SE1650813A1 - Training and testing equipment for leg muscles - Google Patents

Abstract

A training equipment (100) for exercising leg muscles, has an exercise machine (1) having a seat (2), a back support (5) coupled to the seat (2), and a swiveling arm (9) coupled to the legs of a subject (18) displaced by the subject efforts; the exercise machine (1) has a connection arrangement (6, 15), coupling the seat (2) and the back support (5) to define a first operating position for the coupling of the seat (2) and back support (5), designed for leg extension exercises, and a second operating position for the coupling between the seat (2) and back support (5), designed for leg curl exercises. An active energy source (12) is coupled to the swiveling arm (9) and operable to provide a desired resistance against the subject efforts.To be published with Figure 2a

Description

lO TRAINING AND TESTING EQUIPMENT FOR LEG MUSCLES TECHNICAL FIELDThe present invention relates to training and testing equipment for leg muscles, in particular for the so called “Leg Extension” and “Leg Curl” exercises.

BACKGROUND Several configurations exist for leg' extension (LE) and leg curl (LC) training devices: sitting, prone or standing. In terms of biomechanics and ergonomics, there is general agreement on the fact that the best configuration for LE exercise is sitting, while for LC is prone.

Up to the present day, while combined. machines for sitting or standing LC and LE exercises exist, no device so far can be converted from sitting LE to prone LC and viceversa.

Moreover, the vast majority of conventional training devices uses a mechanical weight stack to produce resistance or, to more limited extent, pneumatic canisters, bungee cords or springs.

In addition, EP l 871 494 Al discloses a prone LC device which uses a spinning flywheel to produce resistance, which is referred to in scientific literature as flywheel or isoinertial training. l0 There is vast evidence supporting the efficacy of flywheel training and. more specifically, the use of LC flywheel to strengthen knee flexor muscles and reduce the incidence of injuries, thanks to its capability ofgenerating eccentric overload, i.e. the production ofhigher power in the eccentric action (ECC, i.e. during the muscle lengthening' phase) than in the concentric action (CON, i.e. during the muscle shortening phase of the movement). In this respect, reference may be made to: Askling C, Karlsson J, Thorstensson A, “Hamstring injury occurrence in elite soccer players after preseason strength training with eccentric overload", Scand J Med Sci Sports. 2003 Aug; l3(4):244-50; orTous-Fajardo J, Maldonado RA, Quintana JM, Pozzo M,Tesch PA, “The flywheel leg-curl machine: offering eccentric overload for hamstring development", Int J Sports Physiol Perform. 2006 Sep;l(3):293-8 However, the passive, purely mechanical nature of the device disclosed in above cited EP l 871 494 Al (and otherequivalent devices) involves several important limitations: during ECC the machine can return at most the sameamount of energy accumulated in the flywheel during CON, sothat any excess of ECC power is obtained at the cost of ashorter duration of the braking phase; for* the reason above, the ECC overload is strongly lO dependent on the execution technique and. the degree offamiliarization with the device;the ECC overload can only be attained towards the end of the range of motion (ROM); the end point of the ROM is fixed and identical for each exercise repetition, and it is given by the length of the rope or strap (the end of the stroke corresponds to the rope or strap completely unwound on the shaft);the change of inertia is attained by adding/removingflywheels and/or additional masses on the periphery of the flywheel, which is a time-consuming operation if the inertia has to be changed. between exercise sets and/or between different trainees;the mass and inertia of the lever arm against which the subject is pushing with his legs, greatly reduce the net energy transfer between the subject and the flywheelsince a considerable amount of work is spent to put the lever into motion and subsequently brake it, de facto reducing the amount of achievable overload especially at lower loads (small flywheel for fast, explosive exercises); and the amount of ECC overload and force cannot be controlled a priori, but can only be measured with dedicated real-time feedback systems.motor powered training devices Furthermore, active, lO have been proposed (the so called “isokinetic machines”); their structure resembles a seat with a motor-operated lever arm onto which the subject leg is strapped.

However, these machines are only capable of generating isokinetic resistance (constant speed regardless of the force exerted) both on knee extensors and flexors, and in any case not in prone LC configuration. Furthermore, their cost makes them inaccessible for the vast majority of potential users.

