Osteoporosis

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Low bone mass is a primary risk factor for osteoporotic fractures, followed by hip axis length. Exercise of varying types (including aerobic exercise and strength-training) has a significantly beneficial effect on bone mineral density and is effective for arresting the loss of bone mass in both pre- and postmenopausal women.

CONTENTS

What is osteoporosis?

Osteoporosis is a disorder in which a loss of bone mass and strength leads to fractures. It most commonly occurs in post-menopausal women, in which estrogen deficiency likely has a key role. The concept of osteoporosis has changed markedly over the years. However, the current concept is that osteoporosis occurs along a continuum, in which multiple mechanisms are active, causing a loss of bone mass (typically measured as bone mineral density) and a deterioration in the microarchitecture of the bone structure, leading to a high incidence of fractures (Raisz).


What is the prevalence of osteoporosis?

Various researchers have assessed the prevalence of osteoporosis. Osteoporosis is generally assessed based standard deviations of bone mineral density (BMD) scores. A common definition is to establish osteoporosis as being evident when BMD is further than 2.5 standard deviations below the mean value in normal young men and women (e.g. Li et al.). Sometimes, this is expressed as a T-score. A T-score is a commonly used measurement in the analysis of osteoporosis and describes BMD at a given site in comparison to the young normal reference mean (i.e. a healthy 30-year-old). However, Melton has observed that a diagnosis (and therefore a prevalence figure) will depend on the approach taken to normalize for bone size, the specific site in the skeleton that is measured (e.g. lumbar spine, femoral neck, etc.), and the diagnostic criteria used. Melton has therefore recommended that the prevalence of osteoporosis should rather be assessed with respect to fracture risk instead of by reference to BMD.

Study Population Prevalence
Henry et al. Australian females >79 years females = 87.0%
Liao et al. females aged >80 years in China females = 83.2%
Liao et al. females aged 70 – 79 in China females = 71.8%
Cheng et al. Medicare claimants aged >65 years in the US total = 29.7%
El-Desouki and Sulimani Saudi males males = 21.4%
Li et al. people aged >40 years in China total = 16.1% (males = 11.5%, females = 19.9%)
Emaus et al. people aged >70 years in Norway males = 6.9%, females = 15.3%
Yang et al. females aged 60 – 69 in Taiwan females = 8.62%
Yang et al. females aged 70 – 79 in Taiwan females = 14.14%

Although not all of the data in these studies are directly comparable as they are taken from different skeletal sites, they provide an insight into the relative prevalence of osteoporosis in different populations. Osteoporosis clearly increases in prevalence with increasing age and is generally higher in women than in men. However, there are also significant differences between geographical regions, with Western societies typically displaying a higher prevalence than those in the developing nations.


What is the incidence of osteoporotic fractures?

The incidence of osteoporotic fractures depends strongly upon bone mineral density. Melton et al. examined population-based data from ongoing studies of osteoporosis and fractures among US women and reported that the incidence of cervical femur fractures was 8.3 per 1,000 person-years among women with cervical bone mineral density (BMD) <0.6 g/cm2, and the estimated incidence of intertrochanteric femur fractures was 16.6 per 1,000 person-years among women with intertrochanteric BMD of <0.6g/cm2. Hans et al. reported that the incidence of hip fracture among women with values above the median for femoral neck BMD was 2.7 per 1000 person-years, compared with 19.6 per 1000 person-years for those with values below the median. Nguyen et al. performed a longitudinal, epidemiological, population-based survey in adults >60 years to examine the risk factors for osteoporotic fractures. They reported that the overall incidence of osteoporotic fractures in men and women >60 years was 1.9% and 3.1% per annum, respectively. Johnell and Kanis performed an ambitious study to estimate the global incidence of osteoporotic fractures. In the year 2000, they estimated that 9 million new osteoporotic fractures occurred (including 1.6 million at the hip, 1.7 million at the forearm and 1.4 million of the vertebrae). The researchers observed that a previous estimate set in 1990 of the global incidence of hip fractures was 1.3 million, which implies a growth rate of 25% over the 10 year period.


What are the risk factors for osteoporotic fractures?

A large number of studies have investigated the risk factors for osteoporotic fractures, focusing mainly on bone mass (measured predominantly as bone mineral density), bone geometry of the lower body, micro-architectural properties of the bone and fall-related risks, as shown in the table below:

