Association of spinal curve deformity and back extensor strength in elderly women with osteoporosis in Japan and the United States.

UNLABELLED: The difference in the shape of sagittal spinal curvature and distribution of vertebral fractures in women of comparable age with osteoporosis from Japan and the United States with different cultures and lifestyles was identified. Back extensor strength was significantly associated with lumbar lordosis in Akita group, indicating the potential importance of strengthening the back extensor. INTRODUCTION: The purpose of the study was to assess the association of osteoporotic spinal deformities with back strength in elderly women in Japan and the United States. METHODS: Subjects diagnosed with osteoporosis were selected to participate prospectively. In both groups, we measured the angles of thoracic kyphosis and lumbar lordosis with plain lateral radiographs and back extensor strength. The number of vertebral fractures and the ratio of lumbar fractures to thoracic fractures are also evaluated. The level of participants' daily activities was assessed with use of comparable tests in Akita (quality-of-life score) and Minnesota (physical activity score). RESULTS: A total of 102 Japanese women residing in Akita, Japan (Akita group), and 104 white women evaluated in Rochester, MN, USA (Minnesota group), participated in this study. The angle of thoracic kyphosis and lumbar lordosis was higher in the Minnesota group than in the Akita group. The ratio of lumbar fractures to thoracic fractures was higher in the Akita group than in the Minnesota group. In the Akita group, multiple regression analysis revealed that the angle of lumbar lordosis correlated significantly with back extensor strength. CONCLUSIONS: We identified the difference in the shape of sagittal spinal curvature and distribution of vertebral fractures in women of comparable age with osteoporosis from two geographic areas of the world with different cultures and lifestyles. Back extensor strength was significantly associated with lumbar lordosis in Akita group, indicating the potential importance of strengthening the back extensor for improving or maintaining lumbar lordosis.

Effect of low-intensity back exercise on quality of life and back extensor strength in patients with osteoporosis: a randomized controlled trial.

UNLABELLED: Randomized controlled study in 80 postmenopausal women with osteoporosis was conducted to investigate the effect of a home-based, simple, low-intensity exercise. Low-intensity back-strengthening exercise was effective in improving the quality of life and back extensor strength. INTRODUCTION AND HYPOTHESIS: Back-strengthening exercise is effective in increasing back extensor strength and decreasing risk of vertebral fractures. We hypothesized that a home-based, simple, low-intensity exercise could enhance back extensor strength and improve the quality of life and/or spinal range of motion in postmenopausal women in a short-term follow-up. METHODS: Eighty postmenopausal women with osteoporosis were randomly assigned to a control group (n = 38) or an exercise group (n = 42). Subjects were instructed to lift their upper trunk from a prone position antigravity and maintain the neutral position. Isometric back extensor strength, spinal range of motion, and scores for quality of life were evaluated at baseline and 4 months. RESULTS: Back extensor strength significantly increased both in the exercise group (26%) and in the control group (11%). Scores for quality of life increased in the exercise group (7%), whereas it remained unchanged in the control group (0%). There was a significant difference in quality of life score between the groups (p = 0.012). CONCLUSIONS: Low-intensity back-strengthening exercise was effective in improving the quality of life and back extensor strength in patients with osteoporosis.

Stronger back muscles reduce the incidence of vertebral fractures: a prospective 10 year follow-up of postmenopausal women.

