Trunk Control May Hold a Key to Balance and Fall Risk in Older Adults

Every year, one in three adults over the age of 65 experiences a fall, and the consequences can be devastating: hip fractures, hospitalization, loss of independence, and, in the worst cases, death. For decades, clinicians have relied on screening tools that measure balance from the outside in, timing how long it takes an older person to stand up, walk three meters, turn, and sit back down, or measuring how far they can reach forward before losing stability. A new cross-sectional study from Türkiye suggests that some of the most important information about fall risk may lie deeper, in the fine motor control of the trunk itself, the segment that connects the arms and legs and anchors the entire postural system.

The study, conducted by Pınar Oba of Yozgat City Hospital and the Faculty of Medicine at Sivas Cumhuriyet University, together with Musa Polat of Sivas Cumhuriyet University, and published in BMC Geriatrics, set out to answer a deceptively simple question: does the ability to precisely control the lumbopelvic region, the junction between the lumbar spine and the pelvis, correlate with measured balance performance in older adults? Crucially, the researchers did not stop at a simple correlation. They also accounted for a battery of physical, psychological, and behavioral factors that could confound the relationship, including physical activity levels, fear of falling, anxiety, depression, and general health status.

The technical centerpiece of the investigation was the pressure biofeedback unit, or PBU, a simple but well-established clinical device consisting of an inflatable cushion connected to a pressure gauge. When placed under the lumbar spine, the PBU converts subtle movements of the lumbopelvic region into readable pressure changes, allowing an examiner to quantify how accurately a person can perform targeted trunk movements. In this study, 76 participants aged 65 and older were asked to perform three distinct motor-control tasks: the posterior pelvic tilt, in which the pelvis is rocked backward to flatten the lumbar curve; the abdominal drawing-in maneuver, a subtle contraction of the deep abdominal muscles associated with spinal stabilization; and the trunk extension maneuver, which requires controlled activation of the back extensor muscles.

The researchers then compared these motor-control scores against three widely used balance assessments: the Berg Balance Scale, a fourteen-item gold-standard measure of functional balance; the Functional Reach Test, which quantifies the forward limit of stability; and the Timed Up and Go test, a speed-based measure of mobility that is a staple of fall-risk screening. Using established cutoff values, participants were classified as being at either low or high risk on each measure. The results painted a striking picture: 53.9 percent of the cohort was classified as high risk by the Functional Reach Test cutoffs, 30.2 percent by the Timed Up and Go test, and 23.6 percent by the Berg Balance Scale.

When the researchers cross-tabulated motor-control performance against these risk categories, one task stood out with particular clarity. Performance on the trunk extension maneuver was significantly poorer in every high-risk group, regardless of which balance instrument defined the risk, with p-values ranging from 0.001 to less than 0.001. Posterior pelvic tilt performance was also reduced in the high-risk groups defined by the Timed Up and Go test and the Berg Balance Scale, with p-values between 0.03 and 0.002. In contrast, performance on the abdominal drawing-in maneuver, the task most often associated with so-called core stability training, showed no significant association with any of the balance measures at all.

This last finding may be the most provocative in the entire study. The abdominal drawing-in maneuver has occupied a central place in rehabilitation orthodoxy for decades, on the theory that retraining the deep abdominal muscles restores spinal stability and, by extension, balance. Yet in this cohort of older adults, the ability to perform the maneuver did not track with balance performance once other factors were considered. The trunk extension maneuver and the posterior pelvic tilt, by contrast, correlated significantly with all three balance measures, with p-values ranging from 0.004 to 0.015, and these associations held firm in multivariable regression models that adjusted for age-related confounders, with p-values from 0.01 to less than 0.001.

The psychological and behavioral dimensions of the study add an equally important layer. Participants in the high-risk groups scored lower on the International Physical Activity Questionnaire and on the Tinetti Fall Efficacy Scale, which measures confidence in performing daily activities without falling. Depression scores on the Hospital Anxiety and Depression Scale were elevated only in the high-risk group defined by the Timed Up and Go test, suggesting that mood may interact with mobility more directly than with balance measured in static conditions. In the regression analyses, physical activity emerged as the only independent predictor among these psychosocial variables, associated with Functional Reach Test scores with a standardized beta of 0.40 and a p-value below 0.001, a moderate effect size that underscores how strongly an active lifestyle reinforces the limits of stability.

From a biomechanical standpoint, the findings make intuitive sense. Postural control is fundamentally a multisegmental enterprise: the nervous system continuously coordinates ankle, knee, hip, and trunk strategies to keep the center of mass over the base of support. The trunk, as the central link between upper and lower extremities, contributes both sensory information and mechanical output to this process. The ability to perform a controlled trunk extension, which loads the paraspinal muscles eccentrically and concentrically while stabilizing the pelvis, may reflect the integrity of precisely the neuromuscular circuits that generate hip and trunk strategies when the balance system is challenged. A pelvic tilt task, similarly, demands isolated control of the lumbopelvic rhythm that underlies weight shifting during walking and reaching.

The study’s cross-sectional design imposes the usual caveats. Correlation cannot establish directionality: poor trunk control may contribute to poor balance, or the causal arrow may point the other way, with declining balance leading to disuse and deconditioning of the trunk musculature. The sample of 76 participants, though adequate for the exploratory regression models used, is modest, and the PBU, while validated in clinical settings, is a coarser instrument than laboratory-grade motion capture or electromyography. The authors also relied on self-report questionnaires for physical activity and psychological state, which are subject to recall and response biases. Still, the consistency of the trunk extension finding across all three independent balance measures, and its survival in adjusted models, lends the result a robustness that many single-measure studies lack.

The practical implications are tantalizing for clinicians and researchers alike. If larger longitudinal studies confirm these associations, pressure biofeedback assessment of lumbopelvic motor control could become a low-cost addition to fall-risk screening, performed in minutes with an inexpensive inflatable device in almost any clinic or community setting. More speculatively, targeted training of trunk extension control and pelvic tilt precision, rather than generic core-strengthening programs, might offer a more direct route to preserving balance in aging populations. For now, the study’s central message is clear enough: when it comes to staying upright in later life, the strength of the legs and the sharpness of the vestibular system are only part of the story. The trunk, long treated as a passive link between limbs, may deserve a far more active role in how we assess, and perhaps ultimately prevent, the falls that shadow old age.

Subject of Research: Lumbopelvic motor control and postural balance in older adults

Article Title: The association between task-specific lumbopelvic motor-control performance assessed using pressure biofeedback and postural control in older adults considering physical, psychological, and behavioral factors: a cross-sectional study

Article References: The association between task-specific lumbopelvic motor-control performance assessed using pressure biofeedback and postural control in older adults considering physical, psychological, and behavioral factors: a cross-sectional study. (n.d.). https://doi.org/10.1186/s12877-026-08335-4

Image Credits: AI Generated

DOI: 10.1186/s12877-026-08335-4

Keywords: lumbopelvic motor control, pressure biofeedback, postural control, fall risk, older adults, balance assessment, Berg Balance Scale, Timed Up and Go test, trunk extension, physical activity, fear of falling, geriatrics