Asymmetric outward rolling training device for abdominal anterior lateral muscles

Abstract

A training device for asymmetric training of abdominal muscles, comprising a handle device having a first grip zone for one hand of a user and a second grip zone for the other hand of the same user, and a rolling device comprising a first end and a second end, a distance from each other along a rolling axis, at least one axisymmetric element, when the training device rolls on a flat rolling surface under load during use, the rolling device is allowed to be in rolling contact with the flat rolling surface at a tread region, the tread region comprising: a first tread edge having a first tread diameter near the first end, and a second tread edge having a second diameter near the second end, the second tread edge having a second tread diameter near the second end, the handle device is rotatably connected to the rolling device for rotation relative to the rolling device about a rolling axis, the first tread edge is rotatably secured to the second tread edge such that the tread edges rotate synchronously, the first tread diameter being greater than the second tread diameter.

Description

Technical Field

[0001] The invention relates to an abdominal roller, a training device for exercising to strengthen muscles (especially abdominal muscles). Background Art

[0002] Abdominal rollers with a rolling device connected to the center of a symmetrical handle device that allows a user to perform an outward roll exercise to engage the abdominal muscles are known. For an outward roll exercise (roll-out exercise) utilizing a conventional abdominal roller, the user typically kneels on a cushioned protective pad and holds the handle device of the abdominal roller in both hands, which are positioned vertically below the shoulders, thereby forming a bridge between the hands and knees. During the outward roll movement, the hands are moved away from the knees, extending the hips and shoulders to form a longer bridge between the hands and knees. When fully outward rolled, the user's body is substantially straight, and the portion of the body between the hands and knees hangs above the rolling surface without contacting the rolling surface. The user will then perform a return movement from the fully outward rolled position back to the base position in reverse order, completing an exercise cycle of outward roll and return movement. Alternatively, an unskilled user may perform a short outward roll, extending only the hips, and keeping the hands substantially vertically below the shoulders, thereby less engaging the upper extremity musculature. Strong abdominal muscles are important for stabilizing the trunk and helping to relieve stress in the lumbar spine. Many abdominal exercises are used for abdominal strengthening, with or without the use of commercially available training devices, particularly abdominal rollers.

[0003] The abdominal muscles (rectus abdominis, external obliques, internal obliques, and transverse abdominis) are typically strengthened by actively flexing the trunk using concentric muscle actions (particularly crunches or sit-ups) or by resisting trunk extension (due to external forces such as gravity) using isotropic or eccentric muscle actions (particularly bridge leg lowers or straight leg lowers).

[0004] Abdominal exercises that actively flex the trunk can be problematic for some people with lumbar disc disease due to increased intradiscal pressure and lumbar compression, and for people with osteoporosis due to the risk of vertebral compression fractures. Therefore, abdominal exercises that maintain a healthy posture by maintaining a neutral spine and pelvis are preferred.

[0005] Many of these exercises also activate irrelevant (non-abdominal) muscles, such as the rectus femoris, erector spinae, or upper limb musculature, which may or may not be beneficial. For example, high activation levels from the rectus femoris and erector spinae tend to produce a force couple that attempts to rotate the pelvis forward and increase lumbar lordosis and increase L4-L5 compression; when these conditions are combined with weak abdominal muscle tissue, the risk of lower back pathology increases. The lateral abdominal muscles (external obliques, internal obliques, and transverse abdominis) enhance the stability of the spine and pelvis and increase intra-abdominal pressure (IAP). IAP has been shown to unload the spine by generating trunk extensor moments and tensile loads to the spine. The IAP mechanism makes the trunk a more solid cylinder, resulting in a reduction in axial compression and shear loads on the spine.

[0006] Research has shown that external roll exercises, such as when using a regular abdominal roller, produce the highest activation of the rectus abdominis and, to a lesser extent, the external and internal obliques. Research has also shown that when these external roll exercises are performed correctly, the abdominal musculature will contract primarily and evenly, and the pelvis and spine will be stabilized and held in a beneficial neutral position during the external roll and return movement.

[0007] In addition, studies have shown that the external rolling movement advantageously minimizes the activation of the lower extremity musculature, particularly the rectus femoris and erector spinae. Studies have also shown that external rolling exercises produce a high activation of the upper extremity musculature, particularly the pectoralis major, triceps brachii and latissimus dorsi. These exercises are beneficial for people who have limited time for exercise and whose goal is to perform exercises that provide not only abdominal training but also upper body training. These exercises may not be warranted for individuals with shoulder pathologies. Therefore, users preferably strengthen their abdominal muscles through an external rolling daily exercise using an abdominal roller due to the high effectiveness of the abdominal muscles during external rolling exercises and the low risk of injury due to the neutral position of the spine and pelvis.

[0008] Left-right differences in rectus abdominis size have been reported in users who engage in asymmetric sports (e.g., tennis, golf, and long jump). Left-right differences in rectus abdominis size are associated with the risk of strain injuries. Reducing left-right differences in rectus abdominis size by performing asymmetric training may help reduce the risk of strain injuries.

[0009] Although common abdominal rollers promote asymmetric exercise routines by allowing for a flexed external roll as a variation of the conventional straight external roll, abdominal and oblique EMG activity measured during the flexed external roll exercise was generally no different than the straight external roll exercise. Therefore, common abdominal rollers that allow for a flexed external roll exercise have not been shown to be effective for promoting unilateral abdominal muscle development.

[0010] Conventional abdominal rollers with narrow tread areas on a single wheel, a spherical wheel, or two wheels close to each other are usually designed to be unstable to promote higher activation of the abdominal muscles. The gripping areas of the hands are at a substantially equal distance from the tread area of ​​the rolling device, and the user must balance during the outward roll and return movement. This instability increases the level of activation of the abdominal muscles, but also increases the risk of injury due to loss of control and prevents untrained individuals from fully participating in the exercise. The unstable design also requires the user to distribute his weight evenly on both hands to prevent falling to one side, thus only promoting very limited activation of unilateral muscles. The even distribution of the weight of the user's hands hinders unilateral engagement of the abdominal muscles.

[0011] It is an object of the present invention to provide an advanced training device which eliminates at least one of the above mentioned problems. Summary of the invention

[0012] Among them, the present invention provides a training device for asymmetric training of abdominal muscles, comprising a handle device having a first gripping area for one hand of a user and a second gripping area for the other hand of the same user, and a rolling device comprising a first end and a second end at a distance from each other along a rolling axis, at least one approximately axisymmetric element, which allows the rolling device to roll in contact with a flat rolling surface at a tread area when the training device rolls on the flat rolling surface under load during use, wherein the tread area comprises a first tread edge having a first tread diameter near the first end, and a second tread edge having a second diameter near the second end, the handle device being rotatably connected to the rolling device to rotate relative to the rolling device about the rolling axis, wherein the first edge rotates approximately synchronously with the second tread edge, and the first tread diameter is larger than the second tread diameter.