The long-term protective effect of stronger back muscles on the spine was determined in 50 healthy white postmenopausal women, aged 58-75 years, 8 years after they had completed a 2 year randomized, controlled trial. Twenty-seven subjects had performed progressive, resistive back-strengthening exercises for 2 years and 23 had served as controls. Bone mineral density, spine radiographs, back extensor strength, biochemical marker values, and level of physical activity were obtained for all subjects at baseline, 2 years, and 10 years. Mean back extensor strength (BES) in the back-exercise (BE) group was 39.4 kg at baseline, 66.8 kg at 2 years (after 2 years of prescribed exercises), and 32.9 kg at 10 years (8 years after cessation of the prescribed exercises). Mean BES in the control (C) group was 36.9 kg at baseline, 49.0 kg at 2 years, and 26.9 kg at 10 years. The difference between the two groups was still statistically significant at 10 year follow-up (p = 0.001). The difference in bone mineral density, which was not significant between the two groups at baseline and 2 year follow-up, was significant at 10 year follow-up (p = 0.0004). The incidence of vertebral compression fracture was 14 fractures in 322 vertebral bodies examined (4.3%) in the C group and 6 fractures in 378 vertebral bodies examined (1.6%) in the BE group (chi-square test, p = 0.0290). The relative risk for compression fracture was 2.7 times greater in the C group than in the BE group. To our knowledge, this is the first study reported in the literature demonstrating the long-term effect of strong back muscles on the reduction of vertebral fractures in estrogen-deficient women.

Effect of gender, age, and anthropometry on axial and appendicular muscle strength.

OBJECTIVE: To assess age and gender differences in muscle strength. DESIGN: The strength of back extensors, upper limbs (grip), and lower limbs (knee extensors) was measured. Anthropometric measurements and body mass index also were assessed. RESULTS: Group comparisons were made for each decade. Back extensor strength (BES) in subjects aged 20 to 89 yr ranged from 93 to 832 N in men and from 71 to 440 N in women. BES peaked in the fourth decade for men and in the fifth decade for women. When the two genders were compared, muscle strength in women was less than that in men at all ages. At different decades, women's BES ranged from 54% to 76% compared with that of men's BES. There was a 64% loss of BES in men from the peak in their fourth decade (556 N) to the lowest level in their ninth decade (201 N). Women experienced a 50.4% loss from the peak in their fifth decade (306 N) to the lowest level in their ninth decade (152 N). CONCLUSIONS: Men had a greater loss of BES than women with increasing age. In both genders, there was more loss of BES than appendicular muscle strength. Reduction in BES in women coincided with increased body mass index in older age. In women, there was a negative correlation between body weight and level of physical activity, whereas this finding was not evident in men. Background factors related to a higher incidence of back pain, falls, and fractures, especially in women, may be a reduction in muscle strength, along with increasing age and body mass index. This cross-sectional study showed that physiologic reduction of muscle strength, which began early in life, later stopped and that muscle strength even improved, despite the aging process. Therefore, initiating strengthening exercises at any age is encouraged to prevent the impact of several age-related musculoskeletal challenges.

Bone mass and muscle strength in female college athletes (runners and swimmers).

OBJECTIVE: To determine whether female college athletes had increased muscle strength and bone mass in comparison with age-matched nonathletic female subjects and, if so, whether participation in weight-bearing versus non-weight-bearing exercise made a difference. MATERIAL AND METHODS: We performed a comparative statistical analysis of the bone mineral density (BMD) of the total body, lumbar spine, and femoral neck, maximal oxygen uptake (VO2max), muscle strength, and level of physical activity in 21 runners, 22 swimmers, and 20 control subjects. The study participants were female college students, 18 to 24 years old, who had had more than 8 normal menstrual cycles during the past year. RESULTS: Statistical analyses showed significantly higher VO2max in the two athletic study groups than in the control subjects (P < 0.0001). No significant difference in BMD was noted among the three groups. Total body BMD (r = 0.30; P = 0.02) and femoral neck BMD (r = 0.39; P = 0.002) were positively correlated with weight-bearing activity but not with non-weight-bearing activity. VO2Max (an index of physical fitness) was positively correlated with femoral neck BMD (r = 0.33; P = 0.009) and trochanteric BMD (r = 0.29; P = 0.021). Shoulder muscle strength (determined by isokinetic dynamometry) was positively correlated with total body BMD (r = 0.34; P = 0.007) and lumbar spine BMD (r = 0.28; P = 0.028). Swimmers had higher muscle strength in the back and upper extremities than did runners and control subjects. Hip girdle muscle strength was not significantly different among the three groups. Total body BMD had a positive correlation with percentage of body fat and height. Lumbar spine BMD was higher in subjects who had previously used oral contraceptives. The athletes had a lower percentage of body fat, were less likely to have used oral contraceptives, and had fewer years of normal menses than did the control subjects. CONCLUSION: Our study shows that (1) total body BMD and femoral neck BMD were significantly higher in the study group that performed weight-bearing exercises than in control subjects, (2) swimming exercise had no effect on BMD, and (3) although swimming is not a bone-building exercise, it can significantly improve shoulder, back, and grip muscle strength.

