One-handed dynamic pulling strength with special reference to speed, handle height and angles of pulling

Abstract

A laboratory study was conducted to determine the effects of pulling speed, handle height and angle of pull from the horizontal plane on one-handed dynamic pulling strength. The dynamic strength of nineteen male subjects for a 1 m pull was measured at four different handle heights (40%, 50%, 60% and 70% of shoulder height), at three different angles above the horizontal plane (15°, 25° and 35°), and at three different speeds of pulling (mean speed = 0.7, 1 and 1.1 ms −1). In addition, ratings of perceived exertion were recorded for elbow, shoulder and back. Also, the subjects were required to rate the overall comfort for the pull. Pulling speed, handle height and angle all had a significant effect on both mean and peak dynamic pulling strengths ( p ⩽ 0.01). Among the three variables, pulling speed was found to be the most critical. The mean dynamic strength was 360, 250 and 180 N and the peak strength was 600, 425 and 320 N at 0.7, 1 and 1.1 ms −1, respectively. The strengths decreased with an increase in handle height from 100% at 40% shoulder height to 83% at 70% of shoulder height and were the highest at an angle of 25° from the horizontal plane. The ratings of perceived exertion for all three body parts decreased with an increase in speed of pulling ( p ⩽ 0.01). The high speed pulls were perceived as being more comfortable than low speed pulls ( p ⩽ 0.01). The handles at 50% and 60% of shoulder height and at an angle of 25° were perceived as being more comfortable than those at other heights and angles ( p ⩽ 0.01). It is suggested that biomechanical stresses need to be considered along with physical strength and ratings of perceived exertion and comfort to determine optimum speed, height and angle of pulling for high speed pulling tasks.