[0013] The rolling device of the training device according to the invention may comprise only one approximately axisymmetric element, which allows the rolling device to be in rolling contact with the flat rolling surface at the tread area when the training device rolls on the flat rolling surface under load during use. The tread area comprises a first tread edge close to the first end of the rolling device, and a second tread edge close to the second end of the rolling device. The first edge on the same approximately axisymmetric element as the second tread edge can naturally rotate synchronously with the second tread edge. The rolling device of the training device according to the invention may comprise more than one approximately axisymmetric element. The approximately axisymmetric elements may be fixed to each other directly or indirectly, so that the rolling device in rolling contact with the flat rolling surface during use under load rotates only substantially synchronously with each other, as if it were only one approximately axisymmetric element.

[0014] The training device has a center point located halfway between the first tread edge and the second tread edge on the rolling axis. The center point can advantageously follow a circular path projected on the flat rolling surface during the outward roll and return motion, depending on the first tread diameter, the second tread diameter, and the distance between the first tread edge and the second tread edge, resulting in the training device targeting the anterior lateral abdominal muscles by achieving an asymmetric outward roll routine.

[0015] By fixing the approximately axisymmetric elements of the rolling device to each other, rotation of the approximately axisymmetric elements relative to each other is prevented, even when the force or torque applied to the handle device of the training device during the outward rolling and return movement may not correspond to a circular path, or when the traction force of the rolling device is unevenly distributed.

[0016] Fixing methods for fixing approximately axisymmetric elements to each other for consistent rotation are known. When the diameter of the hole of the wheel is smaller than the outer diameter of the axle, the fixing method can be, for example, an interference fit. In this way, after the parts are pushed together, the wheel and the axle are essentially combined and held together by friction. For example, two wheels fixed to the same axle using the above method can cause the two wheels to be restricted to rotate in unison according to the force applied to the wheels, so that the wheels rotate approximately synchronously with each other. The fixing method can also be more rigid, such as using bolts to fix the wheels to the axle to prevent any rotation of one wheel relative to the other. Another embodiment of the fixing method can be the use of one or more splines, or the use of pins that pass through more than one element in a hole perpendicular to the rolling axis. Fixing the tread edges to each other and / or fixing the wheels to each other can be accomplished by one or more fixing elements or fixing devices. The at least one fixing element is configured to rotationally fix the first tread edge and the second tread edge to each other so that they rotate in unison. The at least one fixing element can be, for example, an axle connecting the first tread edge and the second tread edge, wherein the first tread edge and the second tread edge are rotationally fixedly mounted to the axle such that they rotate together with the axle. The at least one fixing element can also be implemented as a groove of the axle element into which the axisymmetric element can be press-fitted. The handling device can be rotatably freely connected to the rolling device, for example to the axle, thereby allowing the rolling device to rotate while the handling device does not rotate.

[0017] The rolling device has approximately axisymmetric elements whose rotational axes are aligned with the rolling axis of the rolling device, and the one or more approximately axisymmetric elements can contact the flat rolling surface when the rolling device rolls on the flat rolling surface under load. The rolling device can have other elements that are not axisymmetric elements, as long as these other elements do not substantially interfere with the rolling of the rolling device. When the user performs a daily exercise with an outward roll and return motion, the training device rolls under load.

[0018] A nearly axisymmetric element is referred to as an element with cylindrical symmetry which may have geometric irregularities. For example, a tire suitable for rolling may have a basic shape that is an axisymmetric ring that does not interfere with rolling and additional geometric irregular grooves in the tread pattern that make the tire a nearly axisymmetric element.

[0019] The rolling device has a circumferential tread area, wherein when the training device rolls on the flat rolling surface under load during use, the outer surface of one or more approximately axisymmetric elements contacts the flat rolling surface and the weight of the user can press the approximately axisymmetric elements into the flat rolling surface. The tread area can be a continuous segment on one approximately axisymmetric element, or the tread area can be divided over a plurality of tread segments on one or more approximately axisymmetric elements. The axisymmetric element can be a cylindrical element. In the following, the terms are used interchangeably. Other embodiments of the axisymmetric element are also conceivable, such as spherical elements or conical elements.

[0020] The circumferential tread region may be visualized by rolling the training device on a flat rolling surface covered with colored ink. The circumferential tread region will become visible by transferring the ink from the flat rolling surface to the rolling device. The circumferential tread region has a first tread edge at a first end closest to the rolling axis, the first tread edge having a first tread diameter, and the circumferential tread region has a second tread edge at a second end closest to the rolling axis, the second tread edge having a second tread diameter.

[0021] The present invention further provides a training device, wherein the at least one approximately axisymmetric element comprises a first wheel, and the rolling device further comprises another approximately axisymmetric element, the other approximately axisymmetric element comprising a second wheel, wherein the first wheel comprises a first tread edge, and the second wheel comprises a second tread edge. A training device is further provided, wherein the rolling device comprises a cylindrical axle element having a first axle end and a second axle end; and a fixing device, wherein the fixing device connects the first wheel to the first axle end and the second wheel to the second axle end to constrain the wheels to rotate substantially uniformly about the rolling axis.

[0022] In particular, a training device is provided, wherein the fixing device rotationally fixes the wheel to the cylindrical wheel axle element.

[0023] By providing a fixing element to fix each wheel to the cylindrical wheel axle element, the wheels are prevented from rotating relative to each other, even when the force or torque applied to the handle device of the training device during the outward rolling and return movement may not correspond to a circular path, or when the traction of the first wheel is different from the traction of the second wheel. The fixing element used to fix the wheel to the cylindrical element (particularly the straight shaft) limits the first wheel and the second wheel to rotate in unison. When the diameter of the hole of the wheel is less than the outer diameter of the cylindrical wheel axle element, the fixing element can be, for example, an interference material to allow interference fit. In this way, after the parts are pushed together, the wheel and the cylindrical wheel axle element are basically combined and kept together by friction. The fixing device can also be more rigid, such as a bolt, to fix the wheel to the cylindrical wheel axle element. Another embodiment of the fixing device can be one or more splines on the cylindrical wheel axle element, or a pin that passes through the wheel and the cylindrical wheel axle element in a hole perpendicular to the cylindrical wheel axle element.

[0024] One hand of the user can be placed on the first grip area, the other hand of the user can be placed on the second grip area, and the user can move the hand forward on the rolling surface away from the knee during the outward roll motion and return the hand toward the knee during the return motion, thereby completing one cycle of the outward roll and return motion.

