Abstract: A back incline indicator (10) employs a mercury switch (44) and a beeper (72) to indicate to a user (24) whenever the back of the user (24) is bent beyond an acceptable limit, .lambda.crit. The mercury switch (44) and beeper (72) are attached to a casing (38) including a plate (28A) that is parallel to the back of the user (24). The casing (38) is connected by a connector (14) to the shirt collar of the user (24). The mercury switch (44) is set to an angle .theta. from the plate (28A). The value of .theta. determines how much the user's back may be bent before .lambda.crit is reached. The value of .theta. may be set to different amounts as the desired value of .lambda.crit may vary with different uses of the back incline indicator (10).