EP4052766A1

EP4052766A1 - Method and system to determine a personalized electrical muscle stimulation pattern for a subject using an ergometer

Info

Publication number: EP4052766A1
Application number: EP21305243.4A
Authority: EP
Inventors: Lana POPOVIC-MANESKI; Amine METAHNI
Original assignee: Centre National de la Recherche Scientifique CNRS; Universite Claude Bernard Lyon 1 UCBL; Ecole Normale Superieure de Lyon
Current assignee: Centre National de la Recherche Scientifique CNRS; Universite Claude Bernard Lyon 1 UCBL; Ecole Normale Superieure de Lyon
Priority date: 2021-03-01
Filing date: 2021-03-01
Publication date: 2022-09-07

Abstract

The present invention relates to a method for determining an electrical stimulating pattern in a cycle ergometer equipped with a functional electrical stimulation (FES) system, said electrical pattern being personalized to the left and the right lateral parts of a user's body.

The present invention also refers to an ergometer, preferably a cycle ergometer such as an electric stimulation stationary bike, comprising a FES controller with instructions to operate the method of the invention.

Description

FIELD OF INVENTION

The present invention relates to the field of ergometers having a functional electrical stimulation (FES) system. In particular, the present invention relates to the field of the calibration of FES systems, that is to say the determination of suitable parameters for providing an electrical stimulation of the muscle(s) of a subject, for the purpose of an exercising program on the ergometer. The present invention also refers to the analysis of the usable power or force produced by a subject so as to determine at least one electrical stimulation pattern of a muscle, differentiated for the left and the right lateral parts of a subject's body.

BACKGROUND OF INVENTION

Functional Electrical Stimulation (FES) is a well-established rehabilitation technique that delivers pulses of electrical current to the nerves, causing the muscles they innervate to contract. This is possible thanks to the electrodes applied on the skin and linked by cables to a stimulator that generates electrical pulses. These pulses excite the nerve of the weakened or paralyzed muscle so that the muscle contracts.
To date, there are many ergometers (for example, stationary bikes or stationary/indoor rowers or elliptic trainers) equipped with a FES system for the rehabilitation of paralyzed limbs or of limbs requiring rehabilitation. Some of these devices integrate specific functions. For example, the application WO 2018/085770 describes a functional electrical stimulation ergometer incorporating an antispam control unit.
However, the devices currently available on the market still require the assistance of a qualified person to define the electrical stimulation parameters of the FES system, suitable for its user. This phase, called the device's "calibration phase", is therefore long, tedious and delays the phase of using the ergometer corresponding to the individual's physical training phase.
There is therefore a need to provide ergometers equipped with FES with a system which can be calibrated automatically according to the muscular and/or skeleton specificities of its user. In particular, there is a need for this calibration to provide an electrical stimulation scheme specific to the user of the ergometer, taking into account the differences of each muscle or muscle group of the subject, and the differences identified between the right and left sides of the individual's body.
In addition, FES systems may have advantages for people with no medical conditions and no particular disabilities. For example, functional electrical stimulation could help improve muscle work when using the ergometer.
Thus, there is a need to provide ergometers equipped with FES with a system which can automatically provide one or more patterns of electrical stimulation of at least one muscle or muscle group of the subject, so that the mechanical performance on the ergometer during the training phase is maximum. In particular, the present invention aims at providing a stimulation scheme for each muscle or muscle group of the user of the ergometer, differentiated for the right and left parts of the user's body, which makes it possible to minimize muscle fatigue during the implementation of the training phase.

SUMMARY

The present invention thus relates to a method for determining an electrical stimulation pattern of at least one muscle or group of muscles of a lateral part of a user's body, in a motorized cyclic ergometer equipped with a functional electrical stimulation (FES) system, said electrical pattern being personalized to the left and the right lateral parts of the user's body; said method performing, by a data processing unit of the motorized cyclic ergometer, the following steps:

Step (a): the reception of first raw data Δ resulting from activation of at least one muscle or group of muscles of at least one lateral part of the user's body, said first raw data Δ being acquired by at least one sensor of the motorized cyclic ergometer when the lateral part is engaged in a periodic movement by the motorized cyclic ergometer, and when the FES system does not provide any stimulation to any muscle or group of muscles of the lateral part of the user's body;
Step (a'): the iteration of step (a) for the other lateral part of the user's body, preferably simultaneously to step (a);
Step (b): the reception of second raw data Δ' provided by the same at least one muscle or group of muscles of at least one lateral part of the user's body of step (a), said second raw data Δ' being acquired by the same at least one sensor of step (a), when the lateral part is engaged in a periodic movement by the ergometer, and when the FES system provides a stimulation to the at least one muscle or group of muscles of the lateral part of the user's body;
Step (b'): the iteration of step (b) for the other lateral part of the user's body, preferably simultaneously to step (b);
Step (c): the analysis of acquired first and second raw data Δ and Δ' obtained at steps (a) and/or (a'), and (b) and/or (b') to provide for the at least one muscle or group of muscles of the lateral part of the user's body, its active muscle profile (P_s), its passive muscle profile (P_ws) and the corresponding differential muscle profile;
Step (d): the determination of an electrical stimulation pattern for the at least one muscle or group of muscles of the left and right lateral parts of the user's body, from the differential muscle profile of step (c); said electrical stimulation pattern of the at least one muscle or group of muscles comprising one electrical stimulation pattern for said muscle or group of muscles located on the left lateral part of the user's body and one electrical stimulation pattern for said muscle or group of muscles located on the right lateral part of the user's body; and
Step (e): the optional implementation of steps (a) to (d) for a different muscle or group of muscles.