Site-specificity of bone mineral density and muscle strength in women: job-related physical activity.

We proposed that there are significant correlations between muscle strength and bone mineral density in premenopausal women and that these correlations are site-specific. To test this hypothesis, we examined the relationships among site-specific bone mineral density, physical activity, and muscle strength in a group of 96 healthy premenopausal Caucasian women. Bone mineral density was measured at the lumbar spine and at three sites in the proximal femur (trochanter, femoral neck, and Ward's triangle) with dual-energy x-ray absorptiometry and at the mid-radius with single-photon absorptiometry. The muscle strength of hip and spinal muscle groups was determined with a strain gauge isodynamometer, and grip strength was measured with the JAMAR dynamometer. The strength of shoulder girdle muscle groups was evaluated with the use of free weights. Physical activity was determined by surveying the subjects and by using a standardized scale. Data analysis revealed significant linear correlations of muscle strength with bone mineral density at the mid-radius (r = 0.31; P = 0.002) and at the hip (r = 0.26; P = 0.01). Grip strength was significantly correlated with bone mineral density of both the spine and the femur (r = 0.24, r = 0.34; P < 0.05 for both). Back extensor strength correlated with bone mineral density of the hip (Ward's triangle; r = 0.23; P = 0.023). However, there was no significant positive correlation between the strength of the spinal flexor or extensor muscles and the site-related bone mass (lumbar spine). Only one of the three components of the physical activity score (job) positively correlated with vertebral bone mineral density (r = 0.21; P = 0.04). Physical activity negatively correlated with age (r = 0.24; P = 0.02). We conclude that in premenopausal women, the effect of muscle strength on bone mass is more systemic than site-specific. A positive correlation between vertebral bone mass and components of physical activity demonstrates that even job-related physical activity is an important factor in maintaining adequate bone mass.

Musculoskeletal challenges of osteoporosis.

Reduction in the biomechanical competence of the axial skeleton can result in challenging complications. Osteoporosis consists of a heterogeneous group of syndromes in which bone mass per unit volume is reduced in otherwise normal bone, which results in more fragile bone. The geriatric population has an increased risk for debilitating postural changes because of several factors. The two most apparent factors are involutional loss of functional muscle motor units and the greater prevalence of osteoporosis in this population. Obviously, the main objective of rehabilitation is to prevent fractures rather than to treat the complications. These complications can vary from "silent" compression fractures of vertebral bodies, to sacral insufficiency fractures, to "breath-taking" fractures of the spine or femoral neck. The exponential loss of bone at the postmenopausal stage is not accompanied by an incremental loss of muscle strength. The loss of muscle strength follows a more gradual course and is not affected significantly by a sudden hormonal decline, as is the case with bone loss. This muscle loss may contribute to osteoporosis-related skeletal disfigurations. In men and women, the combination of aging and reduction of physical activity can affect musculoskeletal health, and contribute to the development of bone fragility. The parallel decline in muscle mass and bone mass with age is more than a coincidence, and inactivity may explain some of the bone loss previously associated with aging per se. Kyphotic postural change is the most physically disfiguring and psychologically damaging effect of osteoporosis and can contribute to an increment in vertebral fractures and the risk of falling. Axial skeletal fractures, such as fracture of the sacral alae (sacral insufficiency fracture) and pubic rami, may not be found until radiographic changes are detected. Management of chronic pain should include not only improvement of muscle strength and posture but also, at times, reduction of weight bearing on the painful pelvis with insufficiency fractures. Axial skeletal health can be assisted with improvement of muscular supportive strength. Disproportionate weakness in the back extensor musculature relative to body weight or flexor strength considerably increases the risk of compressing porous vertebrae. A proper exercise program, especially osteogenic exercises, can improve musculoskeletal health in osteoporotic patients. Exercise not only improves musculoskeletal health but also can reduce the chronic pain syndrome and decrease depression. Application of a proper back support can decrease kyphotic posturing and can expedite the patient's return to ambulatory activities. Measures that can increase safety during ambulatory activities can reduce risk of falls and fractures. Managing the musculoskeletal challenges of osteoporosis goes hand in hand with managing the psychological aspects of the disease.

