Chair, strength training device and use of a chair as a strength training device

Abstract

Chair (6) which is suitable for strength training and which is designed as an office chair, with an adjustable seat surface (2a) and with at least one resistance sensor, characterized in that the resistance sensor is assigned to a seat surface adjustment.

Description

The invention relates to a chair which is particularly suitable for training forces, according to the respective preamble of claims 1 and 7. The chair is used for training muscles, wherein the muscle or muscles apply a force against the action of at least one resistance transducer of the chair for training purposes. The chair comprises in particular an adjustable seat surface. The invention further relates to a force training device according to the preamble of claim 11 and to the use of a chair as a force training device according to claim 15.TECHNOLOGICAL BACKGROUNDBack diseases frequently cause high costs in healthcare. A major part of the back diseases can be attributed to weak or unharmonically developed muscles.A major part of today's civilization-related back discomfort is associated with muscular weaknesses or muscular imbalance. The discomfort occurs particularly frequently in the region of the lumbar spine. Not only are the large superficial trunk muscles responsible for the stability of the spinal column, but deep muscles have the direct influence on the statics of the spinal column within the individual spinal column segments (segmental stability).Deep torso muscles include the abdominal muscle Obliquus Abdominis Internus (internal oblique abdominal muscles) and the transversus Abdominis muscle (transverse abdominal muscles) and the dorsal muscle musculus multifidus (multifed muscle, low portions). The latter muscles are also referred to in technical world as local stabilizers. These deep muscles are of particular importance in the prevention and therapy of lumbar rear-discomfort.It is problematic that these special muscle groups, in particular therapeutically, are difficult to respond, which is why deficits are currently recognizable with regard to prevention and therapy (instabilities). In particular, in classical back and abdominal muscle exercises, large and superficial muscles are preferably activated and trained, as is the case, for example, with the device described in DE 8 422 587 U1. Targeted training of the deep muscles does not take place or hardly takes place in the device described therein.Special devices for training muscles, for example the trunk muscles, are described in DE 20 2011 051 836 U1 or DE 20 2012 101 188 U1. Such devices require special and therefore complicated handling in that seating without touching the ground and fixing of special body parts are required. Such apparatuses are comparatively bulky and can therefore be found exclusively in training facilities. The invention starts here:SUMMARY OF THE INVENTIONThe object of the invention is to enable training of certain muscle groups, such as the deep torso muscles or the scapula stabilizers, in a manner that is as simple as possible.This object is achieved by a chair according to claims 1 and 7, by a force training device according to claim 11 and by the use of a chair according to claim 15.Accordingly, the chair, which is suitable for training forces and can be formed in particular as an office chair, is designed with an adjustable seat surface. The chair comprises at least one, preferably adjustable, resistance transducer, wherein the resistance transducer is associated with a seat surface adjustment.The chair is both a modern, fully functional chair--with regard to functions and appearance--and a training device with the possibility of being able to carry out targeted training of specific muscle groups, such as the deep torso muscles, at any time and without external aids. A minimum amount of adjustment makes it possible to integrate the exercises into the normal working day. Training for several minutes per day already leads to a stabilization of the deep torso muscles after some time. The chair or the force training device in this way combines the ergonomic properties of a functional chair in accordance with the back (passive back care) with the positive properties of a back training device (active back care).The chair or a force training device formed as a chair can be an office swivel chair which can be adjusted in many ways (height adjustment, inclination adjustment, etc.). A visitor chair can also be provided which has fewer adjustment possibilities than a (office) revolving chair.For activating and training the deep muscles, small movement pulses or movement amplitudes are sufficient, which the user of the chair or of the force training device reaches by moving the seat surface by means of the seat surface adjustment against the resistance of the resistance transducer. The body of the user can remain in the sitting position that he takes when sitting on an office chair, i.e. in a standard sitting position in which the feet maintain contact with the ground. Otherwise, it is not necessary to fix certain parts of the body relative to the force training device or the chair.By the resistance transducer being assigned to the seat surface adjustment, it can be provided that there is a mechanical connection or interaction between the seat surface adjustment and the resistance transducer. The resistance transducer can comprise a spring element, such as a steel spring, or a deformable element, such as a rubber resistor, whereby the seat surface can be acted upon with a spring force during its movement by the seat surface adjustment. For example, it can be