In some embodiments, the motorized cyclic ergometer is a cycle ergometer such as a stationary bike, said cycle ergometer comprising:

a pair of pedals consisting of a right pedal and a left pedal; each pedal being connected to the motor by a crank arm; the position of each left and right crank arm defining a crank angle (α; α') relatively to the horizontal position; the right pedal or right crank arm comprising at least one sensor configured for determining the position of the right pedal or the right crank arm and/or the force applied on said right pedal or right crank arm as a function of the crank angle (α) of the right crank arm; and the left pedal or left crank arm comprising at least one sensor configured for determining the position of the left pedal or the left crank arm and the force applied on said left pedal or left crank arm as a function of the crank angle (α') of the left crank arm;

In some embodiments, the at least one muscle or group of muscles of the lateral parts of the user's body in step (a) or (a') and step (b) or (b') are engaged in a periodic movement by at least one motor of the motorized cyclic ergometer, at a constant speed.
In some embodiments, the constant speed of the motor ranges from 10 rpm to 90 rpm, preferably from 10 rpm to 60 rpm, more preferably is 30 rpm.
In some embodiments, the electrical stimulation at steps (b) and (b') is an isometric electrical stimulation.
In some embodiments, the electrical stimulation current (I) at steps (b) and (b') ranges from 1 mA to 170 mA.
In some embodiments, the electrical stimulation pulse width (PW) at steps (b) and (b') ranges from 50 µs to 1000 µs.
In some embodiments, the electrical stimulation frequency (f) at steps (b) and (b') ranges from 10 Hz to 100 Hz.
The invention further relates to a computer program in an ergometer, preferably in a cycling ergometer, equipped with a FES system, said computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method of the invention.
The invention further relates to an electric stimulation stationary bike comprising:

a motor configured for moving in a periodic movement;
a pair of pedals consisting of a right pedal and a left pedal; each pedal being connected to the motor by a crank arm; the position of each left and right crank arm defining a crank angle (α; α') relatively to the horizontal position;
a functional electrical stimulation (FES) system comprising:
- a module, preferably a computer-based module, comprising a data acquisition system and a FES controller, optionally contained in the stimulator; and
- a stimulator connected to two or more electrical stimulation electrodes; said electrical stimulation electrodes being configured for adhering to at least one targeted muscle or group of muscles of the lateral part of a user's body being engaged in a periodic movement by the stationary bike, and for providing an interface to transmit electrical pulses from the stimulator to the targeted muscle or group of muscles of the lateral part of the user's body;

the right pedal or right crank arm comprises at least one sensor configured for determining the position of the right pedal or right crank arm and/or the force applied on said right pedal or right crank arm as a function of the angular position (α) of the right crank arm;
the left pedal or left crank arm comprises at least one sensor configured for determining the position of the left pedal or left crank arm and/or the force applied on said left pedal or left crank arm as a function of the angular position (α') of the left crank arm;
said FES controller comprising instructions to operate the method for determining a personalized electrical stimulation of the invention.

In some embodiments, the stationary bike is configured for implementing the method of the invention, before implementation of an exercise regime by a user.
In some embodiments, the muscle or group of muscles of the lateral part of the user's body is selected from: quadriceps (vastus lateralis), quadriceps (vastus medialis), quadriceps (rectus femoris), hamstrings, gluteus, gastrocnemius, tibialis anterior, abdominal and back muscles.
In some embodiments, the FES system comprises a user interface for implementing the method according to the invention or for implementing an exercise regime after the method of the invention is implemented.
In some embodiments, the FES system further comprises means for controlling that the electrical stimulation of at least one targeted muscle or group of muscles of the lateral part of the user's body engaged in a periodic movement by the electrical stimulation stationary bike, during an exercise regime, fits with the electrical stimulation pattern obtained by the method of the invention.

DEFINITIONS

In the present invention, the following terms have the following meanings:

