WO2020071986A1

WO2020071986A1 - Flywheel exercise method, apparatus and the use therefor

Info

Publication number: WO2020071986A1
Application number: PCT/SE2019/050946
Authority: WO
Inventors: Fredrik CORREA; Erik Lindberg
Original assignee: Exxentric Ab
Priority date: 2018-10-05
Filing date: 2019-10-01
Publication date: 2020-04-09
Also published as: SE1851210A1; SE542583C2

Abstract

A flywheel exercise apparatus and a method for exercising muscles of a user with eccentric overload in a flywheel exercise apparatus, said method comprising the steps: a) accelerating a flywheel from an initial rotational speed to a top rotational speed using energy provided by muscles of a user in a concentric movement phase combined with energy provided by a motor; and b) decelerating the flywheel from the top rotational speed back to the initial rotational speed using energy provided by the muscles of the user in an eccentric movement phase.

Description

Flywheel exercise method, apparatus and the use therefor

FIELD OF THE INVENTION

In any muscle training exercise, work performed by the muscles can be divided into concentric work, wherein the muscle shortens under an applied load, isometric work wherein the muscle contracts but the muscle length stays constant, and eccentric work, wherein the muscle lengthens under an applied load. The present invention relates to a flywheel exercise apparatus and a method for exercising muscles of a user in a flywheel exercise apparatus by accelerating a flywheel using muscle force provided by the user in a concentric movement phase and decelerating the flywheel using muscle force provided by the user in an eccentric movement phase.

BACKGROUND OF THE INVENTION

In recent years flywheel training has become widely used and recognized for its benefits like motion freedom, eccentric overload and variable resistance and unlimited load. Flywheel training devices have made great progress in strength training and all its various applications (including performance, health, senior training, and rehabilitation). Studies have shown flywheel devices to give an earlier and higher degree of hypertrophy and strength gains, both for concentric and eccentric strength, compared to traditional weights. Besides promoting superior constitutional changes studies have also shown performance benefits in terms of improved sprinting, jumping and change of direction ability.

The operating principle is basically the same for all different kinds of flywheel strength training devices. One or more flywheels are attached to a rotatable shaft. A traction element (e.g. a strap, rope or wire) is attached to the shaft. By rotating the flywheel and shaft a few revolutions, some of the traction element will become wound up on the shaft, which is needed before training can start. When the traction element is pulled by the user in a concentric muscle contraction, the shaft will be subjected to a force, which will accelerate the flywheel. When the traction element is fully pulled out, the continued rotation of the flywheel will instead lead to the rewinding and retraction of the traction element. In order to decelerate the flywheel, eccentric muscle force must be applied by the user. When the flywheel comes to a stop, the traction element is again pulled by the user in a concentric muscle contraction, and the cycle starts again.

The amount of force that will have to be applied to get a certain acceleration depends on the inertia of the flywheel. The flywheel will resist being accelerated leading to the resistance being variable. On a specific inertia a low force input will give a lower resistance and a higher force input more resistance, i.e. the harder you pull, the harder it gets.

All energy that is put into the flywheel during the concentric phase, will have to be absorbed again in the eccentric phase. As the flywheel can always be accelerated a little more, the potential load is unlimited.

A great advantage of flywheel training is the eccentric load, i.e. the load when the muscle attempts to counteract extension. Flywheels can provide eccentric loads of over 100% of the load provided by the concentric force, for example by:

1 ) Decelerating the flywheel in less time eccentrically than it is accelerated concentrically (producing the same amount of energy in less time requires higher power and thus more force).

2) Using one of several possible methods of achieving an eccentric overload. A common method is to engage more muscle mass in the concentric acceleration phase and less muscle mass during the eccentric phase. For example, using knee and hip extension to help accelerate the flywheel in the concentric phase of a biceps curl, and using only the arms to decelerate the flywheel in the eccentric phase, forcing the arms to work under higher eccentric load than they can generate in the concentric phase themselves.

Although these methods for eccentric overload training can be useful, they also have certain limitations. For example, one can only get eccentric overload in a part of the movement, and the methods cannot be applied to all exercises. Additionally, in all flywheel exercise devices friction will inevitably counteract the rotation of the flywheel, thereby causing the load in the eccentric phase to always be slightly lower than the load in the concentric phase.

