LADDER CLIMBING

A portable adjustable step-ladder was designed in order to evaluate and compare biomechanical parameters of a user during climbing. Independent variables were, the slope of the ladder, vertical spacing and depth of the stairs, while the displacement and angular velocity of the hip, knee and ankle from the right inferior limbs along with myoelectric activity of the vastus lateralis, biceps femoris, anterior tibialis and gastrocnemius muscles were set as the dependant variables. Twelve male subjects without any apparent sensory or motor deficiencies were selected on a voluntary basis to participate in the study. Twelve series of five ascents (60 trials) were recorded. Series representing combinations of the different slopes (65-degrees, 75-degrees, 80-degrees), stair depths (7.5 cm and 32 cm) and vertical spacings (27.5 cm and 31 cm) were partially counterbalanced by computer, for all subjects, with randomized numbers. From each trial, temporal, kinematic and electromyographic parameters were sampled for six seconds at a rate of 200 Hertz. Statistical treatment using analysis of variance with repeated measures (3 x 2 x 2 matrix) allowed evaluation of various ladder configurations on the indices retained for analysis. Results showed that individual patterns of motion (within-subject variability) were relatively constant from trial to trial while between-subject variability displayed higher values, particularly at the ankle joint. Although parameters showing the greatest number of significant effects were found to be, in a decreasing order, the slope of the ladder, followed by the rung spacing and the depth of the stairs, no one ladder parameter seemed to alter individual patterns of motion: therefore there is no patent advantage in using a specific configuration. In conclusion, although it would seem appropriate to use a wider step for stair climbing which would entail a greater stabilityfor the user, none of the tested conditions favored one condition over the other.