"Ergometer" refers to a physical exercise machine which makes the user reproduces a movement that would make them move if they were not on the machine. For instance, the ergometer could be a treadmill (reproducing walking/running), an elliptical trainer (reproducing stair climbing), a stationary bike (reproducing cycling), a rowing machine (reproducing rowing, etc. According to one embodiment, the ergometer is a "cycling ergometer" such as a stationary bike or an elliptic trainer, i.e. an ergometer engaging at least one lateral part of the user's body in a periodic movement. The ergometer may also be motorized, i.e. comprise a motor for moving, especially in said periodic movement.
Generally speaking, the present ergometer is a motorized cycling ergometer which at least comprises:
- ∘ Physical exercice means, advantageously comprising a rotating part and at least one pedal for rotating said rotating part, connected to the motor by a crank arm ;
- ∘ A functional electrical stimulation (FES) system, for providing an electrical stimulation to the muscle(s) of the user;
- ∘ At least one sensor, which is preferably part of the FES system ;
- ∘ A data processing unit (for instance a processor), which is also preferably part of the FES system, but note that it can also be remotely located (for instance the processing unit of a server).
"Exercise regime" refers to the individual's physical training phase using the ergometer. According to one embodiment, during the exercise regime, the FES system provides an electrical stimulation to the muscle(s) of the user according to an electrical stimulation pattern that has been previously determined in a separate step. According to one embodiment, the exercise regime does not comprise or is not the phase for determining the electrical stimulation pattern of a user of the ergometer (that is to say is not the calibration phase).
The "lateral part" of the user's body may correspond for instance to an arm, a leg, a limb, an upper extremity or a lower extremity of the user's body.
"Periodic movement" refers to any movement that recurs, identical to itself, at different or equal time intervals. According to one embodiment, the periodic movement is obtained when the ergometer of the invention sets in motion at least one limb (lower limb and/or upper limb) of a subject using said ergometer. According to one embodiment, the periodic movement is obtained when the ergometer of the invention sets in motion at least one muscle or group of muscles of a lateral part (left and/or right) of a subject using said ergometer. According to one embodiment, at least one muscle or group of muscles of a lateral part of the user's body contracts during the periodic movement of said lateral part. A "periodic movement" corresponds to a movement wherein each single point of the trajectory corresponds to a single angle value, for instance a single value of the crank arm angle. In the present invention, "angle" or "crank angle" are used indifferently to refer to the degree of advancement in the periodic movement, even when the periodic movement is not circular and/or when the ergometer does not comprise pedals, by analogy with implementation with a cycling ergometer.
"The lateral part is engaged in a periodic movement by the ergometer" means that at least one muscle or group of muscles located on the right or the left lateral part of the user's body contributes to move, directly or indirectly, said lateral part in a periodic movement when using the ergometer. According to one embodiment, "the lateral part is engaged in a periodic movement by the ergometer" means that at least one muscle or group of muscles located on the lateral part of the user's body moves in a periodic movement when using the ergometer. According to one embodiment, "the lateral part is engaged in a periodic movement by the ergometer" means that at least one muscle or group of muscles located on the lateral part of the user's body moves another muscle or group of muscles located on the same lateral part of the user's body in a periodic movement when using the ergometer.
In preferred embodiments, "the lateral part is engaged in a periodic movement by the ergometer" means that the lateral part does not move by its own action, but only due to the energy provided by the at least one motor of the ergometer.
"Pedal" refers to each of a pair of foot- and/or hand-operated levers used for turning the main rotation axis of a preferred embodiment of said ergometer.
"Personalized electrical stimulation pattern" means that the electrical stimulation pattern takes into account the physiological condition of the user (muscle strength, muscle spasticity, size of segments for instance) and/or the global geometrical configuration (position of the user or placement of electrodes for instance). In the present invention, the FES system will provide for each user of the ergometer, an electrical stimulation pattern for his(her) muscle(s) taking into account the differences between the left and the right lateral parts of the user's body. According to one embodiment, these differences may refer to any abilities of the muscles of a subject, such as, but not limited to: muscle strength, excitability, contractility, elasticity, extensibility and spasticity. According to one embodiment, these differences may refer to any abilities of the muscles of a subject using an ergometer, that may be determined and/or monitored by a sensor, preferably a sensor located on the ergometer. According to an embodiment, these differences may also be related to any abilities of the skeleton of the subject. For instance, fractures or other skeleton disabilities may mechanically limit the movement. An "electrical stimulation pattern" is a profile defining the value, intensity and/or pulse width of the stimulation to be provided for each position of the trajectory, for at least one muscle or group of muscles of at least one lateral part of the user's body. In preferred embodiments, the electrical stimulation pattern comprises the profile for the same at least one muscle or group of muscles of both lateral parts of the user's body.
"Angular position", "angle" or "crank angle" refers, in a cycle ergometer comprising foot and/or hand pedals such as a stationary bike, to the angle between the crank arm position and the horizontal position, in the crank rotation plane. According to one embodiment, the position of each right and left crank arm defines a crank angle (α; α') to the horizontal position. According to one embodiment, the left pedal and the right pedal of the ergometer are in opposite positions (that-is-to say α = α' +180°).
"Subject" or "user" refers to a human (male or female). The user may be a child, a teenager, an adult or an elderly person. According to one embodiment, the human has a disability, preferably a motor disability. According to one embodiment, the human doesn't have any disability. According to one embodiment, the human has a muscle weakness. According to one embodiment, the user's motor disability affects only one lateral part (one side) of the user's body. According to one embodiment, the term "user" in the present invention refers to a human that uses the ergometer of the invention.
"Tangential force" refers to the force which contributes to turning the ergometer main rotation axis, estimated from the force or torque sensors on the left or right pedal or crank arm or from the motor current.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a workflow providing a schematic representation of the steps of the method according to one embodiment of the present invention when the raw data of steps (a) and (b) have been previously acquired and stored in the FES system before the determination by an algorithm of the electrical stimulation pattern personalized to a user.
Figure 2 is a workflow providing a schematic representation of the steps of the method according to one embodiment of the present invention when the FES system is included in an electrical stimulation stationary bike; and when the raw data of steps (a) and (b) have been previously acquired and stored in the FES system before the determination by an algorithm of the electrical stimulation pattern personalized to a user.
Figure 3 is a workflow providing a schematic representation of the steps of the method according to one embodiment of the present invention when the FES system is included in an electrical stimulation stationary bike; and when the raw data of steps (a) and (b) are acquired when the user is on the ergometer, during a preliminary using phase of the ergometer, before the training phase.
Figure 4 is a workflow providing a schematic representation of the steps for determining the maximum stimulation current I_max of the FES system to be applied to the user; preferably during the step (b) of the method of the invention.
Figure 5 is a set of graphs showing the muscle force profile for the left and right quadriceps and the left and right hamstrings depending on the crank angle in a cycle ergometer, when an electrical stimulation is applied ("active profile") or not ("passive profile") to the muscles; the left and right lateral parts of the user's body being engaged in a periodic circular movement by the cycle motor of the ergometer. The differential profile corresponds to the passive profile subtracted from the active profile.

DETAILED DESCRIPTION

The following detailed description will be better understood when read in conjunction with the drawings. For the purpose of illustrating, the system is shown in the preferred embodiments and the block diagrams, comprising the steps of the method, are shown in the preferred embodiments. It should be understood, however that the application is not limited to the precise arrangements, structures, features, embodiments, and aspect shown.

Method for providing an electrical stimulation pattern

The present invention relates to a method for determining an electrical stimulation pattern of at least one muscle, in a FES system. According to one embodiment, the method of the invention is a computer-implemented method, performed by said processing unit of the ergometer/FES system. According to one embodiment, the method is for calibrating the electrical stimulation parameters of a FES system depending on the subject using the FES system and/or on the ergometer chosen for training. According to one embodiment, the method is for determining at least one electrical stimulation pattern to be delivered to at least one muscle or group of muscles of a subject; preferably when said subject will train on an ergometer. According to one embodiment, the method is a calibration method of a functional electrical stimulation (FES) system, said FES system being integrated or not, to an ergometer. According to one embodiment, the method is for determining the variations of the electrical stimulation to be delivered to one or more muscles, on left and/or right lateral part of the body, of the user of the ergometer in order to reduce muscle fatigue and/or improve the mechanical performance of the user when training on the ergometer in an exercise regime. According to one embodiment, the method of the invention is neither a method of diagnostic of a disease or a disability, nor a method of treatment of the subject. According to one embodiment, the method of the invention allows determining the best conditions of using a FES system that have to be provided later to the user of an ergometer, during an exercise regime. Especially, the method of the invention allows determining separate electrical stimulation patterns for at least one muscle of the right and the left lateral parts of the body of the user of the ergometer.
According to one embodiment, the FES system comprises one or more stimulation channels (C). According to one embodiment, the FES system comprises from 1 to 16 stimulation channels. According to one embodiment, the FES system comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16 channels. According to one embodiment, each stimulation channel comprises at least one cathode electrode to be applied on a muscle of a subject. According to one embodiment, the anode electrode is shared for multiple channels. Applying an electrode on a muscle of a subject may be performed for instance by adhering the electrode to the surface of the skin above said muscle.
According to one embodiment, the method of the invention comprises or consists of the following steps:

