Chair for the Lower Back

This application is based on a previously filed Document Disclosure No. 199005, filed Aug. 12, 1988.

1. Field of the Invention

The present invention relates to chairs, particularly chairs for the lower back and exercise chairs designed to be used in strengthening the back muscles.

2. Proir Art

Many exercise devices exist for strengthening the back muscles. However, studies have shown that exercises to strengthen a particular group of muscles, whether in the back or elsewhere, have limitations because of muscle interactions. In particular, exercises for the muscles of the trunk are difficult to accomplish because of interaction of the muscles with other quite powerful muscles particularly those of the legs. Accordingly, stabilization of the pelvic region during the exercise is quite important. With particular reference to the muscles of the lower back, stabilization of the pelvis to prevent rotation thereof during an exercise routine is needed to isolate the lumbar region and provide for an acceptable exercise apparatus. None of the exercise devices in the prior art are effective in pelvic stabilization. See Peterson, et al., Comparison of the effectiveness of two pelvic stabilization systems on pelvic movement during maximal isometric trunk extension and flexion muscle contractions, Physical Therapy, 534-539 (April 1987).

In one aspect of the present invention there is provided an exercise chair for the lower back which includes a base disposed firmly on a floor and having a seat disposed spaced above a floor with a front thigh-supporting portion and a rear portion and body positioning means movably mounted to the base and including a first and second spaced pelvic restraint means for engaging the pelvis to inhibit rotational movement of the pelvis of the user during an exercise movement. Selective resistance means are mounted between the body positioning means and the base to bias during an exercise movement the body positioning means against rearward movement of the body positioning means in response to user force applied by the back of the user.

In other aspects, the selective resistance means includes a plurality of selectively engagable resistance springs mounted between the base and the back positioning means via a hook member. The base includes selective means for engaging each spring by the base to vary the bias applied against the back positioning means by the resistance means. The first pelvic restraint means includes a posterior pelvic restraint pad positioned against the posterior pelvis of a user. The second pelvic restraint means includes a pair of spaced anterior pelvic restraint pads adapted to be positioned against the anterior pelvis adjacent each side of a user. The first and second pelvic restraint means cooperate to inhibit rotation of a pelvis when positioned against a body of a user.

Further aspects of the invention as a chair for general use include selectively operable adjustment means for mounting each pad to the chair for adjustment of the position thereof and being selectively positionable for use as arm rests by a user sitting in the chair by selective operation of the adjustment means. The base also includes a plurality of laterally extending legs at least one pair of which are disposed rearwardly and extend rearwardly a predetermined length to provide rearward lateral stability of the chair when exercises are being performed by a user. Each leg includes a wheel for movement of the chair thereon and selective locking means for inhibiting the rotation of respective wheel when the means is selectively locked to provide the versatility of using the chair as a desk chair in an office or the like.

The chair includes various adjustments for mounting each pad to the chair for adjustment in height and for forward or rearward horizontal movement thereof. The seat is also adjustable in height and rotatable through 360 degrees and lockable in position. The back positioning means includes an upper back support pad which is adjustable in vertical position against the upper back of a user and movable at least 80 degrees.

The novel features which are believed to be characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a right side elevation view of the exercise chair in accord with the present invention;

FIG. 2 is a front elevation of the chair of FIG. 1 with the arm rests positioned for use in an exercise routine;

FIG. 3 is a rear elevation of the chair of FIG. 1 with part of the seat housing removed to illustrate the resistance mechanism;

FIG. 4 is a partial perspective view of the variable resistance apparatus in accord with the present invention; and

FIG. 5 is a diagrammatic illustration of body movement when using the chair for exercising the muscles of the lower back.

With reference now to the drawings, the exercise chair in accord with the present invention is depicted at numeral 10 in FIG. 1. The exercise chair 10 includes a base 11 for support and height adjustment; a seat 12 also having selectively operable position adjustments; and back positioning apparatus 13. Base 11 includes selectively operable adjustment means to mount the seat 12 including support shaft 14 having a threaded section 15 for height adjustment held in position via bolt 15'. A cylindrical frame 16 provides a center for two long rear legs 17 and forward legs 18 of the usual length. Locks 19 prevent movement of wheels 20.

Seat 12 includes a seat frame 22 mounted to be rotatable 360 degrees with respect to the base 11 and secured in a forward position by pin 21 to prevent rotation with respect to base 11. Cushion 23 is standard.

The back positioning apparatus 13 includes a selection mechanism 24 which will be described in more detail hereinbelow and is mounted in a housing 25 that is preferably integral with seat frame 22, and an upper back support pad 26 which includes bracket 26' and is mounted directly above two lumbar support pads 27 that function as posterior pelvic restraints. Pad 26 is mounted on a support arm 28 with pin 30 being used for height adjustment via pin holes 28' and boss 29' with support arm 29 being movable.