provided that during the adjustment of the seat surface, the resistance transducer is mechanically switched on, so that the seat surface is movable against the force of the resistance transducer by the user of the force training device.In particular, low-to-medium-intensive muscle contraction (about 30% of the maximum force) ensures optimum training of the deep torso muscles, which can be trained via a movement of the seat surface against the resistance transducer. According to the invention, it is provided that small movements of the seat surface are carried out with a correspondingly low (non-maximum) resistance.Preferably, it can be provided that the resistance transducer is assigned to a seat surface depth adjustment. With the aid of the seat surface depth adjustment, the seat surface can be moved horizontally forwards and backwards, in particular displaced. The seat surface depth adjustment is usually performed manually in the basic setting of the chair. The resistance transducer assigned to the seat surface adjustment can be adjustable, i.e. the resistance of the resistance transducer to a force applied by the user can be variable or adjustable. The resistance generator can comprise a plurality of resistance elements such as springs or rubber elements, for example a resistance element can be provided for the feed and a resistance element for the return. The training of the force is effected by the seat surface being moved-for example back and forth-against the resistance of the resistance transducer.A seat surface depth adjustment can be understood to mean an adjustment of the seat surface forwards (i.e. further away from the backrest) or backwards (i.e. in the direction of the backrest), as a result of which the seat surface is displaceable with respect to the position of the seat back, for example. If a small depth of the seat surface is set, the distance of the front edge of the seat surface from the position of the backrest is smaller than if a large depth of the seat surface is set. Depending on the position of the seat surface relative to the backrest, the depth of the seat surface can be adapted to the requirements and to the body dimensions of the user.The seat surface depth adjustment can be realized by a sliding mechanism. The sliding mechanism is arranged on a bottom part of the force training device standing on the ground, for example in the upper region of the foot part of the (office) chair. For example, a guide element of the seat surface is arranged in a longitudinally displaceable manner in a guide of the sliding mechanism. The guide element and the guide can be lockable by means of a locking mechanism. A resistance element can be assigned to the guide or to the guide element. For example, a resistance transmitter can be arranged between the guide and the guide element of the seat surface in such a way that the displacement of the guide element relative to the guide of the displacement mechanism takes place against a mechanical resistance. The resistance generator can optionally be switched on mechanically in such a way that the resistance occurs only during muscle training and that it does not occur during the depth adjustment of the seat surface.In the case of a movement according to the invention of the seat surface against the resistance generator in the horizontal plane, in particular during the advancement of the seat surface, training or activation of the Obliquus Internus Abdominis muscle and of the Transversus Abdominis muscle can take place. Thus, the abdominal inner oblique muscles and abdominal transverse muscles can be trained. The musculus multifidus is substantially responsible for pushing the seat surface back against the resistance transducer. Thus, by moving the seat surface of the force training device forward or backward against the resistance transducer, the abdominal inner oblique muscles, the abdominal transverse muscles, and the multifloded muscles of the lumbar back muscles are trained. Even a few training stimuli (muscle contractions) per day are sufficient to improve or maintain the functional state of these muscle groups.It can be provided that the resistance transmitter of the force training device according to the invention is assigned to an inclination adjustment of the seat surface. The resistance transducer can also be assigned to a rotational adjustment of the seat surface, wherein the rotational adjustment enables a rotation of the seat surface about an axis of rotation. A force training device can also be provided in which an actuation of the seat surface depth adjustment, the seat surface inclination adjustment and the seat surface rotation adjustment is provided for the force training.The force training or the activation or training of specific (abdominal) muscle groups is carried out according to the invention in that the seat surface is movable against the resistance transducer. Accordingly, movements can be carried out with which specific muscle groups can be addressed.According to the invention, the force training device can be an office chair with the option of a short, targeted and efficient training of said muscle groups. A short, 2 minute training per day provides sufficient stress stimuli to improve the function or maintenance of the muscle groups. The training takes place directly on the force training device. No further auxiliary means (e.g. add-on devices) are required. Since all exercises are carried out from the seat and the specific adjustment options can also be carried out from this position, the training can be integrated into the normal working process without problems.Training of certain muscle groups is also made possible in