SYNERGISTIC MUSCLE ACTIVATION DEVICE

Abstract

Systems and methods of use for guiding the flow of energy through a subject to stimulate tissue.

Claims

1. A system for delivering more than one energy waveform to a patient, comprising: a first pair of electrodes and a second pair of electrodes adapted to be positioned on the patient and adapted to deliver energy to the patient; and a stimulation control unit in communication with the first and second pairs of electrodes and configured to: combine a first energy waveform having a first frequency and a second energy waveform having a second frequency into a multiplexed signal; and deliver the multiplexed signal to the first pair of electrodes and the second pair of electrodes.

2. The system of claim 1, further comprising an impedance modification element configured to be positioned apart from at least one of the first pair of electrodes and the second pair of electrodes.

3. The system of claim 2, wherein the impedance modification element comprises a cooling element adapted to decrease the temperature of tissue within the patient to thereby increase impedance of tissue within the patient.

4. The system of claim 1, wherein the first energy waveform is a pain-relieving energy waveform and the second energy waveform is a muscle-activating energy waveform.

5. The system of claim 4, wherein the first energy waveform comprises a first set of pulses and the second energy waveform comprises a second set of pulses, wherein the first set of pulses have a lower amplitude and a higher frequency than the second set of pulses.

6. The system of claim 1, wherein the first energy waveform and the second energy waveform are generated by the stimulation control unit.

7. The system of claim 1, wherein the first frequency is different than the second frequency.

8. The system of claim 1, further comprising a housing, wherein the housing comprises the first pair of electrodes, the second pair of electrodes, and the stimulation control unit.

9. The system of claim 1, further comprising a stimulation pad, wherein the stimulation pad comprises the first pair of electrodes and the second pair of electrodes.

10. The system of claim 1, wherein the multiplexed signal is delivered to the first and second pairs of electrodes simultaneously.

11. A system for delivering more than one energy waveform to a patient, comprising: a first set of electrodes and a second set of electrodes adapted to be positioned on the patient and adapted to deliver energy to the patient; and a stimulation control unit in communication with the first and second sets of electrodes and configured to: generate a first energy waveform having a first frequency and a second energy waveform having a second frequency; and deliver the first energy waveform and the second energy waveform to the first and second sets of electrodes.

12. The system of claim 11, further comprising an impedance modification element adapted to increase impedance of tissue within the patient, wherein the impedance modification element is further adapted to increase neuromuscular electrical stimulation by reducing lateral energy spread between the first and second sets of electrodes.

13. The system of claim 12, wherein the impedance modification element comprises a cooling element and is configured to be positioned apart from the first and second sets of electrodes.

14. The system of claim 11, wherein the first energy waveform is a pain-relieving energy waveform and the second energy waveform is a muscle-activating energy waveform.

15. The system of claim 14, wherein the first energy waveform comprises a first set of pulses and the second energy waveform comprises a second set of pulses, wherein the first set of pulses have a lower amplitude and a higher frequency than the second set of pulses.

16. The system of claim 11, further comprising a stimulation pad, wherein the stimulation pad comprises the first and second sets of electrodes.

17. The system of claim 11, wherein the first frequency is different than the second frequency.

18. The system of claim 11, wherein the first energy waveform is delivered from the stimulation control unit to the first set of electrodes and the second energy waveform is delivered from the stimulation control unit to the second set of electrodes.

19. The system of claim 18, wherein the first energy waveform and the second energy waveform are delivered to the first and second sets of electrodes simultaneously.

20. A system for delivering more than one type of energy waveform to a patient, comprising: a stimulation control unit configured to generate a first energy waveform having a first frequency and a second energy waveform having a second frequency; and a first pair of electrodes and a second pair of electrodes in communication with the stimulation control unit, the first and second pairs of electrodes adapted to be positioned on the patient and adapted to deliver energy to the patient, wherein the first and second pairs of electrodes are configured to: receive the first energy waveform and the second energy waveform from the stimulation control unit; and combine the first energy waveform and the second energy waveform into a multiplexed signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 illustrates existing techniques, wherein energy from two pairs or groups of surface electrodes can be combined at depth.

[0026] FIG. 2(a) illustrates existing techniques wherein lateral energy spreading limits the efficiency of energy transfer.