Balance characteristics of persons with osteoporosis.

OBJECTIVE: People affected by osteoporosis are at particular risk for bone fractures caused by falls. Preventive intervention depends on first describing the risk factors for falls present in this population as a group and as individuals. In this preliminary study, balance characteristics of women with and without osteoporosis were measured with computerized dynamic posturography (CDP). DESIGN: A case control design was selected to compare the balance characteristics of each group of patients with osteoporosis. SETTING: Testing was performed in the vestibular assessment area of our multispecialty clinic. SUBJECTS: Patient groups were selected from within our case load. Ten women with osteoporosis were compared with six women with osteoporosis and kyphosis (Cobb angle more than 54 degrees) and with five age-matched normal subjects. INTERVENTIONS: Because this was an observational study, no interventions were used. MAIN OUTCOME MEASURE: Averaged results from all trials of sensory organization tests 5 and 6, with use of sway amplitude and balance strategy scores, were used to compare the performance of each patient group. RESULTS: Both groups with osteoporosis had different balance control strategies than the group without osteoporosis. Specifically, those with osteoporosis had greater use of hip strategies for maintaining balance than did the normal group. Those with kyphosis also had greater postural sway than either of the other two groups. CONCLUSION: Results of this study suggest that there are differences in balance control strategies and sway amplitude between patients with and those without osteoporosis. Further study is recommended in which CDP is used to clarify and confirm these differences. Individual CDP results can be used to optimize habilitative management of these patients.

Physical activity and four-year development of back strength in children.

Physical activity in children is important, both for its direct benefits and for establishing potentially lasting future behaviors. Understanding the development of back strength in children is also important, because decreased back strength is associated with low back pain in adults. We hypothesized the following: (1) a substantial percentage of children do not participate in adequate physical activity; (2) the development of back strength corresponds to the development of strength of appendicular muscles; (3) there is a positive relationship between physical activity and back strength. The study included 53 boys and 43 girls, aged 10 to 19 yr, who had undergone isometric strength testing 4 yr previously. From responses to a questionnaire, each child's level of physical and sedentary activity was calculated. Isometric back flexion and extension were measured with the same method used 4 yr previously. Statistical analyses were performed, including quadratic regressions to estimate the rate of increase in strength, height, and weight. The following results were found: (1) during the month before testing, 21 children participated in physical activity for less than 30 min/day; (2) the level of physical activity was significantly associated with back flexion and back extension (P = 0.03 for both); (3) the peak rate of increase in back strength occurred approximately 1 yr after the peak rate of increase in height. We conclude the following: (1) measures should be taken to increase the involvement of children in athletic activities; 2) physical activity may be important in the development of back strength; (3) the pattern of back strength development seems to be the same as that for development of muscles of the appendicular skeleton.

Low back pain and its relationship to back strength and physical activity in children.