Determining a maximum stimulation current to be applied by the FES system to the user of the ergometer;
Acquiring the passive and active muscle force profiles for each muscle or group of muscles of at least one lateral part of the user's body, said muscle(s) and/or lateral parts of the user's body being set in motion or engaged in a periodic movement by the ergometer; and/or
Determining the electrical stimulation pattern for each muscle of the at least one lateral part of the user's body, set in motion or engaged in a periodic movement by the ergometer; preferably by providing separate patterns for the same kind of muscle located on the left and the right lateral parts of the user body.

According to one embodiment, the method of the invention comprises or consists of:

Step (a): the reception of acquired first raw data Δ; said first raw data Δ being acquired by at least one sensor located on the ergometer when the at least one muscle or group of muscles of a lateral part of the user's body is set in motion or engaged in a periodic movement by the ergometer and when the FES system does not provide any stimulation to any muscle or group of muscles of the lateral part of the user's body;
Step (a'): the iteration of step (a) for the other lateral part of the user's body, preferably simultaneously to step (a);
Step (b): the reception of acquired second raw data Δ'; said second raw data Δ' being acquired by at least one sensor located on the ergometer when the at least one muscle or group of muscles of a lateral part of the user's body is set in motion or engaged in a periodic movement by the ergometer and when the FES system provides a stimulation to the at least one muscle or group of muscles of a lateral part of the user's body;
Step (b'): the iteration of step (b) for the other lateral part of the user's body, preferably simultaneously to step (b);
Step (c): the analysis of acquired first and second raw data Δ and Δ' according to an algorithm in order to provide for the at least one muscle or group of muscles of the lateral part of the user's body, its active muscle profile (Ps), its passive muscle profile (Pws) and the corresponding differential (usable) muscle profile (P_diff); preferably in function of the angular position of the crank arm;
Step (d): the determination of an electrical stimulation pattern for the at least one muscle or group of muscles of the lateral part of the user's body, from the differential muscle profile of step (c).

According to one embodiment, the angle, or angular position, ranges from 0° to 360°.

Steps (a) and (a')

The present section discloses embodiments relative to step (a). Said embodiments similarly and independently apply to step (a').
According to the embodiment as illustrated in Figures 1, 2 and 3, an initial step (step a) of the method consists in the reception of acquired first raw data Δ. Said first raw data Δ is acquired when the FES system does not provide any stimulation to any muscle or group of muscles of the lateral part of the user's body.
According to one embodiment, the first raw data Δ may be selected from pedal position or crank arm angle, force exerted on the pedal, force exerted on the crank arm, velocity, motor current, torque transmitted in the spindle, counter-electromotive force and any other parameters characterizing the use of the ergometer by the subject.
According to one embodiment, the first raw data Δ of step (a) are acquired from one or more sensors located on the ergometer.
According to one embodiment, when the ergometer is a cycle ergometer, such as a stationary bike, the first raw data Δ are acquired from one or more sensors located on the pedals, preferably on the pedal crank arms, of the cycle ergometer such as foot pedals and/or hand pedals. According to one embodiment, the first raw data Δ are acquired from one sensor, preferably a force sensor, located on the left foot pedal and from another sensor, preferably a force sensor, located on the right foot pedal of the cycle ergometer. According to one embodiment, the first raw data Δ are acquired from one sensor, preferably a force sensor, located on the left-hand pedal and from another sensor, preferably a force sensor, located on the right-hand pedal of the cycle ergometer. According to one embodiment, the movement of the left and right pedals is independent of each other. In the present invention, the term "pedal" means an element on which is placed either one foot or one hand, said element being connected to a cycle through a crank so that this element may be set in elliptic, for instance circular, motion.
According to one embodiment, the first raw data Δ are acquired for each user of the ergometer. According to one embodiment, the acquired first raw data Δ vary for each user of the ergometer.
As illustrated in Figures 1, 2 and 3, the first raw data Δ are acquired when the motor, preferably the cycle motor, of the ergometer sets in motion the arms and/or the legs of the user, and when the FES system does not provide any electrical stimulation to the muscles of the user.
According to one embodiment, the first raw data Δ provide information on the force, preferably the tangential force, and/or the power exerted on the ergometer by one muscle or group of muscles of a lateral part of the user's body and/or the weight of said lateral part; said lateral part not receiving any electrical stimulation by the FES system.
According to one embodiment, the first raw data Δ are acquired during a number of movement phases, preferably during a number of periodic movement phases, ranging from more than 0 to 10; preferably from 1 to 5. According to one embodiment, the first raw data Δ are acquired during a number of periodic movement phases equal to 1 or 2.
According to one embodiment, when the ergometer is a cycle ergometer such as a stationary bike, the first raw data Δ are acquired during a number of revolutions of the crank ranging from more than 0 to 10; preferably from 1 to 5. According to one embodiment, the first raw data Δ are acquired during a number of revolutions of the crank equal to 1 or 2.
According to one embodiment, the muscle or group of muscles of a lateral part of the user's body may be selected from: quadriceps (vastus lateralis), quadriceps (vastus medialis), quadriceps (rectus femoris), hamstrings, gluteus, gastrocnemius, tibialis anterior, soleus, abdominals and back muscles.
Step (a') is the iteration of step (a) for the other lateral part of the user's body, preferably simultaneously to step (a).

