Method and device for muscular strengthening of a user Technical field

The present invention relates to a method and a device for muscular strengthening of a user.

Prior art

As is known, muscle contraction is the result of a series of coordinated intracellular modifications which leads to the movement of the muscle fibre and, consequently, of the muscle itself. In order to improve sports performance, an increase in the contractile strength of the muscles involved in the performance of the characteristic gesture is essential. Training is the basis for increasing the contractile strength of muscles and, in particular, resistance training is the most common tool for maximising muscle recruitment.

In this context, there are numerous systems for resistance training, which define different types of muscle contraction.

Isotonic training involves the use of a constant resistance, usually represented by counterweights. During isotonic exercise, two muscle contraction conditions occur: concentric (or positive), when the muscles shorten, and eccentric (or negative), when the muscle resists the workload during elongation. Essentially, two types of equipment can be identified for isotonic exercises: fixed resistance, in which muscle tension varies according to the progress of the articulating lever arm, and variable resistance at specific angles in the range of movement. Such equipment comprises a system of eccentric pulleys which aim to maintain the isotonic condition throughout the entire movement. This type of training has numerous disadvantages: as the resistance is constant, it is excessive at the beginning and end of the movement when the muscle has a lower performance; it is not accommodating for pain, fatigue or the musculoskeletal lever system; it does not allow to exercise at rapid functional speeds; fatigue causes a decrease or impairment in the range of movement; the risk of work overloads can cause muscle injury; it does not allow strengthening during the execution of functional gestures.

It is possible to train against a constant resistance even in isometric conditions, i.e., when the muscle developing tension leads to a shortening of the fibres, but no movement of the lever arm occurs. While the usefulness is undisputed in the clinical field, in professional training procedures it has numerous disadvantages related mainly to the inconsistency with the main features of sports gestures, where the shortening speed of muscle fibres is an essential condition for the coordination and control of the accelerations necessary to produce the characteristic gestures.

In general, constant resistance training strengthening is not recommended, especially in sports areas where the gesture execution speed is closely related to motor coordination (tennis, sprints, boxing, golf, etc.). In fact, having stronger muscles does not mean being able to use the greater contractile properties acquired during the sports gesture. Another contractile muscle strength training system is the isokinetic one. Isokinetic exercise can be described as a movement which takes place at a constant angular velocity, against an accommodating resistance. To perform this training, specific robotic dynamometers are required which can control the execution speed, proportionally adapting the resistance to the strength of the subject throughout the entire movement. After an acceleration step, once a given angular speed has been reached, the device does not allow this speed to be exceeded since the muscle force that would increase the speed of the lever is absorbed and returned as resistance. It follows that the resistance which the patient must face is accommodating, therefore constantly proportional to the strength expressed by the patient himself.

Also in this case, the consistency of the gesture execution speed during training is in contrast with the natural principles of segmental acceleration that characterise all sports performance. Demodromic or isoinertial training uses a system to generate effective training resistance regardless of gravity, as is commonly the case in the use of overloads. The inertia of a flywheel activated by virtue of muscle strength is exploited. In particular, in the concentric step of the movement, a belt housed around the flywheel is unwound and the flywheel acquires speed and enters into rotation. At the end of the concentric step, the inertia of the flywheel pushes it to continue its rotation by winding the belt in the opposite direction, then exerting a force which the musculature will have to actively oppose during the eccentric step. The inertia of the positive dynamic step (concentric) and the negative dynamic step (eccentric) remain the same, so the musculature is stressed with equal resistance in the two steps. Unlike isotonic training, in which the resistance is constant and predetermined by the amount of load chosen, in isoinertial training the resistance remains constant, but adapts to the strength expressed muscularly in the positive dynamic step. However, the devices which produce isoinertial resistance constrain the athlete to gestures with functionalities limited to squatting and jumping exercises, but never allow the execution of functional enhancement exercises such as running, sprinting or circumvention.

Plyometric training is one of the most effective methods to improve explosive power. The purpose of plyometry is to improve the ability of athletes to use force as quickly as possible. However, there are some risks in the practice of this type of training, due to the stress and pressure to which the joints and connective tissue are subjected. For example, the landing surface must necessarily have shock-absorbing properties.

In general, it is important to underline that the increase in contractile properties does not coincide with an adjustment in motor control, i.e., despite having more powerful and faster motors available, the central processing system is not able to use this greater power. The problem is solved by the functional strengthening, muscle strengthening exercises conducted within the sports gesture. Functional training refers to a set of integrated multi-planar movements involving acceleration, deceleration and stabilisation of the joints with the aim of improving motor ability, the strength of the trunk stabilising muscles and neuromuscular effectiveness. Functional training is training aimed at improving movement and not strengthening individual muscles.

