Energy expenditure, productivity, and physical work capacity of sugarcane loaders

Abstract

V̇_o2, _E and heart rates (f_H) were measured in 28 Colombian sugarcane loaders while loading cane and in the laboratory during a V̇_o2max test. Productivity (metric tons day⁻¹) of the workers was also obtained. During work, V̇_o2 was 1.25 I·min⁻, V̇_E 38.8 1 min⁻¹, and f_H 120 beats·min⁻¹. The subjects worked at 42% of V̇_o2max (6.3 ± 1.0 kcal min⁻¹) during the field measurement periods. Energy expenditure was estimated to average 3,281 kcal · 24 hr⁻¹. Productivity was higher in men with lower fat content, resting f_H and f_H at V̇_o2 = 1.25 1-min⁻¹ indicating a positive relationship between productivity and physical fitness. Productivity was not related to age but, since V̇_o2max decreased with age, the relative effort required to maintain productivity increased in the older workers. Efficiency (kg cane loaded·1 V̇_o²⁻¹) and estimated sustained effort (percent V̇_o2max) were not significantly correlated with productivity in this type of discontinuous, moderate work.