This article was written by Jeff Minerd and originally appeared on medpagetoday.com
High-intensity resistance and impact training (HiRIT) improved bone mineral density and physical strength in postmenopausal women with low bone mass, without causing any fractures, researchers reported.
Compared with women who undertook a low-intensity exercise program, those in the HiRIT group experienced bone mineral density (BMD) increases at the lumbar spine (2.9% versus -1.2%, P<0.001) and femoral neck (0.3% versus -1.9%, P=0.004), said Belinda Beck, PhD, of Griffith University in Queensland Australia, and colleagues.
The HiRIT group also had greater improvements in leg extensor strength (37.1% versus 5.1%, P<0.001), back extensor strength (36.3% versus 10.9%, P<0.001), and other measures of functional performance, they wrote online in the Journal of Bone and Mineral Research.
The only adverse event reported in the HiRIT group was a single lower back spasm, the authors said. "Importantly, no fractures or major adverse events were observed, suggesting HiRIT may be safe for postmenopausal women with low to very low bone mass, despite previous safety concerns."
"The limiting feature of high-intensity resistance training in this demographic has traditionally been the perceived increased risk of fracturing fragile bone with heavy loading. We believe this overly conservative approach has contributed to an unnecessary stagnation in the field," Beck's group explained. "The evidence from the LIFTMOR [Lifting Intervention for Training Muscle and Osteoporosis Rehabilitation] trial that high-intensity loading can indeed be tolerated by postmenopausal women with low to very low bone mass justifies a quantum change in attitude in this regard."
The gradual introduction of loading, close ongoing supervision, and focus on correct technique were key to the success of the exercise program, the researchers said.
"We do not recommend individuals with low bone mass undertake the LIFTMOR protocol in an unsupervised environment, even after notable training, because it is not possible to self-monitor technique," they cautioned.
The trial included 101 postmenopausal women (average age 65) with low bone mass (T-score < -1.0). Women with a fracture within the last year, back pain, less than 5 years of menopause, or conditions such as diabetes known to influence bone loss were excluded. They were randomized 1:1 to 8 months of twice-weekly, 30-minute, supervised group sessions of HiRIT or a home-based, low-intensity exercise program.
The HiRIT program consisted of resistance exercises such as the deadlift, overhead press, and back squat, performed in five sets of five repetitions. The impact loading exercise was a jumping chin-up with a drop landing. The low-intensity exercise program consisted of lunges, calf raises, standing forward raises, and shrugs, as well as various stretches.
The primary outcomes were changes in BMD at the lumbar spine and femoral neck. Other outcomes included anthropomorphic measurements such as height and body weight as well as measurements of physical performance.
The HiRIT group had an increase in height compared with the control group (0.2 cm versus -0.2 cm, P=0.004). There was no significant difference between the groups for body weight, the study found.
"Although the current intervention did not have sufficient power to examine falls, improvements were nevertheless observed in characteristics that reduce the risk of falling, namely muscle strength and functional and neuromuscular performance," Beck's group stated. "Improvements in those functional performance scores therefore suggest HiRIT may not only reduce the risk of fracture by enhancing parameters of bone strength but by preventing falls in postmenopausal women with low bone mass."
Study limitations included the fact that it was not adequately powered to assess safety as an outcome. In addition, study participants were relatively healthy, as women with underlying musculoskeletal and serious cardiovascular comorbidities were excluded, they said.
"We therefore recommend circumspection when applying our findings beyond the sample demographic and appropriate screening for contraindications to high-intensity resistance and impact training," they advised.
"In conclusion, the LIFTMOR trial is the first to show that a brief, supervised, twice-weekly HiRIT exercise intervention was efficacious and superior to previous programs for enhancing bone at clinically relevant sites, as well as stature and functional performance of relevance to falls in postmenopausal women with low to very low bone mass," the researchers said. "Further, that no fractures or other serious injuries were sustained by any participant in our study suggests that HiRIT does not pose a significant risk for postmenopausal women with low bone mass when closely supervised, despite a common misconception to the contrary."
"In light of the very positive bone, function, safety, and feasibility outcomes of the LIFTMOR trial, we believe HiRIT to be a highly appealing therapeutic option for the management of osteoporosis in postmenopausal women with low to very low bone mass," they added.