[0025] The rolling device rotates around the rolling axis during the outward rolling and return movements. During the outward rolling and return movements, the handle device having the first gripping area and the second gripping area can freely rotate relative to the rolling device around the rolling axis so that the hand follows a smooth path and maintains approximately the same distance from the rolling surface.

[0026] Grip areas on handle devices are known. The grip areas on handle devices can be unmarked spaces that are obvious to the user for positioning their hands. The handle device can include a cylindrical handle element having a suitable diameter and sufficient length to comfortably position the user's two hands close to each other so as to freely rotate around the rolling axis relative to the rolling device, and the handle device can generally be understood as including an unmarked first grip area at one end of the cylindrical handle element and an unmarked second grip area at the other end of the cylindrical handle element. The grip areas can be clearly marked on the handle device. The markings of the grip areas can be contours, color differences, different shapes or different materials. Each of these details provides special advantages and can be implemented independently of other details.

[0027] The training device can guide the user along a circular path during the roll-out and return motions, allowing the user to initiate a first force via one hand to the first grip area and a second force via another hand to the second grip area. The first force can be viewed as a first vector having a first starting point, a first magnitude, and a first direction, and the second force can be viewed as a second vector having a second starting point, a second magnitude, and a second direction. The first starting point can be in the middle of the first grip area, and the second starting point can be in the middle of the second grip area.

[0028] The first magnitude may be different from the second magnitude, and the first direction may be different from the second direction, while the center point of the training device advantageously continues to move substantially along a circular path projected onto the flat rolling surface.

[0029] During the roll-out motion, due to the diameter difference between the tread edges, the first tread edge will travel further than the second tread edge. The first tread edge can advantageously move further away from the user's knee than the second tread edge, thereby allowing a guided asymmetric roll-out routine. The guided asymmetric roll-out routine enables the user to effectively and safely train the abdominal muscles unilaterally.

[0030] A first hand placed on a first gripping area positioned near a first tread edge may move further away from the user's knee during a roll-out motion than a second hand placed on a second gripping area positioned near a second tread edge, wherein the abdominal muscles on the side of the first hand may have a higher level of activation than the abdominal muscles on the side of the second hand. The user's arm on the side of the second hand may not be fully extended, and the muscles on the side of the second hand may be less activated. Thus, the user may use the second hand on the less engaged side of the body to actively steer and control the roll-out and return motions of the training device.

[0031] The user's arm connected to the first hand may be referred to as the extension arm, and the user's arm connected to the second hand may be referred to as the control arm. The user may target the abdominal muscles to the side of the body more strictly with the extension arm by increasing the body weight directed to the first hand. Advantageously, the abdominal muscles on the side of the extension arm are trained with a higher load. The second hand of the control arm may therefore bear a lighter weight of the body. Advantageously, the control arm will be less activated and may be able to better manipulate, support and control the exercise. The user may perform an inclined roll-out program and rotate the lower body around the longitudinal axis of the body, causing the hips to drop on the side of the extension arm, thereby causing the user's body to be closer to the rolling surface on the side of the extension arm over the entire length of the body. The user may perform a twist roll-out program and cause the hips to drop on the side of the control arm, resulting in a twisted body in a fully rolled-out position when the shoulder of the extension arm will also move contralaterally toward the rolling surface.

[0032] The user can lift one leg during the roll-out and return motion. The stability of the training device is such that the first tread edge is away from the second tread edge, advantageously providing the user with enough stability to rest on only one knee and lift the other leg up off the rolling surface without falling. In this daily exercise, the leg in contact with the rolling surface carries most of the body's weight and can be referred to as the supporting leg. The lateral abdominal muscles are activated to maintain lumbar torsional control by keeping the pelvis and rib cage locked, and to prevent the lifted leg from falling during the roll-out and return motion. The supporting leg can be on a single side of the extended arm.

[0033] The user may alternatively position the supporting leg on the opposite side of the extension arm. Advantageously, these unique asymmetric exercises utilize advanced training devices and involve resisting trunk rotation and extension through isometric or eccentric muscle contractions that maintain a neutral and safe spinal and pelvic posture. It should be noted that the unique and advantageous exercise routines described are exemplary asymmetric external roll exercise routines possible with embodiments of the present invention. The exercise routines are given by way of non-limiting example.

[0034] In the following, the effect of muscle activation of the present invention will be specifically described with reference to a test embodiment, but the present invention is not limited to this test embodiment at all. Each user will perform daily exercises differently using the training device according to the present invention, and the measurement results can show different activation levels and lateral changes.

[0035] The test equipment used is commercially available. The relevant test methods and the specific operation of the relevant instruments used in the test are well known to those skilled in the art.

[0036] A well-trained male user, aged 23 years, has tested a training device according to the invention having a first wheel with a diameter of 145 mm and a second wheel with a diameter of 100 mm. The wheels with a spacing of 600 mm are fixed to the wheel axle and a handle device having a first gripping area and a second gripping area rotating around the wheel axle between the first and second wheels. As a reference, the user has also tested existing abdominal exercises, in particular abdominal tuck and side plank exercises with hip dips without tools, and straight and bent external roll exercises with a standard usable abdominal wheel called AB wheel from Decathlon under the trademark Domyos.

[0037] Users were monitored using electromyography (EMG) analysis equipment, including wireless mini-wave electrodes provided by Cometa and EMG, and the Sports Tools software version 7.0.

[0038] Monitors the following eight muscles of the user:

[0039] Left superior rectus abdominis (LRA up), right superior rectus abdominis (RRA up), left lower rectus abdominis (LRA lo), right lower rectus abdominis (RRA lo), left external oblique (LEO), right external oblique (REO), left internal oblique (LIO), and right internal oblique (RIO).

[0040] The user performed three maximal voluntary contraction (MVC) exercises before the test round and repeated three MVC exercises after the test round: one MVC exercise for the lower and upper rectus abdominis, one MVC exercise for the left external and left internal obliques, and one MVC for the right external and right internal obliques.

[0041] Five exercises were performed using the training device according to the invention.

[0042] like Fig. 8A and Figure 8B The basic rollout shown. The tilt rollout, in which the lower body rotates about the user's longitudinal axis and the hips are lowered to the side of the extension arm. The twist rollout, in which the lower body rotates about the user's longitudinal axis and the hips are lowered to the side of the control arm. Fig. 9 Shown is a leg-lifted roll-out with the support leg on opposite sides of the extension arm. A leg-lifted roll-out with the support leg on one side of the extension arm.

[0043] All exercises are performed once with the large wheel near the left hand and once with the large wheel near the right hand.