Some companies have solved these issues by using only an electric motor as resistance. The motor is then programmed to simulate for example weights or flywheels and thus the overload can be programmed. However, this means that relatively strong electric motors are required, making the machines expensive and heavy, and with mediocre performance despite high consumer prices.

Accordingly, there is still a need for improved methods and devices for eccentric overload training which can alleviate the deficiencies of the existing methods and devices.

SUMMARY OF THE INVENTION

In any muscle training exercise, work performed by the muscles can be divided into concentric work, wherein the muscle shortens under an applied load, isometric work, wherein the muscle contracts but the muscle length stays constant, and eccentric work, wherein the muscle lengthens under an applied load.

One object of the present disclosure is to provide a method and apparatus for exercising muscles of a user in a flywheel exercise apparatus with eccentric overload, which alleviates at least some of the limitations of prior art eccentric overload training methods.

Another object of the present disclosure is to provide a method and apparatus for exercising muscles of a user in a flywheel exercise apparatus with eccentric overload, which allows for a controlled and consistent eccentric overload in a full range of motion of the eccentric movement.

Another object of the present disclosure is to provide a light weight and portable flywheel exercise apparatus for exercising muscles of a user with eccentric overload. The above objects as well as other objects that will become apparent to the skilled person in the light of the present disclosure are achieved by the various aspects of the invention as set out herein.

According to a first aspect of the disclosure, there is provided a method for exercising muscles of a user with eccentric overload in a flywheel exercise apparatus, said method comprising the steps: a) accelerating a flywheel from an initial rotational speed to a top rotational speed using energy provided by muscles of a user in a concentric movement phase combined with energy provided by a motor; and b) decelerating the flywheel from the top rotational speed back to the initial rotational speed using energy provided by the muscles of the user in an eccentric movement phase.

The inventive method allows for eccentric overload training without the limitations of prior art methods in terms of suitable exercises and range of motion. With the inventive method, eccentric overload can be provided in all types of exercises and in the full range of motion. As the apparatus uses the energy provided by muscles of a user in a concentric movement phase combined with the energy provided by the motor, typically only a relatively small motor is required, which allows for the flywheel exercise apparatus to be made light weight and portable.

Flywheels resist changes in rotational speed by their moment of inertia. The amount of energy stored in a flywheel is proportional to the square of its rotational speed.

The initial rotational speed of the flywheel is typically zero. That is, the flywheel is accelerated from zero to a top rotational speed, and then decelerated from the top rotational speed to zero again.

In a preferred embodiment the energy provided by the muscles of the user in the concentric movement phase and the energy provided by the motor are provided simultaneously. The motor then serves to assist the user in the concentric movement phase such that the acceleration of the flywheel becomes greater than it would have been from the energy provided by the muscles of the user alone.

The energy provided by the motor may be provided in the start, middle, and/or end of the concentric movement phase, or continuously throughout the concentric movement phase.

In the subsequent eccentric movement phase, the motor may for example be decoupled or controlled to rotate at the same rotational speed as the flywheel, in order to prevent a braking effect of the motor, which could otherwise assist the user in the eccentric movement phase and thereby reduce the degree of eccentric overload.

In some embodiments, the method further comprises counteracting the

deceleration in step b) using energy provided by the motor. This way an additional eccentric overload can be created, as the muscles of the user not only have to absorb the kinetic energy of the flywheel, but also have to overcome the

resistance created by the motor. The resistance provided by the motor may be provided in the start, middle, and/or end of the eccentric movement phase, or continuously throughout the eccentric movement phase.

In some embodiments, the energy provided by the muscles of the user in a concentric movement phase in step a) is provided by pulling out a wound up traction element configured to act on the flywheel. The traction element may typically be a strap, a belt, a wire, a rope or the like, optionally connected to a grip or harness for the user. The energy provided by the muscles of the user in an eccentric movement phase in step b) can be provided by resisting the pulling force exerted through the traction element as it is rewound.

