or heart rate reserve (HRR)
– Initial goal of 20–30 min per session with slow increase to 30–60 min once tolerated.
– When possible, exercise mode should be weight bearing.
Copyright © 2014 American College of Sports Medicine
Exercise Prescription for Individuals with Osteoporosis
Exercise Prescription for Individuals with Osteoporosis
• Resistance training for individuals with osteoporosis
– Goals
• Improve bone health
• Improve balance to lower risk of falling
– Perform 2–3 d · wk–1, 8–12 repetitions at a moderate intensity (60%–80%)
– Those with osteoporosis should avoid any ballistic or jumping activities.