Steps (b) and (b')

The present section discloses embodiments relative to step (b). Said embodiments similarly and independently apply to step (b').
According to the embodiment as illustrated in Figures 1, 2 and 3, a second step (step b) of the method consists in the reception of acquired second raw data Δ'. By contrast with the first raw data Δ, the second raw data Δ' is acquired when the FES system provides a stimulation to the at least one muscle or group of muscles of the lateral part of the user's body.
According to one embodiment, the second raw data Δ' may be, like the first raw data Δ, selected from pedal position, crank arm angle, force exerted on the pedal, force exerted on the crank arm, velocity, motor current, torque transmitted in the spindle, counter-electromotive force and any other parameters characterizing the use of the ergometer.
According to one embodiment, the second raw data Δ' are acquired from one or more sensors located on the ergometer; preferably located on the pedals, preferably on the pedal crank arms, of the ergometer when the ergometer is a cycle ergometer, such as foot pedals and/or hand pedals. According to one embodiment, the second raw data Δ' are acquired from one or more sensors that are the same sensor(s) used at step (a). According to one embodiment, when the ergometer is a cycle ergometer, the second raw data Δ' are acquired from one sensor, preferably a force sensor, located on the left foot crank arm and from another sensor, preferably a force sensor, located on the right foot crank arm of the cycle ergometer. According to one embodiment, when the ergometer is a cycle ergometer, the second raw data Δ' are acquired from one sensor, preferably a force sensor, located on the left-hand crank arm and from another sensor, preferably a force sensor, located on the right-hand crank arm of the cycle ergometer.
According to one embodiment, the movement of the right and left pedals is independent of each other.
According to one embodiment, the second raw data Δ' are acquired for each user of the ergometer. According to one embodiment, the acquired second raw data Δ' vary for each user of the ergometer.
According to one embodiment, the second raw data Δ' are acquired when the motor of the ergometer, preferably the cycle motor of the ergometer, sets in motion or engages in a periodic movement the arms and/or the legs of the user, and when the FES system provides electrical pulses to the muscles of the user during at least one cycle of motion. According to one embodiment, the second raw data Δ' provide information on the force, preferably tangential force, and/or the power exerted on the ergometer by one muscle or group of muscle of a lateral part of the user's body and/or the weight of said lateral part; when said muscle(s) received electrical pulses by the FES system. According to one embodiment, the second raw data Δ' provide information on the force, preferably the tangential force, and/or the power exerted on the ergometer by one muscle or group of muscles of a lateral part of the user's body; said information taking into account the distinct behavior of said muscle(s) depending on its position on the left or the right lateral part of the user's body; and said muscle(s) receiving an electrical stimulation by the FES system.
The FES system provides a stimulation during the entire revolution of the crank arm during the periodic cyclic movement.
According to one embodiment, the second raw data Δ' are acquired during a number of movement phases, preferably during a number of periodic movement phases, ranging from more than 0 to 10; preferably from 1 to 5. According to one embodiment, the second raw data Δ' are acquired during a number of periodic movement phases equal to 1 or 2. According to one embodiment, the second raw data Δ' are acquired during a number of periodic movement phases equal or different, preferably equal, to the number of periodic movement phases used for the acquisition of first raw data Δ of step (a).
According to one embodiment, when the ergometer is a cycle ergometer such as a stationary bike, the second raw data Δ' are acquired during a number of revolutions of the crank ranging from more than 0 to 10; preferably from 1 to 5. According to one embodiment, the second raw data Δ' are acquired during a number of revolutions of the crank equals to 1 or 2.
According to one embodiment, the stimulated muscle or group of muscles of a lateral part of the user's body may be selected from: quadriceps (vastus lateralis), quadriceps (vastus medialis), quadriceps (rectus femoris), hamstrings, gluteus, gastrocnemius, tibialis anterior, soleus, gastrocnemius, abdominals and back muscles; preferably is quadriceps.
In the present invention, the expression "stimulated muscle" or "targeted muscle" means that said muscle received electrical pulses by the FES system of the ergometer during all number of movement phases while the second raw data Δ' are acquired.
According to one embodiment, during step (b) the FES system provides an electrical stimulation with a stimulation current (I_stim) ranging from 1 mA to 170 mA. According to one embodiment, during step (b) the FES system provides an electrical stimulation with a stimulation current (I_stim) ranging from more than 0% to 100% of a maximum stimulation current (I_max). According to one embodiment, the stimulation current (I_stim) equals to 60% of the maximum stimulation current (I_max).
According to one embodiment, the maximum stimulation current (I_max) is determined in a preliminary step of the method of the invention. According to one embodiment, the maximum stimulation current (I_max) is determined before the implementation of step (a) and/or step (b) of the method of the invention.
According to one embodiment, the stimulation current for step (b) (I_stim) is determined in a preliminary step of the method of the invention. According to one embodiment, the stimulation current for step (b) (I_stim) is determined before the implementation of step (a) and/or step (b) of the method of the invention.
According to one embodiment, when the ergometer is a cycle ergometer, the maximum stimulation current (I_max) is determined according to the method presented in Figure 4. As seen in Figure 4, the first step consists to set cranks of the ergometer at the angle reference (preferably horizontal or more preferably vertical position if the user is in the recumbent position). Then, the brake is turned on to prevent turning the crank arm(s) and the FES stimulation is turned on in order to provide electrical pulses to the targeted muscle by at least one stimulation channel of the FES system. As long as the tangential force F_T exerted on the left and right pedals of the ergometer rises, the stimulation current I is increased in steps of, preferably 5mA for big muscles and 2 mA for small muscles. When a plateau is achieved for the tangential force F_T, the 90% of the stimulation current for which the plateau is reached is determined. The obtained value corresponds to the maximum stimulation current I_max.
Step (b') is the iteration of step (b) for the other lateral part of the user's body, preferably simultaneously to step (b).
In specific embodiments of the invention when only one lateral part of the user is to be stimulated, at least one of steps (a') and (b'), preferably both steps (a') and (b'), are missing from the method of the invention.

Sensors

According to one embodiment, the sensor(s) is(are) located on the ergometer; preferably when the ergometer is a cycle ergometer, the sensor(s) is(are) located on the crank arms and/or the pedals of the ergometer. According to one embodiment, each sensor may independently be a position sensor, an angular encoder, a force sensor, a pressure sensor and/or a torque sensor.

Motor

According to one embodiment, at step (a), (a') and/or step (b), (b') of the method of the invention, the motor sets in motion or engages at least one muscle or group of muscles of a lateral part of the user's body in a periodic movement at a speed ranging from more than 0 rpm to 150 rpm, during the implementation of the method; preferably during the acquisition of the first and second raw data Δ and Δ'. According to one embodiment, at step (a), (a') and/or step (b), (b') of the method of the invention, the motor, preferably the cycle motor, sets in motion the arms and/or legs of the user at a speed ranging from more than 0 rpm to 150 rpm, during the implementation of the method; preferably during the acquisition of the first and second raw data Δ and Δ'. According to one embodiment, the speed of the motor, preferably of the cycle motor, ranges from more than 0 rpm to 180 rpm; preferably from 5 rpm to 100 rpm, more preferably from 10 rpm to 50 rpm. According to one embodiment, the speed of the cycle motor is 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 or 50 rpm; preferably during the acquisition of the raw first and second data Δ and Δ'.
According to one embodiment, during the implementation of the method (step (a), (a') and/or step (b), (b')), the motor, preferably the cycle motor, sets in motion or engages at least one lateral part of the user's body, preferably the arms and/or legs of the user, at a constant speed.

Determining the passive and active muscle profiles Pws and Ps

According to one embodiment, the FES system comprises a control unit able to determine from the acquired first raw data Δ obtained at step (a) or (a'), the power and/or force (Pws) of the muscle(s) of the user set in motion or engaged in a periodic movement by the ergometer without any electrical stimulation, in function of the angle in the periodic movement of the left and/or the right lateral parts of the user's body (α, α') (also called "passive muscle profile").
According to one embodiment, the FES system comprises a control unit able to determine from the acquired first raw data Δ, the power and/or force (Pws) of the muscle(s) of the user set in motion or engaged in a periodic movement by the ergometer without any electrical stimulation, in function of the crank angle of the pedals (also called "passive muscle profile").
According to one embodiment, the FES system comprises a control unit able to determine from the acquired second raw data Δ' obtained at step (b) or (b'), the usable power and/or force (Ps) of the muscle(s) of the user set in motion or engaged in a periodic movement by the ergometer when the FES system provides an electrical stimulation to the muscles, in function of the respective angle in the periodic movement of the left and the right lateral parts of the user's body (α, α') (also called "active muscle profile").
According to one embodiment, the FES system comprises a control unit able to determine from the acquired second raw data Δ', the usable power and/or force (Ps) of the muscle(s) of the user set in motion or engaged in a periodic movement by the ergometer when the FES system provides an electrical stimulation to the muscles, in function of the crank angle of the pedals (also called "active muscle profile").
According to one embodiment, the FES system comprises an algorithm able to provide the differential (usable) muscle force profile from the passive and the active muscle force profiles previously obtained by the method of the invention. For example, Figure 5 shows the active and passive profiles for the quadriceps left and right, and the hamstrings left and right of a user. As seen in Figure 5, from the active and passive profiles, a differential muscle force profile has been calculated by the algorithm for each muscle. In this way, for each muscle of the user, the method of the invention provides the ranges of the crank angle for which the muscles of the user have to be stimulated by the FES system, taking into account the fact that for a same kind of muscle, the need to be stimulated varies between the left and the right lateral parts of the user's body.

Determination of the electrical stimulation pattern

According to one embodiment, the method comprises or consists of determining, for each muscle force profile, at least one electrical stimulation pattern that will be provided by the FES system to the user; said electrical stimulation pattern or sequence depending on the respective angle in the periodic movement of the left and the right lateral parts of the user's body.
According to one embodiment, the method comprises or consists of determining, for each muscle force profile, at least one electrical stimulation pattern that will be provided by the FES system to the user; said electrical stimulation pattern or sequence depending on the crank angle of the cycle ergometer.
According to one embodiment, the electrical stimulation pattern resulting from the implementation of the method, comprises or consists of two sub-patterns: both sub-patterns refer to the same kind of muscle but one sub-pattern corresponds to the electrical stimulation sequence for the muscle located on the left part of the user and the other sub-pattern concerns the electrical stimulation for the muscle located on the right part of the user.
According to one embodiment, the FES system identifies from the differential muscle force profile obtained at the previous steps of the method, the ranges of the periodic movement for which the force exerted by the muscles is positive. According to one embodiment, the algorithm of the FES system identifies from the differential muscle force profile obtained at the previous steps of the method, the ranges of the crank angles for which the tangential force exerted by the muscles is positive (called "calibrated crank angles"). According to one embodiment, the algorithm of the FES system subtracts the passive muscle profile from the active muscle profile in order to provide the differential muscle profile.
According to one embodiment, the algorithm of the FES system further identifies from the differential muscle force profile obtained at the previous steps of the method, the maximum force, preferably the maximum tangential force F_Tmax of the stimulated muscle.
In some embodiments, the FES system determines the angle range(s) where the differential muscle profile has a value over a positive threshold, and selects this (these) range(s) for stimulation during exercise. The threshold may be selected between 5-50% of F_Tmax. The threshold may be for instance 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50% of F_Tmax, preferably 10% of F_Tmax.
In some embodiments, the FES system further shifts the obtained stimulation pattern to begin earlier for an angle value called angle_shift in order to account for the time delay between the beginning of the stimulation and the beginning of generation of the force in the stimulated muscle. The angle shift may be comprised between 0° and 20°. The angle shift may be obtained according to formula $Angle_shift = 60 / velocity (RPM) * 360 (°) * 0.1 s .$
According to one embodiment, the electrical stimulation pattern provides the expected force for the stimulated muscle in function of the angle in the periodic movement. According to one embodiment, the electrical stimulation pattern provides the expected tangential force F_T for the stimulated muscle in function of the calibrated crank angles.
In embodiments, the electrical stimulation pattern provides the stimulation intensity to be provided by the FES to the user at each point of the movement or trajectory, during the exercise regime on the ergometer.
In an embodiment, the method further comprises a step (e) consisting in implementing steps (a) to (d) for a different muscle or group of muscles. When the method comprises step (e), the determined electrical stimulation pattern preferably comprises stimulation patterns for at least two different muscles of groups of muscles of the user's body.

Computer program

The present invention also refers to a computer program comprising instructions to operate the method for determining an electrical stimulation pattern according to the present invention.

FES system

The present invention also refers to a FES system comprising instructions to operate the method for determining an electrical stimulation pattern according to the present invention.
According to one embodiment, the FES system of the invention comprises or consists of:

a module, preferably a computer-based module, comprising a data acquisition system and a FES controller; and
a stimulator connected to one or more electrical stimulation electrodes; said electrical stimulation electrodes being configured for (i) adhering to at least one targeted muscle or group of muscles of a user, set in motion by the ergometer, and (ii) providing an interface to transmit electrical stimulation signals from the stimulator in electrical impulses to the targeted muscle or group of muscles of the user.

According to one embodiment, the FES system of the invention comprises a storage unit for storing the acquired raw data Δ and Δ'.
According to one embodiment, the FES system of the invention comprises a computer program as defined above.
According to one embodiment, the module or the computer-based module of the FES system of the invention may implement the method of the invention as defined above.
According to one embodiment, the FES system of the invention is able to provide distinct electrical stimulation depending on the kind of the muscle, its position on the left or right lateral parts of the user's body and/or the choice of the ergometer (stationary bike or elliptic trainer, for example). According to one embodiment, the FES system of the invention is able to simultaneously provide at least two distinct electrical stimulations to at least two distinct muscles depending on the kind of the muscle, its position on the left or right lateral parts of the user's body and/or the choice of the ergometer (stationary bike or elliptic trainer, for example).

Ergometer

The present invention also refers to an ergometer, preferably a cycle ergometer, equipped with a FES system. According to one embodiment, the ergometer is a cycle ergometer, preferably a stationary bike (also called an electrical stimulation stationary bike).
According to one embodiment, the ergometer of the invention comprises means for implementing the method of the invention as defined above. According to one embodiment, the ergometer of the invention comprises a FES system comprising instructions for implementing the method of the invention as defined above.
According to one embodiment, the ergometer of the invention comprises a module able to:

Determine a maximum stimulation current to be applied by the FES system to the user of the ergometer;
Acquire the passive and active muscle force profiles for each muscle or group of muscles of at least one lateral part of the user's body, said muscle(s) and/or lateral parts of the user's body being set in motion or engaged in a periodic movement by the ergometer; and/or
Determine the electrical stimulation pattern for each muscle of the at least one lateral part of the user's body, set in motion or engaged in a periodic movement by the ergometer; preferably by providing separate patterns for the same kind of muscle located on the left and the right lateral parts of the user body.

According to one embodiment, the ergometer of the invention comprises a module able to implement any steps (a), (a'), (b), (b'), (c), (d) and/or (e) as defined above.
According to one embodiment, the ergometer of the invention comprises or consists of:

means for moving or training in a periodic movement at least one muscle or group of muscle of a lateral part of the user's body; and
a FES system.

The ergometer of the invention further comprises one or more motors.
According to one embodiment, when the ergometer is a cycle ergometer with a cycle motor, means for moving or training in a periodic movement at least one muscle or group of muscle of a lateral part of the user's body comprise or consist of: a pair of pedals consisting of a right pedal and a left pedal; each pedal being connected to the motor by a crank arm; the position of each left and right crank arm defining a crank angle (α; α') to the horizontal position; the right pedal or right crank arm comprising at least one sensor configured for determining the position of the right pedal or right crank arm and/or the force applied on said right pedal or right crank arm as a function of the crank angle (α) of the right crank arm; and the left pedal or left crank arm comprising at least one sensor configured for determining the position of the left pedal or left crank arm and/or the force applied on said left pedal or left crank arm as a function of the crank angle (α') of the left crank arm. According to one embodiment, when the ergometer is a cycle ergometer, the periodic movement is a periodic circular movement.

Uses

The present invention also refers to the use of the method of the invention as defined above. The present invention also refers to the use of a computer program and/or a FES system as defined above.
According to one embodiment, the method, the computer program and/or the FES system of the invention is(are) useful for providing one or more electrical pulses to at least one muscle of the user of the ergometer. According to one embodiment, the method, the computer program and/or the FES system of the invention is(are) useful for providing at least one electrical stimulation pattern to at least one muscle of the user of the ergometer; said electrical stimulation pattern being personalized to the left and right muscle force of the at least one muscle of a lateral part of the user's body; during an exercise regime.
According to one embodiment, the method, the computer program and/or the FES system of the invention is(are) useful for reducing the muscle fatigue when training on an ergometer.
According to one embodiment, the method, the computer program and/or the FES system of the invention is(are) useful for detecting the incorrect placement of the electrodes of the FES system when training on an ergometer.
According to one embodiment, the method, the computer program and/or the FES system of the invention is(are) useful for detecting the incorrect placement of the user when training on an ergometer.
According to one embodiment, the method, the computer program and/or the FES system of the invention is(are) useful for providing a maximum mechanical efficiency to the user of the ergometer.
According to one embodiment, the method, the computer program and/or the FES system of the invention is(are) useful for the increase of muscle mass and strength of a disabled or non-disabled person.
According to one embodiment, the method, the computer program and/or the FES system of the invention is(are) useful for the rehabilitation of movement of a disabled person.
While various embodiments have been described and illustrated, the detailed description is not to be construed as being limited hereto. Various modifications can be made to the embodiments by those skilled in the art without departing from the true spirit and scope of the disclosure as defined by the claims.

Claims

A method for determining an electrical stimulating pattern of at least one muscle or group of muscles of a lateral part of a user's body, in a motorized cyclic ergometer equipped with a functional electrical stimulation (FES) system, said electrical pattern being personalized to the left and the right lateral parts of the user's body; said method performing, by a data processing unit of the motorized cyclic ergometer, the following steps of:
- Step (a): the reception of first raw data Δ resulting from activation of at least one muscle or group of muscles of at least one lateral part of the user's body, said first raw data Δ being acquired by at least one sensor of the motorized cyclic ergometer when the lateral part is engaged in a periodic movement by the motorized cyclic ergometer, and when the FES system does not provide any stimulation to any muscle or group of muscles of the lateral part of the user's body;

- Step (a'): the iteration of step (a) for the other lateral part of the user's body, preferably simultaneously to step (a);

- Step (b): the reception of second raw data Δ' provided by the same at least one muscle or group of muscles of at least one lateral part of the user's body of step (a), said second raw data Δ' being acquired by the same at least one sensor of step (a), when the lateral part is engaged in a periodic movement by the ergometer, and when the FES system provides a stimulation to the at least one muscle or group of muscles of the lateral part of the user's body;

- Step (b'): the iteration of step (b) for the other lateral part of the user's body, preferably simultaneously to step (b);

- Step (c): the analysis of said first and second raw data Δ and Δ' obtained at steps (a) and/or (a') and (b) and/or (b') to provide for the at least one muscle or group of muscles of the lateral part of the user's body, its active muscle profile (P_s), its passive muscle profile (P_ws) and the corresponding differential muscle profile;

- Step (d): the determination of an electrical stimulation pattern for the at least one muscle or group of muscles of the left and right lateral parts of the user's body, from the differential muscle profile of step (c); said electrical stimulation pattern of the at least one muscle or group of muscles comprising one electrical stimulation pattern for said muscle or group of muscles located on the left lateral part of the user's body and one electrical stimulation pattern for said muscle or group of muscles located on the right lateral part of the user's body; and

- Step (e): the optional implementation of steps (a) to (d) for a different muscle or group of muscles.
The method according to claim 1, wherein the motorized cyclic ergometer is a cycle ergometer such as a stationary bike, said cycle ergometer comprising:
- a pair of pedals consisting of a right pedal and a left pedal; each pedal being connected to the motor by a crank arm; the position of each left and right crank arm defining a crank angle (α; α') relatively to the horizontal position; the right pedal or right crank arm comprising at least one sensor configured for determining the position of the right pedal or the right crank arm and/or the force applied on said right pedal or right crank arm as a function of the crank angle (α) of the right crank arm; and the left pedal or left crank arm comprising at least one sensor configured for determining the position of the left pedal or the left crank arm and the force applied on said left pedal or left crank arm as a function of the crank angle (α') of the left crank arm;
and wherein the periodic movement is a periodic elliptic or circular movement.
The method according to claim 1 or claim 2, wherein the at least one muscle or group of muscles of the lateral parts of the user's body in step (a) or (a') and step (b) or (b') are engaged in a periodic movement by at least one motor of the motorized cyclic ergometer, at a constant speed.
The method according to claim 3, wherein the constant speed of the motor ranges from 10 rpm to 90 rpm, preferably from 10 rpm to 60 rpm, more preferably is 30 rpm.
The method according to any one of claims 1 to 4, wherein the electrical stimulation at steps (b) and (b') is an isometric electrical stimulation.
The method according to any one of claims 1 to 5, wherein the electrical stimulation current (I) at steps (b) and (b') ranges from 1 mA to 170 mA.
The method according to any one of claims 1 to 6, wherein the electrical stimulation pulse width (PW) at steps (b) and (b') ranges from 50 µs to 1000 µs.
The method according to any one of claims 1 to 7, wherein the electrical stimulation frequency (f) at steps (b) and (b') ranges from 10 Hz to 100 Hz.
A computer program in an ergometer, preferably in a cycling ergometer, equipped with a FES system, said computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method according to any one of claims 1 to 8.
An electric stimulation stationary bike comprising:
- a motor configured for moving in a periodic movement;

- a pair of pedals consisting of a right pedal and a left pedal; each pedal being connected to the motor by a crank arm; the position of each left and right crank arm defining a crank angle (α; α') relatively to the horizontal position;

- a functional electrical stimulation (FES) system comprising:
- a module, preferably a computer-based module, comprising a data acquisition system and a FES controller; and

- a stimulator connected to two or more electrical stimulation electrodes; said electrical stimulation electrodes being configured for adhering to at least one targeted muscle or group of muscles of the lateral part of a user's body being engaged in a periodic movement by the stationary bike, and for providing an interface to transmit electrical pulses from the stimulator to the targeted muscle or group of muscles of the lateral part of the user's body;

wherein:
the right pedal or right crank arm comprises at least one sensor configured for determining the position of the right pedal or right crank arm and/or the force applied on said right pedal or right crank arm as a function of the angular position (α) of the right crank arm;

the left pedal or left crank arm comprises at least one sensor configured for determining the position of the left pedal or left crank arm and/or the force applied on said left pedal or left crank arm as a function of the angular position (α') of the left crank arm;

said FES controller comprising instructions to operate the method for determining a personalized electrical stimulation pattern according to any one of claims 1 to 8.
The electric stimulation stationary bike according to claim 10, wherein said stationary bike is configured for implementing the method of any one of claims 1 to 8, before implementation of an exercise regime by a user.
The electric stimulation stationary bike according to claim 10 or claim 11, wherein the muscle or group of muscles of the lateral part of the user's body is selected from, quadriceps (vastus lateralis), quadriceps (vastus medialis), quadriceps (rectus femoris), hamstrings, gluteus, gastrocnemius, tibialis anterior, abdominal and back muscles.
The electric stimulation stationary bike according to any one of claims 10 to 12, wherein the FES system comprises a user interface for implementing the method according to any one of claims 1 to 8 or for implementing an exercise regime after the method of any one of claims 1 to 8 is implemented.
The electric stimulation stationary bike according to any one of claims 10 to 13, wherein the FES system further comprises means for controlling that the electrical stimulation of at least one targeted muscle or group of muscles of the lateral part of the user's body engaged in a periodic movement by the electrical stimulation stationary bike, during an exercise regime, fits with the electrical stimulation pattern obtained by the method of claims 1 to 8.