The rotational speed of the flywheel can advantageously be measured using a sensor arrangement. When combined with information about the flywheel inertia, the rotational speed can be used to provide the user with detailed workout information including concentric and eccentric power, range of motion, force, eccentric overload and energy expenditure. In some embodiments, the energy provided by the motor is controlled using a control arrangement. The control arrangement typically includes a motor controller and a microprocessor. The motor controller of the control arrangement may include means for starting and stopping the motor, selecting forward or reverse rotation, selecting and regulating the speed, regulating or limiting the torque, and protecting against overloads and faults. The microprocessor of the control arrangement is preferably capable of receiving information from the sensor arrangement and information about the flywheel inertia and the desired degree of eccentric overload, calculating the required motor output required to obtain the desired degree of eccentric overload, and controlling the motor via the motor controller to generate the required output.

The energy to be provided by the motor may preferably be preset by the user. The energy to be provided by the motor may for example be set as an absolute value, e.g. a specified amount of energy to be added by the motor during each concentric movement phase, or in relative terms, e.g. as a percentage of the energy provided by the user in the concentric movement phase. Thus, in some embodiments, the energy provided by the motor is a function of the energy provided by the muscles of the user in the concentric movement phase. Calculation of motor output and motor control can be momentaneous or based on data from a preceding concentric movement phase. In some cases a first concentric movement phase can be performed without motor assistance in order to determine the energy provided by the muscles of the user alone. The information obtained from the first concentric movement phase is then used to calculate the energy to be added by the motor during each subsequent concentric movement phase.

In some embodiments, the energy provided by the muscles of the user in the concentric movement phase is higher than the energy provided by the motor. In many cases, particularly for high performance users generating high energy, it is preferred that the major part of the energy in the concentric movement phase is provided by the user since this means that a relatively small motor can be used, which allows for the flywheel exercise apparatus to be made light weight and portable. In some embodiments, the energy provided by the muscles of the user in the concentric movement phase is lower than the energy provided by the motor. In some cases where the energy provided by the user in the concentric movement phase is low, e.g. in rehabilitation training, the energy provided by the motor can be higher than the energy provided by the muscles of the user.

According to a second aspect of the disclosure, there is provided a flywheel exercise apparatus for exercising muscles of a user with eccentric overload, said exercise apparatus comprising:

a rotatably mounted flywheel;

a traction element configured to be wound up and to accelerate the flywheel using energy provided by muscles of a user in a concentric movement phase as it is unwound and decelerate the flywheel using energy provided by the muscles of the user in an eccentric movement phase as it is rewound;

a motor operably connected to and configured to accelerate the flywheel;

a sensor arrangement for measuring the rotational speed of the flywheel; and a control arrangement operably connected to the sensor arrangement and the motor;

characterized in that the control arrangement is configured to detect a concentric movement phase using the sensor arrangement and assist the acceleration of the flywheel during the concentric movement phase using energy provided by the motor.

The inventive flywheel exercise apparatus allows for eccentric overload training without the limitations of prior art devices in terms of suitable exercises and range of motion. With the inventive flywheel exercise apparatus, eccentric overload can be provided in all types of exercises and in the full range of motion. As the apparatus uses the energy provided by muscles of a user in a concentric movement phase combined with the energy provided by the motor, typically only a relatively small motor is required, which allows for the flywheel exercise apparatus to be made light weight and portable. In a preferred embodiment, the flywheel exercise apparatus comprises a housing and a flywheel mechanism consisting of a flywheel, a flywheel shaft and a traction element. The traction element is preferably attached to and configured to be wound up around a shaft coupled to the flywheel. The traction element is configured to be unwound and rewound onto the flywheel shaft during use.

In the eccentric movement phase, the motor may for example be decoupled or controlled to rotate at the same rotational speed as the flywheel, in order to prevent a braking effect of the motor, which could otherwise assist the user in the eccentric movement phase and thereby reduce the eccentric overload.

In some embodiments, the control arrangement is further configured to detect an eccentric movement phase using the sensor arrangement and counteract the deceleration of the flywheel during the eccentric movement phase using energy provided by the motor. This way an additional eccentric overload can be created, as the muscles of the user not only have to absorb the kinetic energy of the flywheel, but also have to overcome the resistance created by the motor. The resistance provided by the motor may be provided in the start, middle, and/or end of the concentric movement phase, or continuously throughout the concentric movement phase.

