Physiological limits in lifting.

Two different experiments were conducted to study the effects of frequency, height and load of lift on computed maximal oxygen uptake and to compare the data obtained to a standard bicycle ergometer. A progressive submaximal technique was used to predict maximal oxygen uptake. The results of the present study revealed that across all heights, an increase in either the frequency of lift or load of lift was accompanied by an increase in computed maximal oxygen uptake; however, all maximal oxygen uptake values reported showed a tendency to level off beyond the frequency of five lifts/min. The results also showed that combined arm and leg lifting recorded the highest maximal oxygen uptake followed by leg lifting then arm lifting, respectively. Maximal oxygen uptake values obtained for lifting tasks were much lower than those obtained for a bicycle ergometer. It is therefore recommended that limits for continuous work for a lifting task be based on the attainable maximal oxygen uptake for that particular task and not on a maximal oxygen uptake obtained from another task such as a bicycle ergometer test.