Osteoporosis is a metabolic skeletal disease characterized by decreased bone mineral density (BMD) with a consequent increase in bone fragility and susceptibility to fracture (40). It is estimated that over 200 million people worldwide suffer from osteoporosis (17) and an estimated 54 million men and women ages 50 years or older in the United States have reduced BMD or osteoporosis (47). Interventions for osteoporosis are often directed at attenuating disease as well as risk mitigation and impairments. From a risk perspective, fracture is one of the most prevalent consequences of the disease process. Reports indicate an annual frequency for fractures of greater than 8.9 million, including 1.6 million hip fractures, nearly 75% occurring in women (9,13,15). Fractures of the femoral neck and intertrochanteric regions of the hip are the most common fracture sites followed by spinal compression fractures (thoracic and lumbar spine) (15,16,37). This high prevalence has encouraged the pursuit of newer interventions to reduce osteoporosis mediated fractures and increase BMD.
Over the past decade, knowledge regarding exercise interventions for osteoporosis has expanded, especially in the area of resistance training. Traditional guidelines suggested that regular resistance training alone would improve bone health (2,19). Recent evidence has suggested that greater benefits may be achieved with a combination of controlled higher-impact (loading) exercise and resistance training (49). These recent findings have created a new approach to the traditional model of resistance training for these individuals. Strength and conditioning professionals, armed with newer evidence and physician clearance, have the opportunity to recommend a combination of higher-impact activities (e.g., step classes) and higher intensity resistance training (e.g., >70% 1 repetition maximum) as a means of improving the efficacy of their programming (28,31). This manuscript will present an overview of more recent recommendations for resistance training and loading for individuals with osteoporosis. The first section of the manuscript will provide a review of osteoporosis including diagnosis, types of osteoporosis, and medical management. The second section will discuss the current research and limitations for resistance training. Finally, practical recommendations will be provided for patient education, exercise precautions, and exercise selection for those with osteoporosis.
Strength and conditioning professionals must have a comprehensive understanding of osteoporosis to safely prescribe resistance training interventions for these individuals. This section provides a brief review of how the condition is diagnosed, pathophysiology, types of osteoporosis, risk factors, and medical management.
Osteoporosis is a multifactorial systemic skeletal disease that affects both sexes. Osteoporosis in women is the most commonly reported, but the disease is often overlooked in men (36). The strength and conditioning professional should be aware of this under recognized problem in male clients and provide them with proper education and prevention strategies, as needed. The World Health Organization defines osteoporosis as a spinal or hip BMD of greater than or equal to 2.5 standard deviations below the mean for healthy, young women (T-score of −2.5 SD or below) (36). Bone mineral density is commonly measured with a dual-energy X-ray absorptiometry(DXA) imaging modality, often referred to as a bone density test. The results are primarily expressed as a T-score (Table 1). The Z-score, (another interpretation value obtained from a DXA scan), is a comparison of a person's bone density with that of a person of the same age and sex, which is often used to scrutinize one's BMD for secondary conditions such as illness or disease. Individuals may be diagnosed with osteoporosis based on a Z-score as well; however, this is a less commonly referenced value when compared with T-score. Another classification used to describe impaired BMD is osteopenia, which is characterized by BMD that is lower than normal (T-score between −1 and −2.5 but not low enough to be classified as osteoporosis). Clients who have osteopenia are at a greater risk for developing osteoporosis over time (41,47). The American College of Radiology Appropriateness Criteria for Osteoporosis and Bone Mineral Density recommends a DXA screening examination for postmenopausal women greater than 50 years of age and women who are in their late 40's transitioning into menopause. In addition, the criteria recommend DXA testing for men greater than 50 who have conditions (e.g., chronic glucocorticoid therapy, cancer treatments that interfere with endocrine function, or alcoholism) placing them at risk for fracture or reduced BMD (34). For clients with osteoporosis, it is recommended that the strength and conditioning professional determine the degree of bone density a client may have by communicating with the patient's physician because more severe osteoporosis may be a contraindication for higher level resistance training. The strength and conditioning professional should be familiar with the WHO Fracture Risk Assessment Tool when considering exercise prescription within this population (37).
TYPES OF OSTEOPOROSIS
The current body of literature describes 3 common types of osteoporosis: primary, senile, and secondary (42). Primary (type I) or “postmenopausal” osteoporosis is the most common type of osteoporosis which results in trabecular (spongy) bone loss (23,41,42). Estrogen deficiency is believed to be the main underlying cause for this form of osteoporosis (26), which is why women are 8 times more likely to get primary osteoporosis than men (25). Bone loss may begin to occur after the age of 30 when the rate of bone remodeling begins to decline. In women, bone loss accelerates after the age of 45 when estrogen production slows and menopause begins usually at an average age of 51 (11). Women transitioning into or who have entered menopause have a much lower estrogen level, which can lead to a 2–3% loss in bone density in the first 5 years after menopause (41). In men, bone loss (e.g., trabecular thinning) accelerates around the age of 45–50 years when there is a reduction of testosterone production (37,41). Researchers have found several factors associated with primary osteoporosis which are outlined in Table 2 (7,23,25,26,37,41).
