The effect of working posture on the Nigerian hoe farmer

The Nigerian traditional hoes are short-handled and are used in a bending posture. This puts the spinal muscles in tension in order to counter-balance the force of gravity. Sharp pains result low in the back, energy is wasted in combatting gravity and low work output is obtained. This paper evaluates the forces acting on the spine of the farmer hoeing in two working postures and tests the results with human energy measurements. It was found that the spinal muscle force and the lumbosacral joint reaction, while using the traditional hoe modified with a 150 cm long handle, were only 20% and 38% of those of the short-handled hoe respectively. In addition, while the traditional hoe demanded human energy at the rate of 7·7 kJ/m and 34·5 kJ/m 3 of soil, the long-handled modification required only 4·7 kJ/min and 22·9 kJ/m 3 of soil. The paper points out the need either to eliminate the tools that require excessive bending in their use, or to modify them within limits of practicability.