In some embodiments, the control arrangement of the flywheel exercise apparatus includes a user interface wherein the energy to be provided by the motor can be set by a user. In a preferred embodiment, the user interface is in the form of an app on a mobile device of the user.

The energy to be provided by the motor may preferably be preset by the user. The energy to be provided by the motor may for example be set as an absolute value, e.g. a specified amount of energy to be added by the motor during each concentric movement phase, or in relative terms, e.g. as a percentage of the energy provided by the user in the concentric movement phase. Thus, in some embodiments, the energy provided by the motor is a function of the energy provided by the muscles of the user in the concentric movement phase. Calculation of motor output and motor control can be momentaneous or based on data from a preceding concentric movement phase. In some cases a first concentric movement phase can be performed without motor assistance in order to determine the energy provided by the muscles of the user alone. The information obtained from the first concentric movement phase may then be used to calculate the energy to be added by the motor during each subsequent concentric movement phase.

In some embodiments, the energy provided by the muscles of the user in the concentric movement phase is higher than the energy provided by the motor. In many cases, particularly for high performance users generating high energy, it is preferred that the major part of the energy in the concentric movement phase is provided by the user since this means that a relatively small motor is can be used, which allows for the flywheel exercise apparatus to be made light weight and portable.

In some embodiments, the energy provided by the muscles of the user in the concentric movement phase is lower than the energy provided by the motor. In some cases where the energy provided by the user in the concentric movement phase is low, e.g. in rehabilitation training, the energy provided by the motor can be higher than the energy provided by the muscles of the user.

As the apparatus uses the energy provided by muscles of a user in a concentric movement phase combined with the energy provided by the motor, typically only a relatively small motor is required, which allows for the flywheel exercise apparatus to be made light weight and portable. In some embodiments, the motor of the flywheel exercise machine has a maximum mechanical output power of 1500 W or less, preferably 1000 W or less, more preferably 500 W or less.

In some embodiments, the motor is integrated in the flywheel exercise apparatus.

In some embodiments, the motor is part of a module which can be detached from the flywheel exercise apparatus.

According to a third aspect of the disclosure, there is provided the use of a motor for assisting the acceleration of the flywheel of a flywheel exercise apparatus as it is accelerated using energy provided by the muscles of the user in a concentric movement phase in order to achieve an eccentric overload when the flywheel is subsequently decelerated using energy provided by the muscles of the user in an eccentric movement phase.

In some embodiments the motor is further used to counteract the deceleration of the flywheel during the eccentric movement phase in order to achieve a further eccentric overload when the flywheel is decelerated using energy provided by the muscles of the user in an eccentric movement phase.

The flywheel exercise apparatus and of the third aspect of the disclosure may be further defined as described above with reference to the first or second aspect of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, which are exemplary embodiments, and wherein:

FIG. 1 a is a perspective view of a prior art flywheel exercise apparatus;

FIG. 1 b is a perspective view from below of a prior art flywheel exercise

apparatus;

FIG. 2 is a perspective view from below of an embodiment of the inventive flywheel exercise apparatus;

FIG. 3 is a perspective view from below of an embodiment of the inventive flywheel exercise apparatus;

FIG. 4 is a perspective view from below of an embodiment of the inventive flywheel exercise apparatus.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The basic constructional and functional features of a prior art flywheel exercise apparatus are illustrated in FIG. 1 a and 1 b.

With reference to FIG. 1 a and 1 b, the flywheel exercise apparatus 10 comprises a housing 12 and a flywheel mechanism consisting of a flywheel 14, a flywheel shaft 16 and a traction element 18 attached to the flywheel shaft 16 and configured to be wound, unwound and rewound onto the shaft during use.