The Applicant has realized that there is a strong interest around training devices targeted to leg muscles - especially knee muscles, like hamstrings, which suffer a high rate of injuries in sports like soccer. However: no device on the market is capable of converting between the most biomechanically efficient configurations,i.e. seated LE and prone LC; conventional weight machines do not offer the beneficial effects of flywheel training' in terms of ECCoverload; the few existing flywheel LE or LC devices suffer from the intrinsic limitation of being passive mechanicaldevices; and the existing active (motor powered) devices for open-chain exercises on knee muscles only offer isokineticresistance, cannot be converted into prone LC lO configuration, and have an excessive cost for a vast majority of potential users.

SUMMARY The aim of the present invention is consequently to overcome, at least in part, the issues highlighted previously, and in particular to provide an improved equipment for testing and training of leg muscles.According to the present invention, a device for testing and training of leg muscles is thus provided, as defined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGSFor a better understanding of the present invention,preferred embodiments thereof are now described, purely by way of non-limiting example, with reference to the attached drawings, wherein:- Figure la shows a schematic lateral view of anexercise machine of a testing and training equipment according to one embodiment of the present invention, in a first operating configuration, for a seated LE exercise; - Figure lb shows a schematic lateral view of theexercise machine, in a second operating configuration, fora prone LC exercise; - Figure 2a shows a schematic lateral view of the exercise machine of Figure la with the trainee performing aseated LE exercise; - Figure 2b shows a schematic lateral view of theexercise machine of Figure lb, with the trainee performinga prone LC exercise; - Figure 3 is a schematic block diagram of anelectronic control system coupled to the exercise machinein the testing and training equipment; and - Figures 4a and 4b show plots of physical quantities related to exercises performed with the exercise machine in the testing and training equipment.

DETAILED DESCRIPTION OF EMBODIMIENTSAs will be detailed in the following disclosure, an aspect of the present solution envisages the design of a multifunction exercise machine, particularly for kneemuscles exercises (both extensors and flexors), providingone or more of the following features: from. an ergonomics point of view, easy conversion between the two most efficient configurations for each type of exercise, i.e. seated. LE and, prone LC, thanks to a mechanical conversion arrangement coupling' a seat and a back support of the exercise machine; active nature by using an active source of energy (such as an electric motor) to provide resistance to lO overcome the limitations of conventional. passive devices(such as the fact that ECC energy cannot be higher thanCON); mimicking the peculiar variable resistance typical of flywheel exercise devices, without actually using a mechanical flywheel and without the limitations of this range of devices - such as the identical ROM for each repetition;allowing a fast change of inertia by acting on the user interface, even during the execution of an exercise (as opposed to mechanical equipment which require adding,removing or replacing flywheels);offering several training modes in the same machine: e.g. isoinertial, isokinetic, isotonic (i.e. with constant force, as in weight devices), elastic (i.e. simulating the behaviour of rubber bands), or a combination thereof; allowing separate adjustments for the CON and ECC resistance; fully reprogrammable to allow upgrades by adding newfeatures or potential new training paradigms, which. mayarise from current or future scientific research.

The mechanical configuration of the exercise machine,with generally denoted with l, is now discussed in detail, reference to Figure la (which schematically shows a possible embodiment of the exercise nmchine l. in the LE configuration), and to Figure lb (which schematically showsa possible embodiment of the exercise machine l in the LCconfiguration).

The exercise machine l comprises:a seat 2, linked to a frame 3 of the exercise machinel through a hinge 4, pivoting around an axis A; a back support 5 anchored to the seat 2 through amechanical linkage 6, including a first and second linked levers 7a, 7b coupled. together~ at a hinge 8; the first linked lever 7a is moreover coupled to the seat 2 via afurther hinge 8'; a swiveling arm 9, coupled to the seat 2 and designedto be coupled to the legs of a subject; a foot rest lO, carried by the distal end of theswiveling arm 9, with an adjustable distance d from the arm's centre of rotation 9', and. having two load cells (here not shown) integrated in pads lO' of the foot rest lO to measure the subject's left and right force (forces may be assessed separately and an imbalance index may be determined); an electric motor l2 linked to the swiveling arm 9 bya sturdy chain 13, and configured to cause rotation of thesame swiveling arm. 9 about an axis of rotation at thecentre of rotation 9'; and a slotted guide 14 made in the frame 3 and in which lO the hinge 8 between the linked. levers 7a, 7b may slide between two end positions.