Study Description Finding
Cummings et al. The researchers performed a prospective study in 9,703 females aged >65 years. They measured the bone mineral density (BMD) of the subjects and followed-up after an average of 1.6 years. The researchers found that the risk of hip fracture was inversely related to BMD. However, they also concluded that BMD only accounts for a part of the age-related increase in the risk of hip fracture in women.
Cummings et al. The researchers performed a prospective study in 8,134 women aged >65 years or more. They measured the bone mineral density (BMD) of the subjects and followed-up after an average of 1.8 years. The researchers found that with each standard deviation decrease in femoral neck bone density, there was a corresponding increase in the age-adjusted risk of hip fracture of 2.6 times. They found that females with a bone density in the lowest quartile had an 8.5 times greater risk of hip fracture than those in the highest quartile.
Hui et al. The researchers performed a prospective study in 521 women. They measured the bone mineral density (BMD) of the subjects and followed-up after an average of 6.5 years. The researchers reported that the incidence of fracture increased with both increasing age and decreasing radius bone mass.
Hui et al. The researchers performed a prospective study of 386 free-living females and 135 females living in a retirement home. The researchers initially measured radial bone mass and then recorded non-spine fractures over an average follow-up period of 6.7 years in the free-living females and over 5.5 years in the 135 females living in a retirement home. The researchers found that for every 0.1g/cm reduction in bone mass, there was a 2.2 times greater risk of fracture for the free-living females and a 1.5 times greater risk of fracture for the retirement-home females.
Melton et al. The researchers examined population-based data from ongoing studies of osteoporosis and fractures among women residing in Rochester, Minnesota. The researchers reported that hip fractures were uncommon among women with a femoral bone density >1.0g/cm2 but their frequency increased as bone density reduced below that level.
Melton et al. The researchers measured bone mineral density (BMD) at the lumbar spine and cervical and intertrochanteric regions of the proximal femur in 304 females aged 30 – 94 years. The researchers reported that, after adjusting for age, BMD predicted fracture risk.
Ross et al. The researchers performed a prospective study to assess the contribution of bone mass and existing fractures as predictors of the risk for new vertebral fractures in postmenopausal Japanese-American women. They measured bone mass of the distal radius, the proximal radius, and the calcaneus. The researchers reported that differences of 2 standard deviations in bone mass were associated with 4 – 6 times the risk of new vertebral fractures while the presence of a single fracture was associated with 5 times the risk of new vertebral fractures, and the presence of two or more fractures was associated with 12 times the risk of new vertebral fractures.
Hans et al. The researchers performed a prospective study in 5,662 elderly women and recorded bone mineral density (BMD) of the calcaneus before following-up for the incidence of fractures over an average of 2 years. The researchers reported that a 1 standard deviation reduction led to a 1.7 – 2.0 times greater risk of hip fracture.
Faulkner  et al. The researchers performed a study to examine whether femoral geometry was associated with hip fracture risk in 8,074 women aged >67 years. The researchers measured bone mineral density (BMD) and bone geometry, including hip axis length (the distance from greater trochanter to inner pelvic brim), neck width and the neck/shaft angle. Then, they followed-up the subjects over an average of 1.6 years. The researchers reported that a decrease in femoral neck BMD of 1 standard deviation led to a 2.7 times greater risk of hip fracture while an increase in hip axis length of 1 standard deviation led to a 1.8 times greater risk of hip fracture but there was no association between neck width or the neck/shaft angle and risk of hip fracture.
Alonso et al. The researchers performed a cross-sectional study to assess the effect of femoral bone mineral density (BMD) and femoral neck geometry (hip axis length, neck-shaft angle and mean femoral neck width) on hip fracture risk in 411 patients with hip fractures and 545 persons healthy controls. The researchers reported that femoral neck BMD was significantly lower and neck-shaft angle and mean femoral neck width were significantly higher, in the hip fracture group in comparison with the controls. The researchers found that a reduction in femoral neck BMD of 1 standard deviation was associated with a 4.52 times greater risk of hip fracture of 4.52 in men and a 4.45 times greater risk in women, while an increase in neck-shaft angle of 1 standard deviation was associated with a 2.45 times greater risk of hip fracture in men and a 3.48 times greater risk in women, and an increase in mean femoral neck width of 1 standard deviation was associated with a 2.15 times greater risk of hip fracture in men and a 2.40 times greater risk in women.
Duboeuf et al. The researchers examined whether hip axis length and femoral neck bone mineral density (BMD) were significant predictors of hip fracture in a subsection of the EPIDOS prospective cohort, which is a multi-center study of 7,575 elderly women living at home, aged 75 – 95, and based in France. The researchers identified three groups: a healthy control group, a cervical fracture group and a trochanteric fracture group. The researchers reported that in the cervical fracture group but not in the trochanteric fracture group, hip axis length was significantly longer than in controls. The researchers reported that in the trochanteric fracture group, upper and lower femoral neck BMD was lower than in the control group. However, in the cervical fracture group, only the upper part of the femoral neck BMD was lower than in the control group. The researchers therefore concluded that hip axis length is a predictor of femoral neck fracture and that femoral neck BMD distribution differs between groups at risk of either cervical and trochanteric fractures.
Gnudi  et al. The researchers compared the proximal femur geometry and femoral neck bone mineral density (BMD) in 111 postmenopausal women with hip fracture and 329 healthy controls. The researchers reported that the fracture group displayed a lower femoral neck BMD, a longer hip axis length and a more valgus neck-shaft angle. The researchers found that both hip axis length and neck-shaft angle were able to predict hip fracture risk independently of femoral neck BMD.
Dargent-Molina et al. The researchers examined the effect of femoral neck bone mineral density (BMD) and potential fall-related risk factors (self-reported physical capacity, neuromuscular function, mobility, visual function, and use of medication) on the risk of hip fractures in a subsection of the EPIDOS prospective cohort, which is a multi-center study of 7,575 elderly women living at home, aged 75 – 95, and based in France. The researchers found four independent fall-related predictors of hip fracture: slower gait speed, difficulty in doing a tandem walk, reduced visual acuity and small calf circumference.
Grisso et al. The researchers performed a case-control study of 174 elderly women with a first hip fracture to assess the contribution of risk factors for falls to the overall risk of hip fracture. The researchers reported that an increased risk of hip fracture was indeed associated with risks associated with falls, including leg dysfunction, visual impairment, previous stroke, Parkinson's disease and the use of long-acting barbiturates.
Nguyen et al. The researchers performed a longitudinal, epidemiological, population-based survey to examine the risk factors for osteoporotic fractures. The researchers reported that the main predictors of fractures in both men and women were femoral neck bone mineral density, body sway and quadriceps strength.
Cauley et al. The researchers performed a longitudinal cohort study to assess the association between physical activity and fractures and falls in 2,731 elderly men (average age of 79). They measured the total and active energy expenditure and the minutes per day spent in sedentary and moderate intensity activities over a 5 day period. They monitored falls and fractures over a 12-month follow-up period. In the 12-month follow-up period, the  researchers reported that males <80 years old with the lowest active energy expenditure had a 25% lower risk of falling than men with the highest active energy expenditure. They reported that men >80 years the lowest active energy expenditure had a 43% higher risk of falling than men with the highest active energy expenditure. They reported that men with <33 minutes/day of moderate activity had a 70% greater risk of fractures.