[0027] FIG. 2(b) illustrates an exemplary embodiment in which exemplary impedance modification elements reduce the outward direction lateral spreading of energy.

[0028] FIGS. 3(a)-3(g) illustrate several example layouts of electrode arrays implemented on a stimulation pad.

[0029] FIGS. 4(a)(i)-4(c)(iv) provide an overview of the rapid-switching embodiment functionality, as well as several example implementations thereof.

[0030] FIGS. 5(a)-(e) provide exemplary embodiments that utilize temperature gradients.

[0031] FIGS. 6(a)-(d) provide an overview of situations where fixed phase delays between stimulation channels are non-ideal, and an explanation of why precise timing control is important. Also shown is an example embodiment of a device, system, and method of use.

[0032] FIGS. 7(a)-(c) illustrate several embodiments where at least two stimulation waveforms are utilized during treatment.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0033] The disclosure herein provides systems and methods for neuromuscular electrical stimulation of muscle and/or nervous tissue using mechanisms to improve user comfort. Various aspects of the disclosure described herein may be applied to any of the particular applications set forth below or for any other types of electrical stimulation and sensing systems or methods. The invention may be applied as a standalone system or method, or as part of an integrated medical treatment system. It shall be understood that different aspects of the disclosure can be appreciated individually, collectively, or in combination with each other.

[0034] In some embodiments, the system includes at least components: surface electrodes that are used to couple electrical energy into and out of the body, a mechanism, device, or method to improve comfort during energy application, and a stimulation control unit that creates the stimulation energy pulses and delivers them to the surface electrodes. In some embodiments, the stimulation electrodes are assembled into a custom stimulation pad such that electrode layout and configuration will be pre-optimized for a particular region of the body. The control unit communicates with the stimulation pad through a wired connection, radiofrequency transmission, optical, acoustic, or electromagnetic signals, or another suitable mechanism. The control unit is a separate unit that may be located some distance from the person receiving therapy. In an alternate embodiment, the control unit may be integrated into a housing unit comprising the stimulating electrodes and/or surface cooling components.

[0035] In some embodiments, the control unit includes components such as a signal generator, memory, processor, and power supply. The primary operation of the control unit may be provided by a microprocessor, field programmable gate array (FPGA), application specific integrated circuit, some combination of these mechanisms, or another suitable mechanism. When activated, the control unit generates electrical stimulation signals that are transmitted to the surface electrodes in the stimulation pad, which couple the energy into the body to activate muscles. Some electrical stimulation parameters, including the duration of therapy, may be adjustable by the operator through buttons, knobs, dials, or switches on the control unit. Other electrical stimulation parameters, such as stimulation pulse energy amplitude and phase delay between pulses applied to different pairs or groups of electrodes, may be adjusted by the user through control unit controls or may be automatically optimized using automatic algorithms implemented by the control unit. In some embodiments, the control unit also fundamentally controls at least some aspect of the mechanism implemented to improve user comfort.

[0036] In some embodiments, the control unit is capable of transmitting stimulation pulses on at least 2 and preferably many more (ex. 8-10) channels simultaneously and independently. In many cases, applying current to two or more pairs or groups of electrodes independently is advantageous to simply splitting the current from a single channel across two or more parallel electrode configurations. In the situation where current from a single channel is split (i.e. two or more electrode pairs receiving the signal are not receiving independent energy signals) between two or more electrode pairs, equal distribution of the original energy is not guaranteed. For example, without wishing to be bound by any theory, it is believed that if about 40 mA of supply current is split between two electrode pairs, perfect balancing of electric impedance between each electrode pair is required if about 20 mA will travel along each route. This situation of balanced impedance pathways is unlikely to occur in vivo. In addition to the ability to transmit stimulation pulses on independent channels simultaneously, some embodiments of the control unit are also capable of creating arbitrary phase delays between pulses originating from different channels.

[0037] In some embodiments, the stimulation pad is comprised of a thin and flexible housing with an adhesive hydrogel backing to facilitate maintenance of skin contact with the person receiving NMES. The hydrogel backing will also enhance the coupling of electrical energy and signals between stimulation electrodes and the person's body. Hydrogel backing may allow for skin adhesion in the regions including electrodes or in larger regions. The stimulation pad will be configured to include or interface with mechanisms, devices, and/or methods to improve comfort during energy delivery. The stimulation pad includes two or more strategically-placed surface electrodes that are used to deliver electrical energy to muscles and/or nerves in order to produce muscle contraction.