The housing 12 is preferably made of steel or aluminum and comprises a platform 20 supported by four legs 22. The housing 12 is designed to support the weight of a user standing on top of the platform 20. The top side of the platform 20 may optionally be provided with a non-slip surface to ensure proper grip for the feet of the user. On a central portion of the platform 20 an opening 24 is provided. The opening 24 is adapted to allow passage of the traction element 18 from a user situated on the top side of the platform 20 down to a traction element receiving portion 26 of the shaft 16, which is rotatably attached to the bottom side of the platform 20 by a number of shaft mounts 28 provided with suitable bearings or the like. The shaft 16 extends in a longitudinal direction from the platform opening 24 and protrudes through the housing wall. The flywheel 14 is attached to the protruding portion of the shaft 16 and adapted to rotate with the shaft.

The traction element 18 is preferably a strap or belt made of a strong but flexible material, for example nylon or canvas, and the width of the traction element 18 is selected such that it can be conveniently wound up around the traction element receiving portion 26 of the shaft 16 without becoming tangled or pinched. A first end of the traction element 18 is secured in the shaft 16. The traction element receiving portion 26 of the shaft 16 is substantially spool shaped with two spaced apart disc shaped walls making sure that the traction element is collected in an ordered fashion as it is wound up. A grip or harness may be attached to the end of the traction element. The type of grip or harness may be selected depending on the exercise to be performed. Examples include various handles, bars, waist belts, wrist or ankle belts, body harnesses, etc. In the embodiment of FIG. 1 a a straight bar 30 is attached.

In some embodiments, as shown in FIG. 1 a, the length of the traction element 18 is variable. To keep excess length of the traction element out of the way, a pulley 32 is arranged between the bar 30 and the traction element 18. The traction element 18 extends from the shaft 16, through the platform opening 24, up around the pulley 32 and the back down through the platform opening to the bottom side of the platform 20 where it is secured at the desired length by a traction element locking arrangement 34.

The flywheel 14 is removably attached to the protruding portion of the shaft 16.

The flywheel 14 can be removed by detaching the flywheel locking device 36 and sliding the flywheel off of the shaft. The flywheel 14 is adapted to rotate with the shaft 16. This is achieved for example by providing the flywheel receiving portion of the shaft with a non-circular cross section and providing the flywheel with an opening having a corresponding non-circular cross section, such that the flywheel will rotate with the shaft when locked in place on the flywheel receiving portion of the shaft.

The flywheel exercise apparatus 10 further comprises a sensor arrangement 38 for measuring the rotational speed of the flywheel 14. In the embodiment of FIG.

1 b, the sensor arrangement 38 is provided in the form of an optical reflection sensor configured to detect passing features on the shaft surface. The signal from the sensor arrangement can then be relayed to a user interface 42, optionally via a wireless transmitter (not shown). The user interface is preferably in the form of an app on a mobile device of the user. When combined with information about the flywheel inertia, the rotational speed can be used to provide the user with detailed workout information including concentric and eccentric power, range of motion, force, eccentric overload and energy expenditure.

The flywheel 14 is preferably made of a metal, such as steel. The mass and shape of the wheel may be selected in order to obtain a suitable inertia. In FIG. 1 a a single flywheel is shown, however it is also possible to use two or more flywheels in combination to get higher inertia.

In any muscle training exercise, work performed by the muscles can be divided into concentric work, wherein the muscle shortens under an applied load, isometric work, wherein the muscle contracts but the muscle length stays constant, and eccentric work, wherein the muscle lengthens under an applied load. Before the workout is started, the flywheel 14 and shaft 16 must be rotated a few revolutions, so that at least some of the traction element 18 is wound up on the shaft. When the traction element 18 is pulled by the user in a concentric muscle contraction, the shaft 16 will be subjected to a force, which will cause the shaft 16 and flywheel 14 to rotate. The higher the force applied by the user, the higher the rotational acceleration of the flywheel will be. The amount of force that will have to be applied to get a certain acceleration depends on the inertia of the flywheel 14.

In other words, the energy provided by the muscles of the user is converted to kinetic energy stored in the rotating flywheel. When the traction element 18 is fully pulled out, the continued rotation of the flywheel will instead lead to the rewinding and retraction of the traction element 18. In order to decelerate the flywheel, eccentric muscle force must be provided by the user. The higher the kinetic energy stored in the rotating flywheel, the higher the energy provided by the muscles of the user in an eccentric movement phase must be to absorb the kinetic energy of the flywheel. When the flywheel comes to a stop, the movement can be repeated.

