Table 1

Main effect model for effort as a function of lifting task parameters

Effect	Point estimate	Standard error	Degrees of freedom	p value
New variable (Sum) = 2 × weight level + horizontal distance level + twisting angle level + vertical travel distance level.
Intercept	−1.980	0.071	216	<0.0001
Weight of load	0.999	0.008	17E3	<0.0001
Horizontal distance	0.572	0.008	17E3	<0.0001
Twisting angle	0.610	0.008	17E3	<0.0001
Vertical travel distance	0.512	0.008	17E3	<0.0001