Exercise apparatus including tethered mass confines for movement on horizontal track

An inertial exercise apparatus and method for exercising body muscles using acceleration and deceleration forces. A mass slidably mounted along a track is connected to a body part by a tether in such a way that the body part accelerates the mass along the track, and thereafter the motion of the mass is converted without substantially decreasing the speed of the mass to a motion which can be decelerated by the body part. In a preferred embodiment, the mass is accelerated toward a curved central portion of the track which then reverses the motion of the mass, after which the mass is decelerated. A rotating mass can also be utilized.

TECHNICAL FIELD 
The present invention relates to apparatus for exercising muscles of the 
human body, and more particularly relates to an inertial exerciser for 
using acceleration and deceleration forces to exercise muscles of body 
parts. 
BACKGROUND ART 
In most activities, muscles of the body are required to provide forces for 
two functions. One primary function is to overcome resistive loads which 
in general include friction and gravity forces. The second primary 
function is to provide a force to accelerate and decelerate the body part 
itself plus any extra mass imposed on the body part. The proportion of 
these two functions varies depending upon the activity and the specific 
limb and joint engaged in the activity. In medical terminology, an 
acceleration force is produced by a concentric contraction while a 
deceleration force is produced by an eccentric contraction. 
In throwing and racket sports, the importance of the acceleration and 
deceleration function of the muscles cannot be overestimated. A major 
league pitcher who throws a fast ball at 95 miles per hour must accelerate 
his arm to that speed and more before releasing the ball, and the arm must 
then be decelerated to avoid injury. Thus, the deceleration forces 
generated within a muscle can be very high. 
In most known devices for exercising body muscles, the body part involved 
moves in one direction against a resistance, and then comes to a stop, 
followed by return motion to the starting point. Such exercises involve 
both resistive loads and acceleration and deceleration forces. In weight 
lifting, the resistive loads are very high. The acceleration and 
deceleration forces can also be high because the forces are proportional 
to the amount of mass being accelerated as well as to the rate of 
acceleration. During a bench press it has been shown that the acceleration 
forces can be as high as 35-40 percent of the weight being pressed. U.S. 
Pat. No. 3,851,874 discloses an exercise apparatus involving both 
resistive and acceleration/deceleration forces, wherein a cord passing 
through a pulley is pulled to lift a suspended weight at the other end of 
the cord or to stretch a spring. U.S. Pat. No. 2,396,106 discloses an 
exerising device including a handle joined to a weight by means of an 
elongate spring steel blade, so that the weight oscillates and causes 
vibratory stimulation of the body parts. 
U.S. Pat. Nos. 3,917,281; 4,034,991 and 3,794,329, each disclose swing 
training apparatus in which a golf club or the like is guided by being 
slidably attached to a track in order to teach an accurate swing 
trajectory. 
SUMMARY OF THE INVENTION 
The present invention provides a novel exercise apparatus capable of 
exercising body muscles using acceleration and deceleration forces. The 
apparatus allows momentum, generated during concentric contraction of the 
muscles in order to produce an acceleration force, to be converted to 
place the muscles into eccentric contraction to produce a deceleration 
force. The apparatus can be used to provide a repetitive 
acceleration/deceleration muscle loading cycle. 
Generally described, an exercise apparatus embodying the present invention 
for exercising the muscles of a body part comprises a mass, means for 
connecting the body part to the mass such that force applied to a first 
direction by the body part accelerates the mass, and, after a 
predetermined amount of movement of the mass, decelerates the mass, the 
change from acceleration to deceleration of the mass occurring without 
significant decrease in the speed of the mass. 