In particular, the back support 5 is coupled to the linkage 6 via an articulated parallelogræn l5, which is configured to adjust the position of the same back support 5 in the LE configuration. The articulated parallelogram l5 is moreover coupled to the seat 2 via a further hinge 16.During* conversion between LE and. LC configurations,the hinge 8 slides into the slotted guide l4 form a first to a second end position. The kinematics is designed so that the levers 7a, 7b allow only one degree of freedom to the seat 2 and back support 5, which then move into the correct desired reciprocal position.The conversion is done by unlocking the seat 2 or back support 5, swinging one of them to the desired position and locking them. again with. any suitable mechanical locking means (here not discussed in detail).

Additionally, as an added safety precaution, a mechanical stopper (here not shown) can be added to prevent the rotation of the swiveling arm. 9 beyond the physiological ROM for each configuration.

Figures 2a, 2b depict a subject l8 exercising in the two configurations (LE, Figure 2a, and LC, Figure 2b) with an indication of the CON and ECC phases of each exercise.In LE configuration (Figure 2a), the targeted muscles are the knee extensors (vastus lateralis and medialis and rectus femoris) and the CON phase corresponds to a knee extension.

In LC configuration (Figure 2b), the targeted muscles are the hamstrings and biceps femoris and the CON phase oorresponds to a knee flexion.

A block diagram of an electronic control system, generally denoted with 20, coupled to the exercise machine 1 (here shown only in part) in the training and testing equipment, here denoted with 100, is depicted in Figure 3.

The electronic control system 20 comprises: an angular sensor 22, an encoder, a facoder, a e.g. tacho generator, or any equivalent sensor, coupled to the electric motor 12, in order to measure angular displacement 6 (or speed o) thereof; a load cell 23 embedded. in a left pad. 10' of the footrest 10, to measure the force FR exerted by the right foot of the subject;an identical load cell 24 embedded in a right pad 10' of the footrest 10, to measure the force FL exerted by the left foot of the subject; a distance sensor 25, an array of photocells, a e.g. linear encoder, a linear potentiometer, or any equivalent sensor, to measure the distance d of the adjustable footrest 10 from the centre of rotation 9' of the swiveling lO ll arm 9;an optional first configuration transducer 26, e.g. aphotocell, a proximity sensor, a contact switch, or any equivalent sensor, to sense the LC configuration of the exercise machine l; an optional second configuration transducer 27, configured to sense the LE configuration of the exercisemachine l; an electronic control unit 28, such as a microprocessor, a microcontroller, a PC-based or equivalent intelligent unit, electronically coupled to the angular sensor 22, load cells 23, 24, distance sensor 25 and configuration transducers 26, 27 (if present), and configured to process the input data received therefrom (angular displacement 9 or angular speed w, total force or force split into right and left forces E§, FL, distance d), in order to drive the electric motor l2 with suitable signals Sd according to a desired training mode, thereby controlling rotation of the swiveling arm 9; control unit 28 is therefore configured to execute, by means of anembedded processor (microprocessor, microcontroller, DSP,ASIC or other programmable logic), a suitable software (firmware) stored in a related non-volatile memory 28', in order to implement the control action; and an external man-machine interface 29 (implemented by a lO l2 personal computer~ PC, a mobile electronic device with atouch screen unit or equivalent unit, or any other similardevice), configured to input exercise parameters to the control unit 28, for selecting or defining a desired e.g. training mode, and optionally provide a real-time feedback on the training variables during exercise (force, speed, power, or others).

Depending on the selected training mode, the control unit 28 processes the input data and controls the motorspeed or torque: - in isotonic (constant force) mode, the control unit 28 computes the torgue T from the measured forces FR, FL and distance d: T = (FR + FL) - d, and then drives the electric motor 12 in closed loop untilthe measured torque T equals desired preset values for CONand ECC; - in elastic mode, the machine simulates a spring or rubber band with resistance proportional to angular displacement 6; the control unit 28 implements a closed loop control to drive the electric motor l2 until the following torque is measured: T = k6, where k may be different (different stiffness) for CON andECC; - in isokinetic mode, the control unit 28 drives the electric motor l2 at constant speed, respectively at preset lO l3 CON and ECC values. In a default operating mode, during CON the electric motor l2 and, hence, the swiveling arm 9 is still until the subject exceed a minimum force threshold on the footrests, while during ECC the swiveling arm 9 rotates at the preset speed, pushing against the subject's leg and forcing the same subject into an ECC muscle action.