Senile (type II) osteoporosis often occurs after the age of 70 years, which results in both cortical (hard) and trabecular (spongy) bone loss (38). Women are 2 times more likely to suffer from senile osteoporosis than men and this form of osteoporosis often results from an age related vitamin D deficiency which leads to poor calcium uptake, increased parathyroid hormone release, as well as bone resorption (16).
Secondary osteoporosis can occur at any age and is often caused by chronic diseases, endocrinopathies, metabolic conditions, nutritional deficiencies or absorption disorders, alcoholism, and certain medications (Table 3) (23,26,32,41,42).
Besides a resistance training program, the physician may prescribe medications and dietary supplementation (4,16). Of particular interest to the strength and conditioning professional is the use of medications by the client. Several medications have been approved by the Food and Drug Administration (FDA) for the prevention and/or treatment of osteoporosis which include: bisphosphonates, calcitonins, and estrogen therapies (4). Bisphosphonates are a group of medications that are now in their third generation of production and include Fosamax, Actonel, and Boniva (4,45). They have been found to inhibit bone resorption (e.g., osteoclast activity) before affecting bone formation (e.g., osteoblast activity) (45). The primary reported side effect of this medication is the occurrence of osteonecrosis of the jaw and individuals with renal disease should avoid this medication (4,24). Clients need to follow specific guidelines for drug consumption to allow for proper absorption of the medication. The oral bisphosphonates must be taken in the morning, before consumption of food or drink for at least 30 minutes (4,18) and clients must refrain from lying down for 30 minutes after administration of the drug (because of the potential for gastrointestinal irritation). Table 4 provides information about these medications (4,18,45).
The strength and conditioning professional must be aware of these medications and their potential side effects because they may influence the client's performance during their exercise program. Also, the timing of medication is important to ensure proper absorption and avoid unwarranted side effects. An awareness of the short-term side effects of these medications such as adverse effects to the gastrointestinal system can be instrumental in making a proper referral to the client's primary care physician. The client's medications and any supplements (e.g., vitamin D) should be reviewed by the strength and conditioning professional before program design and can often be appropriately addressed with a dietician consultation. In addition, hormone therapy is common and should also be considered by the strength and conditioning professional during this time.
RESISTANCE EXERCISE PROGRAMMING
Current evidence suggests a combined program of higher impact or loading activities and higher intensity resistance training is superior because of the benefits of improving BMD versus resistance training alone (28,31). The higher loading of the musculoskeletal systems (e.g., Wolff's law) stimulates osteoblast activity to remodel and strengthen the bone (6). Despite these benefits, this type of training does come with a higher risk of injury. It is important for the strength and conditioning professional to make sure that the client is safe to participate in such activities. Research has demonstrated that individuals with osteoporosis may have weakness in the low back extensors and lower extremity muscles (e.g., quadriceps) (6). Before implementing an exercise program, it is advised that physician clearance is obtained. Exercise programming should include a comprehensive program that focuses on reducing common impairments (such as joint pain), improving strength and mobility, as well as increasing BMD. Although performance improvements are often a primary concern, programming must be safe and designed with an understanding of risk for fracture and other injuries.
Research regarding the efficacy of resistance exercise programs for individuals with osteopenia and osteoporosis has grown over the past decade. An emerging body of literature has suggested that resistance training alone, or basic activities such as walking fail to stimulate significant increases in BMD versus higher loading activities, as illustrated in this manuscript, which require increased muscle force production and bone loading (29,33,48).
Several systematic reviews and meta-analyses have evaluated the growing body of literature pertaining to resistance training interventions for individuals with reduced BMD (osteopenia or osteoporosis) (12,27,29,30,35,39,43,44). The current literature suggests that interventions need to have a higher loading capacity (exceed the minimum essential threshold) to stimulate an increase in BMD. Thus, research using higher-impact loading or high-intensity exercise protocols seem to have more promising results (27).
