Isometric Pushing, Pulling, and Lifting Strengths in Three Postures.
Proc of the Human Factors Soc 33D Ann Mtg Denver Colorado Oct 16- 20 1989 1989 Oct; 1:634-640
Nine underground coal miners (mean age = 36.9 Yr +/- 6.3 Sd; height = 174.5 Cm +/- 7.4 Sd; weight = 87.8 Kg =/- 12.5 Sd) participated in a U.S. Bureau of Mines study examining the effects of posture on isometric strength. Five tests of static strength (maximum push, maximum pull, maximum lift with elbows flexed at 90 deg, maximum lift with lifting handle 45.7 Cm [18 inches] above floor, and maximum push up with handle at eye height) were performed in three postures: standing, kneeling on one knee, and kneeling on two knees. Results indicated that neither test of lifting strength was affected by posture (p > 0.05). However, maximum pulling strength was significantly greater when kneeling on one knee (p < 0.001) Than when standing or kneeling on both knees. Also, maximum pushing strength was greater when kneeling on both knees than when standing (p < 0.05). The test of maximum push up was not affected by posture (p > 0.05), and the forces generated in the three postures for this test were highly correlated (r = 0.94). Results of these strength tests may be useful when recommending appropriate postures to assume when performing specific underground materials-handling tasks.
Proc. of the Human Factors Soc., 33D Ann. Mtg., Denver, Colorado, Oct. 16- 20, 1989, V. 1, PP. 634-640