Based on these studies, it appears that low bone mass is a primary risk factor for osteoporotic fractures. However, it also appears that the geometry of the lower body bones is also a risk factor, with hip axis length (the distance from greater trochanter to inner pelvic brim) being the main geometrical risk factor identified. Finally, the risk of falls also affects the risk of osteoporotic fractures, with risk factors for falls including leg dysfunction and leg strength.


What factors influence bone mineral density?

Several studies have assessed the factors that influence bone mineral density and have generally found that increased physical fitness, physical activity and muscular strength are all correlated with higher bone mineral density in most populations, as shown in the table below:

Study Description Finding
Pocock et al. The researchers examined the relationship between physical fitness (predicted maximal oxygen uptake) and bone mineral density (BMD) in the femoral neck, lumbar spine and forearm in 84 normal women, including 46 postmenopausal subjects. The researchers found that femoral neck and lumbar BMD were significantly correlated with physical fitness as well as with age and weight. However, the researchers also found that in the 46 postmenopausal subjects, physical fitness was the only significant predictor of femoral neck BMD although both weight and physical fitness were significant predictors of BMD.
Aloia et al. The researchers examined the relationship between physical activity and bone mineral density (BMD) in 24 healthy, premenopausal women (average age 39.0 ± 1.39 years). The researchers recorded physical activity using an accelerometer. The researchers reported that physical activity levels were correlated with spinal BMD but not BMD of the distal portion of the radius.
Williams et al. The researchers measured the bone mineral density (BMD) in a group of 20 male runners (both consistent and inconsistent runners) and in a group of age-matched controls. The researchers found that the consistent runners displayed significantly more BMD than the controls but the inconsistent runners did not display any significant difference in BMD to the controls.
Block et al. The researchers assessed the bone mineral density of 46 young men, including 28 who engaged in regular exercise. The researchers reported that spinal trabecular bone mineral density and spinal integral bone mineral content were significantly greater in the exercise group than in the control group.
Pocock et al. The researchers assessed the contribution of age, muscular strength, physical fitness and body mass index (BMI) in to proximal femoral (at 3 different sites), lumbar spine and forearm bone mineral density (BMD) in 73 healthy females aged 20 – 75 years. The researchers reported that muscular strength and BMI were independent predictors of BMD at all 3 sites on the proximal femur as well as in the lumbar spine and forearm, while physical fitness was an independent predictor of proximal femur BMD.
Bevier et al. The researchers assessed the contribution of body composition, maximal aerobic capacity, grip strength and back strength to bone mineral density (BMD) in 91 healthy men and women, aged 61 – 84 years. The researchers reported that in females, grip strength correlated with both forearm and spine BMD, while in males grip strength correlated with forearm density and back strength correlated with both spine and forearm density. Maximal aerobic capacity did not predict either spine or forearm BMD in females but did predict spine BMD in males. The researchers concluded that a combination of body mass and grip strength best predicted BMD in elderly women while a combination of back strength and maximal aerobic capacity best predicted BMD in elderly men.
Snow‐Harter et al. The researchers examined the contribution of bodyweight, muscular strength and exercise patterns to bone mineral density (BMD) at the proximal femur (at the femoral neck and at the trochanter) and spine in 59 women aged 18 – 31 years. The researchers reported that femoral neck BMD was significantly correlated with back strength and bodyweight, while trochanteric BMD and overall hip BMD were significantly correlated with biceps, back, and hip adductor strength, and lumbar spine and mid-radius BMD were significantly correlated with overall muscular strength.
Kritz‐Silverstein et al. The researchers assessed the contribution of grip strength to bone mineral density (BMD) at the spine, hip, wrist and radius in 649 postmenopausal women aged >65 years. The researchers reported that only women who exercised displayed a correlation between grip strength and BMD and yet grip strength was an independent predictor of general bone density.
Sinaki et al. The researchers assessed the contribution of back extension strength to lumbar spine bone mineral density (BMD) in 68 healthy postmenopausal females. The researchers reported a significant positive correlation between back extension strength and lumbar spine BMD, even when corrected for age. They also observed a significant positive correlation between bodyweight and lumbar spine BMD.
Sinaki et al. The researchers assessed the contribution of back extension strength and physical activity to lumbar spine bone mineral density (BMD) in 68 healthy postmenopausal females. The researchers reported a significant positive correlation between back extension strength and lumbar spine BMD, between bodyweight and lumbar spine BMD, and between physical activity levels and lumbar spine BMD.
Madsen et al. The researchers assessed the contribution of quadriceps strength to bone mineral density (BMD) of the tibia and forearm in 66 healthy women, aged 21 – 78 years. The researchers found significant correlations between BMD of the proximal tibia and of the forearm and quadriceps strength. The researchers found that in a multiple regression analysis, quadriceps strength was a better predictor of tibial BMD but not of forearm BMD than age, height, or bodyweight.
Snow‐Harter et al. The researchers assessed the contribution of muscular strength and physical activity to bone mineral density (BMD) in 50 healthy men ranging from 28 – 51 years. The researchers reported that overall BMD was significantly correlated with back and biceps strength. Moreover, the researchers reported that back strength was the only independent predictor of spine and femoral neck BMD and was also the best predictor of BMD at the trochanter, Ward's triangle (a fracture-prone area in the femoral head), tibia and whole body.
Krall and Dawson-Hughes The researchers examined the effect of walking, independently of other types of physical activity, on bone mineral density (BMD) and rates of bone loss from the lumbar spine and whole body in 239 healthy, postmenopausal women. The researchers found that women who walked >7.5 miles per week had higher mean whole body, legs and trunk BMD than women who walked <1 mile per week.
Orwoll et al. The researchers compared radial and vertebral bone mineral density (BMD) in a group of subjects aged 40 – 85 years who had been swimming regularly for at least 3 years with a control group. Neither group performed any other type of exercise. The researchers found that in males, both radial and vertebral BMD were significantly in the swimmers compared to the non-swimmers. However, there was no difference between swimmers and non-swimmers in females.

