Electromagnetic field versus circuit weight training on bone mineral density in elderly women
Abstract Clinical Interventions in Aging Volume 10 pages539-548 Published March 9, 2015
Background and purpose: Osteoporosis is a common skeletal disorder with costly complications and a global health problem and one of the leading causes of morbidity and mortality worldwide. Magnetic field therapy and physical activity have been proven as beneficial interventions for prevention and treatment of osteoporosis. The purpose of this study was to compare the response of bone mineral content and bone mineral density (BMD) in elderly women to either low-frequency low-intensity pulsed magnetic field (LFLIPMF) or circuit weight training (CWT) on short-run basis (after 12 weeks).
Patients and methods: Thirty elderly women, aged 60–70 years, were randomly assigned into two groups (magnetic field and CWT) (n=15 each group). The session was performed three times per week for magnetic field and CWT groups, for 12 weeks. BMD and bone mineral content of lumbar spine (L2–L4) and femoral neck, trochanter, and Ward’s triangle were evaluated before and after 12 weeks of treatment.
Results: Both magnetic field and CWT for 12 weeks in elderly women seem to yield beneficial and statistically significant increasing effect on BMD and bone mineral content (P<0.05). But magnetic field seems to have more beneficially and statistically significant effect than does CWT.
Conclusion: It is possible to conclude that LFLIPMF and CWT programs are effective modalities in increasing BMD but LFLIPMF is more effective in elderly women.
Introduction
Strength training is one of the most frequent types of exercise programs applied in order to improve BM in elderly people. The increased mechanical stress on the bone provided by this type of training has been demonstrated as a causal factor of osteogenesis.16
To our best knowledge, enough data are not available comparing the effects of electromagnetic field and circuit resistance training on BMD and BMC. This study was therefore designed to compare the effects of electromagnetic field and circuit weight training (CWT) on BMD and BMC in elderly women.
Patients and methods
Subjects
Thirty sedentary elderly women whose age ranged from 60 to 70 years were screened and selected randomly from outpatient clinic, Faculty of Physical Therapy, Cairo University, to participate in this study. Participants were randomly assigned to two equal groups: group A (n=15) received electromagnetic field and group B (n=15) received CWT. They participated in the study for 12 weeks (three sessions/week).
Outcome measures
Both groups underwent an identical battery of tests: baseline (pretreatment) and after-treatment program (3 months posttreatment). The evaluated parameters include BMD and BMC of femoral neck, trochanter, Ward’s triangle, and lumbar spine (L2–L4). The assessors were initially blinded to the participants’ treatment assignments. All the subjects in the two groups were advised to continue their medications regimen, diets, and daily living physical activity level until the end of the study.
Interventions
Both treatment programs were conducted for participants three times per week for 12 weeks in the outpatient clinic, Faculty of Physical Therapy, Cairo University.
Electromagnetic field
Subjects received their medications plus low-frequency, low-intensity pulsed electromagnetic field (PEMF) therapy three times per week for 3 months. The therapy session involved the following:
The subject was placed in a comfortable supine position over the motorized bed.
The options of the appliance were adjusted to very low frequency (33 Hz) and very low intensity (50 Gauss), for 30 minutes, according to the manual of installation.
Circuit weight training program
The exercise program was determined in accordance with the American College of Sport Medicine (ACSM) guidelines. Sufficient warm-up and cooldown (about 5–10 minutes) in the form of stretching of major muscle groups, flexibility movements, active movements of limbs, breathing exercises, and walking at low intensity (50% of maximum heart rate) were performed before and after CWT. CWT exercises program was performed 30–38 minutes. The program started and progressed gradually in intensity. All 30 participants showed good adherence and acceptance to complete the program. No serious adverse effect was reported in either group.
Results
Subjects in both groups improved in their BMC and BMD of neck of femur after treatment, but there was significantly more improvement in the electromagnetic field group (32.05% and 15.58% vs 1.93% and 3.24%, respectively, for CWT group). Subjects in both groups improved in their BMC and BMD of trochanter after treatment, but there was significantly more increase in BMC and BMD in the electromagnetic field group (21.25% and 20.31% vs 1.36% and 2.58%, respectively, for CWT group). The BMD of Ward’s triangle increased in both groups, but with more significant increase in the electromagnetic field group (32.14%) than in the CWT group (4.03%). Concerning the BMC and BMD of L2, L3, and L4, subjects in both groups improved significantly after treatment, but posttreatment scores were significantly different between the two groups for these variables, with electromagnetic field group showing better improvement (18.06% and 32.25% for L2 BMC and BMD; 23.63% and 23.95% for L3 BMC and BMD; 35.57% and 27.55% for L4 BMC and BMD) than CWT group (0.4% and 2.27% for L2 BMC and BMD; 0.53% and 2.5 for L3 BMC and BMD; 0.24% and 2.58% for L4 BMC and BMD).
Discussion
The improvement of BMC and BMD after electromagnetic field exposure could be attributed to its piezoelectric effect on bone cells, which stimulates calcium deposition in bone. This is supported by the findings of Carpenter and Ayrapntyan,23 who concluded that the application of electromagnetic field results in the flow of ionic electric current in bone tubules which acts as an action potential to bone marrow to generate blood and collect calcium. These electrical impulses direct bone growth and the formation of bone cells through calcium deposition.
Results of our study are in agreement with those of Darendeliler et al24 who proposed a number of different mechanisms by which electromagnetic field affects bone tissue: first, it has been shown to stimulate calcification of the fibrocartilage. Second, the increased blood supply that arises due to the effect of electromagnetic field on ionic calcium channels has been implicated as a reason for improved bone healing. Third, electromagnetic field has been suggested as having an inhibitory effect on the resorption phase on bone repair, leading to the early formation of osteoids. A fourth mechanism by which electromagnetic field is thought to have an effect on bone repair is its influence on increasing the rate of bone formation by osteoblasts.
Furthermore, several cellular mechanisms, including increases in growth factors, increases in mineralization, angiogenesis, collagen production, and endochondral ossification, result from electromagnetic field stimulation. Also, it has been shown that there is a decreased osteoclastic activity following electromagnetic field exposure.25 The neurophysiological effects of PEMF on bone tissue has been explained by Selvam et al26 who stated that PEMF has been shown to positively affect
enzyme-based processes at the cellular level and stimulate growth factors involved in cellular repair and bone formation. Every cell membrane carries an electromagnetic charge, and PEMF alters this charge by causing the movement of ions across the cell membrane. PEMF has been shown to exert an anti-inflammatory effect through restoration of plasma membrane calcium ATPase activity.