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

Gait initiation is a deceptively complex act. The nervous system must shift the body’s center of mass forward and toward the swing limb, unweight the trailing leg, and generate carefully sequenced bursts of muscle activity, all within a few hundred milliseconds. During this window, sensory receptors embedded in muscles, tendons, joints, and skin fire continuously, informing the central nervous system about joint position, movement velocity, and load. Researchers have long measured how quickly muscles respond to perturbations in people with chronic ankle instability, but far less attention has been paid to the afferent side of the circuit — the incoming stream of proprioceptive signals that arrives before any muscle can react. Because direct recordings of these nerve signals in humans are ethically and technically impractical, the research team turned to a computational approach.

The study combined detailed biomechanical analysis of gait initiation with a neurophysiological model of proprioceptor behavior. Participants, including individuals with chronic ankle instability and healthy controls, walked in a motion capture laboratory equipped with force plates that recorded the ground reaction forces beneath each foot. From the movement trajectories and forces, the researchers reconstructed the mechanical events inside and around the ankle joint: changes in joint angle, angular velocity, muscle fascicle length, and the deformation of skin and joint capsules. These mechanical variables were then fed into mathematical models describing how different classes of proprioceptive afferents translate mechanical deformation into trains of neural impulses.

The models captured the behavior of several key sensory populations. Muscle spindles, the primary detectors of muscle length and stretch velocity, were modeled with their characteristic dynamic and static response components. Golgi tendon organs, which signal tensile load within tendons, were modeled as force-sensitive elements. Cutaneous and joint mechanoreceptors, which fire in response to skin stretch and joint capsule deformation, were included as well. Each model produced an estimate of instantaneous firing rate — effectively, a simulated neurogram of what the ankle’s sensory apparatus was telling the spinal cord and brain at every millisecond of the gait initiation sequence.

The central finding is striking: in individuals with chronic ankle instability, the estimated timing of proprioceptive afferent activity was systematically altered during the anticipatory postural phase of gait initiation. Whereas healthy participants showed well-organized, temporally structured afferent volleys that preceded and accompanied the postural adjustments needed to step forward, the unstable ankles displayed shifts and distortions in these signal patterns. In practical terms, the sensory information reaching the nervous system about the ankle’s position and loading arrived in a different temporal pattern than in uninjured joints. Because the nervous system depends on precisely timed sensory feedback to calibrate motor commands, even modest shifts in afferent timing could degrade the coordination of the postural adjustments that keep the body balanced during the transition to stepping.

The researchers emphasize that the disruption is not simply a matter of weaker signals. The models suggested changes in the relative timing between different receptor populations, meaning that the brain may receive internally inconsistent information about what the ankle is doing. Muscle spindle signals indicating one joint position may arrive in a different relationship to cutaneous signals than the nervous system has learned to expect. This form of sensory reweighting or desynchronization is thought to be a hallmark of the maladaptations that follow ligament injury, when damaged mechanoreceptors in the torn ligament are lost and remaining receptors must compensate — often imperfectly — for the missing input.

What makes this approach particularly powerful is that it opens a window onto a process that has been essentially invisible in human experiments. Traditional assessments of proprioception in chronic ankle instability, such as joint position matching tasks or thresholds for detecting passive movement, measure perception at one static moment in time. They cannot capture the rapid, continuous stream of sensory traffic that flows during movement. By deriving afferent firing patterns from movement data through validated receptor models, the study provides a dynamic, millisecond-by-millisecond estimate of sensory signaling during a functional task. This is a fundamentally different lens from reactive measures such as reaction times or postural sway scores, which reflect the end result of sensory-motor integration rather than its incoming raw material.

The clinical implications are potentially significant. Rehabilitation programs for chronic ankle instability currently emphasize balance training, strengthening, and perturbation-based exercises, which are effective for many but not all patients. If the root of the problem lies in altered afferent timing during the anticipatory phase of movement, then therapies could be designed specifically to recalibrate sensory signaling. Tasks that demand precise ankle positioning under time pressure, or training environments that manipulate the relationship between movement and sensory feedback, might encourage the nervous system to relearn the temporal patterns it lost after injury. The modeling framework also suggests new outcome measures: instead of relying solely on questionnaires and postural tests, clinicians could one day track afferent timing metrics derived from inexpensive motion capture to quantify sensory recovery objectively.

