Determining the Effects of a 4-Week Structured Strength and Flexibility Exercise Program on Functional Status of Subjects with Osteoporosis
Osteoporosis is a systemic disease resulting in low bone mineral density, increased risk of fractures, and falls, muscle weakness, and compromised balance. Nutrition and physical exercise have been shown to be effective in the treatment of low bone mineral density and, with more severe osteoporosis, as adjuncts to pharmaceutical treatments. However, living with osteoporosis may diminish an individual’s ability and confidence to perform activities that enhance bone density.
This study investigated the following question: In women with osteoporosis, will there be a greater improvement in balance, lower-extremity strength, mobility, and confidence in performing ambulatory activities after participating in a structured exercise program as compared to a control group?
This was a prospective comparative trial in which 48 women who had a confirmed diagnosis of osteoporosis were enrolled in either an exercise group (a 4-week exercise program) or a control group (no structured exercise). Functional outcomes using valid and reliable tools were measured before and after exercise in the study group and at comparable times in the control group. Differences in function were assessed by paired t tests to evaluate group differences in functional outcomes.
Of the 48 women recruited, 45 completed the study. Women in the exercise group (n = 27) demonstrated an increase in balance and lower-extremity strength over women in the control group (n = 18). Both groups showed an increase in mobility but no change in confidence in ambulation.
This study showed that women with osteoporosis demonstrated improved balance and lower-extremity strength after participating in a structured exercise program. These changes may be important in improving overall functional status.
Keywordsosteoporosis functional status activity-specific balance chair stand test balance test timed up and go
Osteoporosis is a systemic disease resulting in low bone density, increased risk of fractures and falls, muscle weakness, and compromised balance [8, 20]. The World Health Organization defines osteoporosis as a bone mineral density (BMD) value that is more than 2.5 standard deviation (SD) units below the mean BMD value for a young gender- and race-matched reference group . According to the Centers for Disease Control and Prevention, 48.3% of US adults age 65 and older during 2005 to 2010 had osteoporosis of the lumbar spine or femoral neck .
Nutrition and physical exercise have been shown to be effective in the treatment of low bone mass and, along with pharmaceutical treatments, of more severe osteoporosis [8, 10, 15, 16, 19]. Positive effects of structured exercise on strength and flexibility have been reported . Resistive exercises, in conjunction with whole-body vibration and proprioceptive exercise, appear to slow BMD loss in post-menopausal women with low bone mass [12, 17]. A combination of walking, resistance training, impact exercises, and aerobic exercises is recommended for enhancement of hip and spine BMD . However, living with osteoporosis may have a debilitating effect on an individual’s confidence to perform the activities necessary to enhance BMD. Fear of sustaining a fracture can lead to reduced physical activity in people with osteoporosis. A lack of activity leads to reduced lower-extremity strength and balance, which, in turn, produces a decline in functional status, a phenomenon that has not been studied. In a systematic review regarding the effects of exercise on low bone mass/osteoporosis, Howe et al. identified 43 randomized controlled trials with a combined total of more than 4000 participants, although none of the studies included functional status as an outcome measured .
Therefore, this study sought to assess changes in physical function and confidence in individuals with osteoporosis when performing ambulatory activities after participating in a structured exercise program. The specific aims were to determine whether there were improvements in balance, lower-extremity strength, mobility, and confidence in performing ambulatory activities following participation in a 4-week exercise program as compared to a control group.
This study was designed as a prospective comparative cohort trial to evaluate the Helen Hayes Hospital Strong Bones, Stronger Me (HHH SBSM) exercise program and was approved by the hospital’s institutional review board. The study used a prospective design to compare subjects with osteoporosis enrolled in the HHH SBSM program and a concurrent matched control group of patients being treated at the Hospital’s Osteoporosis Center. Informed consent was obtained from all participants. There was a $96 fee for participation in the exercise program.