High-impact programs may include activities such as jogging, step classes, and select plyometric drills (if appropriate considering overall fitness level and comorbidities), whereas high-intensity resistance training may include exercises such as bar squats, deadlifts, and barbell bench press (30). Of note, the functional nature of activities such as squats and deadlifts have the potential to carry over into attributes well beyond improving one's BMD. Proper form is essential with any resistance training to avoid aberrant adaptations and ensuing injury (21,22). The research evaluating combined programs of higher-impact loading and high-intensity resistance training have shown significantly favorable outcomes in preserving or increasing BMD at the lumbar spine, hip, and wrist (5,30,46,49). The Lifting Intervention for Training Muscle and Osteoporosis Rehabilitation Trial investigated and compared the effects of either 8 months of twice-weekly 30-minutes supervised high-intensity progressive resistance training and impact loading with a low-intensity home-based exercise program (controls) of the same duration and dose among postmenopausal women with osteoporosis (44). Results of the study found that subjects in the high-intensity progressive loading group had greater improvements in functional performance and BMD than controls. Thus, high-impact activities may be most effective at producing increases in BMD at specific regions of the body such as the hip (14,36,50).
Although current research has demonstrated positive changes for those participating in high-impact exercises, it seems they may be short term. Heinonen et al. (14) studied the effects of an 18-month high-impact program on 84 women (premenopausal) randomized into an exercise and control group. The authors found significant postintervention increases in femoral neck BMD when compared with a control group. However, the increase in BMD was not maintained at a 3.5-year follow-up, which may be the result of the intervention only lasting 18-months (14). Ahola et al. (1) found that a 6-month high-impact program was associated with bone changes up to 12 months. The long-term effects of these programs are still understudied which should be considered when prescribing these programs to osteoporotic clients. Table 5 provides a summary of recent selected studies on higher-impact loading and high-intensity resistance programs.
Although, the newer research is promising, there are several questions that need to be answered including long-term efficacy, mechanism to stimulate bone growth, and what is the minimum loading or muscle force threshold to stimulate bone growth. In addition, many individuals may not be able to participate in these activities because of severe osteoporosis or other comorbidities. One concern of programs used in research trials resides in the intervention timeline, as discontinuation would seemingly cause a down-regulation of bone stimulating factors. Other research has produced different results. Nikander et al. (35) conducted a systematic review and meta-analysis on the effects of resistance training on osteoporosis and found that exercise significantly enhanced bone strength at loaded sites in children but not in the adults (35). A meta-analysis found that mixed loading exercise programs which combine jogging with other low-impact activities seem effective in reducing postmenopausal bone loss of the hip and spine (30). These contrary findings demonstrate the need for more quality research evaluating the effects of this type of exercise on osteoporosis. Nevertheless, evidence does exist to support higher-impact loading and high-level resistance training for improving and preserving BMD (27).
Based on current evidence, a more comprehensive approach to preventing osteoporosis should begin in childhood and progress well into adult years that includes addressing potential risk factors, higher intensity resistance training, and appropriate loading that reaches the minimum essential threshold (3). Considering varied results reported in the literature, there is not a single approach that has shown to be most effective; however, it is clear that loading through weight-bearing and resistance training is efficacious.
This section provides practical recommendations for the strength and conditioning professional. As mentioned above, osteoporosis is a multifactorial disease process that requires a working knowledge of the pathophysiology, an understanding of how it has affected the specific client (e.g., previous fracture or medication therapies), and an understanding as to the recommendations from the client's physician. As previously stated, osteoporosis is often a silent disease. Thus, recognizing risk factors for osteoporosis may be an invaluable skill set that lends to a referral to an appropriate health care professional for preparticipation screening (e.g., DXA examination). A brief discussion regarding client education, exercise precautions, and exercise selection is presented in the following sections.
Because osteoporosis itself is a silent condition, until injury occurs such as fractures or spinal deformities (kyphosis), the client with osteoporosis should be educated about the disease and the long-term consequences. Specific strategies for preventing further bone loss should be established before beginning an exercise program. Some suggested client education topics include: avoiding potential risk factors (discussed previously in the manuscript), dietary guidelines, and supplementation (e.g., calcium and vitamin D intake). The client should also be educated on safe activities to be performed at work and at home such as proper lifting of objects. Guidelines for resistance training and aerobic exercise should also be taught and are discussed in the subsequent sections.
When developing a training program for a client with osteoporosis it is necessary to be aware of specific precautions. Severity of the disease progression should significantly influence decision making which can be determined via medical imaging such as a DXA scan. Consultation with a physician familiar with the clients' condition should be a requisite criterion for prescribing any program. Strength and conditioning professionals should error on the side of caution when developing a training program, as excessive loads can lead to inflammation, premature degenerative changes, or fracture. Progressions should be incremental and based on medical advice. Training progressions which are too aggressive may result in muscle soreness, joint pain, or antalgic gait (limping or inability to fully weight bear on an extremity) patterns. At times there may be no observed warning before an injury; therefore, outward appearances should not be considered the only sign of excessive loading. Because bone weakening most often occurs in specific areas such as the hips and spine, particular awareness of these regions should be considered when developing a training program. Specifically, the strength and conditioning professional should have their client avoid excessive or repetitive spinal flexion if a client is known to have moderate to severe osteoporosis as this places increased force through the anterior margin of the vertebral body and may lead to a vertebral compression fracture (40). Finally, clients with known osteoporosis may be taking vitamin D and calcium supplements which could result in low blood pressure, dizziness, weakness, and fatigue (8). This must be considered to maintain a safe environment and avoid incidents such as falls. The consequence of a fall in this population could be severe as reduced BMD increases the likelihood of fractures In addition, it may be appropriate in some cases to perform a balance screen among clients that have anxiety related to falling.