the simplest possible manner by the fact that in a force training device which is designed as a chair and which comprises at least one resistance transducer, it is provided that the chair has armrests, in particular armrests fastened to the backrest, that the armrests have an adjustment, in particular a longitudinal adjustment, and that the resistance transducer is assigned to the armrest adjustment. In this way, shoulder blade stabilizers can be trained with the aid of the force training device according to the invention.Force training is accordingly effected by moving the armrests against the resistance transducer which is associated with the armrest longitudinal adjustment. The strength of the resistance transducer can be dependent on the respective deflections of the component of the force training device connected to the resistance transducer.A fixing element for fixing the chair to the ground during training can be provided.Training of certain muscle groups is also made possible in a simple manner by a chair or office chair, in which, in addition to a backrest, a seat and a seat surface which can be adjusted relative to the backrest and at least one resistance transmitter, it is provided that the resistance transmitter is assigned to the seat surface adjustment. The chair can preferably be designed such that the at least one resistance transducer is associated with a seat surface depth adjustment, that is to say an adjustment mechanism for adjusting the position of the seat surface relative to the backrest in a direction which runs substantially perpendicular to the plane of the (upright) backrest.Preferably, recesses can be arranged in the backrest and / or in the seat, whereby the backrest is suitable for being surrounded, in particular in the inverted seat position on the chair. A further resistance transducer can be provided, which is associated with the backrest and / or armrest adjustment.Training of certain muscle groups is also achieved in the simplest possible manner by using a chair, in particular office chair, with backrest, seat and seat surface, as a force training device. The use of the chair as a force training device is suitable for training the muscles, wherein a seat surface adjustment and or an armrest adjustment is provided, and wherein at least one resistance transducer is assigned to the seat surface adjustment and / or the armrest adjustment.Training of certain muscle groups can also be easily made possible by re-constructing a chair to a force training device according to the method according to claim 16. In this case, a resistance transmitter is mechanically assigned to the seat surface adjustment and / or the armrest adjustment in such a way that a resistance transmitter is arranged in the region of the seat surface adjustment and / or the armrest adjustment, as a result of which the seat surface and / or the armrest is adjustable against the resistance of the resistance transmitter.The aforementioned components as well as the claimed components to be used according to the invention described in the exemplary embodiments are not subject to any particular exceptional conditions in terms of their size, shape design, material selection and technical design, so that the selection criteria known in the field of application can be used without limitationsFurther details, features and advantages of the subject matter of the invention are evident from the dependent claims, as well as from the following description and the associated drawing, in which-by way of example-an exemplary embodiment of a force training device or a chair is shown. Individual features of the claims or of the embodiments can also be combined with other features of other claims and embodiments.BRIEF DESCRIPTION OF THE FIGURESThe drawing shows FIG. 1a shows a force training device designed as an office chair in a schematic, perspective illustration; FIG. 1 bshows a chair according to FIG. 1 awith a seat surface depth adjustment; FIG. 2 shows a backrest of a chair for training forces in a schematic front view; FIG. 3 shows a backrest of a chair for training forces in a schematic side view; FIGS. 4 a / 4 b show a seat surface of a chair for training forces in a schematic front view; FIG. 4 cshows a seat surface of a chair for training forces in a schematic plan view; FIGS. 5a / 5b show a seat surface of a chair or force training device in schematic plan view FIG. 6 shows a backrest of a chair or force training device in a schematic side view FIG. 7 shows a backrest, having armrests, of a chair or force training device in a schematic perspective illustration; FIG. 8 shows a foot frame of a chair or force training device in a side view; and FIG. 9 shows a cross section of the torso of a user of the chair for force training in a schematic illustrationDETAILED DESCRIPTION OF EMBODIMENTSA force training device which is formed as a chair can be gathered from FIG. 1 a. According to FIG. 1 b, the seat surface 2 aof the force training device 6 or the chair 6 is adjustable horizontally (i.e. in the direction of the arrow back and forth). For adjusting the seat surface 2 a, a seat surface adjustment is provided, which can be arranged on the underside of the seat surface 2 a. The chair or the force training device 6 comprises at least one resistance transducer. The resistance transducer is associated with the seat surface adjustment.As shown in FIG. 1 b, the seat bottom adjustment includes a seat bottom depth adjustment. With the seat surface depth adjustment, the seat surface depth is adjustable. For this purpose, the seat surface 2a is displaced forwards or backwards, as indicated by the arrows in FIG. 1b. A resistance