Mining Publication: Effects of Posture on Back Strength and Lifting Capacity

• Back
• Kneeling
• Lifting or lowering
• Standing

The Bureau of Mines performed a pilot study examining the effects of posture on back strength and Maximum Acceptable Weight of Lift (MAWL) on six healthy male subjects (M = 32 years + 4 SD). Six back strength measurements (3 static and 3 dynamic) were made while the subjects were kneeling and standing. In addition, these subjects (who were unaccustomed to lifting in these postures) volunteered to participate in a study of psychophysically determined MAWL in both postures. Results of the back strength tests showed a significantly lower peak torque per body weight output in kneeling versus standing back strength measurements for five out of six test comparisons (p < .05). Subjective estimates of lifting capacity in the kneeling posture were significantly lower than those for the stooped posture (p < .05). The results of back strength and lifting capacity in these two postures provide useful information to consider in determining the physiological and psychophysical stresses imposed by these work postures.