Many oral medications used to treat osteoporosis (Table 4) have positional precautions that prohibit lying flat for 30–60 minutes after administration. Although most clients are well aware of these precautions it does not preclude the strength and conditioning professional from taking the necessary steps to avoid unwarranted side effects.
With respect to training precautions, specific activities that may promote injury are those that either load the bone in an aberrant manner or those that pose a safety risk for falls. Regardless of the injury mechanism, the primary reason for precautions is to prevent fracture. For example, common gym exercises such as abdominal crunches on a ball or Yoga positions that require sustained spinal flexion such as the child's pose (Figure 1) may place a client with osteoporosis at risk for a compression fracture of the vertebral bodies (40). In addition, activities such as squatting with heavy loads may produce axial compression that is excessive and render the spinal segments at risk for fracture, particularly if appropriate spinal positioning is not maintained.
Individuals with osteoporosis, young adults, and premenopausal women may benefit from higher impact or high-intensity resistance training, which may increase BMD and reduce the risk for osteoporosis. However, these exercises must be prescribed with caution because of the risk of injury and fracture among patients with an established reduction in BMD. The client must have appropriate muscular strength and motor control to perform higher level movements and a period of progressive loading is recommended to adapt to increasing load, velocity, and complexity of the movements. Table 6 provides recommendations for higher impact and high-intensity exercise for these individuals based on recent evidence (10,14).
Figures 2–4 provide examples of high-impact exercises which have demonstrated improved BMD for those with below average values (12). These are only examples and each client should be evaluated on a case by case basis for appropriateness of specific exercises.
Step dropping exercise
An adjustable step is used which starts at a height of 8.5 cm. The client is asked to stand on top of a step maintaining their “landing foot” off the edge and then initiate a fall by quickly flexing the hip and knee of their stance foot. Clients should land flat footed and soften the landing but minimize excessive hip and knee flexion. The exercise can be progressed by increasing the step height in 5 cm increments up to 63.5 cm (Figure 3).
Abandoned bilateral forearm exercises
The client begins in a tall kneeling position with both shoulders flexed forward to 90° followed by a fall forward catching themselves with their outstretched hands on the floor. This exercise should be approached with extreme caution as there have been reports of apprehension with some participants (12) (Figure 4). Modifications of these exercises could be to fall forward to an elevated surface to decrease the fall height initially.
Unilateral fall against a wall
The client stands in front of a wall with shoulders flexed forward to 90°. The client is positioned so their fingertips are in contact with the wall to establish their base line distance. A fall is initiated by leaning forward toward the wall and the client alternately uses their left or right upper extremity to catch the fall. They should be instructed to contact the wall with their palm first and elbow extended as much as possible (Figure 4). Clients who are unable to perform this exercise as described may modify the exercise by catching the fall with both hands at same time.
Reduced BMD is primarily an age related consequence of hormonal changes, activity decline, and risk factors arising from pathology and medication intake. Osteoporosis is characterized by reduced BMD which is often a silent condition that surfaces as a diagnosis after injury or age appropriate screening. The strength and conditioning professional may encounter men and women with a formal diagnosis or risk factors. Given the potential risk for fracture from inappropriate activity recommendations, it is key to identify those at risk and take the necessary steps to avoid undue injury. Once diagnosed with osteoporosis, safe activity guidelines for resistance training and aerobic activity must be determined. High-impact activities and higher intensity resistance training has shown superior benefits for increasing and preserving BMD but does include a higher risk of injury compared with standard resistance training. These types of programs may not be for every client who makes appropriate screening by the strength and conditioning professional before participation important. It is imperative that strength and conditioning professionals maintain an awareness of the disease process, risk factors, and appropriate activity guidelines.
- A referral for medical screening before participation in an exercise program is advised for those at risk for osteoporosis including but not limited to postmenopausal women and those with a history of glucocorticoid use or other risk factors.
- Higher-impact loading and high-intensity resistance training shows superior benefit for improving BMD versus resistance training alone but has a higher risk for injury and should be commenced in a progressive manner and based on fitness levels and consideration of comorbidities (e.g., osteoarthritis or fall risk)
- Individuals with a diagnosis of osteoporosis should avoid lying flat for up to 60 minutes after oral intake of bisphosphonates (e.g., Fosamax [Alendronate], Actonel [Risedronate], Boniva [Ibandronate])
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