Among the various possibilities of carrying out functional workouts, the one that has had the greatest response and diffusion is auxotonic training, conducted with elastics. Elastic resistance has the advantage of being progressive and guiding the athlete to proportional, protected and well- controlled recruitment. Such a solution is also widespread in the field of rehabilitation, as it is extremely protective for skeletal muscles.

Flowever, the use of elastic resistance poses some problems. Due to its progressive features, it reaches high values precisely when the skeletal muscle decreases its efficiency. In addition, its size cannot be controlled during training and this exposes the athlete to risks of overtiredness and injuries. In particular, the commitment to movement control is also high in the return step to the starting position, as the tension accumulated with the lowering in tension on the equipment must be gradually released and the consequent elastic return must be mastered. The tension to be adjusted also in the return step of the exercise and the need to compensate destabilising forces constrains the athlete to maintain correct posture at all times.

Object of the invention

In this context, the technical task underpinning the present invention is to provide a method and a device for muscular strengthening of a user, which obviate the drawbacks of the prior art cited above.

In particular, the object of the present invention is to propose a method for muscle strengthening of a user which allows high efficiency throughout the exercise, while limiting the risk of injury to the user. A further object of the present invention is to provide a stable, easily transportable and user-friendly device for muscular strengthening for a user.

A further object of the present invention is to propose a method for muscular strengthening of a user usable in both training and rehabilitation. The technical task set and the objects specified are substantially attained by a method and a device for muscular strengthening of a user, comprising the technical features as set out in one or more of the accompanying claims.

Brief description of the drawings

Further features and advantages of the present invention will become more apparent from the approximate and thus non-limiting description of a preferred, but not exclusive, embodiment of a method and a device for muscular strengthening of a user, as illustrated in the accompanying drawing in which figure 1 illustrates a device for muscular strengthening, object of the present invention, in perspective view.

Detailed description of preferred embodiments of the invention With reference to the figures, number 1 denotes a device for muscular strengthening of a user.

The device 1 comprises a cable 2 intended to be connected to a user who needs to carry out the muscular strengthening. For example, the cable 2 is of the static type with low inertial component. An elastic cord is arranged at one end thereof which is connected to the user.

Such a cable 2 is wound around a reel 3 so that it can be wound/unwound with respect thereto and extends at least in part between the reel 3 and the user who is carrying out the muscle strengthening.

The device 1 comprises

- an unwinding/winding means 4 for unwinding/winding the cable 2 relative to the reel 3;

- an acquisition means 14 for acquiring a parameter identifying a tension of the cable 2; - a comparison means 15 for comparing the parameter with at least one pre-set range of values so as to control the unwinding/winding means 4 for unwinding/winding the cable 2 in such a way as to bring the parameter back inside the range, in the event that the parameter is outside the range.

Preferably, the acquisition means 14 and the comparison means 15 are arranged inside a control unit 14, 15 communicating with the unwinding/winding means 4.

Preferably, the device 1 comprises a user interface device, for example a touch screen, through which the user sets the range and acts on the operation of the device 1. The touch screen may be integrated into the device 1 or into a mobile device, such as a tablet, communicating with the device 1.

Preferably, the unwinding/winding means 4 varies the unwinding/winding speed of the cable 2 relative to the reel 3 as a function of at least one input coming from the comparison means.

In particular, if the acquired parameter is below a minimum value of the range, the unwinding/winding speed is decreased; if the acquired parameter is above a maximum value of the range, the unwinding/winding speed is increased.

Preferably, the comparison means 15 is configured to adapt, during the operation of the device 1 , to a variation of the initially set range. Thereby, it is possible to vary the range of values during the exercise and/or set a resistance curve defined by a plurality of successive ranges of values over time.

Preferably, the unwinding/winding means 4 for unwinding/winding the cable 2 comprises a motorised means 5 for setting the reel 3 in rotation. Preferably, the motorised means 5 comprises a DC motor 6. Preferably, the motor 6 is of the brushless type.

The motorised means 5 also comprises a shaft on which the reel 3 is rotatably mounted. A reducer 9 and a joint 10 are interposed between the motor 6 and the shaft.

During the cable 2 unwinding step, i.e., when the user trains moving away from the device 1 , the parameter identifying the tension of the cable 2 is an electric parameter of the motor 6, for example torque, voltage or current.

Preferably, the motor 6 is associated with a system of capacitors for dissipating the electrical energy generated thereby during the operation of the device 1.

