Figure 18.1 Relation of elbow and shoulder moments to ladder slant. Figure 18.2 Relation of trip, knee and ankle moments to ladder slant in male subjects.

Bloswick and Chaffin (1990) used integrated electromyographic (IEMG) activity of the erector spinae as a measure of low back stress during ladder climbing activities. They found that for males the erector spinae activity was approximately 65 per cent of static maximum and increased slightly as the ladder slant went from 70 degrees to 90 degrees (vertical). They also found that peak erector spinae IEMG activity approached 100 per cent of static maximum as climbing speed increased when using vertical ladders.