An exercise apparatus embodying the present invention for exercising the 
muscles of a body part can comprise a mass confined for movement along a 
path, means for changing the direction of movement of the mass along the 
path without significantly decreasing the speed of the mass, and 
interconnecting means for connecting the mass to the body part, the 
interconnecting means being operable by the muscles of the body part to 
accelerate the mass along the path to the location at which the mass 
changes direction, and to decelerate the mass after the mass changes 
direction. The path preferably comprises a guide track with the mass being 
slidably mounted for movement along the guide track, and the means for 
changing the direction of the mass preferably comprises a curve in an 
intermediate portion of the guide track. In the preferred embodiment, the 
curve in the guide track turns 180.degree.. The interconnecting means 
preferably comprises a tether attached to the mass and passing through a 
tether guide ring adjacent to the curve in the guide track, so that when 
the tether is pulled the mass is accelerated toward the tether guide ring, 
is changed in its direction of travel by the curve in the guide track, and 
changes direction without any substantial decrease in speed so that the 
tether is pulled through the tether guide ring in the opposite direction 
as the body part exerts a force thereon to decelerate the mass. 
The apparatus can also comprise a linear track, a mass slidably mounted for 
movement along the linear track, a tether attached at one end thereof to 
the mass, and at the other end thereof to handle means for engaging a body 
part so as to permit the tether to be pulled by the body part, and tether 
guide means adjacent to a central location along the linear track for 
confining the tether to a given area, whereby the tether is pulled to 
accelerate the mass from one end of the track until the mass passes the 
tether guide means, and thereafter the mass pulls against the tether. 
A method of exercising muscles of a body part embodying the invention 
comprises the steps of accelerating a mass with the muscles of the body 
part by moving the body part in a first direction, changing the direction 
of movement of the mass independently of the muscles of the body part 
without significantly decreasing the speed of the mass, and decelerating 
the mass with the muscles of the body part while moving the body part in a 
second direction opposite to the first direction. In one mode, the method 
can be carried out by accelerating the mass by pulling the mass toward the 
body part and, subsequent to the change of direction of the mass, pulling 
against the movement of the mass to decelerate the mass. In another mode, 
the method can comprise pushing against the mass to accelerate the mass 
away from the body part and, subsequent to the change of direction of the 
mass, pushing against the mass to decelerate the mass. 
In the method and apparatus of the present invention, it is preferable that 
the path of travel of the mass be in an approximately horizontal plane, in 
order to minimize the influence of gravity on the primarily acceleration 
and deceleration forces created during operation of the invention. 
Thus, it is an object of the present invention to provide an inertial 
exercise apparatus for exercising body muscles using acceleration and 
deceleration forces. 
Another object of the present invention is to provide an inertial exercise 
apparatus in which a body part is connected to a mass in order to move the 
mass in such a way as to create acceleration and deceleration forces in 
the muscles of the body part.

DETAILED DESCRIPTION 
Referring now in more detail to the drawing, FIG. 1 shows a schematic 
representation of an inertial exercise apparatus 10 embodying the present 
invention. The apparatus 10 includes a horizontal curved track 12. The 
track 12 includes a 180.degree. bend, the center of which is designated as 
point 14. The point 14 is also the center of the track 12, which includes 
two straight legs 15 and 16 extending from the curve and being rigidly 
attached to a vertical support surface 17 at the opposite ends of the 
track 12. A pair of shock absorbers 19 and 20 are mounted adjacent or 
surrounding the track 12 where the opposite ends of the track 12 meet the 
support surface 17. It will be understood that the shock absorbers 19 can 
be provided with an adjustable mounting to permit them to be positioned 
closer to the midpoint 14 of the track 12 so as to vary the effective 
length of the track 12. 
Slidably mounted for travel along the track 12 is a mass 22 which includes 
a sleeve-type bearing 23 to reduce the friction between the mass 22 and 
the track 12 as much as possible. The mass is preferably thin in profile, 
and is sufficiently short in its dimension along the track 12 to be able 
to freely negotiate the radius of curvature of the track 12. The radius of 
curvature of the track 12 can be selected in order to vary the quickness 
with which the direction of movement of the mass 22 is changed as the mass 
22 travels along the track 12. A plurality of track supports 25 are 
provided to either support the track 12 from beneath as shown, or suspend 
it from above. The mass 22 and bearing 23 are constructed in a well known 
manner to that the track supports 25 do not interfere with the movement of 
the mass 22 along the track 12. The mass can be removed from the track 12, 
so that a mass of a desired weight can be selected to fit the needs of a 
particular user. 