[0044] For reference, perform four common exercises: abdominal contraction, straight outward roll with the AB wheel, bent outward roll to the left and right with the AB wheel, and side bridge with the hips sinking to the left and right.

[0045] All exercises were performed with a pause in the extreme position, where the average isovolumetric activation level of the muscle was measured. The average values ​​of the isovolumetric phase are listed in the table below as a percentage of the MVC level.

[0046]

[0047]

[0048] The following conclusions can be drawn from the test results. The reference exercises showed strong unilateral activation with low activation levels, such as the side bridge with hip drop, or high levels of activation with only limited lateral variation in muscle activation, such as the bent outward roll with the AB wheel. It should also be noted that the symmetrical reference exercises (such as the abdominal pull-in) and the straight outward roll with the AB wheel showed some unintentional uneven distribution of activation levels between left and right, which may be due to unconscious preferences of the user or due to compensation for instability.

[0049] A variety of exercises with the training device according to the invention advantageously activate muscles at a high level and unilaterally at the same time. The basic external roll with the stable training device according to the invention has only slightly lower muscle activation compared to the external roll exercise with the unstable AB wheel. Advantageously, the unilateral variation in the daily exercise increases the activation level and adds the lateral difference in muscle activation. The inclined external roll exercise shows a reduced activation level of the lower and upper rectus abdominis, but with a very high unilateral activation of the external oblique muscles, which makes this exercise very suitable for the targeted training of the external oblique muscles on a single side. The twisted external roll targets all muscles unilaterally at a very high level, making it very suitable for unilateral training of advanced athletes. The external roll exercise with the leg raised has an even higher activation of all muscles, far exceeding the level provided by the conventional AB wheel, without introducing uncomfortable instability or compromising the safety of the spine by keeping the spine in a neutral position, making it even more suitable for professional athletes.

[0050] Thus, the training device according to the present invention uniquely provides a simple tool to safely and comfortably perform a variety of asymmetric abdominal exercise routines, thereby unilaterally and efficiently targeting different abdominal muscles in an unprecedented manner.

[0051] The present invention provides a training device, preferably wherein the first gripping area is substantially closer to the first tread edge than the second gripping area, and the second gripping area is substantially closer to the second tread edge than the first gripping area. During unilateral exercise, the first magnitude of the first force of the first hand of the extension arm may be greater than the second magnitude of the second force of the second hand of the control arm. The first gripping area being substantially closer to the first tread edge than the second gripping area may ensure the stability and safety of the training device. The distance between the first starting point of the first force and the first tread edge may be shorter than the distance between the second starting point of the second force and the first tread edge. The starting point of the resultant force of the first vector of the first force plus the second vector of the second force may advantageously be located between the first tread edge and the second tread edge, so that even when the first magnitude of the first force becomes substantially greater than the second magnitude of the second force, the training device will remain stable on both wheels.

[0052] The present invention provides a training device having a first starting point in the middle of a first gripping area and a second starting point in the middle of a second gripping area, preferably wherein the distance between the first starting point and the first tread edge is less than 80%, in particular less than 65%, more in particular less than 50% of the distance between the second starting point and the first tread edge.

[0053] In particular, a training device wherein the distance between the second starting point and the second tread edge is less than 80%, in particular less than 65%, more in particular less than 50%, of the distance between the first starting point and the second tread edge to provide stability during the rolling-out and returning movements even when the second magnitude of the second force becomes substantially greater than the first magnitude of the first force.

[0054] The invention provides a training device, wherein the first gripping area and the second gripping area are located between the first tread edge and the second tread edge. The training device can have a simple design and an uneven distribution of weight between the first gripping area and the second gripping area does not cause the training device to tip over.

[0055] The invention provides a training device, wherein a handle device comprises a cylindrical handle element, wherein the cylindrical handle element comprises a first gripping area and a second gripping area. The first gripping area and the second gripping area advantageously always rotate synchronously with each other. The invention provides a training device, which comprises a handle device, which comprises a first cylindrical handle element with a first gripping area and a second cylindrical handle element with a second gripping area, wherein the first cylindrical handle element and the second cylindrical handle element rotate relative to each other. The first element and the second element can be rotated separately around a rolling axis and independently of each other, wherein both hands can find their own neutral position.

[0056] The element of the handle device with the first gripping area or the second gripping area can rotate freely around the rolling axis located outside the rolling device. The cylindrical handle element can be positioned in a central hole passing through the rolling device, wherein the first gripping area is on one side of the rolling device and the second gripping area is on the other side of the rolling device.

[0057] The present invention provides a training device, which comprises a first axisymmetric element made of metal and a second axisymmetric element made of plastic, such as a cylindrical element, one of the first axisymmetric element and the second axisymmetric element is part of a rolling device, and the other of the first axisymmetric element and the second axisymmetric element is part of a handle device, wherein the metal element is positioned within the plastic element to form a rotating joint.

[0058] The cylindrical handle element can be advantageously made of a sturdy material, particularly metal, and can be installed to pass through a cylindrical axle element made of a low-friction material (particularly plastic) to form a swivel joint. The cylindrical axle element can be advantageously made of a sturdy material (particularly metal), and can be installed to pass through a cylindrical handle element made of a low-friction material (particularly plastic) to form a swivel joint. In addition, the metal can be steel, and optionally, a protective zinc coating, a chrome coating or a plastic coating is applied to the metal cylindrical element. The coating reduces friction and makes the metal cylindrical element suitable for smooth rotation in a cylindrical contact with the plastic cylindrical element. Plastics are generally low-friction materials relative to metal, particularly nylon, HDPE or PP. By making the inner diameter of the plastic cylindrical element greater than the outer diameter of the metal cylindrical element, the plastic cylindrical element can be freely rotated around the metal cylindrical element in the form of a swivel joint. The plastic cylindrical element is easy to produce, and a sturdy and lightweight component of a training device is provided. Furthermore, it should be noted that friction can be advantageously reduced by many other known means, in particular lubrication or geometries having ridges that reduce the contact area between the sliding surfaces.

[0059] Each of these details provides particular advantages and may be implemented independently of the other details.

[0060] The gripping area may be marked with a soft pad made of EVA foam or rubber for greater comfort. The gripping area may be designed in an ergonomically optimal shape. In addition, the gripping area may be a thermoplastic material ergonomically shaped for optimal comfort. The gripping area may be reflectively symmetrical in a plane passing through the rolling axis to provide the same optimal ergonomic support when the first gripping area is held with the left hand and the second gripping area is held with the right hand as when the first gripping area is held with the right hand and the second gripping area is held with the left hand. The first gripping area may have a different basic design than the second gripping area, and the angle of the hand on the first gripping area to the rolling axis may be different from the angle of the hand on the second gripping area to the rolling axis.