Based on these studies, it appears that physical fitness, physical activity levels and overall muscular strength are key factors that predict bone mineral density and therefore bone mass.


Is aerobic exercise useful for osteoporosis?

A number of studies have investigated the use of aerobic exercise interventions for the treatment of osteoporosis, as shown in the following table:

Study Description Finding
Roghani et al. The researchers assessed the effect of a 6-week intervention comprising sub-maximal aerobic exercise with and without external loading on bone metabolism and balance in 36 postmenopausal women with osteoporosis. They randomly allocated the subjects into: treadmill walking, treadmill walking with weighted vest, and control groups. The treadmill walking groups performed 18 sessions of sub-maximal treadmill walking for 30 minutes, 3 times a week either with or without a weighted vest (4 -8% of body weight). The researchers found that fat mass decreased and fat-free mass increased significantly in the weighted vest group. They also reported that Bone-specific Alkaline Phosphatase (BALP) increased and N-terminal telopeptide of type 1 collagen (NTX) decreased significantly in both treadmill walking groups. BALP has been used as a bone formation marker in several previous studies and has been assessed as having high accuracy and sensitivity in this respect. NTX provides a measurement of the rate of bone turnover. The researchers observed that balance (as measured by the near-terminal stand score) increased in the treadmill walking groups and decreased in the control group (treadmill walking: +49.7%, treadmill walking plus weighted vest: +104.7, and control: -29.0%) but the increase was greater in the treadmill walking plus weighted vest group.
Gunendi et al. The researchers assessed the effect of a sub-maximal aerobic exercise program on postural balance in 25 postmenopausal women with osteoporosis. The researchers reported that balance ability, as assessed by the Timed Up and Go test, four square step test, Berg balance scale and Kinaesthetic ability trainer 3000, was significantly improved after exercise training.
Yamazaki et al. The researchers performed a prospective study to assess the effect of moderate walking exercise on bone metabolism in 50 postmenopausal women with osteopenia or osteoporosis. The researchers allocated the subjects to either an exercise group or to a control group. The exercise group performed daily outdoor walking at 50% of maximum oxygen consumption for at least 1 hour and comprising >8000 steps, 4 days a week for a 12-month period. The researchers reported that lumbar bone mineral density (BMD) in the exercise group increased in comparison with the control group. However, this difference occurred as a result of a reduction in BMD in the control group rather than because of an increase in the exercise group. Additionally, the researchers reported that urinary N-terminal telopeptides of type I collagen (NTX) levels reduced in the exercise group, thereby suggesting that the mechanism by which BMD is retained by walking is the suppression of bone turnover rather than an increase in bone formation.
Chow et al. The researchers assessed the effect of 2 different exercise programs on bone mass in 48 postmenopausal females aged 50 – 62 over a 1-year period. The researchers randomly allocated the subjects into either a control group, an aerobic exercise group or a combined aerobic and strength exercise group. The researchers reported that at 1 year, both exercise groups displayed higher levels of physical fitness and bone mass than the control group but there was no difference between the exercise groups in respect of either physical fitness or bone mass.
Martin and Notelovitz The researchers assessed the effect of aerobic training volume in combination with calcium supplementation on lumbar (L2-L4) bone mineral density (BMD) and forearm BMD in 55 postmenopausal women over a 1 year period. The researchers divided the subjects into a control group a high-volume exercise group and a low-volume exercise group. The exercising subjects performed aerobic exercise on treadmills at 70 – 85% of maximal heart rate for either 30 or 45 minutes, 3 times per week. The researchers reported that the control, low- and high-volume exercise groups altered lumbar BMD by 0.61 ± 3.40, -0.48 ± 3.63, and 0.81 ± 4.53%, respectively.