A tether 27, such as a flexible cord or cable, is detachably fixed at one 
end thereof to the mass 22. Intermediate the length of the tether 27, the 
tether 27 passes through a tether guide ring 28, which is mounted adjacent 
to the track 12 near the center point 14, and confines the path of travel 
of the tether 27 to a given area between the track and the tether guide 
ring 28. Attached to the opposite end of the tether 27 is a handle or grip 
29 adapted to be grasped or otherwise engaged by a person 30. As shown in 
FIG. 1, the person 30 is grasping the handle 29 with a hand. However, it 
should be understood that the grip can be constructed to be temporarily 
engaged with any portion of the body that can be moved about a joint. 
In operation of the inertial exercise apparatus 10, a body part is engaged 
with the handle 29. In FIG. 1, a person 30 is shown grasping the handle 29 
with a hand, ready to pull the handle 29 away from the tether guide ring 
28. The starting position of the mass 22 is adjacent to one of the shock 
absorbers 19 or 20. Exertion of force by the person 30 accelerates the 
mass 22 along the track 12, and this involves a concentric contraction of 
the arm and shoulder muscles producing an acceleration force in the 
muscles. As the mass approaches the center point 14 of the track 12, the 
track 12 curves and redirects the motion of the mass in the opposite 
direction without slowing the mass. Since the mass is now moving away from 
the person 30, the force of the mass attempts to pull the tether 27 back 
through the tether guide ring 28. Opposition of the person 30 to this 
force of the mass involves an eccentric contraction of the arm and 
shoulder muscles producing a deceleration force in the muscles. In this 
phase of the exercise, the body part is moving in a direction opposite to 
that required for accelerating the mass 22. The exercise is complete when 
the person 30 has stopped motion of the mass 22 at a point along the 
opposite leg of the track 12 from that along which movement of the mass 22 
began. If the person 30 is not able to completely stop motion of the mass 
22, deceleration is completed by the shock absorber 19 or 20. If desired, 
the person 30 may immediately begin to repeat the exercise by pulling on 
the tether 27 to begin to accelerate the mass 22 in the opposite direction 
along the track 12. 
As will be seen from the foregoing discussion of operation of the apparatus 
10, the track 12 is preferably disposed in a horizontal plane, since 
tilting of the track 12 out of the horizontal plane would introduce the 
effect of gravity into the exercise. 
FIG. 2 shows a different mode of operation of the apparatus 10. In FIG. 2, 
the person 30 is shown ready to exert a force upon the tether 27 by 
pushing against the handle 29, instead of pulling against the handle 29 as 
was the case in FIG. 1. The movement of the mass 22 is exactly as 
described in connection with FIG. 1, the only difference being that the 
person supplies the acceleration and deceleration forces by a pushing 
motion instead of by a pulling motion. 
FIG. 3 shows a second embodiment of an inertial exercise apparatus 35 
embodying the present invention. In the embodiment shown in FIG. 3, the 
apparatus 35 includes a linear track 36 extending between a vertical 
support 37 and a rigid barrier 38. The barrier 38 is relatively massive 
and includes a resilient surface 39, such as stainless steel, facing the 
vertical support 37. A shock absorber 40 is provided on the track 36 
adjacent to the vertical support 37. 
A mass 41 including a bearing 42 is mounted for slidable movement along the 
track 36 in a manner similar to that described above in connection with 
the mass 22 of FIG. 1. The mass 41 further includes a rounded hardened 
contact surface 43 on the end of the mass facing the barrier 38. A tether 
45 extends from the mass 41 through a small guide opening 46 in the 
barrier 38 to a handle or grip 47. 
