Hand-held exercise weight

Abstract

An improved hand-held barbell type exercise weight that reduces muscle fatigue consists of a circular disk that has a vertical axis perpendicular to the base of the disk, a horizontal axis perpendicular to the vertical axis and a lateral axis perpendicular to both the vertical and horizontal axes and intersecting the axes at the approximate centroid of the circular disk. The disk has an axially extending cylindrical void extending axially along the vertical axis and through the disk forming a hollow circular disk where the void is symmetrical to the plane of the vertical axis. A cylindrically shaped grip bar having a central axis that is co-axial with the lateral axis extends laterally across the void and through the centroid of the disk.

Description

FIELD OF INVENTION

This invention relates to an improved hand-held barbell type exercise weight that minimizes torsion induced muscle fatigue.

BACKGROUND OF THE INVENTION

Barbell type hand-held exercise weights are well known in the prior art. The hand-held barbell has a grip extending between two opposing bodies of the same weight which are generally disk shaped. The centroid, or center of gravity, is a point where the entire mass of the weights and grip can be centered. The centroid in a barbell is usually located at the mid-point of the grip that extends between the weights. When exercising with a barbell, the exerciser will repeat movement of the weights in a cyclic manner using a barbell of identical weight held by each arm. The movement is intended to exercise the biceps, triceps, deltoids, and other muscles of the arms and shoulders. Forearm muscles include the brachioradialis, the mensor carpi radialis, the pronator teres, the flexor carpiradialis, and the palmaris muscle. When there is a slight imbalance between the opposing weights, the exerciser compensates by instinctively applying an opposing torque to counter balance the barbell. If the exerciser, for example, works on toning the bicep muscle, he pivots the barbell about his elbow. As the bicep is flexed and contracted, rotation of the barbell also occurs that is counteracted by the forearm muscles. The cyclic rotation of the barbell produces an internal offsetting torque that is dependant upon the mass moment of inertia of the barbell; this cyclic internal torque eventually fatigues the forearm muscles and consequently the effectiveness of the exercise routine in developing or toning the biceps muscles. It is therefor desirable to have a hand held exercise weight that substantially reduces the mass moment of inertia about the mutually perpendicular axes for the same weight being held. An object of this invention therefore is to provide a hand-held weight that is regular toroidal or regular polygon configured having its centroid at its geometrical center and a grip bar extending across the toroid with the grip bar centroid coincident with that of the toroid or right prism body having a regular polygon base (The toroid being the limit of the regular polygon when the number of sides increase substantially such that the polygon approaches a circular shape).

SUMMARY OF THE INVENTION

There is, therefore, provided according to the present invention, a hand-held exercise weight that has a mass moment of inertia that substantially reduces the cyclic forces acting on the forearm during an exercise routine to reduce muscle fatigue.

The preferred embodiment of the present invention consists of a disk that has a vertical axis perpendicular to its circular base at the geometrical center of the circular base. The disk has an axially extending void that extends vertically through it forming a cylindrical boundary surface that is symmetrical to a plane containing the vertical axis. The mass moment of inertia of the disk about the vertical axis is approximately the difference between the mass moment of inertia of a solid disk less the moment of inertia of a solid disk having the moment of inertia of the mass that would occupy the void. A grip for having a central axis perpendicular to the vertical axis extends through the void and has a center of gravity coincident with the centroid of the disk. When the disk rotates perpendicularly to the vertical axis, cyclically, a torque is induced that is the product of the mass moment of inertia about the vertical axis and the angular acceleration of the disk which is maximum as the disk cyclically changes direction of rotation. However, the moment of inertia for the disk is substantially less than the moment of inertia of a barbell resulting in less stress upon the forearm muscles.

