with reference to fig1 a - 1g , an embodiment of a rebounder 100 will be described . the rebounder 100 is ideally used with dry - filled , gel - filled , or any other medicine balls of various weights and / or sizes , or regular balls . the medicine ball is thrown by an exerciser against the rebounder 100 and the rebound returns the medicine ball to the exerciser . each time the exerciser throws the medicine ball ( acceleration ), the rebounder 100 guides the exerciser to catch the returned medicine ball and follow through with corresponding deceleration . in alternative embodiments the rebounder 100 is used for other rebounding applications that those shown and described herein . the rebounder 100 includes a base 110 and a frame 120 that is pivotally connected to the base 110 for adjusting an angle of the frame 120 relative to the base 110 . the frame includes a first hoop member (“ first hoop ”) 130 of a first diameter / maximum dimension and a second hoop member (“ second hoop ”) 140 of a second diameter / maximum dimension less than the first diameter of the first hoop 130 . in alternative embodiments , the first member 130 and the second member 140 may have configurations other than circular ( e . g ., hexagonal , octagonal , pentagonal , polygonal ). a flat , substantially circular rebounding surface / mat 150 is attached to the first hoop 130 via a plurality of springs 160 extending there between . the mat 150 may include a target 155 in a center of the mat 150 . the target 155 improves the focal point and assists in aiming the medicine ball , and the target 155 allows points for accuracy for game competition and for performance evaluation . the second hoop 140 is supported by the first hoop 130 , extending above , over , and in front of the springs 160 via spoke truss support 170 ( the spoke truss construction is only one possible means for providing support for the second hoop 140 ; plates or other shapes of spokes and attachment point ( s ) can still offer the bumper benefit and extra strength from the circular truss ). the base 110 includes a front section 180 including opposite curved floor contact tubes 190 , a rear section 200 including opposite straight floor contact tubes 210 , a left side rail 220 , and a right side rail 230 . the floor contact tubes 190 , 210 include foam rubber grip surfaces 235 thereon to provide the maximum grip to the floor surface to prevent sliding of the base 110 relative to the floor . opposite terminal ends of the floor contact tubes 190 , 210 are pivotally connected to opposite terminal ends of the side rails 220 , 230 . the rear section 200 includes transport wheels 240 at ends of the side rails 230 . respective studs 250 extend upwardly from the side rails 220 , 230 for receiving annular weights ( e . g ., olympic - style weights ). one end of a back handle arm 260 forms a “ t ” with the opposite straight floor contact tubes 210 and pivots with contact tubes 210 . a back handle 270 is disposed at an opposite end of the back handle arm 260 . the rear part of the first loop 130 is adjustably and movably coupled to the back handle arm 260 via a collar pin 280 , a clamp collar 290 , and a clamp knob 300 . a rear of the back handle arm 260 includes position holes 290 for adjustably mounting the claim collar 290 and clamp knob 300 to the back handle arm 260 at a desired location for setting the rebounding surface 150 at a desired angle / incline . the handle arm 260 has a large number of angles / inclines ( e . g ., from 0 degrees to 50 degrees by 5 degree increments , 11 positions ). to adjust the angle / incline of the frame 120 relative to the base 110 , the clamp knob 300 is pulled and / or rotated ( untightened ) so that clamp collar 290 is no longer secured in a position hole 290 , and the clamp collar 290 is moved to the desired location / position hole on the back handle arm 260 . the clamp knob 300 may automatically engage each position hole 290 as the clamp collar 290 slides along the back handle arm 260 and / or the clamp knob 300 is rotated ( tightened ) so that clamp collar 290 is secured in a desired position hole 290 so that the rebounder 100 is at a desired angle // incline . the first hoop 130 and the rebounding surface 150 define a first plane and the second hoop 140 defines a second plane . the second plane is parallel with the first plane and is disposed above the first plane ( closer to the exerciser than the rear section 200 ). the second hoop 140 extends above , over , and in front of the springs 160 ( closer to the exerciser than the rear section 200 ), protecting the springs 160 from the heavy medicine balls thrown at the rebounder 100 . thus , the second hoop 140 forms a bumper to prevent the medicine ball ( s ) from hitting and damaging the springs . in the embodiment shown , each stud 250 for plate weights may receive up to four 45 lb . olympic - style weights . these weights reduce movement of the rebounder 100 during recoil ( when heavy medicine balls ( e . g ., 12 lbs to 40 lbs ) are thrown ) with all types of floor surfaces . fig2 a - 2f show the rebounder 100 in an angled / inclined condition ( e . g ., highest position , position 11 , 50 degree angle / incline ). fig3 a - 3f show the rebounder 100 in the same angled / inclined condition as fig2 a - 2f , and shows how the rebounder 100 may be transported by lifting the rebounder 100 at the bottom of the first hoop 130 so that the rebounder 100 pivots upwardly and is supported by the transport wheels 240 . the exerciser may then steer the rebounder 100 and push / pull the wheeled rebounder 100 to a desired location and position . fig4 a - 4f show the rebounder in a horizontal or low - compression jogger position for cardiovascular work . easy on the spine and knees , the uniformly round surface of the mat 150 provides solid support for the feet and ankles during jumping , hopping and jogging exercise . fig5 a - 5f show the rebounder 100 in a horizontal condition with the clamp knob 300 and the collar 290 removed from back side and installed on an underside of rebounder 100 to lock it in a compact , flat configuration / position for storage and / or shipping . training with the rebounder 100 helps develop core strength , agility and improved reaction time . exercisers &# 39 ; speed , range of motion and quality of movement improve at every level of function . regardless of the direction from which the medicine ball ( e . g ., dry - filled medicine ball ) is thrown , the medicine ball returns perpendicular to the rebounding surface 150 . each time the exerciser throws the ball ( acceleration ), the rebounder 100 guides the exerciser to catch the ball and follow through with corresponding deceleration . in the embodiment shown , the rebounding angle adjusts to eleven levels ( e . g ., from 0 degrees to 50 degrees by 5 degree increments ) to accommodate exercisers of any height , enabling them to exercise from seated , kneeling and standing positions . the rebounder 100 also serves as a low - compression jogger ( fig4 a - 4g ) for cardiovascular work . easy on the spine and knees , the uniformly round surface of the mat 150 provides solid support for the feet and ankles during jumping , hopping and jogging exercise . advantages of the rebounder 100 include the following : strong frame construction enables a strong rebound force and long life ; second hoop 140 protects springs 160 from direct impact from heavy medicine balls that could otherwise destroy the springs 160 ; long life of frame 120 and mat 150 as the impact load from the medicine ball is distributed on a large number of springs ; the second hoop 140 causes the exerciser to aim more accurately because there is no rebound from a medicine ball that hits the second hoop 140 ; the second hoop 140 and spoke construction creates a stronger circular truss than the strength of both rings added together ; the studs accommodate weights to reduce movement of the frame 120 and the base 120 relative to the floor surface during recoil ; the springs 160 include a thick wire construction and are high - strength springs ; the back handle arm has a large number of angles / inclines ; at a flat level ( fig4 a - 4f ), the rebounder 100 can still be jumped , hopped , or run on even with weights ; foam rubber grip surface 235 around all four floor contact tubes 190 , 210 provide the maximum grip to the floor to prevent sliding ; the target 155 in center of mat 150 improves the focal point and assists in aiming the medicine ball ; and the target 155 allows points for accuracy for game competition and for performance evaluation . the above figures may depict exemplary configurations for the invention , which is done to aid in understanding the features and functionality that can be included in the invention . the invention is not restricted to the illustrated architectures or configurations , but can be implemented using a variety of alternative architectures and configurations . additionally , although the invention is described above in terms of various exemplary embodiments and implementations , it should be understood that the various features and functionality described in one or more of the individual embodiments with which they are described , but instead can be applied , alone or in some combination , to one or more of the other embodiments of the invention , whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment . thus the breadth and scope of the present invention , especially in the following claims , should not be limited by any of the above - described exemplary embodiments . terms and phrases used in this document , and variations thereof , unless otherwise expressly stated , should be construed as open ended as opposed to limiting . as examples of the foregoing : the term “ including ” should be read as mean “ including , without limitation ” or the like ; the term “ example ” is used to provide exemplary instances of the item in discussion , not an exhaustive or limiting list thereof ; and adjectives such as “ conventional ,” “ traditional ,” “ standard ,” “ known ” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time , but instead should be read to encompass conventional , traditional , normal , or standard technologies that may be available or known now or at any time in the future . likewise , a group of items linked with the conjunction “ and ” should not be read as requiring that each and every one of those items be present in the grouping , but rather should be read as “ and / or ” unless expressly stated otherwise . similarly , a group of items linked with the conjunction “ or ” should not be read as requiring mutual exclusivity among that group , but rather should also be read as “ and / or ” unless expressly stated otherwise . furthermore , although item , elements or components of the disclosure may be described or claimed in the singular , the plural is contemplated to be within the scope thereof unless limitation to the singular is explicitly stated . the presence of broadening words and phrases such as “ one or more ,” “ at least ,” “ but not limited to ” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent .
a rebounder for rebounding a ball includes a base ; a frame pivotally connected to the base for adjusting an angle of the frame relative to the base , the frame including a first member having a first maximum dimension and a second member having a second maximum dimension less than the first member , the second member structurally supported by the first member ; a rebounding mat ; a plurality of springs coupling the rebounding mat to the first member , and wherein the second member is disposed forward of the springs and configured to protect the springs from contact by the ball .