In operation of the embodiment shown in FIG. 3, the handle 47 is engaged 
with a body part and pushed or pulled to move the mass 41 from a position 
adjacent to the support 37 along the track 36 toward the barrier 38. When 
the mass 41 reaches the barrier 38, and the hardened contact surface 43 
engages the resilient surface 39 of the barrier 38. a nearly elastic 
collision occurs, and the mass 41 returns toward the support 37 without 
any substantial reduction in speed of the mass 41. This results in the 
acceleration forces, created in the muscles of the body part during the 
pulling of the mass 41 toward the barrier 38, being immediately converted 
into deceleration forces as the muscles attempt to slow down the movement 
of the mass 41 away from the barrier 38. The shock absorber 40 completes 
deceleration of the mass 41 if the person using the apparatus 35 is unable 
to completely stop the mass 41. As in the embodiment shown in FIG. 1, the 
mass 41 of FIG. 3 can be accelerated and decelerated by either a pulling 
or a pushing action. 
FIG. 4 shows a third embodiment of an inertial exercise apparatus 50 
according to the present invention. The apparatus 50 includes a linear 
track 51 which extends between two vertical supports 52 and 53. Shock 
absorbers 54 and 55 are provided adjacent to the supports 52 and 53. A 
mass 57 including a bearing 58 is slidably mounted for movement along the 
track 51. A tether 60 extends from the mass 57 through a tether guide ring 
61 that is mounted adjacent to the track 51 midway along the length of the 
track 51. A handle 62 is attached to the end of the tether 60 opposite the 
end attached to the mass 57. 
Operation of the embodiment shown in Fig. 4 is similar to that described 
above in connection with the other embodiments. The person utilizing the 
apparatus 50 exerts a force on the handle 62 in a direction away from the 
track 51. The force is exerted along the tether 60 to the mass 57, which 
begins to accelerate from a position adjacent to one of the vertical 
supports 52 or 53 toward the other vertical support. During the initial 
movement of the mass 57, acceleration forces are created in the muscles of 
the body part exerting a force on the handle 62. As the mass 57 passes the 
tether support ring 61, the mass 57 begins to pull the tether 60 back 
through the guide ring 61, and therefore pulls the body part toward the 
guide ring 61. The further motion of the mass 57 creates deceleration 
forces in the muscles of the body part as the muscles are used to 
decelerate the mass 57 to rest. It will thus be seen that although the 
mass 57 does not change its direction of travel, its motion converts 
acceleration forces in the muscles to deceleration forces very quickly and 
without any substantial decrease in the speed of the mass. 
FIGS. 5 and 6 show a fourth embodiment of an inertial exercise apparatus 70 
according to the present invention. A mass in the form of a disc 72 is 
mounted for rotation about a horizontal axle 73 passing through the center 
of the disc 72 and fixed thereto. The axle 73 is journalled at its ends in 
a pair of bearings 74 that are appropriately supported on standards (not 
shown) or suspended from above. A tether 77 is attached at one of its ends 
to the side of the disc 72 at a point 76 located near the circumference of 
the disc 72. The tether 77 extends from the point 76 between a pair of 
guide rollers 79 located in the same horizontal plane as the axle 73. The 
tether then further extends to a handle 80 attached to its other end, such 
that a person 30 grasping the handle 80 can exert force away from the disc 
72, and thereby cause rotation of the disc 72 about the axle 73. Although 
the person 30 is shown as grasping the handle 80 above and behind the 
person's head, it will be understood that the handle 80 can be adapted to 
receive other parts of the body, such as the feet, and can be pulled away 
from the disc 72 by any desired motion of a body part about a joint. 
In the embodiment shown in FIG. 5, rotational movement of the disc 72 is 
limited by a pair of stops 82 and 83 extending from the circumferential 
surface of the disc 72. The stops 82 and 83 engage a pair of shock 
absorbers 84 and 85, respectively. The shock absorbers 84 and 85 are 
preferably moveable into varying positions around the disc 72, in order to 
change the amount of rotational motion of the disc 72 that is permitted. 