OBJECTIVE: The objective of the study was to determine the occurrence of low back pain and its relationship to back strength and physical activity in children. METHODS AND MATERIALS: The study included 53 boys and 43 girls aged 10 to 19 years from a group of 116 children who had undergone isometric strength testing 4 years previously. No intervention was performed. Each child was asked five questions concerning low back pain. A questionnaire to quantify participation in athletic activities and manual labor was used as the basis for calculation of each child's activity level. Isometric back flexor and extensor strength were measured with the same method used 4 years previously. Statistical analyses were performed with appropriate correction for confounding factors. RESULTS: The frequency of low back pain and the relationship between low back pain and age, between low back pain and back strength, and between low back pain and physical activity were determined. There was a history of low back pain in 51%, and the frequency of low back pain in the past year was 35%. Eight percent of the children had been limited by low back pain, and 7% had seen a doctor for the pain. The first incident of low back pain occurred at a mean age of 12.3 years. The frequencies of a history of low back pain and of low back pain in the past year increased significantly with age (p = 0.02 and 0.01 respectively). Increased physical activity was significantly associated with a history of low back pain (p = 0.03), and increased back flexor strength was significantly associated with a history of low back pain and of low back pain in the past year (p = 0.03 and 0.008, respectively). The rate of low back flexor or strength over 4 years had a significantly positive association with the occurrence of low back pain in the past year (p = 0.008). CONCLUSIONS AND RELEVANCE: Low back pain is common in children, and, in contrast to adults, low back pain in these children was more common with increased physical activity and stronger back flexors. We believe the main causes of low back pain in children are musculotendinous strains and ligamentous sprains.

Correlation of trunk muscle strength with age in children 5 to 18 years old.

OBJECTIVE: To determine the correlation of trunk muscle strength with age in children and the effect of gender on changes in trunk muscle strength. MATERIAL AND METHODS: Strength of the back extensors and back flexors was evaluated in 137 healthy boys and 109 healthy girls who were 5 to 18 years old. Anthropometric determinations of height and weight were done in all study subjects. Maximal back muscle strength was measured with an isometric dynamometer (BID-2000). Standardized positioning techniques were used to allow comparison with the follow-up evaluations. RESULTS: Regression analysis revealed significant increases in trunk strength with increasing age; the strength of the boys began diverging from that of the girls at age 9 to 10 years. Back extensor strength also increased with increasing height and weight, and expected differences were noted between boys and girls. Strength levels ranged from 80 to 774 newtons (18 to 174 lb). Mean back extensor strength in 2-year age intervals ranged from 153 newtons (34.4 lb) in girls 5 to 7 years old to 504 newtons (113.3 lb) in boys 16 to 18 years of age. (Each newton is equal to 0.2248 lb.) CONCLUSION: Results of this study demonstrated that age, height, and weight are all important predictors of trunk strength in children, and the effects of these factors are modulated by gender.

Can strong back extensors prevent vertebral fractures in women with osteoporosis?

OBJECTIVE: To determine the influence of back extensor strength on vertebral fractures in 36 women with osteoporosis. DESIGN: We conducted a cross-sectional study of female patients with osteoporosis by assessing anthropometric variables, bone mineral density, muscle strength, level of physical activity, and radiographic findings in the spine. MATERIAL AND METHODS: The 36 study subjects with osteoporosis, who ranged from 47 to 84 years of age, satisfied specific inclusion and exclusion criteria that minimized confounding factors related to pathophysiologic features, diet, and medications. A physical activity score was determined for each subject on the basis of daily physical activities relating to homemaking, occupation, and sports. RESULTS: The range of the physical activity scores-from 2 to 13-indicated that no subject was involved in unusually demanding physical activities. Bone mineral density values ranged from 0.49 to 0.92 g/cm2. Thoracic kyphosis ranged from 31.0 to 84.0 degrees. Isometric strength of the back extensor muscles ranged from 7.3 to 34.0 kg. Statistical analysis demonstrated a significant negative correlation between the strength of the back extensor muscles and thoracic kyphosis. Significant negative correlations were also found between back extensor strength and the number of vertebral compression fractures and between bone mineral density and the number of vertebral fractures. CONCLUSION: The negative association between back extensor strength and both kyphosis and number of vertebral fractures suggests that increasing back strength may prove to be an effective therapeutic intervention for the osteoporotic spine. In persons with stronger back muscles, the risk of vertebral fractures will likely decrease.

Correlation of back extensor strength with thoracic kyphosis and lumbar lordosis in estrogen-deficient women.