Support pads 27 are rotatably mounted on a generally U-shaped axle 31, with pin holes 32 for adjustable height via pins 34, on support posts 33 rigidly mounted to seat frame 22 (FIGS. 2-3). The two arm rests 35 can be turned inwardly about the axis of post 36 and locked in position for use as anterior pelvic restraints. The arm rests 35 are mounted on mechanical adjustment means including a swivel post 36 connected to the end of a grooved slidable rod 37 which is rotatably operable only by crank mechanism 38. The arm rest assemblies are mounted on support posts 40 also employing a slidable rod/crank height adjustment assembly 39 substantially identical to 37 and 38. The arm rests 35 are pivotally mounted forwardly to allow them to swivel inboard from the rear to the FIG. 1 position and no locking means need be used to hold them in place because the arm rests 35 are rotatable only 90 degrees to the FIG. 3 position.

The selection mechanism 24 is mounted below seat 23 and contains variable resistance which is applied via support arm 29 to pad 26. FIG. 4 illustrates a portion of the mechanism 24. Both lower ends of support arm 29 are formed as loops 50 that fit on sprockets 48 which are located just outboard of housing 25. The end walls 41 of housing 25 includes an axle 42 extending laterally there across and mounted to sprockets 48 which are mounted to the outside of walls 41. Springs 43 are mounted on the axle 42 by welding or other appropriate means and include a lower "L-shaped" end 46 which is formed as a hook member to engage pin 44 as axle 42 is rotated counterclockwise (as viewed from the right side of the chair, FIG. 1). Accordingly, as support arm 29 is rotated rearwardly by force against pad 26 it will be resisted by a force determined by the number of springs 43 engaged sequentially by pin 44. Knob 47 can be grasped to pull pin 44 outwardly and thus allow an end 46 to rotate with spring 43 and provide no resisting force. The chair 10 has eight springs 43, four on either side and the springs 43 in each group of four are selected by a pin 44. Brackets 45 are used to support the pin 44.

Hand lever 49 connects to a body portion 54 having a selection pin 51 and two hinges: center hinge 52, for center of sprocket 48, and outside hinge 53 for connection to end 50 of arm 29. Hinges 52 and 53 allow for the lever 49 to be moved from sprocket 48 and allow end 50 to rotate freely around sprocket 48 via selection pin 51. Lever 49 is pulled outwardly to disengage pin 51 from sprocket 48 and allow end 50 to rotate freely around sprocket 48. Thus, with lever 49 pulled outwardly, downward pressure on the lever 49 will cause end 50 to rotate around sprocket 48 and cause the back support pad 26 to move forwardly (to follow the user bending forwardly). If the lever 49 is now pushed inwardly, pin 51 will engage a slot in sprocket 48, engaging the selected resistance springs 43 with back pad 26 via arms 29. If the user pushes rearwardly to return to the upright position, the force encountered is determined by the number of springs 43 that have been engaged by movement of respective pins 44. Each spring 43 is rated at 25 lbs. force. Preferably axle 42 is mounted on bearings 56 to better distribute the force loading thereon.

The operation and use of the chair 10 is as follows. The height of the seat frame 22 is adjusted in the usual manner by rotating the threaded support shaft 14 in frame 16 and locking it in position via bolt 15'. The wheels 20 are locked via locks 19 to stabilize the chair 10 in position to not roll during movement by a user. The seat frame 22 is rotated to the forward position and locked into place via pin 21 to prevent rotation of seat frame 22 with respect to base 11. The height of pads 26 and 27 are adjusted as discussed above. Pads 27 are placed against the posterior pelvis to perform as posterior pelvic restraint pads and arm rests 35 are rotated into position as anterior pelvic restraint pads. The posterior restraint pads 27 are to be positioned prior to the anterior pads 35.

With the chair 10 adjusted for the user 57, exercise is performed by leaning forward at the waist and forcing the back pad 26 in contact with the user's back by pushing downwardly on hand lever 49 which has been moved outwardly to disengage pin 51 from sprocket 48, (FIG. 5). Once the user has moved forwardly the desired distance, which may be up to 40 degrees in arc, the lever 49 is pushed inwardly and pin 51 is engaged into a slot 55 of sprocket 48. At this point, the user 57 moves rearwardly 80 degrees against the resistance assembly to allow the support arms 29 to be moved to the desired position for normal sitting. Pin 47 is pushed inward to engage all springs 43 for support in the seated position. The lever 49 is then pushed inwardly to engage the sprocket 48 via pin 51 to keep the back pad 26 in the desired position during normal use of the chair 10. Arm rests 35 are returned to the normal position and a locking mechanism may be included to hold them in the arm rest position. The chair 10 is designed so that a user may obtain full range-of-motion of the lower back muscles (lumbar extensors) by being movable rearwardly of the upright position.

While the invention has been described with respect to certain specific embodiments, it will be appreciated that many modifications and changes may be made by those skilled in the art without departing from the spirit of the invention. It is intended, therefore, by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention.