The heart rate development and time consumption of four Zimbabwean forest workers engaged in manual harvesting were studied to assess their performance strategy and whether this strategy was affected by differences in fluid consumption. Each worker was studied during 8 consecutive working days and produced 2.4 m3 pulpwood/day. They consumed either 0.17 l or 0.6 l of water each 1/2 hour with one fluid scheme assigned to each day according to a randomised block (person) design with four replicates (days). All workers were found to harvest large trees at the start of the working day and small trees at the end. All workers took longer to complete their task when on the low fluid scheme, however, the effect on the heart rate development varied for the individual workers as the strategies adopted to accommodate the stress inflicted by the low fluid scheme, varied for the individual workers. It is recommended that sufficient fluid supply during work be accompanied by training of the workers to convey the need and benefits of sufficient fluid consumption.