We recruited 48 women between 55 and 80 years old with a diagnosis of osteoporosis confirmed by BMD test (T score more than − 2.5 standard deviations below normal): 30 participants in the exercise group and 18 in the control group. All subjects who needed an assistive device for ambulation (n = 2), former participants of the SBSM program, or women who also participated in a structured exercise program or class outside of HHH were excluded (n = 1). Study group subjects who missed a maximum of two of eight sessions were given the opportunity to complete these sessions by adding an additional week to the program. Three study group subjects who could not complete all eight sessions because of scheduling conflicts were not included in the study. Control group subjects, who were diagnosed with osteoporosis and did not participate in structured exercise, were matched to subjects in the study group by gender, age (± 5 years), and history of previous non-traumatic fracture (yes or no).
For the study group, data collected 1 to 7 days before the first exercise session included baseline assessments using the validated scales described below. These scales measured balance, lower-extremity strength, mobility, and confidence in performing ambulatory activities for the study group. Post-program assessments were obtained within 7 days of completion of the last exercise session. Baseline and post-program assessments on control group subjects were performed 4 to 5 weeks apart. All assessments were administered by three doctor of physical therapy (DPT) students who were trained for up to 2 h each by the principal investigator (PI) to administer tests. Whenever possible, the same assessor performed pre- and post-program assessments for the same subject. The DPT students recruited subjects for the control group. The recruiting student did not test the subjects he or she recruited.
The following valid and reliable outcome measures were used.
Berg Balance Scale
The Berg Balance Scale (BBS) is a 14-item scale designed to measure balance in adults in a clinical setting. The lowest score that applied for each category was recorded. In each item, points were deducted if the time or distance requirements were not met, the subject’s performance required supervision, or the subject required assistance from a supportive device or the examiner. A score from 0 to 20 represents balance impairment, 21 to 40 represents acceptable balance, and 41 to 56 represents good balance. The BBS has been shown to be a valid and reliable assessment [15, 16]. The BBS has a high relative reliability, with inter-rater reliability estimated at 0.97 (95% CI 0.96 to 0.98) and intra-rater reliability estimated at 0.98 (95% CI 0.97 to 0.99) .
Chair Stand Test
The Chair Stand Test (CST) is used to measure lower-extremity muscle strength. The subject is asked to complete as many sit-to-stand movements from a standard chair, without the use of upper extremities, as possible in 30 s. Higher numbers on this test reflect greater muscle strength. The test is valid and reliable as a measure of lower-extremity strength and as a predictor of falls [1, 13]. The reliability of CST has been reported at between 0.84 and 0.92 .
Timed Up and Go Test
The Timed Up and Go (TUG) test is used to assess mobility in older adults. It is performed indoors, on a flat surface, with no obstacles. Subjects stand up from a standard armchair, walk a distance of 3 m, and return to the chair. Time to completion is recorded, with faster times showing improved mobility. The subject has one practice trial prior to the test and must use the same assistive device each time the test is performed. The TUG test has been shown to be a valid and reliable assessment [6, 7, 8, 9, 10, 11, 12] and has shown intra-rater and inter-rater reliability (r = 0.93 and 0.96, respectively) .
Activities-Specific Balance Confidence Scale
Group differences in demographics and performance at baseline were assessed using Student’s t tests. Within-subject changes or differences for each test were assessed with Student’s paired t tests. Alpha level was set at ≤ 0.05. All analyses were performed using SAS version 6. Power analysis was based on data from a study by Patil et al. , which determined that a sample size of 26 would yield 80% power to detect significant within-subject differences for study outcomes.