FIG. 2 shows an embodiment of the inventive flywheel exercise apparatus 10. The flywheel exercise apparatus of FIG. 2 is largely similar to the flywheel exercise apparatus of FIG. 1 , but comprises an electric motor 44 operably connected to and configured to accelerate the flywheel 14. The electric motor 44 is integrated with the shaft 16 and has a built in sensor arrangement 38 for measuring the rotational speed of the shaft 16 and flywheel 14. The electric motor 44 is controlled by a control arrangement 40 operably connected to the sensor arrangement 38 and the motor 44.

The sensor arrangement 38 in the embodiment of FIG. 2 is integrated in the electric motor 44. The signal from the sensor arrangement can then be relayed to a user interface 42, optionally via a control arrangement 40 and wireless transmitter (not shown). The user interface 42 is preferably in the form of an app on a mobile device of the user. When combined with information about the flywheel inertia, the rotational speed can be used to provide the user with detailed workout information including concentric and eccentric power, range of motion, force, eccentric overload and energy expenditure. The control arrangement 40 is configured to detect a concentric movement phase using the sensor arrangement 38 and assist the acceleration of the flywheel 14 during the concentric movement phase using energy provided by the electric motor 44.

When the traction element 18 is pulled by the muscles of the user in a concentric movement phase, the control arrangement will receive signals from the sensor arrangement 38 indicative of an acceleration of the rotation, and the direction of the rotation, of the shaft 16 and flywheel 14. The control arrangement 40 in turn signals to the motor 44 to assist the acceleration of the flywheel. The amount of assistance can be preset by the user in the user interface 42, either as an absolute value or as a function of the energy provided by the muscles of the user in the concentric movement phase.

The additional energy provided by the motor 44 thus increases the kinetic energy of the flywheel 14, and accordingly increases the energy that must be provided by the muscles of the user in the eccentric movement phase to absorb the kinetic energy of the flywheel. In other words, an eccentric overload is obtained.

When the traction element 18 is fully pulled out, the continued rotation of the flywheel 14 will lead to the rewinding and retraction of the traction element 18. The rewinding initiates the eccentric movement phase, where the user decelerates the flywheel 14 by resisting the pulling force exerted through the traction element 18 as it is rewound. During the eccentric movement phase, the electric motor 44 is controlled to rotate at the same rotational speed as the flywheel 14, in order to prevent a braking effect of the motor, which could otherwise assist the user in the eccentric movement phase and thereby reduce the eccentric overload.

Optionally, the electric motor 44 can be used to create an additional eccentric overload by being engaged also during the eccentric movement phase. In this case, the control arrangement 40 is further configured to detect an eccentric movement phase using the sensor arrangement 38 and counteract the

deceleration of the flywheel 14 during the eccentric movement phase using energy provided by the motor. FIG. 3 shows an embodiment of the inventive flywheel exercise apparatus 10. The flywheel exercise apparatus of FIG. 3 is largely similar to the flywheel exercise apparatus of FIG. 2, but instead of an electric motor being integrated with the shaft, an electric motor 46 is instead operably connected to the shaft 16 by a drive belt 48. The electric motor 46 is controlled by a control arrangement 40 operably connected to the sensor arrangement 38 and the motor 46.

In the embodiment of FIG. 3, the sensor arrangement 38 is separate from the motor 46 and provided in the form of an optical reflection sensor configured to detect passing features on the shaft surface. The signal from the sensor arrangement 38 can then be relayed to a user interface 42, optionally via the control arrangement 40 and wireless transmitter (not shown). The user interface 42 is preferably in the form of an app on a mobile device of the user. When combined with information about the flywheel inertia, the rotational speed can be used to provide the user with detailed workout information including concentric and eccentric power, range of motion, force, eccentric overload and energy

expenditure.

The control arrangement 40 is configured to detect a concentric movement phase using the sensor arrangement 38 and assist the acceleration of the flywheel 14 during the concentric movement phase using energy provided by the electric motor 46.