Aging and osteoporosis have been associated with skeletal changes. Back extensor strengthening exercises are highly recommended for management of back pain, especially back pain related to osteoporosis. To our knowledge, the correlation of thoracic kyphosis, lumbar lordosis, and sacral inclination with back extensor strength, physical activity, and bone mineral density has not been critically studied in healthy, active, estrogen-deficient women. In a study of 65 such women (ages 48-65 yr), back extensor strength, bone mineral density, and physical activity score were evaluated and measured. These factors were then correlated with radiographic factors: (1) vertebral body ratios (anterior/posterior height) calculated for each vertebra from T-4 through L-5; (2) kyphosis index determined by adding the anterior heights of each vertebral body, T-4 through T-12, and then dividing the total by the corresponding sum of the posterior heights of each vertebral body; (3) thoracic kyphosis; (4) lumbar lordosis; and (5) sacral inclination. Back extensor strength had a significant negative correlation with thoracic kyphosis (r = -0.30, P = 0.019) and a positive correlation with lumbar lordosis (r = 0.26, P = 0.048) and sacral inclination (r = 0.34, P = 0.009). However, bone mineral density and physical activity score did not show any significant correlations with the radiographic factors. The results indicate that the stronger the back extensor, the smaller the thoracic kyphosis and the larger the lumbar lordosis and sacral inclination. We conclude that back extensor strength is an important determinant of posture in healthy women. However, prescribing back extensor strengthening exercises alone may also increase lumbar lordosis, which is not desirable.

Three-year controlled, randomized trial of the effect of dose-specified loading and strengthening exercises on bone mineral density of spine and femur in nonathletic, physically active women.

The objectives of this study were to evaluate (1) the effect of spinal muscle strengthening by loading exercises on the bone mineral density (BMD) of the spine, and (2) the effect of upper extremity loading exercises on the BMD of the midradius and femur in healthy, premenopausal women. The study design was a randomized, controlled trial of 3 years' duration. Ninety-six healthy, premenopausal, white women aged 30-40 years participated; 67 completed the study. All subjects were in good health (normal menses) and were active, but not athletic (that is, not involved in a regular sport activity). Subjects were randomized to an exercise or control group. The exercise group performed a supervised, non-strenuous, weight-lifting exercise program. Exercise performance was supervised once a week at the medical facility. In addition, the subjects performed the exercises twice a week on their own. Dietary calcium intake was to be maintained at 1,500 mg/day in both groups. Bone density was measured at the lumbar spine and hip with dual-energy X-ray absorptiometry at 0, 1, and 3 years. BMD of the midradius was measured with single photon absorptiometry. Measurements of muscle strength were obtained at baseline and every 3 months for 3 years. Maximal oxygen uptake was measured, and the level of physical activity was recorded. Compliance with the exercise program was excellent during the first year of the study, but decreased thereafter. At the end of 3 years, subject withdrawal was about 34% from the exercise group and about 22% from the control group (total subject withdrawal was about 30%). Muscle strength in the exercise group increased significantly at all involved skeletal sites (p values all < 0.001). There was a modest positive correlation between the BMD of Ward's triangle with spinal flexor strength (r = 0.32, p = 0.008) and with grip strength (r = 0.38, p = 0.001). Comparing study groups, we found no significant effect of the loading and nonstrenuous strengthening exercises in the exercise group or free physical activity group (our control group) on BMD at the spine, hip, or midradius measurement sites. In active, but not athletic premenopausal women, additional moderate weight-lifting exercises showed no significant effect on BMD.

Effect of physical activity on bone mass.

Maintenance of bone mass depends on several factors, including proper level of physical activity, hormones, and nutrition. Prescribing effective weight-training and weight-bearing exercise programs for improving bone mass is highly desirable. Specificity of each exercise program can contribute to an increment or reduction of bone mass. Cessation of physical activity induces rapid metabolic bone changes, although the effects on bone mass take time to develop. Therefore, weight-bearing and periodic high-intensity loading exercises are recommended for maintenance of bone mass in the spine and lower extremities. Patients who endure a period of immobility such as prolonged bed rest should resume their daily activities in addition to supervised exertional exercises. While research continues in an effort to find ways to increase bone mass despite aging and negative genetic factors, more focus can be given to building a solid skeletal foundation through good nutritional and exercise habits developed early in life.