Smith et al. The researchers assessed the effect of exercise on radius, ulna, and humerus bone mineral density (BMD) in 142 middle-aged women over a 4-year period. The researchers allocated the subjects to either an exercise or a control group. The exercise group exercised 3 times a week for 45 minutes per session. The researchers reported that BMD declined significantly in all three bones in both arms in both groups but the rate of decline was significantly less than that of the control group for 12 of the 18 bone variables measured.
Snow‐Harter et al. The researchers compared the effects of either resistance training or weight-bearing aerobic exercise on mineral density (BMD) of the spine (L2-4) and right proximal femur in a group of healthy college women (average age 19.9 years). The researchers randomly allocated the subjects to either a control group, a resistance-training group or to a jogging group. The researchers reported that lumbar BMD increased  in both the jogging and resistance-training groups (1.3 ± 1.6% and 1.2 ± 1.8% respectively) and there was no significant difference between groups, although both groups were significantly different from the control group.
Dalsky et al. The researchers performed a non-randomized, controlled trial to assess the effect of weight-bearing aerobic exercise training and detraining on lumbar bone mineral density (BMD) in 35 postmenopausal women, 55 to 70 years old. The researchers allocated the subjects to either an exercise group or to a control group. The weight-bearing aerobic exercise training involved walking, jogging or stair climbing at 70 – 90% of maximal oxygen uptake capacity for 50 – 60 minutes, 3 times per week. The researchers reported that BMD increased 5.2% in the exercise group and decreased -1.4% in the control group after 9 months.
Hatori et al. The researchers assessed the effect of exercise intensity on bone mineral density (BMD) of the lumbar vertebrae in 33 postmenopausal women. The researchers randomly allocated the subjects to either a control or to 1 of 2 exercise groups. The exercise groups performed walking at either above (exercise-above) or below (exercise-below) the anaerobic threshold, for 30 minutes, 3 times a week for 7 months. The researchers found that the control group decreased lumbar BMD by 1.7 ± 2.7%, the exercise-below group decreased lumbar BMD by 1.0 ± 3.1% and the exercise-above group significantly increased lumbar BMD by 1.1 ± 2.9%.
Cavanaugh and Cann The researchers investigated the effect of brisk walking on the rate of loss of spinal trabecular bone mineral density (BMD) in 17 postmenopausal women, aged 49 – 64 years, over a 1 year period. The researchers allocated the women into either walking or non-walking groups. The walking group performed 15 – 40 minutes of walking a heart rate of between 60 – 85% of maximal age adjusted heart rate, 3 days per week for 1 year. The researchers reported that the walking group and non-walking group lost a significant amount of BMD (5.6 ± 1.4% and 4.0 ± 1.2% respectively) and the loss of BMD was not significantly different between the two groups.
Nelson et al. The researchers assessed the effects walking in combination with increased dietary calcium on trabecular bone mineral density (BMD) of the lumbar spine at L1-L3 and L2-L4 and of the femoral neck in 36 postmenopausal women, aged 60.2 ± 6.5 years, over a 1 year period. The researchers allocated the subjects into four groups across two variables: either high- or moderate-calcium doses, and either exercise or no-exercise. The researchers reported that lumbar spine BMD at L1-L3 increased by 0.5% in the exercise groups but decreased by 7.0% in the no-exercise groups. However, there were no differences between exercise and no-exercise groups in respect of BMD of the L2-L4 lumbar spine or of the femoral neck. Dietary calcium appeared to affect femoral neck BMD but not BMD at the lumbar spine at either L1-L3 and L2-L4 and The researchers concluded that walking exercise and dietary calcium may affect different bone sites.

Based on these studies, it seems that most forms of weight-bearing aerobic exercise training are effective for arresting the reduction in bone mineral density and may also lead to increases in bone mineral density.


Are combined training programs useful for osteoporosis?