In accordance with an embodiment, the acquisition means 14 for acquiring the parameter may comprise at least one sensor which determines the tension of the cable 2. In particular, a plurality of sensors is arranged on the cable 2. Thereby, the device 1 also functions efficiently when the user trains by moving towards the device 1 , i.e., when he is pulled by the cable 2 towards it. This training step is of fundamental importance for top-level athletes. In fact, from a muscular point of view they are close to perfection and to overcome their limit they need stimuli at a cognitive and sensory level. In other words, they must convince themselves that their body can actually go beyond the limit. The training towards the device 1 allows precisely this.

In this context, sensitising the cable 2 is of paramount importance to safeguard the user. In fact, to allow the user to exercise moving towards the device 1 , the cable 2 must be wound quickly. In order to offer this high winding speed, the brushless motor 6 absorbs a lot of energy and consequently delivers a high torque. Therefore, the user risks serious injuries if unexpected events were to occur during the exercise.

Sensitising the cable 2 allows to obtain direct data on the tension of the cable 2. Depending on the desired winding speed, the tension of the cable 2 is kept constant or in a range of values.

Preferably, the unwinding/winding means 4 comprises a distribution system 7 for distributing the cable 2 on the reel 3 during the winding step. Such a system is connected to the motorised means 6 by means of a mechanism 8. In particular, it is connected to the shaft of the reel 3.

The distribution system 7 is interposed between the reel 3 and the user. It comprises a distribution device 11 movable along a direction substantially parallel to the length of the reel 3. The length of the reel 3 herein means a direction along which the cable 2 is wound. Usually, such a direction is substantially parallel to a rotation axis of the reel 3.

In particular, the distribution device 11 is movable by means of a coupling with an endless screw 12 rotated by the mechanism 8. Preferably, the distribution device 11 is also connected to a bar 13 having a guiding function.

The operation of the device for muscular strengthening and a method for muscular strengthening of a user, object of the present invention, is described below. Such a method is advantageously implemented by a device 1 having one or more of the features described previously.

Consider a condition where the user is connected to cable 2 and a range of values has been set.

The user is carrying out a training. Thus, the cable 2 is unwound/wound relative to a reel 3 at a given unwinding/winding speed. In particular,

During the unwinding/winding step, a parameter identifying a tension of the cable 2 is acquired and such a parameter is compared with the pre-set range.

If the parameter falls inside the range, the cable 2 continues to be unwound/wound at the same unwinding/winding speed.

If the parameter is outside the range, the unwinding/winding speed is varied so as to bring the parameter back inside the range.

The acquisition of the parameter, the comparison with the range of values and any variation in the unwinding/winding speed occur continuously during the unwinding/winding step of the cable 2.

In particular, the step of varying the winding/unwinding speed 2 takes place:

- if the parameter is below a minimum value of the range, by increasing said unwinding/winding speed;

- if the parameter is above a maximum value of the range, by decreasing the unwinding/winding speed.

Preferably, the range of values can be varied during the step of unwinding/winding a cable 2. Thereby, it is possible to correct within the training, without interrupting it, the resistance offered by the cable 2. In addition, it is possible to set up an "ad hoc” training for a sport (and in particular, for the athletic gesture which characterises that sports activity) by defining a resistance curve.

If the user trains moving away from the device 1 (in particular from the reel 3), the cable 2 is unwound from the reel 3. The parameter identifying the tension of the cable is acquired, for example by means of the electric parameters of the motor 6, and the unwinding speed is varied as described above, if the parameter is outside the range. In this situation, the tension offered by the cable 2 is directed in the direction at least partially opposite that of the user's motion.

If the user trains moving towards the device 1 (in particular towards the reel 3), the cable 2 is wound on the reel 3. In order to allow the user to train safely, the parameter is acquired using the sensors arranged on the cable 2. If necessary, the winding speed is adjusted accordingly as described above. In this situation, the user is pulled towards the reel 3 by the cable 2. In other words, the motion of the user substantially agrees with the direction of the tension offered by the cable 2 The features of the device and method for muscular strengthening of a user, according to the present invention, are clear from the description, as are the advantages.

In particular, the fact that the cable is governed by a DC motor controlled by a control unit allows to provide the user with a dynamic workload, with controlled variation. Thereby, the muscle works with high efficiency throughout the exercise, unlike what happens in the known solutions. In particular, the maintenance of the tension inside the range which is carried out by the motor takes place regardless of the movement speed and accelerations of the user. As a result, low loads are sufficient to maximise muscle recruitment and control, so the risk of injuries due to excessive and potentially risky workloads is overcome. Therefore, the device and method are easily usable both during training and during rehabilitation.

Furthermore, the provision of sensors on the cable allows the user to train even while moving towards the device, a feature which is lacking in the known solutions and allows to train muscle coordination, in addition to stimulating the user from a motivational point of view.