However, by strapping the subject's leg to the pads lO',the electric motor l2 can actively pull the leg also duringthe CON phase; or, conversely, the electric motor l2 can be “passive” also during ECC, requiring a minimum. pulling force to overcome a (positive or negative) threshold andinitiate the movement. ln short, the isokinetic mode will offer the followingfour options (considering the machine in LE configuration), where “passive” means that the movement is initiated by the subject, pushing or pulling, while “active” means that themovement is continuous regardless of the subject'sbehaviour:CON=passive CON=active CON=passive CON=activeECC=active ECC=active ECC=passive ECC=passiveCON if continuous If continuousrotation T > positive T > positivethreshold thresholdECC continuous continuous if ifrotation T < negative T < negativethreshold threshold lO l4 Consequently, these will be the targeted muscles and the type of action involved: CON=passive CON=active CON=passive CON=activeECC=active ECC=active ECC=passive ECC=passiveCON CON action ECC action CON action ECC actionrotation on knee on knee on knee on kneeextensors flexors extensors flexorsECC ECC action ECC action CON action CON actionrotation on knee on knee on knee on kneeextensors extensors flexors flexors These control features give the user a unique range ofoptions to train and - thanks to the real-time feedback and data export capability of the software - to test various combinations such as: CON/ECC ratio in the same muscle, CON/CON and ECC/ECC ratio between one muscle and its antagonist, etc. This may prove paramount in the evaluation and training of athletes, since many injuries are caused by a functional imbalance between one muscle and itsantagonist, or a poor CON/ECC ratio; - in isoinertial mode, the machine simulates thebehaviour of a flywheel, whose working principle is described by the following expressions: T IQ d dm/dtwhere T is the torque and d is the angular acceleration (time derivative of angular speed m). lO To recreate the same resistance, the electric motor l2 is controlled in speed and accelerated (CON) or decelerated (ECC) proportionally to the T/I ratio, where T is the total measured torque and I is the inertia set in the software interface (via external man-machine interface 29).

In particular, since I is a software parameter, it can be different for CON and ECC, resulting in the unique feature of offering different inertia for the two phases.Since the energy stored in the “virtual” flywheel isproportional to inertia:E=1/2Iw2the possibility of varying the inertia separately for CONand ECC allows the machine returning more energy during ECC than the work done during' CON, thus providing true ECC overload independently from the ROM and executiontechnique, which is one of the main limitations ofmechanical flywheel devices. And of course, this alsoallows for fast change of inertia (even during theexercise) as opposed to mechanical devices where thisrequires time-consuming replacement of the flywheels.Furthermore, unlike conventional devices, the ECCphase is initiated by reversing the motor speed. This canbe done when the desired displacement is reached, as in passive devices, or when the machine senses no more force on the footrests. With this option, the subject is in lO l6 control of when initiating the ECC phase and is not limited to an identical ROM for each repetition. Another unique option allows adjusting the duration of the transition phase from CON to ECC, from abrupt to smoother depending on the type of application and training preferences.

Finally, several other combinations are possible, such as:isoinertial mode with different speed for CON and ECC (as shown in Figure 4A): during speed reversal (INV), the higher or lower motor can reach an initial ECC speed (vmm) (in absolute value) than the speed attained at the end of the CON action So it is possible to make the action (VcoN)- more explosive in one phase than the other. And with the added degree of freedom of possibly different inertia for the two phases, one can decide separately the amount of execution speed. and amount of power and force for each phase; mixed flywheel/isokinetic mode (as shown in Figure 4B): during ECC, the machine turns into isokinetic mode, meaning that the speed is maintained (the “virtual flywheel” is not slowed down) no matter how hard the subject brakes. This allows for virtually unconstrained ECC overload, limited only by the subject's maximal force. Thismixed mode is believed to be a powerful stimulus ineccentric training, while retaining the safety of lO l7 controlled, preset speed of isokinetic mode.

Other additions can include the generation of superimposed torque ripple on the resistance generated, with adjustable frequency and amplitude, to combine vibration training with the aforementioned training modes, as well as randonl torque jitter* to train the subject's reactivity to unexpected perturbations.

The advantages of the discussed solution are clear from the foregoing description.

