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. 2026 Jul 8;17:1871218. doi: 10.3389/fphys.2026.1871218

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Copyright © 2026 Hu, Liu, Jiang, Wang, Qian, Ren and Kui.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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Four line graphs compare the evolution of engagement index, fatigue index, LF/HF ratio, and RMSSD across operational sequences one to five for baling, rotary tillage, and sowing activities. Baling consistently shows higher engagement and LF/HF ratio but lower fatigue and RMSSD, while rotary tillage trends toward higher fatigue and RMSSD but lower engagement and LF/HF ratio over cycles. Sowing remains intermediate in most metrics. — Temporal evolution of central and autonomic physiological metrics over the continuous 5-hour driving protocol: (A) Engagement Index (EI), (B) Fatigue Index (FI), (C) LF/HF ratio, and (D) RMSSD. Solid lines denote group means, and shaded regions represent the 95% confidence intervals (CI).