Chronic tension in the upper trapezius (UT), often caused by poor ergonomics, prolonged posture, or psychological stress, contributes to musculoskeletal discomfort, headaches, and impaired interoceptive awareness. Although surface electromyography (sEMG) biofeedback can promote UT relaxation, traditional systems using conventional displays often fail to sustain engagement. Virtual reality (VR) offers a more immersive alternative, provided that latency remains below perceptual thresholds. We introduce VRxBioRelax, a closed-loop VR biofeedback system that streams sEMG data from Delsys Trigno Avanti sensors via MQTT to a Unity scene. Muscle activation drives a dynamic dawn-to-dusk landscape synchronized with a progressive muscle relaxation protocol. To validate system responsiveness, 87,716 EMG samples from the NinaPro DB2 dataset were replayed at $\sim$75 Hz. Timestamps at four key stages-acquisition, Root Mean Square (RMS) processing, network receipt, and rendering-revealed mean latencies of 0.50 ms (processing), 5.62 ms (network), and 19.22 ms (rendering), yielding an average end-to-end delay of 25.34 ms. Notably, 99.3% of frames arrived within 50 ms. One-sided t-tests confirmed mean latency was significantly lower than both the 30 ms VR comfort limit ($t_{87\,715}=-25.2$, $p=5.9{\times}10^{-140}$) and the 50 ms clinical benchmark ($t_{87\,715}=-133.3$, $p<10^{-300}$). These findings support VRxBioRelax for use in remote interoceptive training, stress reduction, and telepresence-enabled rehabilitation.

翻译：上斜方肌（UT）的慢性紧张通常由不良人体工学、长时间固定姿势或心理压力引起，会导致肌肉骨骼不适、头痛及内感受意识受损。尽管表面肌电图（sEMG）生物反馈可促进UT放松，但采用传统显示器的系统往往难以维持用户参与度。虚拟现实（VR）技术提供了更具沉浸感的替代方案，但其延迟需保持在感知阈值以下。本文提出VRxBioRelax——一种闭环VR生物反馈系统，通过MQTT协议将Delsys Trigno Avanti传感器采集的sEMG数据流式传输至Unity场景。肌肉激活驱动动态的黎明至黄昏景观演变，并与渐进式肌肉放松方案同步。为验证系统响应性，我们以$\sim$75 Hz频率回放NinaPro DB2数据集中的87,716个肌电样本。在四个关键阶段（信号采集、均方根（RMS）处理、网络接收与渲染）的时间戳分析显示：平均延迟分别为0.50 ms（处理）、5.62 ms（网络）和19.22 ms（渲染），端到端平均延迟为25.34 ms。值得注意的是，99.3%的帧在50 ms内完成传输。单侧t检验证实平均延迟显著低于30 ms的VR舒适阈值（$t_{87\,715}=-25.2$，$p=5.9{\times}10^{-140}$）和50 ms的临床基准（$t_{87\,715}=-133.3$，$p<10^{-300}$）。这些发现支持VRxBioRelax在远程内感受训练、压力缓解及远程临场康复中的应用潜力。