Baseline characteristics and physical function in the control group and the Strong Bones Stronger Me (SBSM) exercise group (mean ± SD)
Control (n = 18)
SBSM (n = 27)
68.8 ± 6.8
68.1 ± 5.7
63.5 ± 3.1
63.7 ± 2.2
134.3 ± 22.4
142.6 ± 22.2
24.0 ± 3.6
25.3 ± 3.9
BBS score (0–56)
52.4 ± 3.5
51.3 ± 4.2
CST (# repetitions)
13.8 ± 3.2
12.1 ± 2.9
TUG (time in sec)
8.3 ± 1.7
8.6 ± 2.0
91.8 ± 8.4
90.2 ± 6.7
Physical function post-test values in the control group and Strong Bones Stronger Me (SBSM) exercise group (mean ± SD)
Control mean (n = 18)
Control SD (n = 18)
SBSM mean (n = 27)
SBSM SD (n = 27)
BBS (0 to 56)
The study showed improvement in balance and lower-extremity strength in women with osteoporosis who attended the eight-session SBSM exercise program. The program may provide tools to help people with osteoporosis to overcome fear of injury and to participate in strength and balance programs in their efforts toward improving physical function, perhaps even bone health. The program was designed on the principles of progressive resistive and weight-bearing exercises to maximize bone stimulation. Free-weights ranging from 1 to 5 pounds were used to produce specific functional strength in shoulder and elbow muscles . Elastic bands and exercise balls were used to target back extensor and shoulder girdle muscles in order to achieve postural correction and thoracic stability . Sit-to-stand and Pilate’s hip exercises improved balance and stability, which was measured using the BBS and CST . Mat exercises were specific to improving upper- and lower-abdominal muscle strength and lumbar stability. A 4-in. step was utilized for step exercises to improve hip, knee, and ankle strength, coordination, and balance. These components of the SBSM program produced positive changes after 4 weeks in balance and lower-extremity strength, measured using the BBS and CST, respectively. Sit-to-stand and step exercises were used to improve mobility, measured using the TUG test; however, the SBSM and control groups showed similar improvements in TUG test scores. Participants reported improved confidence in performing exercises and ambulatory activities in general, although this change was not reflected in improved ABC scores, perhaps because of a ceiling effect (i.e., baseline ABC scores were already at or above 90 out of 100).
This study had limitations. Blinding was not possible for this study, and so both the subjects and the students performing the recruitment and assessment knew participants’ group status. However, the standardized nature of the tests should preclude observer bias. Inter- or intra-rater reliability was not assessed in this study, although prior reports indicate that the tests used are highly reliable. The sample size was small, although our power analysis showed adequate numbers. Potentially, a longer-term study might be able to determine whether or not confidence in performing ambulatory activities would improve in the SBSM group. Finally, both the SBSM and control groups were relatively high functioning, with high baseline scores on balance for both groups on the BBS (over 50 out of 56 at baseline) and the ABC scale (over 90%). It is unknown whether the SBSM program would benefit a more compromised population.
Dohrn et al. conducted a randomized controlled trial on 91 participants to study short- and long-term effects of balance training in community-dwelling older adults with osteoporosis . The study concluded that short-term balance training improved habitual physical activity but did not produce significant changes in gait speed, balance performance, or fall risk, for which a structured physical activity program was required. Our study was able to demonstrate a change in balance and strength through a structured exercise program.
In a similar study to determine the effects of a simple exercise program on balance and strength in post-menopausal women with osteoporosis, Otero et al. concluded that low-intensity exercises using readily available equipment can significantly improve strength and balance in women with osteoporosis . Their study lasted for 6 months and used balls, seats, mats, ropes, and domestic dumbbells made of bottles filled with water or sand. Our program was highly structured and included body mechanics and nutrition-based education. Duckham et al. conducted a randomized controlled trial of the effectiveness of community group and home-based falls prevention exercise programs on bone health in older people and concluded that a more intense and structured program was required to improve BMD and reduce fall risk . Our exercise program provided a structured exercise regimen that improved functional outcomes even after only 4 weeks.
In conclusion, there is data to support that bone health can be improved by exercise, nutrition, and medication. However, fear of sustaining a fracture can become a barrier to movement and exercise. This inactivity leads to loss of flexibility, strength, and balance, which, in turn, increases fall risk and incidence of fractures. This study showed that a structured exercise program with education on correct body mechanics improved balance and lower-extremity strength in individuals with osteoporosis. Individuals’ confidence in performing ambulatory activities did not change after participating in our 4-week exercise program, although baseline values were already high.
Compliance with Ethical Standards
Conflict of Interest
Payal Sahni, PT, DPT, MCMT, and Jeri W. Nieves, PhD, declare that they have no conflicts of interest.
All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2013.
Informed consent was obtained from all patients for being included in this study.
Required Author Forms
Disclosure forms provided by the authors are available with the online version of this article.
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