Another embodiment of this invention consists of a right prism body having a regular polygon base with a finite number of sides and a vertical axis perpendicular to the plane of the regular polygon base at its geometrical center. (A right prism having a regular polygon base with an infinite number of sides in the limit is a disk which is the preferred embodiment.) The right prism body has an axially extending void extending through the right prism body where the void is bounded by the right prism body forming a boundary surface. The boundary surface is symmetrical to a plane containing the vertical axis. A horizontal axis of the right prism is perpendicular to the vertical axis and a lateral axis is perpendicular to both the vertical axis and horizontal axis. The axes intersect and the point of intersection is coincident with the centroid of the right prism. A grip bar having a central axis is carried by the right prism body such that the central axis is co-axial with the lateral axis and extends through the void where the centroid of the grip bar is coincident with the centroid of the right prism body.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages will become appreciated as the same become better understood with reference to the following specification, claims and drawings wherein:

FIG. 1 is a perspective view of the preferred embodiment of this invention;

FIG. 2 is a front view of FIG. 1;

FIG. 3 is a right side elevational view of FIG. 2;

FIG. 4 is a bottom view of FIG. 2;

FIG. 5 is a perspective view of a typical barbell of the prior art; and

FIG. 6 is a perspective view of an alternative embodiment of this invention.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of the preferred embodiment of this invention, namely, an improved exercise weight that reduces the cyclic forces acting on the forearm of the user and consequently muscle fatigue. As can be seen in FIG. 1, a cylindrical disk 1 is illustrated where the hollow portion of the disk is a void 2 extending axially along vertical axis 5 where the vertical axis is co-axial with the x-axis. As can further be seen in FIG. 1, vertical axis 5 (x-axis) is perpendicular to the plane containing lateral axis 8 (z-axis and horizontal axis 7 (y-axis) and intersects axes z and y approximately at the centroid 3, or center of gravity, of cylindrical disk 1. A grip bar 4 has a central axis 6 which is co-axial with the z-axis. In the preferred embodiment, grip bar 4 is cylindrically shaped and has a centroid that is approximately coincident with centroid 3 of cylindrical disk 1. Thus, the entire weight of the composite of the cylindrical disk 1 and grip 4 is centered at centroid 3.

By referring to FIGS. 1,2,3, and 4 the mass moment of inertia for cylindrical disk 1 about the x-axis can be seen to be approximately the difference between the moment of inertia about the x-axis of the solid disk having a radius of r and the moment of inertia about the x-axis of a disk having a radius r. The moment of inertia, I_x, therefore is $\frac{{\mathrm{Mr}}_o^2}{2}-\frac{M_i{r}_i^2}{2}$
where M is the mass of cylindrical disk having a radius r and M is the mass of a cylindrical disk having the radius r. The moment of inertia for grip bar 4 about the x-axis is likewise illustrated in FIGS. 1,2,3, and 4, and is one-twelfth ( 1/12) of the mass (m) of cylindrical grip bar 4, multiplied by the length (L) squared of the grip bar. The moment of inertia of the cylindrical disk 1 with the cylindrical void 2 there through and grip bar 4 is $\frac{{\mathrm{Mr}}_o^2}{2}-\frac{M_i{r}_i}{2}+\frac{1{\mathrm{mL}}^2}{12}.$
Any angular acceleration about vertical axis 5 (x-axis) will result in forces acting on the forearm muscles of an exerciser who resists a torque about vertical axis 5 (x-axis).

The moment of inertia of cylindrical disk 1 about horizontal axis 7 (y-axis) is $\frac{{\mathrm{Mr}}_o^2}{4}-\frac{M_i{r}_i^2}{4};$
the moment of inertia about horizontal axis 7 of cylindrical disk 1 and grip bar 4 is approximately $\frac{{\mathrm{Mr}}_o^2}{4}-\frac{M_i{r}_i^2}{4}+\frac{1{\mathrm{mL}}^2}{12}.$
Thus, any angular acceleration of cylindrical disk 1 about horizontal axis 7 (y-axis) will result in forces acting on the forearm muscles of an exerciser.