When the traction element 18 is pulled by the muscles of the user in a concentric movement phase, the control arrangement will receive signals from the sensor arrangement 38 indicative of an acceleration of the rotation, and the direction of the rotation of the rotation, of the shaft 16 and flywheel 14. The control

arrangement in turn signals to the motor 46 to assist the acceleration of the flywheel 14. The amount of assistance can be preset by the user in the user interface 42, either as an absolute value or as a function of the energy provided by the muscles of the user in the concentric movement phase. The additional energy provided by the motor 46 thus increases the kinetic energy of the flywheel, and accordingly increases the energy that must be provided by the muscles of the user in the eccentric movement phase to absorb the kinetic energy of the flywheel 14. In other words, an eccentric overload is obtained.

When the traction element 18 is fully pulled out, the continued rotation of the flywheel 14 will lead to the rewinding and retraction of the traction element 18. The rewinding initiates the eccentric movement phase, where the user decelerates the flywheel by resisting the pulling force exerted through the traction element as it is rewound. During the eccentric movement phase, the electric motor 46 is controlled to rotate at the same rotational speed as the flywheel 14, in order to prevent a braking effect of the motor, which could otherwise assist the user in the eccentric movement phase and thereby reduce the eccentric overload.

Optionally, the electric motor 46 can be used to create an additional eccentric overload by being engaged also during the eccentric movement phase. In this case, the control arrangement 40 is further configured to detect an eccentric movement phase using the sensor arrangement 38 and counteract the

deceleration of the flywheel 14 during the eccentric movement phase using energy provided by the motor.

FIG. 4 shows an embodiment of the inventive flywheel exercise apparatus comprising an electric motor in the form of a detachable module configured to act on the flywheel directly. The flywheel exercise apparatus of FIG. 4 is largely similar to the flywheel exercise apparatus of FIG. 3, but instead of the electric motor being operably connected to the shaft by a drive belt, the motor 50 is operably

connected directly to the flywheel 14 by means of a drive wheel 52 in contact with and configured to rotate the flywheel.

In the embodiment of FIG. 4, the sensor arrangement 38 is separate from the motor 50 and provided in the form of an optical reflection sensor configured to detect passing features on the shaft surface. The signal from the sensor arrangement 38 can then be relayed to a user interface 42, optionally via a control arrangement 40 and wireless transmitter (not shown). The user interface 42 is preferably in the form of an app on a mobile device of the user. When combined with information about the flywheel inertia, the rotational speed can be used to provide the user with detailed workout information including concentric and eccentric power, range of motion, force, eccentric overload and energy

expenditure.

The control arrangement 42 is configured to detect a concentric movement phase using the sensor arrangement 38 and assist the acceleration of the flywheel 14 during the concentric movement phase using energy provided by the electric motor 50.

When the traction element 18 is pulled by the muscles of the user in a concentric movement phase, the control arrangement 40 will receive signals from the sensor arrangement 38 indicative of an acceleration of the rotation, and the direction of the rotation, of the shaft 16 and flywheel 14. The control arrangement 40 in turn signals to the motor 50 to assist the acceleration of the flywheel 14. The amount of assistance can be preset by the user in the user interface 42, either as an absolute value or as a function of the energy provided by the muscles of the user in the concentric movement phase.

The additional energy provided by the motor 50 thus increases the kinetic energy of the flywheel, and accordingly increases the energy that must be provided by the muscles of the user in the eccentric movement phase to absorb the kinetic energy of the flywheel 14. In other words, an eccentric overload is obtained.

When the traction element 18 is fully pulled out, the continued rotation of the flywheel 14 will lead to the rewinding and retraction of the traction element 18. The rewinding initiates the eccentric movement phase, where the user decelerates the flywheel 14 by resisting the pulling force exerted through the traction element 18 as it is rewound. During the eccentric movement phase, the electric motor 50 is controlled to rotate at the same rotational speed as the flywheel 14, in order to prevent a braking effect of the motor, which could otherwise assist the user in the eccentric movement phase and thereby reduce the eccentric overload. Optionally, the electric motor 50 can be used to create an additional eccentric overload by being engaged also during the eccentric movement phase. In this case, the control arrangement 40 is further configured to detect an eccentric movement phase using the sensor arrangement 38 and counteract the

deceleration of the flywheel 14 during the eccentric movement phase using energy provided by the motor 50.

