Objective Osteoporosis is widely recognized as a prevalent skeletal condition among women after menopause, resulting in reduced bone mineral density (BMD) and a heightened risk of fractures, and reduced quality of life (QoL). Impaired back extensor muscle function can exacerbate postural deformities, pain, functional limitations, and reduced social participation. Despite growing evidence on muscle function, the specific roles of back extensor muscle strength and endurance in different QoL domains remain unclear. This study aimed to investigate the associations between back extensor muscle strength and endurance and multiple domains of QoL in postmenopausal women with osteoporosis.
Materials & Methods In this cross-sectional study, 56 postmenopausal women aged 50–70 years with osteoporosis (T-score ≤ -2.5) were recruited via convenience sampling from an outpatient osteoporosis clinic. Back extensor muscle strength was measured using a back–leg–chest dynamometer, and endurance was assessed with the timed loaded standing test. QoL was evaluated using the QUALEFFO-41 questionnaire covering pain, physical function, social function, general health, and mental health. Descriptive statistics (mean±SD) summarized demographic and clinical characteristics. Pearson correlation coefficients (PCC) were used to examine relationships between muscle function and QoL domains, with significance set at P<0.05.
Results Participants had a mean age of 64.09±6.42 years and a mean body mass index (BMI) of 26.34±12.3 kg/m². Muscle endurance showed significant negative correlations with pain (PCC=-0.622, P<0.001), physical function (PCC=-0.501, p < 0.001), social function (PCC=-0.409, P =0.007), mental health (PCC=-0.441, P=0.003), and total QoL score (PCC=-0.628, P <0.001). Muscle strength had weaker negative correlations with pain (PCC=-0.350, P=0.023), physical function (PCC=-0.452, P =0.003), and total QoL (PCC=-0.351, P =0.023), and was not significantly associated with other domains. Neither strength nor endurance showed significant associations with general health (P >0.05).
Conclusion Back extensor muscle endurance is more strongly and broadly associated with multiple QoL domains than muscle strength in postmenopausal women with osteoporosis. These findings highlight the importance of prioritizing endurance training in rehabilitation programs to enhance physical, psychological, and social well-being and to promote functional independence in this population.