[0061] In daily exercise, during the outward rolling movement, the first hand may be externally rotated and the second hand may be adducted. It may be advantageous to give the first grip area and the second grip area an ergonomic shape that allows inward and outward movement of the hands and prevents injuries. The present invention provides a training device, wherein the handle device includes a support handle that is substantially perpendicular to the rolling axis. By having a support handle connected to the first grip area, for example, in a position where the thumb is substantially perpendicular to the rolling axis, the thumb of the first hand can curl around the support handle and the first hand may conveniently need to be less adducted in the fully outward rolled position.

[0062] The training device may have specific dimensions that provide particular advantages to the user. A center point of the training device may move generally along a circular path projected onto the flat rolling surface, the circular path having a radius defined by the first tread diameter, the second tread diameter, and the distance between the first tread edge and the second tread edge. A taller user may require a training device that moves along a circular path with a larger radius, while a shorter user may require a training device that moves along a circular path with a smaller radius. One routine may be a full roll-out, where a larger radius is preferred, and another routine may be only a short roll-out, where a smaller radius is preferred.

[0063] The present invention provides a training device comprising a centre point which follows a circular path with a radius projected onto the flat rolling surface when the training device is rolled under load on the flat rolling surface during use, preferably wherein the radius is between 80 cm and 500 cm, in particular between 120 cm and 300 cm, more in particular between 140 cm and 250 cm.

[0064] The present invention provides a training device comprising a distance between a first tread edge and a second tread edge, preferably wherein the distance is greater than 7 cm, in particular greater than 14 cm, more in particular greater than 20 cm.

[0065] It may be advantageous for the user to have the first gripping area and the second gripping area at a distance that is approximately the same as the width of the user's shoulders. It may be advantageous when the first gripping area and the second gripping area are positioned between the first tread edge and the second tread edge. A training device having a large distance between the first tread edge and the second tread edge may also be advantageous for greater flexibility in daily exercise. The present invention provides a training device, preferably wherein the distance between the first tread edge and the second tread edge is from about 20 cm to about 120 cm, in particular from about 30 cm to about 90 cm, more particularly from about 40 cm to about 80 cm, even more particularly from about 50 cm to about 70 cm. It should be noted that the training device may, for example, preferably be stored in a small place, in particular in a suitcase for travel. The short distance between the first tread edge and the second tread edge may also be advantageous because the load on the cylindrical element may be lower. A short cylindrical element may be less likely to bend or break than a long cylindrical element. The present invention provides a training device, preferably wherein the distance between the first tread edge and the second tread edge is less than 80 cm, in particular less than 60 cm, more in particular less than 40 cm.

[0066] It may be advantageous to provide a stable exercise device when the rolling device is positioned between the first grip area and the second grip area.

[0067] The training device can be easily disassembled and assembled by the user for storage.

[0068] The present invention provides a training device, preferably wherein the first tread diameter is 5% to 100% larger than the second tread diameter, particularly 20% to 80% larger, more particularly 35% to 65% larger. This may be advantageous for training devices for users of various lengths.

[0069] The present invention provides a training device, preferably wherein the second tread diameter is greater than 7 cm. Advantageously, the hands do not touch the rolling surface during exercise. The compact training device is preferably easy to carry and store.

[0070] Furthermore, the invention provides a training device, preferably wherein the first tread diameter is less than 50 cm, particularly less than 35 cm, more particularly less than 25 cm. However, larger wheels are advantageous for daily exercise lifted from the floor or on specific rolling surfaces, particularly on loose sand or uneven rolling surfaces.

[0071] The present invention provides a training device in which the wheels have tires. Advantageously, better performance is achieved by providing a flexible pad that absorbs shocks and maintains a strong grip of the wheel on the rolling surface.

[0072] In addition, the present invention provides a training device, wherein the tire is made of a high friction material. The high friction material further increases the grip of the wheel on the rolling surface during the outward roll and return motion, which may be advantageous when the training device is used on a smooth and dry rolling surface. Advantageously, the present invention provides a training device, wherein the high friction material comprises rubber (e.g., PU). By preventing the wheel from sliding relative to the rolling surface, the training device will better follow the circular path and deviate from the circular path less due to sliding. The user may be able to distinguish the first force from the second force, and therefore experience more control, and be more effective in unilaterally targeting specific abdominal muscles. By applying a first magnitude that is substantially different from the second magnitude or applying a first direction that is substantially different from the second direction, while the center point of the training device remains substantially on its circular path, the user can unilaterally and more effectively target specific muscles.

[0073] The tire may be molded directly onto the wheel. The tire may be made of a different material than the wheel. The invention provides a training device in which the tire has a high friction tread. The high friction tread increases the grip of the wheel on the rolling surface. The invention provides a training device in which the tread on the wheel has a tread pattern. The tread pattern may be advantageous when the training device is used on a soft or loose rolling surface. Other tread patterns may be advantageous on rough or wet rolling surfaces. Each of these details provides particular advantages and may be implemented independently of one another or in combination with one another.

[0074] The training device may have a spring mechanism connecting the rolling device to the handle device. When the training device rolls outward, the spring mechanism may be rolled up, and towards the end of the rollout, the user is supported by the increased pull-back force of the spring. The pull-back force during the rollout stroke is stored as energy in the spring. This stored energy in the spring may be released during the return movement and support the user. In this way, the user may be helped to perform the rollout exercise, and the spring mechanism may prevent uncontrolled rollout and return movements.

[0075] Further advantageous embodiments are described in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] The present invention will now be described in detail, however by way of example only, with reference to the exemplary embodiments shown in the accompanying drawings. In the drawings:

[0077] Figure 1 shows a perspective view of a first embodiment of a training device according to the invention;

[0078] Figure 2 shows a front view of a second embodiment of a training device according to the invention;

[0079] Figure 3 shows a front view of a third embodiment of a training device according to the invention;

[0080] Figure 4 shows a front view of a fourth embodiment of a training device according to the invention;

[0081] Figure 5 shows a front view of a fifth embodiment of a training device according to the invention;

[0082] Fig. 6A shows a front view of a sixth embodiment of a training device according to the invention, with one side of the training device in use;

[0083] Figure 6B A front view of a sixth embodiment of a training device according to the invention is shown, wherein the training device is Fig. 6A The other side is in use;

[0084] Fig. 7A shows a top view of a seventh embodiment of a training device according to the invention;

[0085] Figure 7B Shows Fig. 7A A cross section marked by section line AA of a seventh embodiment of FIG.