[0038] In some embodiments, the stimulation electrodes are arranged in an array with a predetermined layout (see, for example, FIG. 3). In some embodiments, the stimulation electrodes are arranged in a configurable array. The array may be configurable such that, at any given time, only a subset of the electrodes in the array may be actively delivering energy to a person receiving NMES. However, electrodes inactive for energy delivery may still be configured to deliver relevant information (such as the electrical impedance between it and a second electrode in the array) to the control unit. In a variation embodiment, the stimulation pad may include only 2 stimulation electrodes, with both electrodes being active during NMES energy delivery. In another variation embodiment, the surface electrodes may not be contained in a larger stimulation pad. Instead, discrete electrodes of any size or shape could be utilized by an NMES operator and placed in the position deemed by the operator to be most suitable.

[0039] In some embodiments, two or more groups of electrodes are arranged in specific patterns on a stimulation pad (see, for example, FIG. 4). The stimulation pad, control unit, or both include electronic components that allow for rapid switching of the polarity of specific electrodes in the group. To be successful, the electric field created by voltage differences between electrodes must be altered on a time-scale that is faster or similarly fast as current travels through tissue between electrodes. Given that modern electronics allow for nanosecond switching of electrical components and signals, it is believed that this is readily achievable. Initially, electronics in the control unit apply a voltage potential between two electrodes in a given group of three or more electrodes. This voltage potential creates a flow of current that travels broadly between the two electrodes. After a very short time following injection of current into tissue (due to the voltage potential between electrodes), the relative polarity of electrodes in the group is shifted by electronic switching components (controlled by software, firmware, or hardware based timing means), causing the direction of current flow to be altered.

[0040] By way of a simplified example, referring to FIGS. 4(a)-(c), initially electrode 1 may be relatively positively charged, while electrode 2 may be relatively negatively charged, while electrode 3 may be neutral. This creates a current flow between electrodes 1 and 2. After a very short period of time (determined by the separation distance between electrodes), electrode 1 becomes neutral, while electrode 2 is given a relatively positive charge and electrode 3 is given a relatively negative charge. This step creates current flow between electrodes 2 and 3. In total, when timing is precisely correct, in essence current travels between electrodes 1 and 3 with a bend in direction towards electrode 2. Minor alterations to the method (for example, adding slight charge to the neutral electrode) allows for further tuning of total current injection and direction. Specific configurations of electrode groups used ensure penetration of applied current to deep muscle tissues. Through increased control of current directionality, lateral spreading of applied energy can be minimized or contained in a constructive way, increasing the efficiency of the NMES device and thus reducing the amount of current density needed in superficial regions to induce muscle contraction in deeper regions. This method will improve comfort during NMES energy delivery.

[0041] In some embodiments, two or more pairs or groups of electrodes are utilized during NMES in conjunction with a mechanism allowing for the transfer of thermal energy. The mechanism may be an active source of thermal energy (for example, a heating or cooling device), or a passive conduit for energy (for example, a heat sink mechanism). The embodiment may achieve improved user comfort by warming, cooling, or selectively warming and cooling tissue region(s) in proximity to the location of NMES delivery. In one implementation of this embodiment, cold temperatures are applied to body regions in the lateral edges of the electrode configuration (see, for example, FIG. 5). In some implementations, cold may also be applied to the region of body tissue in between electrode regions. Application of cold temperatures will increase tissue electrical impedance, proportionally reducing energy distribution in these regions. Effectively, cold application forces a greater proportion of energy delivered by surface electrodes to more central regions, where tissues are warmer, thereby reducing the lateral spreading of current. More of the initial energy from each pair or group of electrodes used to transmit energy into the body enters into the overlapping region between electrode pairs or groups, and thus the total sum of energy reaching target muscle tissues is improved. This improvement allows for lower energy levels to be used initially, reducing current density in superficial tissues and increasing comfort during NMES.

