Exercise devices – For head or neck
Reexamination Certificate
2000-06-30
2002-09-24
Donnelly, Jerome W. (Department: 3764)
Exercise devices
For head or neck
C482S013000, C482S907000, C482S137000
Reexamination Certificate
active
06454680
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for exercising or rehabilitating neck extensors.
Most of the movements of the joints and especially limbs of the human body are based on a structure in which a tubular bone is joined to another tubular bone via a so-called hinge joint. The movement resembles the action of a mechanical hinge and takes place mainly two-dimensionally about a pivot point with a constant radius. An example of such movement is that of the elbow joint. However, the action of a hinge joint is not quite as simple as this, but this is the basic principle.
The action of the spine is not as simple as this. The spinal column consists of vertebrae and disks between them. Adjacent vertebrae are joined together via the disk and so-called facet joints. Successive vertebrae and the disk between them are called a functional spine unit (FSU). The movements of the spine cannot be described on the principle of the hinge joint, but the FSU always works in a three-dimensional fashion, comprising both rotation and sliding in different directions of motion.
Due to the structure of a pair of vertebrae, in which the facet joints and spinal processes limit the movement in the extension direction, the spine does not work like a hinge joint in the extension-flexion direction. The extension of the spine takes place as a series of “opening movements” of individual FSU structures as each inter-vertebral space is increased while the facets lean on each other. Correspondingly, the inter-vertebral space becomes narrower as the spine is flexed. This narrowing takes place as a series of flexion movements occurring progressively in motional segments from the top downwards. In movements in the flexion-extension direction, some sliding also takes place at the same time (Dvorak J & Dvorak V: Manual Medicine: Diagnostics. Georg Thieme Verlag, Stuttgart, 1990; Nordin M & Frankel V H (ed.): Basic Biomechanics of the Musculosceletal System: Lea Febiger, Philadelphia 1980; White A M & Panjabi M: The basic kinematics of the human spine 1978; 3:13 and White A M & Panjabi M: Clinical Biomechanics of the Spine. Lippincott, Philadelphia, 1978).
In consequence of this mechanism, the flexion movement of the spine does not follow a radial arc about a single centre, but the movement takes place on the principle of a changing centre of motion. For instance, by observing the path of the head, this results in a path resembling an elliptical rather than a circular arc. The radius of the ellipse is largest when the spine is fully extended and smallest when the spine is fully flexed.
In prior art, an apparatus for exercise and/or rehabilitation of neck extensors with flexion and extension movements between an extreme flexion position and an extreme extension position is known. The apparatus comprises an equipment frame, a seat provided with a back rest, and holding means for holding a person's body substantially immobile in position in relation to the back rest. Furthermore, the apparatus comprises a link rod pivoted by its first end on the equipment frame via a first joint permitting a turning motion about a swing axis perpendicular to the vertical middle plane of the seat. In addition, the apparatus comprises a head rest functionally connected to the link rod so that the link rod participates in turning the head rest during an exercise movement while the person's head is leaning against the head rest, and a resistance means for providing resistance to the exercise movement. An apparatus of this type is known e.g. from specification U.S. Pat. No. 5,336,138, wherein the head is held in a supporting frame acting as a head rest that holds the person's head via contact with the back and sides of the head. The supporting frame is joined to the link rod. The lower end of the link rod is mounted with a ball joint on the back rest of the seat.
A problem with the prior-art apparatus is that the path of the part holding the head does not coincide with the natural path of motion of the head during flexion and extension of the neck because in the prior-art apparatus the turning motion takes place about a single centre, which means that the path is a circular arc. However, as stated above, the natural path of the head is not a circular arc but a path of a different type. In flexion and extension exercises with prior-art apparatus, an incorrect motional pattern is learned and the incorrectly applied load may result in a risk of injury. Besides, the chafing of the head against the head rest is annoying.
SUMMARY OF THE INVENTION
The object of the present invention is to eliminate the drawbacks described above. A specific object of the present invention is to disclose an apparatus in which a head rest path deviating from a circular path is achieved so that the head rest moves along a path corresponding to the natural path of motion of the cervical spine.
The apparatus of the invention comprises an equipment frame, a seat provided with a back rest, and holding means for holding a person's body substantially immobile in position relative to the back rest; a link rod pivoted by its first end on the equipment frame via a first joint permitting a turning motion about a swing axis perpendicular to the vertical middle plane of the seat; a head rest functionally connected to the link rod so that the link rod participates in turning the head rest during an exercise movement while the person's head is leaning against the head rest, and a resistance means for producing a force opposing the exercise movement.
According to the invention, the apparatus comprises adjusting elements for adjustment of the position of the seat in relation to the equipment frame. The head rest is substantially fitted to receive the upper part of the person's neck, preferably the area of the topmost two cervical vertebrae. The apparatus comprises a multi-joint angular linkage mechanism, of which the link rod constitutes a part, said multi-joint angular linkage mechanism being connected to the head rest so as to cause it to move during an exercise movement along a curved path that substantially coincides with the natural path of the neck during flexion and extension movements of the neck without producing any relative motion between the head rest and the point of contact between the neck and the head rest.
Using the adjusting elements of the seat, a person can be individually positioned in a precisely defined position relative to the equipment frame and the mechanism turning the head rest. By fitting the head rest so that it meets the upper part of the neck, preferably the area of soft tissue of the neck, which lies in the upper region of the cervical spine in the area of the topmost cervical vertebrae c
1
and c
2
, an exercise movement is achieved that does not stress the muscles connecting the cranial base to the upper part of the cervical spine, thus ensuring that no sliding occurs between the topmost cervical vertebrae as in prior-art apparatus. The multi-joint angular linkage mechanism allows head rest motion along a path corresponding to the natural path of neck motion so that the head rest does not move in relation to the neck during exercise and no mutual chaffing occurs but the head rest follows the same path with the neck. The magnitude and application of stress following natural paths can be adjusted during physical exercise. The advantages of stress following natural paths include the following. During exercise, the stress is applied in the correct manner to the tissues to which it is intended to be applied. Furthermore, correct motional patterns are learned. This means that the motional patterns learned during exercise are likely to be correctly observed even outside the exercise or rehabilitation situation. In addition, the risk of injury due to incorrect stress during exercise and rehabilitation is reduced.
In an embodiment of the apparatus, the path of the head rest is a path with a varying radius, such as an elliptical path. As the flexion-extension movement of the spine does not take pl
DBC International Oy
Donnelly Jerome W.
Young & Thompson
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