Effect of back supports on back strength in patients with osteoporosis: a pilot study.

OBJECTIVE: To determine the effect of application of back supports on back strength in subjects with osteoporosis. DESIGN: In a prospective, randomized, controlled study, we compared compliance and evaluated changes in back strength in 45 women with osteoporosis who were older than 40 years of age and were randomly assigned to one of three groups: (1) postural exercise only, (2) postural exercise and a conventional thoracolumbar support, or (3) postural exercise and a Posture Training Support (PTS) (a weighted kypho-orthosis). MATERIAL AND METHODS: Of the 45 study participants, 15 were assigned to a PTS group, 15 to conventional thoracolumbar support, and 15 to no orthosis. All subjects were instructed in basic body mechanics and postural exercises. Back extensor strength, grip strength, and patient's physical activity were measured at baseline and at subsequent 8-week intervals for a 16-week period. Each patient's compliance during the study period was also recorded. RESULTS: compliance was poor among the thoracolumbar group; only 5 of the 15 subjects completed the study (P<0.001), in comparison with 11 of the 15 patients in the control group and all 15 in the PTS group. Analysis revealed statistically significant mean increases in back strength in the PTS group (23%) and the control group (13%) and a nonsignificant increase in the thoracolumbar group (15%), although poor compliance in the thoracolumbar group yielded insufficient power to detect a significant difference in this group. No statistically significant difference was found between the improvements in the PTS and control groups, possibly because of the small sample size in this pilot study. One patient who wore the PTS for only 4 hours a day rather than 8 hours had the largest percentage increase in back extensor strength of this group (78%). At 16 weeks, decreases in back strength of more than 5% below the initial measurements were noted in 1 of 11 subjects (9%) who completed the control arm of the study, 2 of 14 (14%) who completed the PTS arm, and 2 of 5 (40%) who completed the thoracolumbar arm. CONCLUSION: Compliance with use of the PTS was better than that with the thoracolumbar support. Back extensor strength may increase in patients who comply with the PTS and postural exercise program. We caution, however, that this pilot study requires replication in a larger series to determine the clinical and statistical generalizability of these findings to a wider population.

Effect of back-strengthening exercise on posture in healthy women 49 to 65 years of age.

OBJECTIVE: To evaluate the effect of back-strengthening exercise on posture in 60 healthy estrogen-deficient women. DESIGN: The 60 study subjects were randomly assigned to either an exercise or a control group, and various factors were assessed at time of enrollment in the study and at 2-year follow-up. MATERIAL AND METHODS: The 32 women in the exercise group were instructed in progressive back-strengthening exercises, whereas the 28 women in the control group had no exercise prescription and were asked to continue their usual physical and dietary activities. At baseline and 2-year follow-up examinations, back extensor strength was measured with a strain-gauge dynamometer, and lateral roentgenograms of the thoracic and lumbar areas of the spine were obtained to measure the angles of thoracic kyphosis, lumbar lordosis, and sacral inclination. The changes in radiographic measurements and back extensor strength were analyzed statistically. RESULTS: Back extensor strength increased significantly in both the exercise and the control groups, but no radiographic measurements were significantly different between these groups. The significant increase in back extensor strength in both groups of healthy women suggested that the original grouping did not accurately reflect the amount of exercise. Thus, the 60 subjects were reclassified for comparison on the basis of increase in back extensor strength--27 with more than or equal to the mean increase of 21.1 kg and 33 with less than 21.1 kg. Furthermore, each of these groups of subjects was subdivided on the basis of degree of thoracic kyphosis. Among the subjects with substantial thoracic kyphosis, those with a significant increase in back extensor strength had a significant decrease in thoracic kyphosis (-2.8 +/- 4.2 degrees; P = 0.041), whereas those with a small increase in strength had a nonsignificant increase in thoracic kyphosis (1.8 +/- 5.3 degrees). The increase in back extensor strength did not seem to affect mild degrees of kyphosis. CONCLUSION: Increasing the back extensor strength in healthy estrogen-deficient women helps decrease thoracic kyphosis.