generator is assigned to the seat surface depth adjustment, whereby a displacement of the seat surface 2 ais possible with the seat surface depth adjustment released against a (mechanical) resistance. By the user of the force training device 6 pushing the seat surface 2a against the resistance (back and forth), the user applies forces in which certain groups of muscles are addressed. In particular, deep-lying trunk muscles are activated by the force training during the displacement of the seat surface 2 a, for example the Obliquus abdominis muscle (8), the Transversus abdominis muscle (9) or the Multifidus muscle (10). A part of the muscle groups ( 8, 9, 10) that can be activated with the force training device 6 can be taken from the schematic sectional illustration of the torso 12 of a user of the force training device 6 according to FIG. 9. As an orientation aid, a lumbar vertebra 11 can be removed from the sectional representation of the fuselage section 12 according to FIG. 9.According to FIG. 2, the backrest 7 of the force training device 6 has recesses 1 cin the lower region. The backrest 7 can furthermore have in the central region recesses 1 bfor gripping around the chair 6 with the arms of the user. The upper edge 1a of the backrest may be rounded.According to FIG. 5 a, the seat surface 2 acan also have recesses 2 bat the front and / or rear seat surface edge.Thus, a use of the chair 6 as a force training device is made possible, in which the backrest 7 is suitable for being surrounded, in particular in the inverted sitting position on the chair.According to FIGS. 2 and 3, the backrest 7 can be designed such that functional training of both the back muscles (with the back sitting on the cushion) and the abdominal muscles (with the abdomen sitting on the cushion) becomes possible. The training of the back muscles is started from a slightly pre-inclined position.It can be seen from FIGS. 2 and 3 that a soft, rounded termination of the upper edge 1 ais provided in order to prevent pressure points on the body here. Recesses 1b for the arms may be provided on both sides to allow the arms to be positioned in the function of "abdominal muscle training" (including the back 7). Further, recesses 1 cof the back 7 are provided on both sides in the lower portion to allow leg freedom in the function of "abdominal muscle training".A height adjustment (indicated in FIG. 3 by the arrow 1 d) of the backrest 7 can be provided in order to be able to individually adjust the closure upwards to the height of the shoulder leaves (back muscle training) or of the sternum (abdominal muscle training).A gradually adjustable angle of inclination 1 eof the backrest 7 can also be provided forwards, for example up to approximately 30 degrees with respect to the vertical. Therefore, three different backrest positions can be seen from FIG. 3. Opposite the substantially perpendicular backrest (middle illustration), a backrest position inclined forwards by 30 degrees (left illustration) and a backrest position inclined backwards by 45 degrees (right position) are illustrated.From the seated position, the backrest 7 is tilted slightly forwards (to a somewhat 30 degrees with respect to the perpendicular=first position). After adjustment of the resistance transducer, a stretching movement (=extension) of the back takes place in a defined angular range (up to max. 45 degrees beyond the perpendicular) by activation of the back muscles (final position).The training person sits down in the inverted position on the chair 6. When the backrest is adjusted neutral (starting position), the upper body is inclined (up to max. 30 degrees) forward (final position) by activation of abdominal muscles.The resistance generator enables a gradually adjustable or individually adjustable resistance. The entire system--consisting of a resistance transmitter between the seat and the backrest 7 and a variable material condition of the backrest itself--produces a slightly "curved resistance", i.e. no purely rotational resistance. This leads to better activation of the target muscles with a correspondingly smaller change in hip angle. In the two main functions, therefore, "rolling-up movements" tend to occur, consisting of the combination of hip joint and spinal column movements. In the case of purely rotational resistance sensors, on the other hand, a pure hip joint movement (which is undesirable here) must be assumed.A schematic front view of the seat surface can be seen from FIG. 4 a. According to FIGS. 4 a, 4 b, 4 c, 5 aand 5 b, the seat surface 2 amust be designed, in addition to the basic ergonomic requirements, such that functional training of both the back muscles (with the back sitting on the cushion) and the abdominal muscles (with the abdomen sitting on the cushion) becomes possible. The seat or the seat surface 2 acan be shaped in the form of a saddle. Since training is performed with relatively high resistance, this requires optimum intrinsic stabilization via the lower extremities. By "saddle-shaped" shaping at both ends (the upper legs are positioned in a slight V-shape), the self-stabilization is improved.Leg freedom is ensured by a recess 2 bat the front and rear seat surface edges, in particular during abdominal muscle training.FIG. 4 b shows a seat surface with a seat surface inclination adjustment. The seat surface 2 acan be inclined to the right or to the left, wherein the inclination movement according to FIG. 4 bis indicated by two arrows. However, an inclination towards the front and towards the rear can also be provided. Alternatively, an inclination in any direction may be provided.The seat surface 2 aof a force training device 6, in