In any case, it is once again emphasized. that the disclosed 'training and testing equipment 100 provides a multifunction strength training machine specifically targeted. to leg Inuscles, which can be quickly converted between seated Leg Extension and prone Leg Curl configuration and, in particular, the use of an electricmotor l2 driven by an intelligent control unit 28 allows to generate variable resistance with desired control features (e.g. mimicking the behaviour of flywheel and isokineticexercise devices) in a wide range of trainingconfigurations.

Finally, it is clear that modifications and variations may be made to what is described and illustrated herein,without thereby departing fron1 the scope of the presentinvention, as defined in the appended claims.

In particular, it is underlined that other equivalent 18 mechanical solutions may be envisaged to convert the exercise machine 10 between the LE and LC configurations.or different, Further, sensors may be coupled to the control unit 28, in order to implement the desired control action.

The control unit 28 may be able to store in theassociated non-volatile memory 28' all the trainingvariables (speed, force, power, etc), and moreover the same information may be presented to the subject l8 during theexercise via the external man-machine interface 29.

Moreover, a different active source of energy may be used, instead of an electric motor, such as an electromechanical, electro-pneumatic, electro-hydraulic, or any equivalent system.

Claims (10)

1. A training equipment (100) for exercising leg muscles, comprising an exercise machine (1) having a seat (2), a back support (5) coupled to the seat (2), and a swiveling arm (9) designed to be coupled to the legs of a subject (18) and to be displaced by the subject efforts, characterized in that the exercise machine (1) comprises a connection arrangement (6, 15), coupling the seat (2) and the back support (5) and configured to define a first operating position for the coupling of the seat (2) and back support (5), designed for leg extension exercises, and a second operating position for the coupling between the seat (2) and back support (5), designed for leg curl exercises, and. by further* comprising' an active energy source (12) coupled. to the swivelingu arm. (9) and. operable to provide a desired resistance against the subject efforts.

2. The equipment according to claim 1, wherein the connection arrangement (6, 15) includes a næchanical linkage (6), having a first and second linked levers (7a, 7b) coupled at a hinge (8); the exercise machine (1) further including a frame (3) having a slotted. guide (14), and. the hinge (8) sliding within the guide (14) to cause the coupling between the seat (2) and back support (5) to shift from the first to the second stable operating positions. l0

3. The equipment according to claim 2, wherein the connection arrangement (6, 15) further includes an articulated parallelogram (15), which is configured to adjust the position of the back support (5) and is coupled to the seat (2) via a hinge (l6).

4. The equipment according to any of the preceding claims, wherein the active energy source (12) includes an electric motor, coupled to the swiveling arm (9) to control its movement.

5. The equipment according to any of the preceding claims, further comprising an electronic control system (20), configured to drive the active energy source (12) according to a desired exercise program; wherein the electronic control system (20) comprises a control unit (28), and feedback sensors (22-27) coupled to the control unit (28) to provide information on the operation of the exercise machine (l); wherein the control unit (28) is configured. to drive the active energy source (12), based on the information provided by the feedback sensors (22-27) and the desired exercise program.

6. The equipment according to claim 5, wherein the control unit (28) is provided with a memory (28'), configured to store lO 21 the information provided by the feedback sensors (22-27); further including a man-machine interface (29) operable by the control unit (28) to [provide to the subject (l8') real-time information about the performed exercises.

7. The equipment according to any of claims 4-6, whereinthe exercises include an eccentric action, ECC, phase, i.e. amuscle lengthening phase, and a concentric action, CON, phase, i.e. a muscle shortening' phase; and. wherein the electronic control system (20) is configured to control the active energy source (12) so as to provide separate and independent resistance adjustment for the ECC phase and the CON phase.

8. The equipment according to claim 7, wherein theelectronic control systen1 (20) is configured. to control theactive energy source (l2) to implement different exercisemodes, among which: isotonic (constant force), isokinetic(constant speed), elastic (resistance proportional todisplacement), isoinertial (resistance proportional to acceleration), or a combination thereof; wherein the electronic control system (20) is configured to implement equal or different exercise modes in the ECC and. CON phases of the exercise.

9. The equipment according to any of the preceding clams, 22 wherein the control system (20) is configured to superimpose onthe generated. resistance to the subject efforts additional stimuli, such as superimposed vibrations and/or random perturbations.

10. An exercise machine (l) for* the training' equipment (100) according to any of the preceding claims.