Posture Training Support: preliminary report on a series of patients with diminished symptomatic complications of osteoporosis.

Back supports are often used to minimize or prevent complications of osteoporosis. Nevertheless, the few related studies to date reveal that the currently available thoracolumbar and lumbosacral supports have substantial limitations, including (1) poor compliance because of discomfort or restricted motion, (2) expense, (3) unacceptable cosmetic and aesthetic appearance, and (4) medical contraindications to the use of rigid supports. We report the initial results of a clinical trial of the Posture Training Support (a thoracolumbar support) in 29 women and 1 man with osteoporosis or osteopenia of the spine (ages 37 to 87 years), who were referred because of back pain or kyphosis. We hypothesize that this inexpensive, unobtrusive device promotes improvement in posture and reduces back pain either by acting as a proprioceptive reinforcer or by producing a force posteriorly below the inferior angles of the scapulae and thus decreasing the anterior compressive forces that are commonly exerted on the spine. Among the 23 patients who reported substantial back pain before use of the support, relief of the pain was "significant" in 17 and minimal in 6. Nineteen patients noted improvement in their posture. No patient reported worsening of back pain or posture, nor did any patient discontinue use of the device for cosmetic reasons, discomfort, or other complaints. Four patients previously could not tolerate other back supports, and 14 had previously used other supports without substantial improvement. These preliminary results suggests that the Posture Training Support may be of considerable symptomatic and prophylactic value to patients with osteoporosis who cannot tolerate conventional back supports.

Effect of electrical stimulation on lumbar paraspinal muscles.

Forty healthy, sedentary, premenopausal women were entered into a randomized, single-blind, controlled study to determine the effects of capacitively coupled electrical stimulation on the strength of the lumbar paraspinal muscles and the bone mineral in the lumbar spine. All were between 35 and 45 years of age and had normal physiologic estrogen. The study group received electrical stimulation over the lower lumbar paraspinal muscles for 30 minutes twice a day. Isometric strength of the lumbar paraspinal muscles was assessed with a strain-gauge dynamometer at entry and again after 3, 6, 9, and 12 months. Bone mineral was measured in the lumbar spine by dual-energy x-ray absorptiometry at entry and at 6 and 12 months. After 3 months, the median increase in isometric strength was 8.1% in the study group and 1.6% in the control group (P < 0.03). This initial difference was maintained during the remainder of the study. No further changes were seen between the two groups at 6, 9, and 12 months. It was concluded that capacitively coupled electrical muscle stimulation can, throughout a 1-year period, improve and maintain isometric strength of the lumbar paraspinal muscles independent of exercise, but it has no measurable effect on bone mass in the lumbar spine.

Physical activity, but not aerobic capacity, correlates with back strength in healthy premenopausal women from 29 to 40 years of age.

The correlation of muscle strength at various sites of the axial and appendicular skeleton with physical activity and aerobic capacity was assessed in women 29 to 40 years old. Muscle strength of the spine and upper extremities was determined with strain gauges in 96 healthy white women, and power grip was used as an indicator of upper extremity strength. The physical activity score, which reflected the level of daily weight-bearing activity and was based on a standardized scale, ranged from 3 to 15. Maximal oxygen uptake (aerobic capacity) was measured in 69 of the 96 subjects. The mean values for maximal oxygen uptake were 1.9 liters/min and 27.9 ml/kg per minute when normalized for weight. In general, muscle strength was significantly correlated between axial and appendicular sites; thus, the axial musculature usually represents overall muscle strength. Maximal oxygen uptake in milliliters per kilogram per minute was not correlated with back extensor strength or upper extremity strength. Physical activity score was significantly correlated with back extensor strength but not with maximal oxygen uptake (aerobic capacity) either in liters per minute or in milliliters per kilogram per minute. Thus, maximal oxygen uptake is an invalid marker for level of daily weight-bearing physical activity.