[0086] Fig. 8Ashows a top view of a second embodiment of a training device according to the present invention, wherein a user is in a starting position for a first roll-out exercise routine;

[0087] Figure 8B shows a top view of a second embodiment of a training device according to the present invention, wherein a user is in a fully rolled-out position of a first roll-out routine;

[0088] Fig. 9 shows a side view of an eighth embodiment of a training device according to the present invention, wherein a user is in a fully rolled-out position of a second roll-out routine, wherein one leg is lifted off a rolling surface on one side of an extension arm;

[0089] Fig.10 shows a perspective view of an eighth embodiment of a training device according to the present invention, used by a user in a fully rolled-out position of a third roll-out routine;

[0090] Fig.11A shows a top view of a ninth embodiment of a training device according to the invention having an ergonomically shaped gripping area;

[0091] Fig. 11B A ninth embodiment of a training device according to the invention is shown in a front view.

[0092] It should be noted that the drawings are only schematic and schematic representations of exemplary embodiments of the present invention. These embodiments are given by way of non-limiting examples. In the drawings, identical or corresponding parts are represented by the same reference numerals. DETAILED DESCRIPTION

[0093] Figure 1 A training device 1 is shown, comprising a rolling device 2 having a first end 201 and a second end 202 spaced apart at a distance from each other along a rolling axis 3, having a plurality of approximately axisymmetric elements 21 around the rolling axis 3 and non-axisymmetric elements 22 that do not interfere with the rolling of the rolling device 2. All elements of the rolling device 2 are produced from plastic using one mould and are therefore fixed to each other and rotate in unison.

[0094] Figure 1A training device 1 is depicted rolling on a flat rolling surface 4 under a load, and a plurality of approximately axisymmetric elements 21 are in contact with the flat rolling surface 4. The flat rolling surface or support surface may be, for example, a floor. When the rolling device 2 in this embodiment of the invention is not under load, the approximately axisymmetric elements 21 will only be in contact with the flat rolling surface 4 at two points. The weight of the load presses the plurality of approximately axisymmetric elements 21 having a spherical shape onto the flat rolling surface 4, causing the material 231, 232, 233 of the approximately axisymmetric elements to sag inwardly and creating a circumferential tread area 24 during one complete rotation. The depression of the material in the first area 231 may be smaller than the depression of the material in the second area 232, thereby completely distributing the weight over the plurality of tread area segments 241, 242, 243 and creating a wide circumferential tread area 24, thereby creating a stable training device 1.

[0095] Circumferential tread region 24 has a first tread edge 251 closest to first end 201 of rolling device 2 having a first tread diameter, and has a second tread edge 252 closest to second end 202 of rolling device 2 having a second tread diameter.

[0096] A first tread diameter of first tread edge 251 is greater than a second tread diameter of second tread edge 252 . Figure 1 Further shown is a handle device 5 on the training apparatus 1, which comprises a first gripping area 511, a second gripping area 512 and a cylindrical handle element 53 fixed to each other with an interference fit. The handle device 5 is connected to the rolling device 2 to rotate relative to the rolling device 2 about the rolling axis 3. The cylindrical handle element 53 is made of metal.

[0097] Figure 2 Shown is a training apparatus 1 with a rolling device 2 comprising a first wheel 261 with a first tread edge 251 and a second wheel 262 with a second tread edge 252, a cylindrical axle element 28 made of metal with a first axle end 281 and a second axle end 282, and a fixing device 29, wherein the fixing device 29 connects the first wheel 261 to the first axle end 281 and the second wheel 262 to the second axle end 282 to constrain the wheels 261, 262 to rotate substantially in unison about the rolling axis 3. The handle device 5 comprises a plastic tube as a cylindrical handle element 53, the plastic tube having a first gripping area 511 and a second gripping area 512, both gripping areas being marked with an EVA foam coating surrounding the plastic tube.

[0098] Figure 3 A training device 1 according to the invention is shown, which is similar to Figure 2The difference is that the handle device 5 comprises a first cylindrical handle element 531 with a first gripping area 511 and a second cylindrical handle element 532 with a second gripping area 512. The first cylindrical handle element 531 and the second cylindrical handle element 532 are respectively rotatable around the rolling axis 3 and independently of each other, wherein both hands can find their own neutral position.

[0099] The wheel 26 is made of polypropylene and has a tire 27 made of PU rubber, which is molded directly on the wheel 26. The fixing means 29 for connecting the wheel 26 to the cylindrical axle element 53 is a cylindrical plug made of nylon, which has splines in the longitudinal direction, which are pressed through the hole of the wheel 26 and through the inside of the cylindrical axle element 53, thereby forming an interference fit.

[0100] Figure 4 A training device 1 according to the invention is shown, which has a first handle element 531 of a handle device 5, which has a first gripping area 511 located outside the rolling device 2 and is free to rotate around the rolling axis 3, and a second cylindrical handle element 532, which has a second gripping area 512 located outside the rolling device 2 and is free to rotate around the rolling axis 3 independently of the first gripping area 511. The first gripping area 511 is positioned approximately perpendicular to the rolling axis 3. This position may be advantageous for users who have difficulty in pronation of the forearm. During the outward roll and return movement, the handle device 5 with the first gripping area 511 still rotates relative to the rolling device 2 around the rolling axis 3, so that the hand follows a smooth path, maintaining approximately the same distance from the rolling surface 4. First starting point 541 at first gripping area 511 is substantially closer to first tread edge 251 than second starting point 542 at second gripping area 512, and second starting point 542 at second gripping area 512 is substantially closer to second tread edge 252 than first starting point 541 at first gripping area 511. For example, at some point during an outward rolling routine, the combined force defined by adding the first vector of the first force to the second vector of the second force may advantageously have combined starting point 543 between first tread edge 251 and second tread edge 252, so that the training device will remain stable on both wheels 261, 262 even when the first magnitude of the first force becomes substantially greater than the second magnitude of the second force.

[0101] Figure 5A training device 1 according to the invention is shown, which has a first cylindrical handle element 531 of a handle device 5 with a long gripping area 51 located outside the rolling device 2 and freely rotating about the rolling axis 3, and a second cylindrical handle element 532 with a gripping area 51 located outside the rolling device 2 and freely rotating about the rolling axis 3 independently of the first cylindrical handle element 531. The first cylindrical handle element 531 has an unmarked long gripping area 51, which is much larger than the width of a hand, thereby allowing the user to place the hand in multiple positions.

[0102] The user may choose to place the first hand on the first cylindrical handle element 531 near the first wheel 261 as the first gripping area 511. The user may choose to place the second hand on the first cylindrical handle element 531 near the second wheel 262 as the first alternative second gripping area 5121. Or the user may choose to place the second hand on the second cylindrical handle element 532 as the second alternative second gripping area 5122. The first gripping area 511 is substantially closer to the first wheel 261 than the second gripping areas 5121, 5122, and the second gripping areas 5121, 5122 are substantially closer to the second wheel 262 than the first gripping area 511.

