Micro-Labor Science: A Multiscale Biochemical and Physiological Framework for Workload and Fatigue

This work introduces Micro-Labor Science, a new interdisciplinary framework that models workload and fatigue as emergent properties of multiscale biochemical and physiological processes. Unlike traditional labor science—which relies primarily on macroscopic indicators such as posture, environmental ergonomics, working hours, and subjective fatigue—this framework integrates metabolic flux, oxygen transport, respiratory acid–base regulation, neurotransmitter turnover, visual biochemistry, and sex-specific physiological parameters into a unified internal load model. The paper formulates differential equations for key physiological state variables (glycogen dynamics, blood glucose, pCO₂–pH balance, oxygen saturation, serotonin turnover, vitamin A cycling, and stress-induced respiratory changes) and defines subjective fatigue as a nonlinear function of these internal states. The model naturally reproduces empirically observed phenomena such as the nonlinear decline in performance after 6–8 hours of continuous work, sex differences in endurance and metabolic cost, and the impact of environmental factors on physiological strain. Comprehensive appendices provide quantitative treatments of soft drink and energy drink components, micronutrient deficiencies, dietary supplements, and optimal work–rest scheduling based on internal load dynamics. Together, these elements establish a mechanistic foundation for a new generation of labor science that connects biochemistry, physiology, ergonomics, and organizational practice. This preprint aims to provide a theoretical scaffold for future empirical validation and to stimulate interdisciplinary discussion on the physiological basis of sustainable work.