The study also fits into a broader scientific movement that treats sensory timing as a central currency of motor control. Research across domains, from upper limb reaching to locomotion in older adults, has shown that the nervous system is exquisitely sensitive to delays and variability in sensory feedback. Even artificial delays of tens of milliseconds can disrupt motor learning and adaptation. In this light, chronic ankle instability can be understood not merely as a mechanical joint problem or a strength deficit, but as a disorder of sensorimotor timing — a failure of the dialogue between the ankle and the spinal cord to keep the conversation synchronized during the most demanding phases of movement.

There are, of course, important caveats. The afferent patterns in this study are model-derived estimates, not direct neural recordings, and their accuracy depends on the fidelity of the underlying neurophysiological models and the biomechanical reconstructions. Individual variability in anatomy, injury history, and compensation strategies means that the group-level patterns reported here may not apply uniformly to every patient. The researchers also note that gait initiation, while clinically relevant, is only one of many tasks in which altered afferent timing could play a role; landing, cutting, and uneven-terrain walking may each impose distinct sensory demands. Future work combining these modeling techniques with other modalities, such as electroencephalography or high-density electromyography, could trace how altered afferent timing propagates through the central nervous system to produce the characteristic motor deficits of the condition.

Nevertheless, the study marks an important step toward a mechanistic, quantitative understanding of one of sports medicine’s most stubborn problems. By converting observable movement into estimated neural signaling, it transforms chronic ankle instability from a fuzzy clinical label into a measurable pattern of sensory disruption with specific temporal signatures. If subsequent studies confirm and extend these findings, the humble ankle sprain — so often dismissed as a trivial injury — may finally be understood at the level of the nerve impulses it deranges, and treated accordingly.

Subject of Research: Model-derived proprioceptive afferent timing during gait initiation in chronic ankle instability

Article Title: Model-derived proprioceptive afferent timing during gait initiation in chronic ankle instability

Article References: Bijari, K., Sadeghi, H., Yousefi, M., & Yiou, E. (2026). Model-derived proprioceptive afferent timing during gait initiation in chronic ankle instability. Scientific Reports. https://doi.org/10.1038/s41598-026-71074-4

Image Credits: AI Generated

DOI: 10.1038/s41598-026-71074-4

Keywords: chronic ankle instability, proprioception, gait initiation, afferent timing, muscle spindles, Golgi tendon organs, sensorimotor control, computational modeling, biomechanics, ankle sprain, postural control, neurogram

Balance is one of the most demanding tasks the aging brain performs. Every second of standing involves a continuous negotiation between sensory feedback from the feet, joints, and vestibular system and motor commands that make millimeter-scale corrections to keep the body’s center of mass over its base of support. As people age, this negotiation becomes less reliable, and falls become a leading cause of injury and loss of independence. Postural scientists often quantify stability by tracking the center of pressure, the point at which the ground reaction force passes under the feet. A wandering, jittery center of pressure trajectory signals effortful, corrective balance control, while a smooth trajectory reflects a system that anticipates and manages perturbations before they become threats.

To probe how Tai Chi might influence this system, the research team recruited thirty-six older adults with substantial Tai Chi experience and twenty-five age-matched healthy older adults with no Tai Chi background. Participants performed four standing tasks of increasing difficulty: a quiet stance with feet comfortably apart, a narrow stance with feet brought close together, and a tandem stance performed twice, once with the left leg forward and once with the right leg forward. Each configuration progressively shrinks the base of support and forces the postural control system to work harder, which allowed the researchers to observe how the brain and body respond as stability becomes more precarious.

The technological centerpiece of the study was functional near-infrared spectroscopy, a non-invasive optical technique that measures changes in oxygenated hemoglobin in the outer layers of the brain. Because neurons that are actively firing demand more oxygen, shifts in hemoglobin concentration serve as a proxy for cortical activation. Unlike functional MRI, fNIRS allows participants to stand, sway, and shift weight naturally, making it well suited to studying posture in real time. The researchers focused on a network of regions of interest critical to movement: the primary motor cortex, which issues motor commands; the primary somatosensory cortex, which integrates body-position feedback; the supplementary motor area, which plans and sequences movement; and the dorsolateral prefrontal cortex, which contributes attention and executive control to demanding tasks.

The results revealed a consistent pattern of cortical advantage among the Tai Chi practitioners. Compared with controls, they showed greater activation in the left primary somatosensory cortex during the tandem stance with the left leg forward, greater activation in the right dorsolateral prefrontal cortex during the narrow stance, and elevated activation in the right primary motor cortex during both the narrow stance and the tandem stance. These differences were statistically robust, with p-values ranging from 0.02 to below 0.01. Perhaps more striking, the practitioners displayed stronger functional connectivity, both within and between the primary motor cortex, the primary somatosensory cortex, and the supplementary motor area, with all comparisons reaching significance at p below 0.05. In practical terms, the brain regions responsible for sensing the body and commanding movement were talking to each other more coherently in the Tai Chi group.