In FIG. 5, the stops 82, 83 and shock absorbers 84, 85 are positioned so 
that the point 76 at which the tether 77 is attached to the disc 72 is 
permitted to move from a position directly above the axle 73 to a position 
directly below the axle 73. 
The mass of the disc 72 is balanced about any diameter thereof. The rotary 
inertia of the disc 72 can be varied by providing a pair of radial tracks 
87 extending one on each side of the axle 73. Weights 88 are slidably 
mounted along the tracks 87, and can be fixed in desired postions along 
the tracks 87 by tightening set screws 89. 
In operation of the embodiment of the invention shown in FIGS. 5 and 6, a 
body part is engaged with the handle 80, with the point 76 at which the 
tether is attached to the disc 72 located out of the horizontal plane of 
the axle 73. The force exerted on the handle causes rotational 
acceleration of the disc 72 until the point 76 passes through the plane of 
the axle 73, whereupon the force exerted on the handle is immediately 
converted to a force attempting to decelerate the mass 72. The 
acceleration of the disc 72 produces an acceleration force in the muscles 
of the body part. When the point 76 passes through the plane of the axle 
73 and changes the direction of the tether 77, a deceleration force is 
produced in the muscles of the body part. The conversion from acceleration 
to deceleration occurs essentially instantaneously without slowing of the 
speed of rotation of the disc 72. If the person 30 is not able to 
completely stop motion of the disc 72, one of the stops 82, 83 will engage 
its respective shock absorber 84, 85. Then, the exercise can be repeated 
by accelerating the disc 72 in the opposite rotational direction. 
FIG. 7 shows a fifth embodiment of an inertial exercise apparatus 90 
according to the present invention. The apparatus 90 is similar to the 
disc apparatus 70 shown in FIGS. 5 and 6. However, the tether 77 is 
attached at its end opposite the handle to a pulley 92 which rotates with 
the axle 73. This permits the tether 77 to wrap around the pulley 92 
multiple times. Thus, in operation of the apparatus 90, beginning with the 
tether 77 wrapped around the pulley 92, exertion of the body part to pull 
the tether 77 away from the disc 72 causes rotational acceleration of the 
disc 72 by unwrapping the tether 77 from the pulley 92. The acceleration 
of the disc 72 may thus continue for several rotations of the disc, until 
the tether 77 is completely unwrapped from the pulley 92, at which time 
the rotation of the disc 72 will immediately begin to "reel in" the tether 
77. Thus, continued exertion of the body part is immediately converted 
from a force tending to accelerate the disc 72, into a force tending to 
decelerate the disc 72. Because of the multiple rotations of the disc 72 
in operation of the embodiment shown in FIG. 7, stops on the 
circumferential surface of the disc, such as stops 82 and 83 of the 
apparatus 70, are not suitable for stopping rotation of the disc 72 in the 
event that the person 30 is unable to do so. Therefore, a shock absorber 
94 is fixedly mounted in the path of the tether 77. The shock absorber 94 
includes a longitudinal opening through which the tether 77 freely passes. 
A stop 95 which will not pass through the opening in the shock absorber 94 
is fixed to the tether 77 between the shock absorber 94 and the handle. 
Thus, the stop 95 limits the amount of the tether 77 that can be wound 
about the pulley 92, and stops rotation of the disc 72 upon engagement 
with the shock absorber 94. 
Those skilled in the art will understand from the foregoing that the 
present invention provides a novel method and apparatus for exercising 
muscles of the body by creating primarily acceleration and deceleration 
forces in the muscles, rather than resistive forces. Thus, the present 
invention can be utilized to prepare persons for sports and other 
activities in which the acceleration and deceleration function of the 
muscles is important. 
Although the present invention has been described in detail with particular 
reference to the preferred embodiments thereof, it should be understood 
that variations and modifications can be effected within the spirit and 
scope of the invention as described hereinbefore and in the appended 
claims.