A number of studies have investigated the use of combined training interventions involving two or more of aerobic, resistance and stretching exercises for the treatment or prevention of osteoporosis, as shown in the table below:

Study Description Finding
Kemmler et al. The researchers performed a long-term trial to assess the effect of combined, supervised exercise training on fracture incidence and bone mineral density over 12 years in 85 postmenopausal, osteopenic women. The women were randomly allocated to either an exercise training group or two a lifestyle control group. The exercise training involved 2 group sessions/week and 2 home training sessions/week. The group sessions involved 20 minutes of warm-up/endurance, 3 – 5 minutes of jumping and 35 – 40 minutes of resistance exercise. The researchers reported that while there was a trend for overall fracture risk to be lower in the exercise group, this was not statistically significant. However, they did find that the exercise group lost significantly less bone mineral density at the lumbar spine (0.8% vs. -4.0%) and femoral neck (-3.7% vs. -6.7%).
Tolomio et al. The researchers assessed the effects of a multicomponent dual-modality exercise program on bone mass and quality in addition to physical function in 125 postmenopausal women with low bone mineral density. The subjects were randomly allocated to either a non-training control group or to an 11-month exercise program comprising strength, aerobic capacity, balance, joint mobility involving both land-based and in-water activities and comprising both group and home-based exercise periods. exercise regimen. The researchers reported that the exercise group significantly improved femoral neck T-score while the control group significantly reduced this measurement. The T-score is a commonly used measurement in the analysis of osteoporosis and describes bone mineral density at a given site when compared to the young normal reference mean (i.e. a healthy 30-year-old). Additionally, the researchers reported that the exercise group significantly improved physical function while the control group did not improve or declined.
Arnold et al. The researchers performed a randomized clinical trial to compare the effects of combined exercise protocols of either aquatic exercise or land exercise on balance, functional mobility, and quality of life in 68 women with osteoporosis. The subjects were allocated to either an aquatic exercise group, a land-based exercise group or to a non-exercising control group. Both training groups exercised in a supervised setting for 50 minutes, 3 times per week, for 20 weeks. The researchers reported that one balance measure (backward tandem walk) significantly improved with aquatic exercise compared to land-based exercise and there were no significant differences between the exercise interventions and the control, except for ratings of global change, where participants in the aquatic exercise group were three times more likely to report improvement than those in the control group.
Kemmler et al. The researchers performed a study to assess the impact of combined exercise training on bone, body composition, blood lipids, physical fitness, and menopausal symptoms in 78 early postmenopausal women with osteopenia. The researchers allocated the subjects into an exercise group, who performed 2 sessions per week for 38 months, or a non-training control group. The researchers reported that significant differences between the groups in the changes in lumbar spine bone mineral density were observed (0.7% vs. -3.0%) and in bone mineral density at the femoral neck (-0.7% vs. -2.6%). The researchers also reported that the exercise group also displayed significantly greater changes in respect of body composition, blood lipids and menopausal symptoms than the control group. The researchers reported that maximal isometric strength and 1RM strength increased significantly in the exercise group by 10 – 36% and 15 – 43% respectively but neither improved in the control group.
Carter et al. The researchers performed a randomized controlled trial to assess the effects of a combined stretching and resistance training program in 93 women with osteoporosis. The subjects were allocated to either an exercise group or to a control group for a 20-week intervention, attending classes twice per group. The researchers observed that the exercise group improved dynamic balance, static balance and knee extension strength by 4.9%, 6.3% and 12.8% more than the control group, although only the differences in dynamic balance and knee extension strength were significant.
Shirazi et al. The researchers performed a randomized controlled study to evaluate the effects of a 12-week exercise and education program in Iranian women aged 40 – 65 years. The home-based exercise prescription comprised resistance training with elastic bands, balance training and a walking program. The researchers reported that the training group displayed significant improvements in levels of physical activity, lower body strength, and static and dynamic balance, whereas no significant changes occurred in the control group.
Heinonen et al. The researchers performed a randomized intervention trial to assess the effects of an 18-month protocol of high-impact combined-modality exercise on bone mineral density (BMD), muscular strength and dynamic balance, which are risk factors for osteoporotic fractures, in 98 healthy, sedentary, premenopausal women. The researchers randomly allocated the subjects to either an exercise group or to a control group. The control group performed supervised exercise sessions 3 times a week for 18 months, involving a 15-minute warm-up, 20 minutes of multidirectional high-impact exercises (jumping), 15 minutes of stretching and non-impact exercises, and 10 minutes of cooling down. The researchers reported that femoral neck BMD increased by significantly more in the exercise group than in the control group (1.6% vs. 0.6%) while the distal radius, a non-weight-bearing site, displayed no significant difference between groups.

Based on these interventions, combined training interventions involving two or more of aerobic, resistance and stretching exercises appear to be useful for the treatment or prevention of osteoporosis.


Is resistance training useful for osteoporosis?