[0103] Fig. 6A and Figure 6B A symmetrical training device 1 for asymmetrical training of the abdominal muscles according to the invention is shown. The training device 1 can be easily tilted to Fig. 6A The training shown has an asymmetric orientation to the left and Figure 6B Shown to the right are switches between trainings with an asymmetric orientation.

[0104] exist Fig. 6AIn the embodiment of the present invention, when the training device 1 is rolled on the flat rolling surface 4 under load during use, the rolling device 2 has a first wheel 261 and a second wheel 2621 in rolling contact with the flat surface 4. The tread region 24 has two tread region segments 2411, 2421. The tread region 24 has a first tread edge 2511 with a first tread diameter closest to the first end 2011 of the rolling device 2, and the tread region 24 has a second tread edge 2521 with a second tread diameter closest to the second end 2021 of the rolling device 2. The first tread diameter of the first tread edge 2511 is greater than the second tread diameter of the second tread edge 2521. The user may choose to place the first hand on the first cylindrical handle element 531 close to the first wheel 261 as a first alternative 5111 to the first gripping area. Alternatively, the user may choose to place the first hand on the second cylindrical handle element 532 close to the first wheel 261 as a second alternative 5112 to the first gripping area. The user may choose to place a second hand on the first cylindrical handle element 531 close to the second wheel 2621 as a second gripping area 5121. The first gripping areas 5111, 5112 are substantially closer to the first wheel 261 than the second gripping area 5121, and the second gripping area 5121 is substantially closer to the second wheel 2621 than the first gripping areas 5111, 5112.

[0105] exist Figure 6B In Fig. 6A The same training device 1 of FIG. 2 is tilted so that when the training device 1 rolls on the flat rolling surface 4 under load during use, the rolling device 2 has a first wheel 261 and a second wheel 2622 in rolling contact with the flat surface 4. The tread area 24 has two tread area segments 2412, 2422. The tread area 24 has a first tread edge 2512 with a first tread diameter closest to the first end 2012 of the rolling device 2, and the tread area 24 has a second tread edge 2522 with a second tread diameter closest to the second end 2022 of the rolling device 2. The first tread diameter of the first tread edge 2512 is larger than the second tread diameter of the second tread edge 2522.

[0106] The user may choose to place the first hand on the first cylindrical handle element 531 near the first wheel 261 as the first alternative to the first gripping area 5111. Alternatively, the user may choose to place the first hand on the second cylindrical handle element 532 near the first wheel 261 as the second alternative to the first gripping area 5112. The user may choose to place the second hand on the second cylindrical handle element 532 near the second wheel 2622 as the second gripping area 5122. The first gripping areas 5111, 5112 are substantially closer to the first wheel 261 than the second gripping area 5122, and the second gripping area 5122 is substantially closer to the second wheel 2622 than the first gripping areas 5111, 5112.

[0107] Fig. 7A A training device 1 according to the invention is shown, having a rolling device 2, comprising a first wheel 261 and a second wheel 262 having a tire 27 with a tread pattern 271, a cylindrical axle element 28 made of plastic having a first axle end 281 and a second axle end 282, and a fixing device 29, wherein the fixing device 29 connects the first wheel 261 to the first axle end 281 and the second wheel 262 to the second axle end 282. Interlocking teeth 291 are provided as fixing devices 29 on both wheels 261, 262 and on both axle ends 281, 282 of the cylindrical axle element 28, in order to restrict the wheels to rotate substantially uniformly about the rolling axis.

[0108] Figure 7B Shows Fig. 7A The cross section of the first wheel 261 and the second wheel 262 is represented by the section line AA. The tread pattern 271 of the first wheel 261 and the second wheel 262 shows a geometric irregularity of an approximately axisymmetric shape. The handle device 5 includes a cylindrical wheel axle element 53 made of metal. The first gripping area 511 and the second gripping area 512 are made of rubber and are clearly marked as gripping areas with anti-slip patterns 55. The training device 1 can be easily assembled and disassembled by the user. Along the rolling axis 3, all elements can be pulled apart. The first gripping area 511 is connected to the cylindrical handle element 53 with an interference fit and can be removed by pulling. Then, the first wheel 261 with a loose fit can be easily pulled out from the cylindrical handle element 53, and then the second wheel 262 with a loose fit can also be pulled out from the cylindrical wheel axle element 28. Finally, the second gripping area 512 can be pulled out from the cylindrical handle element 53, which again has an interference fit. All separated elements are flat and can be easily stored.

[0109] Fig. 8A and Figure 8BA top view of a user 6 with a training device 1 according to the invention is shown, the user performing a basic outward rolling exercise routine. The user kneels on a padded protective pad 41 and holds the first gripping area 511 and the second gripping area 512 of the training device 1 with both hands, which are positioned vertically below the shoulders, thereby forming a bridge between the hands and the knees, as shown in FIG. Fig. 8A During the outward roll, the hands are moved away from the knees, extending the hips and arms and flexing the shoulders to form a longer bridge between the hands and knees. In a full outward roll, the user's body is essentially straight and the portion of the body between the hands and knees hangs above the rolling surface without contacting it, as shown in Figure 1. Figure 8B The user will then perform a return movement from the fully rolled out position back to the basic position in reverse order, completing one exercise cycle of the roll-out and return movement. The training device 1 has a center point 7 halfway between the first wheel 261 and the second wheel 262 on the rolling axis. The center point 7 advantageously moves substantially along a defined circular path 71 projected on the flat rolling surface during the roll-out and return movement.

[0110] During the roll-out motion, the first hand 61 placed on the first gripping area 511 located proximate to the first wheel 261 advantageously moves farther away from the user's knee than the second hand 62 placed on the second gripping area 512 located proximate to the second wheel 262, thereby allowing for a guided asymmetric roll-out routine. Figure 8B , the arm on the side of the first hand 61 is depicted to be extended and activated, and the arm on the side of the second hand is bent and less activated. The user's arm connected to the first hand 61 is referred to as the extension arm 63, and the user's arm connected to the second hand 62 is referred to as the control arm 64. The angle of the first hand 61 to the rolling axis 3 is different from the angle of the second hand 62 to the rolling axis 3. Figure 8B It is shown that during this roll-out routine, when the user 6 is in the fully rolled-out position, the first hand 61 is abducted and the second hand 62 is adducted.