The embodiments of FIG 3 and 4 have the advantage that the motor 46, 50 may be conveniently retrofitted to existing flywheel exercise devices.

While the invention has been described herein with reference to various exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or feature to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A method for exercising muscles of a user with eccentric overload in a flywheel exercise apparatus, said method comprising the steps:

a) accelerating a flywheel from an initial rotational speed to a top rotational speed using energy provided by muscles of a user in a concentric movement phase combined with energy provided by a motor; and b) decelerating the flywheel from the top rotational speed back to the initial rotational speed using energy provided by the muscles of the user in an eccentric movement phase.

2. The method according to claim 1 , wherein the initial rotational speed of the flywheel is zero.

3. The method according to any one of the preceding claims, wherein the energy provided by the muscles of the user in the concentric movement phase and the energy provided by the motor are provided simultaneously.

4. The method according to any one of the preceding claims, further comprising counteracting the deceleration in step b) using energy provided by the motor.

5. The method according to any one of the preceding claims, wherein the energy provided by the muscles of the user in a concentric movement phase in step a) is provided by pulling out a wound up traction element configured to act on the flywheel.

6. The method according to claim 5, wherein the energy provided by the muscles of the user in an eccentric movement phase in step b) is provided by resisting the pulling force exerted through the traction element as it is rewound.

7. The method according to any one of the preceding claims, wherein the rotational speed of the flywheel is measured using a sensor arrangement.

8. The method according to any one of the preceding claims, wherein the energy provided by the motor is controlled using a control arrangement.

9. The method according to any one of the preceding claims, wherein the energy provided by the motor is preset.

10. The method according to any one of the preceding claims, wherein the energy provided by the motor is a function of the energy provided by the muscles of the user in the concentric movement phase.

11. The method according to any one of the preceding claims, wherein the energy provided by the muscles of the user in the concentric movement phase is higher than the energy provided by the motor.

12. The method according to any one of the preceding claims, wherein the energy provided by the muscles of the user in the concentric movement phase is lower than the energy provided by the motor.

13. A flywheel exercise apparatus for exercising muscles of a user with eccentric overload, said exercise apparatus comprising:

a rotatably mounted flywheel;

a motor operably connected to and configured to accelerate the flywheel;

14. The flywheel exercise apparatus according to claim 13, wherein the traction element is configured to be wound up around a shaft coupled to the flywheel.

15. The flywheel exercise apparatus according to any one of claims 13-14, wherein the control arrangement is further configured to detect an eccentric movement phase using the sensor arrangement and counteract the deceleration of the flywheel during the eccentric movement phase using energy provided by the motor.

16. The flywheel exercise apparatus according to any one of claims 13-15, wherein the control arrangement includes a user interface wherein the energy to be provided by the motor can be set by a user.

17. The flywheel exercise apparatus according to any one of claims 13-16, wherein energy provided by the motor is a function of the energy provided by the muscles of the user in the concentric movement phase.

18. The flywheel exercise apparatus according to any one of claims 13-17, wherein the energy provided by the muscles of the user in the concentric movement phase is higher than the energy provided by the motor.

19. The flywheel exercise apparatus according to any one of claims 13-18, wherein the energy provided by the muscles of the user in the concentric movement phase is lower than the energy provided by the motor.

20. The flywheel exercise apparatus according to any one of claims 13-19, wherein the maximum mechanical output power of the motor is 1500 W or less.

21. The flywheel exercise apparatus according to any one of claims 13-20, wherein the motor is integrated in the flywheel exercise apparatus.

22. The flywheel exercise apparatus according to any one of claims 13-20, wherein the motor is part of a module which can be detached from the flywheel exercise apparatus.

23. Use of a motor for assisting the acceleration of the flywheel of a flywheel exercise apparatus as it is accelerated using energy provided by the muscles of the user in a concentric movement phase in order to achieve an eccentric overload when the flywheel is subsequently decelerated using energy provided by the muscles of the user in an eccentric movement phase.