A number of studies have investigated the use of resistance training for the treatment of osteoporosis, as shown in the table below:

Study Description Finding
De Matos et al. The researchers performed a prospective study to assess the effect of a program of closed kinetic chain resistance training on bone mineral density in 59 postmenopausal women with osteopenia or osteoporosis. The researchers allocated the subjects into either a resistance training group or a control group who performed no exercise. The researchers reported that the resistance training group displayed a 1.17% increase in lumbar spine bone mineral density and the control group displayed a 2.26% decrease in lumbar spine bone mineral density. However, the difference between groups was not statistically significant.
Hongo et al. The researchers performed a randomized controlled trial to investigate the effect of a home-based, low-intensity back-strengthening exercise on quality of life and back extensor strength in 80 postmenopausal women with osteoporosis. The researchers randomly allocated the subjects to either a control or to an exercise group. The exercise group performed 1 set of 10 prone back extensions per day, 5 days a week without supervision at home. The researchers found that the exercise group significantly increased back extensor strength (26%) but also somewhat oddly increased in the control group (11%). Additionally, the researchers found that quality of life scores increased in the exercise group (7%) but remained unchanged in the control group.
Sinaki and Mikkelsen The researchers performed an intervention trial in 59 postmenopausal females aged 49 – 60 years with spinal osteoporosis and back pain. The researchers allocated the patients to groups performing either extension exercises, flexion exercises, combined exercises, or no exercises. The researchers performed spinal x-ray studies before treatment and at follow-up, which occurred between 1 – 6 years. The researchers reported that additional wedging or compression fractures occurred as follows: extension (16%), flexion, (89%), combined (53%) and no-exercise (67%). On this basis, spinal flexion exercise appears to be less desirable than spinal extension exercise in patients with postmenopausal osteoporosis.
Nelson et al. The researchers performed a 1-year randomized controlled trial to examine the effect of high-intensity strength training exercise 2 days per week on the risk factors for osteoporotic fractures in 40 postmenopausal women, aged 50 to 70 years. The researchers allocated the subjects to either an exercise group or to a control group. The researchers reported that femoral neck bone mineral density (BMD) and lumbar spine BMD increased by 0.9 ± 4.5% and 1.0 ± 3.6%, respectively, in the exercise group and decreased by -2.5 ± 3.8% and -1.8 ± 3.5%, respectively in the control group. The researchers also observed that muscle mass, strength and dynamic balance all increased in the exercise group and decreased in the control group.
Gleeson et al. The researchers assessed the effect of resistance training on bone mineral density (BMD) of the lumbar spine in 68 premenopausal women over a 1 year period. All subjects were given a daily 500mg supplement of calcium. The researchers allocated the subjects to either a control group or to a machined-based resistance-training group. The researchers reported that the resistance-training displayed a non-significant increase in lumbar BMD of 0.81% while the control group displayed a non-significant decrease of 0.5%. However, there was a significant difference between the two groups.
Pruitt et al. The researchers assessed the effect of resistance training on bone mineral density (BMD) of the lumbar spine, femoral neck and distal wrist in 17 early postmenopausal women over a 9 month period. The researchers allocated the subject to either a resistance-training group or to a control group. The resistance-training group exercised for 3 times per week. The researchers reported that lumbar BMD increased by 1.6 ± 1.2% in the resistance-training group but decreased by -3.6 ± 1.5% in the control group. The difference between the two groups was significant.
Beverly et al. The researchers assessed the effects of short periods of resistance exercise on bone mineral content (BMC) in 99 subjects, including 69 age-matched controls and 30 elderly patients with wrist fractures. The subjects performed an exercise regimen that involved squeezing a tennis ball as hard as possible for 30 seconds per day for 6 weeks. The researchers reported that following 6 weeks of exercise there was a increase in grip strength of 14.5% and an increase in BMC of 3.4%.
Rockwell et al. The researchers assessed the effects of resistance training on lumbar spine bone mineral density (BMD) in 17 women over a 9 month period. The researchers allocated the women to either an exercise group (mean age 36.2 ± 1.3 years) and a control group (mean age 40.4 ± 1.6 years). All of the women consumed 500mg calcium per day. The researchers reported that lumbar spine BMD in the exercise group decreased by 3.96% at 9 months but there was no change in lumbar BMD in the control group.
Snow‐Harter et al. The researchers compared the effects of either resistance training or weight-bearing aerobic exercise on mineral density (BMD) of the spine (L2-4) and right proximal femur in a group of healthy college women (average age 19.9 years). The researchers randomly allocated the subjects to either a control group, a resistance-training group or to a jogging group. The researchers reported that lumbar BMD increased  in both the jogging and resistance-training groups (1.3 ± 1.6% and 1.2 ± 1.8% respectively) and there was no significant difference between groups, although both groups were significantly different from the control group.

Based on these interventions, most resistance training interventions appear to be useful for the treatment or prevention of osteoporosis. They appear to be as effective as weight-bearing aerobic exercise.


Do reviews of exercise confirm its usefulness for osteoporosis?