The researchers interpret this enhanced coordination as cortical synchronization, a state in which sensorimotor regions operate as an integrated unit rather than as loosely coupled specialists. Such synchronization is thought to reflect neural efficiency: when communication between sensory and motor areas is strong, the brain can detect a loss of balance earlier and issue corrective commands with less delay and less compensatory recruitment of higher cognitive regions. The elevated prefrontal activation seen in practitioners during the narrow stance may indicate that experienced Tai Chi practitioners can flexibly bring attentional resources to bear precisely when a task becomes difficult, a capacity that often declines with age and is strongly linked to fall risk.

The behavioral side of the study told an equally compelling story. On the Berg Balance Scale, a widely used clinical measure of functional balance, the Tai Chi practitioners scored significantly higher than the non-practitioners, with p below 0.01. Analysis of center of pressure recordings added finer-grained detail. In the anterior-posterior direction, the practitioners showed lower sample entropy and lower mean power frequency, both indicating that their sway was smoother and less erratic. Sample entropy quantifies the unpredictability of a signal; a lower value means the trajectory is more regular and controlled. Mean power frequency reflects how fast the center of pressure oscillates, so a reduction suggests slower, more deliberate adjustments rather than rapid, reactive jerks.

Frequency-domain analysis sharpened this picture further. When postural demands increased, the Tai Chi group exhibited greater energy in low-frequency bands and reduced energy in mid-frequency bands compared with controls. In postural research, low-frequency sway is often associated with slow, strategic weight shifts driven by anticipatory control, while mid-frequency components are linked to faster corrective reflexes. The practitioners’ profile therefore points to a postural strategy that relies less on last-second rescue maneuvers and more on continuous, graceful regulation. As the authors conclude, long-term Tai Chi practitioners demonstrated greater cortical regulation in postural control, characterized by smoother and less abrupt postural adjustments and a reduced reliance on rapid corrective responses when stability was challenged.

Several caveats frame the significance of these findings. The study was cross-sectional, comparing existing practitioners with non-practitioners rather than randomly assigning novices to training, so it cannot fully rule out the possibility that people with naturally superior balance and brain organization are more drawn to Tai Chi in the first place. The sample sizes, while adequate for the mixed-model statistical analysis the researchers employed, were modest, and the participants were healthy older adults rather than frail individuals at high risk of falling. Longitudinal trials will be needed to confirm that Tai Chi training itself drives the cortical adaptations observed here. Nevertheless, the convergence of evidence, from clinical balance scores to hemodynamic brain imaging to the physics of sway, forms a coherent and biologically plausible account of how a centuries-old movement practice tunes the modern aging brain.

The implications reach well beyond martial arts studios. Falls among older adults impose enormous medical and personal costs worldwide, and interventions that are safe, low-impact, and engaging are urgently needed. If practicing Tai Chi strengthens the functional connectivity of the sensorimotor network and cultivates a calmer, more anticipatory postural style, it offers a rare combination of accessibility and mechanistic depth. The study also highlights the value of portable neuroimaging tools like fNIRS, which allow scientists to watch the brain work during real movement rather than inferring its behavior from static scans. For millions of older adults wondering whether slow, deliberate movement can genuinely change the body’s relationship with gravity, this research provides a measurable answer: in the brains and balance of long-term practitioners, the evidence is written in oxygen, connectivity, and the quiet steadiness of every step.

Subject of Research: Cortical adaptation and postural control in long-term Tai Chi practitioners among older adults

Article Title: Long‑term Tai Chi practice promotes cortical synchronization in postural control among older adults

Article References: Chen, X., Sun, J., Sun, T., Yang, X., Jiang, J., & Niu, W. (2026). Long‑term Tai Chi practice promotes cortical synchronization in postural control among older adults. BMC Complementary Medicine and Therapies. https://doi.org/10.1186/s12906-026-05600-2

Image Credits: AI Generated

DOI: 10.1186/s12906-026-05600-2

Keywords: Tai Chi, postural control, older adults, functional near-infrared spectroscopy, cortical synchronization, functional connectivity, center of pressure, balance, primary motor cortex, somatosensory cortex, fall prevention, neurophysiology