[0111] Fig. 9A side view of a user 6 having a training device 1 according to the present invention is shown performing another unique asymmetric roll-out routine, depicted in a fully rolled-out position. The user 6 has an extension arm 63 on the left side of the body and a control arm 64 on the right side of the body. The user 6 raises the left leg to the side of the extension arm 63 and activates the right leg, which becomes the supporting leg 65. The roll-out and return motion of this unique asymmetric routine involves resisting trunk rotation and extension through balanced or eccentric muscle contractions diagonally across the anterior and lateral abdominal wall, advantageously with a high unilateral activation of the lateral oblique muscles on the left and the medial oblique muscles on the right. The training device 1 has a handle device 5 having a cylindrical handle element 53 with an unmarked long grip area 51 that allows the user to place both hands on the long grip area 51. The user 6 may naturally choose to place the first hand 61 closer to the first wheel 261 as the first gripping area 511 , and place the second hand 62 closer to the second wheel 262 as the second gripping area 512 .

[0112] Fig.10 A perspective view of a user 6 with a training device 1 according to the present invention is shown performing another unique asymmetric roll-out routine depicted in a fully rolled-out position. The user 6 has an extension arm 63 on the right side of the body and a control arm 64 on the left side of the body. The user 6 has tilted the body to perform an inclined roll-out routine that advantageously activates the lateral abdominal muscles to the side of the extension arm 63. The user's lower body 66 is rotated about the longitudinal axis of the body and the right hip 67 is lowered to the side of the extension arm 63.

[0113] During the outward roll motion, the first wheel 261 travels farther away from the user's 6 knees than the second wheel 262, thereby allowing the user to lift the left shoulder 68 by extending the control arm 64, causing the user's 6 body to be advantageously closer to the rolling surface of the side of the extension arm 63 over the entire length of the body to more effectively target the lateral abdominal muscles.

[0114] Fig.11A and Fig. 11B A top view and a front view of a training device 1 according to the invention are shown, having ergonomically shaped gripping areas 511 , 512 made of a rubber-like material for optimal comfort.

[0115] Fig.11A The gripping areas 511, 512 are shown to be reflectively symmetrical in a plane passing through the rolling axis 3 perpendicular to the projection plane, so as to provide the same optimal ergonomic support when the first gripping area 511 is gripped with the left hand and the second gripping area 512 is gripped with the right hand as when the first gripping area 511 is gripped with the right hand and the second gripping area 512 is gripped with the left hand.

[0116] The first gripping area 511 has a basic design different from that of the second gripping area 512, and in the fully rolled-out position, the angle of the hand on the first gripping area 511 with respect to the rolling axis 3 due to the outward rotation is different from the angle of the hand on the second gripping area 512 with respect to the rolling axis 3 due to the inward rotation.

[0117] The first gripping area 511 comprises a support handle 5111 located at the thumb substantially perpendicular to the rolling axis 3. Advantageously, the thumb of the first hand can be curled around the support handle 5111 and the first hand can be conveniently less adducted in the fully rolled-out position.

Claims

1. A training device for asymmetric training of abdominal muscles, comprising: A handle device having a first gripping area for one hand of a user and a second gripping area for the other hand of the same user, and Rolling equipment, including: The first end and the second end are spaced a distance apart from each other along the rolling axis, at least one axisymmetric element allowing the rolling device to come into rolling contact with the flat rolling surface at the tread area when the training device rolls on the flat rolling surface under load during use, Wherein, the tread area includes: a first tread edge, proximate the first end, having a first tread diameter, and a second tread edge, proximate the second end, having a second diameter, The handle device is rotatably connected to the rolling device to rotate relative to the rolling device about the rolling axis, wherein The first tread edge is rotationally fixed to the second tread edge so that the tread edges rotate synchronously, and wherein, The first tread diameter is greater than the second tread diameter.

2. The training device according to claim 1, further comprising: At least one securing element rotationally secures the first tread edge and the second tread edge to each other such that during use, under load, the first tread edge and the second tread edge rotate synchronously in rolling contact with the flat rolling surface.

3. The training device according to claim 1, wherein: The at least one axisymmetric element comprises a first wheel, and The rolling device further comprises another axisymmetric element, the other axisymmetric element comprising a second wheel, wherein The first wheel includes the first tread edge, and The second wheel includes the second tread edge.

4. The training device according to claim 2, wherein: The fixing element is configured to rotationally fix the first tread edge and the second tread edge to each other directly or indirectly so as to be rotationally synchronized.

5. The training device according to claim 3, further comprising an axle element having a first axle end and a second axle end; wherein The at least one fixing element connects the first wheel to the first axle end and the second wheel to the second axle end such that the first wheel and the second wheel rotate in unison about the rolling axis.

6. The training device according to claim 3, wherein: The first wheel and the second wheel are mounted to an axle element, and the at least one fixing element is configured to rotationally fix the first wheel and the second wheel to the axle element.

7. The training device according to claim 1, wherein: The handle device is free to rotate about the rolling axis.

8. The training device according to claim 1, wherein: The first gripping area is substantially closer to the first tread edge than the second gripping area, and the second gripping area is substantially closer to the second tread edge than the first gripping area.

9. The training device according to claim 1, comprising: A center point, when the training device rolls on the flat rolling surface under load during use, the center point follows a circular path with a radius projected on the flat rolling surface, wherein the center point is located halfway between the first tread edge and the second tread edge on the rolling axis.

10. The training device according to claim 9, in, The circular path has a radius of between 80 cm and 500 cm during use.

11. The training device according to claim 1, comprising: a first axisymmetric element made of metal, and The second axisymmetric element, made of plastic, One of the first axisymmetric element and the second axisymmetric element is part of the rolling device, and The other of the first axisymmetric element and the second axisymmetric element is part of the handle device, wherein The first axisymmetric element of metal is positioned within the second axisymmetric element of plastic to form a revolute joint.

12. The training device according to claim 1, wherein: The first tread edge and the second tread edge are made of a high friction material.

13. The training device according to claim 3, wherein: The first wheel and the second wheel include tires having a high friction tread.

14. A training device for asymmetric training of abdominal muscles, comprising: a longitudinally extending rolling device having at least one axisymmetric element having a tread region and configured to roll over a support surface at said tread region, wherein the tread region has a first tread edge with a first tread diameter and a second tread edge with a second tread diameter, wherein the first tread edge and the second tread edge are a distance from each other; and further comprising a handle device having a first gripping region and a second gripping region for gripping by respective hands of a user; wherein the handle device is rotatably mounted to the rolling device such that during use, the rolling device moves relative to the handle device over the support surface; and wherein the first tread diameter is greater than the second tread diameter; and Further included is a fixing element to fixedly position the first tread edge and the second tread edge relative to each other so that the first tread edge and the second tread edge roll in unison.

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