A small number of reviews have investigated the use of exercise interventions for the treatment of osteoporosis, as shown in the table below:

Study Description Finding
Howe et al. The reviewers performed a Cochrane review of randomised controlled trials (RCTs) to examine the effect of exercise on the prevention of bone loss and fractures in postmenopausal women. They identified 43 RCTs. The reviewers reported that the most effective type of exercise for increasing bone mineral density for the neck of the femur was non-weight bearing, lower body resistance training. They reported that the most effective intervention for increasing bone mineral density of the spine was combined exercise programs. The reviewers did not identify any effect of exercise on the numbers of fractures. The reviewers concluded that exercise has a significant effect on bone mineral density. They suggest that exercise is a safe and effective way to avoid the loss of bone mineral density in postmenopausal women.
Nikander et al. The reviewers performed a systematic review and meta-analysis to assess the effects of long-term supervised exercise on lower-body bone strength in various age groups. The reviewers found 10 randomised controlled trials (RCTs). The reviewers produced an analysis that demonstrated that weight-bearing exercise was able to result in 1 – 8% increases in bone strength at various sites in children and adolescents, while in premenopausal women increases of 0.5 – 2.5% were more likely.
Wolff et al. The reviewers performed a review and meta-analysis to assess the effect of exercise on bone mass in both pre- and postmenopausal females. They identified 25 met the inclusion criteria and were maintained for further analyses. The reviewers reported that combined results from the randomized controlled trials  showed a consistent pattern the prevention or even a reversal of bone loss in both pre- and postmenopausal women. They found that the average difference in bone loss between the exercise and control groups was 0.9% and that these findings were similar across lumbar spine and femoral neck measurements.

Based on these reviews, it appears that exercise has a significant effect on bone mineral density and is effective for arresting the loss of bone mass in both pre- and postmenopausal women.


Evidence-based recommendations for exercise

Some reviews have made evidence-based recommendations for the treatment of osteoporosis that include non-pharmacological treatments.

Study Recommendation
Sinaki The researcher recommended that exercise prescription in osteoporosis need to take care to match the needs of the patient. The reviewer suggests that if exercise does not take musculoskeletal status into account, it could have negative consequences. That being said, the reviewer also suggests that in osteoporosis, axial strength and stability are the main and the spinal extensors should be strengthened with progressive resistance as tolerated. Additionally, the reviewer recommends that exercise programs should address balance and leg strength training to reduce the risk of falls.
Burr et al. The researcher made 5 recommendations based on research. The researcher recommended that (1), osteoporotic patients at high risk of fracture should not perform trunk flexion but can perform trunk flexion or isometric exercises, (2) osteoporotic patients recovering from hip fracture should not perform exercises for more than 15-30mins per session during early rehabilitation process, weight-bearing exercise can be started after 18 days, and resistance training can be started 1 month after inpatient rehabilitation, (3) osteoporotic patients can safely perform both aerobic exercise and resistance training but intensity be light-to-moderate at the start, (4), osteoporotic patients should avoid powerful twisting movements of the trunk, and (5) osteoporotic patients should avoid maximum-intensity physical activity.
Papaioannou et al. The researchers prepared the 2010 clinical practice guidelines for the diagnosis and management of osteoporosis in Canada. Within that document, they made 3 recommendations in relation to the ways in which exercise can improve, physical function, strength, balance and quality of life for osteoporotic patients. The researchers recommended that (1) both resistance training and weight-bearing aerobic exercise are beneficial for those with osteoporosis or at risk for osteoporosis, (2) core stability exercise and exercises to compensate for postural weakness or abnormalities are beneficial for individuals who have incurred vertebral fractures, and (3) balance training, such as Tai Chi, or specific balance or gait training may be beneficial for those at risk of falls.
Pfeifer et al. The researchers suggest that the risk of osteoporotic fractures can be reduced using a multidisciplinary program, including education, environmental modifications, aids, and exercise programs designed to increase bone mineral density (BMD) and reduce the incidence of falls. They suggest a specific focus on back strengthening exercises, which can reduce thoracic hyper-kyphosis, vertebral fracture, loss of height and anterior rib cage pain.

Based on these guidelines, it appears that exercise interventions to help prevent and treat osteoporosis should include strengthening exercises to help improve balance, leg strength, back strength and core strength, as tolerated by the individual on a case-by-case basis.


Conclusions

On the basis of these studies and reviews, the following conclusions might be drawn:

Area Recommendation
Risk factors for osteoporotic fractures Low bone mass is a primary risk factor for osteoporotic fractures. Hip axis length is the main geometrical risk factor, while the risk of falls also affects the risk of osteoporotic fractures, with fall risk being mainly dictated by lower body strength and function.
Effect of exercise on osteoporosis Exercise of varying types has a significant effect on bone mineral density and is effective for arresting the loss of bone mass in both pre- and postmenopausal women.
Optimal aerobic exercise for osteoporosis Aerobic exercise interventions to help prevent and treat osteoporosis focus on weight-bearing movements.
Optimal strengthening exercise for osteoporosis Resistance training interventions to help prevent and treat osteoporosis should include exercises to help improve balance, leg strength, back strength and core strength, as tolerated by the individual on a case-by-case basis.


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