Removing the thermal component from heart rate provides an accurate VO2 estimation in forest work.Heart rate (HR) was monitored continuously in 41 forest workers performing brushcutting or tree planting work.  10-min seated rest periods were imposed during the workday to estimate the HR thermal component (ΔHRT) per Vogt et al. (1970, 1973).  The VO2 estimated, from measured HR and from corrected HR (thermal component removed), were compared to VO2 measured during work and rest.  Varied levels of HR thermal component (ΔHRTavg range: 0-38 bpm) originating from a wide range of ambient thermal conditions, thermal clothing insulation worn, and physical load exerted during work were observed.  74% of VO2 prediction error variance was explained by the HR thermal component.  Work VO2 can be estimated accurately in the presence of thermal stress using Vogt et al.'s method, which can be implemented easily by the practitioner with inexpensive instruments.
THERM