Similarly, the approximate moment of inertia about the lateral axis 8 (z-axis) may be derived and will be found to be $I_{}=\frac{{\mathrm{Mr}}_o^2}{4}-\frac{M_i{r}_i^2}{4}+\frac{1{\mathrm{mL}}^2}{3}.$
FIG. 6 illustrates a typical prior art barbell 10 which consists of a pair of cylindrical disks 11 and 11′. The centroid of each disk is displaced from the centroid of the barbell (not shown) by a distance which is approximately one-half of the length of grip member 12. The mass moment of inertia about lateral axis 13 (z′-axis) barbell 9 is I=MR+½mr where M is the mass of a cylindrical disk 11, R is the radius of the disk, and ½ mr is the moment of inertia of grip member 12 about lateral axis 13 (z′-axis). Thus, for angular accelerations equivalent to those experienced by an exerciser using the preferred embodiment of this invention, the forces acting on the forearm of the exerciser would be substantially less and consequently less fatiguing.

Another embodiment to this invention is illustrated in FIG. 6. Exercise weight 14 has a vertical axis 16 (x″-axis), a horizontal axis 17 (y″-axis), and a lateral axis 18 (z″-axis) that intersect approximately at the centroid or center of gravity of exercise weight 14. As can be seen in FIG. 6, exercise weight 14 has a right prism shape with a base 19 having a regular polygon shape, namely, of equal length sides and equal angles formed by the intersections of the sides. Although FIG. 6 illustrates an axially extending void 21 having regular polygon shaped walls 22, forming the boundary surface of void 21, the boundary surface could also be circular with a center located on vertical axis 16 (x″-axis). The boundary surface of void 21 is symmetrical to the place containing vertical axis 16 (x″-axis) and a handle or grip bar 23′ extends axially through void 21 and has a central axis that is co-axial with lateral axis 18. As the number of sides of the polygon base increase to an infinitive number, the polygon base approaches a circle. Consequently, the moments of inertia of cylindrical disk 1 approximate those of exercise weight 14 and both weights, therefore, when contrasted to the forces produced in the exerciser's forearm when exercising a bicept muscle, would be substantially less than a prior art barbell resulting in less muscle fatigue.

While I have shown and described embodiments of an improved hand held exercise weight, it is to be understood that the invention is subject to many modifications without departing from the scope and spirit of the claims recited herein.

Claims

1. An improved hand-held exercise weight comprising:

(a) a disk having a vertical axis and a base where said vertical axis is perpendicular to the plane of said base and intersects said base at its geometrical center, said disk having an axially extending void therethrough where said void is bounded by said disk forming a boundary surface such that said boundary surface is symmetrical to a plane containing said vertical axes, said disk further having a horizontal axis perpendicular to said vertical axis and a lateral axis perpendicular to both said vertical and horizontal axes, and where said disk has a centroid located approximately at the intersection of said axes.

(b) a grip bar having a central axis carried by said disk where said central axis is substantially co-axial with said lateral axis and extends laterally through said void.

2. The improved hand held exercise weight recited in claim 1 where said grip bar is cylindrically shaped.

3. The improved hand held exercise weight recited in claim 1 where said boundary surface is a cylindrical surface.

4. The improved hand held exercise weight recited in claim 1 where said boundary surface is a regular polygon surface.

5. An improved hand-held exercise weight comprising:

(a) a right prism having a regular polygon base, and a vertical axis perpendicular to the plane of said regular polygon base, said vertical axis intersecting said plane at the geometrical center of said regular polygon base, where said right prism body has an axially extending void therethrough, and where said void is bounded by said right prism body forming a boundary surface such that the boundary surface of said void is symmetrical to a plane containing said vertical axis, said right prism body further having a horizontal axis perpendicular to said vertical axis and said horizontal axis and where said right prism body has a centroid at the intersection of said axes;

(b) a grip bar having a central axis carried by said right prism body where said central axis is substantially co-axial with said lateral axis and extends through said centroid, and where said grip bar extends axially through said void.

6. The improved hand held exercise weight recited in claim 5 where said grip bar is cylindrically shaped.

7. The improved hand held exercise weight recited in claim 5 where said boundary surface is a cylindrical surface.

8. The improved hand held exercise weight recited in claim 5 where said regular polygon base is a polgon having a sufficient number of sides to approximate a circle.