which the force training is effected by a rotation of the seat surface 2 a, can be seen from FIG. 4 c. For the seat surface rotational adjustment, a rotary plate 13 is provided, which can be arranged below the seat surface 2 a.According to FIG. 5 a, the seat surface 2 aincludes recesses 2 b. The seat surface depth adjustment of the seat surface 2 atakes place according to FIG. 5 bin the horizontal direction, which is indicated by two arrows in FIG. 5 b.It can be seen schematically in FIG. 6 that a (further) resistance transducer 3 ais arranged approximately in the connection between the seat 2 aand the backrest 7 of the chair ( 6). A training of force can be effected by tilting the backrest 7 against the resistance transducer 3 a.The backrest 7 according to the force training device according to FIG. 6 serves as an individually adjustable resistance surface. For the training, a special resistance generator is connected (in the connection between the seat and the backrest 7). The resistor is simple, adjustable from the seated position. Option: In addition, a further individually adjustable resistance transmitter (integrated into the backrest) is used. Both resistance generators result in the totality of a "curved" resistance profile which differs from a purely rotational resistance. Integration of a resistance transmitter ( 3 a) (e.g. gas compression springs) in the connecting element between the seat and backrest 7. The back 7 of the chair may bend itself depending on the force applied to it.FIG. 6 also shows an adjusting device 3 b, for example with a scale on the resistance transducer. From FIG. 6 a resistance transducer 3c can be seen which is worked into the backrest 7. The resistance transducer can be, for example, conically shaped carbon rods. A modular principle can be used as the basis for this.FIG. 7 shows a force training device with armrests. The armrests 4a must allow "inverted seating" (abdominal muscle training). They also serve as a resistance surface for training the scapula fixing muscles. By suspending the armrests 4a on the system of the backrest, leg freedom is achieved. An additional height adjustment 4 bmay be suitable for adaptation to different body dimensions. An integration of a resistance transducer 4c running in the horizontal direction can be provided (e.g. spring or plastic element). By means of a longitudinal adjustment of the armrest support, further special muscle groups can be trained. For this purpose, it can be expedient if at least one resistance transducer is assigned to the armrest (longitudinal) adjustment.At least one further resistance transducer can be arranged in the region of the connection between the armrest and the fastening on the backrest of the chair.Referring to FIG. 8, the force training device includes a foot that results in increased stability to standing. Optionally, fixation to the ground may be required. An increase in the radius of the footprint can be provided by means of a cantilever 5 a. A central fixing element 5b, which can be operated by the foot or is triggered by the load on the backrest, can be provided in the central column of the foot to the ground (e.g. rubber buffer).In contrast to classic training devices, there are intentionally no devices for a specific fixing of the body (e.g. pelvic straps or the like). In contrast, the concept provides self-stabilization of the body via the lower extremities. In particular, the feet of the user resting on the ground contribute to stabilization of the position of the user. This is otherwise achieved in an alternative embodiment of the chair according to the invention or force training device by a stable seat on the seat surface 2 adesigned according to the "saddle principle" in conjunction with the central locking of the foot element ( 5 b). This has the advantage, on the one hand, that the muscles work "in chains" and thus the risk of overloading the locomotor apparatus, in particular the back, is minimized. On the other hand, time-consuming inhibiting sleepers, which are certainly also disruptive overall for many, such as the application of a lap belt or the locking of a fixing roller, are completely eliminated.Seating surfaces with any or hardly any or no contour can optionally be provided, since the (sliding) effect and / or the movement effect of the chair according to the invention or of the force training device according to the invention can be achieved by a plurality of forms of the seat or of the seating surface.Furthermore, the force training device provides complex training of all relevant muscle groups. In classical training devices, these functions are generally distributed over a plurality of-in this case at least 3-devices. The force training device enables and recommends the training of all relevant muscle groups in order to avoid or compensate for muscle imbalance (versus one-sided training, e.g. only of the back muscles).The force training device is designed such that the training can be carried out with the least possible effort. This is primarily taken into account by normal operating conditions, which do not permit a complicated procedure around training. Training can be performed at any time and discretely as compared with conventional training means.This aspect is also underlined not least by the design, which is consistently oriented to the requirements of modern working worlds, i.e. does not put the character of a training device in the foreground at all. In order to achieve these claims, a number of special innovative features are required, which are as unapprecially incorporated into the concept as possible.The focus of the concept is on apparatus, individually adjustable (gradually adjustable) resistance generators 3 a, 3 c, 4 cwhich enable training stimuli required for targeted trunk muscle training or scapula stabilizer training. A training effect is obtained in that the backrest 7 or the arm braces 4 aare moved against the resistance by active use of the torso muscles or the scapula locators in a defined adjustment range.The special design / shaping of the force training device 6, in particular the design of the seat and backrest geometry, ensures that these movements can be carried out from an individually fitting, stable and back-appropriate positioning.The design of the armrest system (FIG. 7 ) provides the possibility of training the upper back, especially the scapula stabilizing muscles. By a displacement or pulling movement of the arms on the arm supports in the horizontal direction, a targeted training of the scapula locators takes place. These muscle parts are considered on the one hand to be particularly susceptible to "weakenings" and on the other hand have great significance for an upright, healthy posture. A special resistance transmitter 4c integrated into the system between armrest and backrest provides adequate stress stimuli.LIST OF REFERENCE CHARACTERS1 abehring upper edge 1 brecess 1 crecess 1 drelevation of the backrest 1 ereclination angle 2 af seating surface 2 brecess 3 aresistance generator 3 badjustment device 3 cresistor generator 4 ae armrest 4 brelevation 4 cresistor generator 5 acantile 5 bfixed element 6 chair / force training device 7 backrest 8 musculus obliquus abdominis 9 musculus transversus abdominis 10 musculus multifidus 11 lumbar vertebra 12 user's torso portion 13 rotary plate

Claims

Chair (6) which is suitable for training forces and which is formed as an office chair, having an adjustable seat surface (2a) and having at least one resistance transducer, characterized in that the resistance transducer is associated with a seat surface adjustment.Chair (6) according to claim 1, wherein the depth of the seat surface (2a) is adjustable, characterized in that the resistance transducer is associated with the seat surface depth adjustment.A chair (6) according to claim 1 or 2, characterized bya controllable resistance transducer.A chair (6) according to any one of claims 1 to 3, wherein the inclination of the seat surface (2a) is adjustable, characterised in that the resistance transducer is associated with the seat surface inclination adjustment.Chair (6) according to one of claims 1 to 4, wherein the seat surface (2a) is adjustable rotatably about an axis of rotation, characterized in that the resistance transducer is associated with a seat surface rotation adjustment.Chair (6) according to one of claims 1 to 5, characterised in that a training of force can be carried out by moving the seat surface (2a) against the resistance transducer.The chair (6) according to any one of claims 1 to 6, having a seat and a backrest (7) and having at least one resistance transmitter, characterized in that the chair has armrests (4a), in particular armrests (4a) fastened to the backrest (7) or to the seat, in that the armrests (4a) have an armrest adjustment, in particular an armrest longitudinal adjustment, and in that the resistance transmitter is associated with the armrest adjustment.Chair (6) according to claim 7, characterized in that a training of force can be carried out by moving the armrests (4a) against the resistance transducer.Chair (6) according to one of claims 1 to 8, characterised in that the strength of the resistance transducer is dependent on the respective deflections of the component of the force training device (6) connected to the resistance transducer.The chair (6) according to any one of claims 1 to 9, characterized in that a fixing element (5b) is provided for fixing the chair to the ground during training.A force training device which is formed as an office chair, having a backrest (7), a seat, a seat surface (2a) which can be adjusted relative to the backrest (7), at least one resistance transmitter, and in particular having an armrest (4a), characterized in that the resistance transmitter is assigned to a seat surface adjustment.A force training device according to claim 11, wherein the depth of the seat surface (2a) is adjustable, characterised in that the resistance transducer is associated with the seat surface depth adjustment.The force training device according to claim 11 or 12, characterized by recesses (1b, 1c) arranged in the backrest (7) and / or in the seat, whereby the backrest (7) is suitable for being enclosed, in particular in the inverted seat position on the chair (6).The force training device according to any one of claims 11 to 13, characterized byat least one further resistance transmitter which is associated with a backrest and / or an armrest adjustment.Use of an office chair with a backrest (7), seat and seat surface (2a) as a force training device, in particular for training the muscles, wherein a seat surface adjustment and / or an armrest adjustment is provided, and wherein at least one resistance transducer is assigned to the seat surface adjustment and / or the armrest adjustment.Method for converting or retrofitting an office chair to the force training device, in particular for training muscles, wherein the chair has a seat surface adjustment and / or an armrest adjustment, characterized in that a resistance transmitter is arranged in the region of the seat surface adjustment and / or the armrest adjustment, whereby the seat surface (2a) and / or the armrest (4a) is adjustable against the resistance of the resistance transmitter.

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