[0042] In a variation embodiment, a stimulation pad is configured to house or interface with electronics capable of generating a static or dynamic magnetic field. It is known that the direction of a charged particle traveling through a magnetic field will be influenced by the presence of the field. Without wishing to be bound by any theory, it is believed that the presence of a precisely located, sufficiently strong, and properly timed magnetic field may further assist in preventing or reducing the lateral spread of current traveling between surface electrodes. As noted above, any reduction in lateral spreading of energy will improve the efficiency of coordination between energy applied by different pairs or groups of electrodes, thus lowering the total amount of energy required to achieve a desired degree of muscle contraction.

[0043] In some embodiments, two or more pairs or groups of electrodes are utilized in conjunction with a sensor system (see, for example, FIGS. 6(a)-(d)). The sensor system (for example EMG, strain gauge, accelerometer, temperature sensor, sensor measuring another parameter descriptive of muscle contraction, etc.) attaches to the body of the user in the vicinity of the target muscle group and is positioned in a manner so as to be capable of producing an output that is indicative of the degree of muscle contraction induced through the application of energy during NMES. The sensor system remains in communication with the control unit through a wired connection or other suitable means. During operation, stimulation signals are delivered near-simultaneously to two or more pairs or groups of electrodes, with energy from each electrode set cooperating in an additive way at depth to activate a target muscle. The term near-simultaneously is used to indicate a slight (ex. 0.3-10 ms) phase delay between signals originating from different electrode pairs or groups. During energy application, the sensor(s) measure parameters that are indicative of the degree of contraction produced in the target muscle tissue. Feedback from the sensor(s) is used to adjust and optimize the phase delay between signals applied by different electrode sets in order to improve energy cooperation at depth. In an example embodiment, the control unit initiates NMES by cycling through a default series of stimulation/sensing events using a predetermined series of phase delay shifts between channels. The phase delay profile that produces the strongest muscle contraction is chosen for use during NMES. In a variation of this embodiment, a processor in the control unit calculates an ideal delay profile given sensor data (for example by interpolating data between the two phase delay profiles that performed the best), thus allowing for a final phase delay profile that was not initially programmed into the control unit. As mentioned previously, the ideal phase delay will optimize energy coordination at depth, lowering the total energy that is required to produce a given degree of muscle contraction. These lower current density requirements will improve both the comfort and safety of NMES.

[0044] In some embodiments, multiple energy waveforms are used in conjunction with one another to reduce discomfort during stimulation. In one example embodiment, one or more independent channels are in electrical communication with each electrode pair or group utilized. Accordingly, at least two types of electrical energy are applied by the control unit: a first stimulation waveform capable of achieving local pain relief (for example, waveforms commonly associated with TENS) and at least one additional waveform, such as those typically used to induce muscle contraction during NMES. Generally speaking, waveforms during TENS tend to have higher pulse repetition frequencies and lower amplitude than those used during NMES. This combination approach to energy delivery will allow for simultaneous pain relief and induced muscle contraction, thus improving comfort during NMES therapy.

[0045] In some embodiments, each electrode set or pair is capable of applying both types of electrical waveforms to the body. This is a significant advance over devices and methods disclosed in the prior art because in many desired stimulation locations (ex. triceps or quadriceps), there exists limited space to place electrodes. Thus, if separate electrodes are necessitated to deliver pain-relief waveforms, less space is available for electrodes that deliver muscle-activating waveforms. Low current density energy from different sets of electrodes can combine synergistically at depth to produce a high current density in target regions, and thus using a greater number of electrode sets to deliver muscle-activating waveforms decreases the energy density required to be delivered by each (and thus increases comfort). Therefore it is desirable to not occupy any available electrode space in the intended region of stimulation by separate electrodes that apply only pain-relief waveforms. It is notable that reducing electrode size so that more electrodes may fit in one region is not a practical option, since comfort in general is proportional to electrode size. In the preferable embodiment presently described, both pain-relief and muscle-activating waveforms are multiplexed for application by the same set of electrodes (see, for example FIGS. 7(a)-(c)). This multiplexing process may be repeated by several sets (i.e. pairs or groups) of electrodes in a given stimulation region.

[0046] In a variation of the embodiments described in the previous paragraph, specially-placed electrodes deliver pain-relief electrical waveforms while additional, separate electrodes provide muscle stimulation waveforms. In certain scenarios, extremely localized pain relief waveform stimulation may provide superior comfort improvement relative to more widespread distribution of applied energy. Without wishing to be bound by any theory, it is believed that this may be the case for challenging stimulation subjects (e.g., obese/overweight, edematous, elderly) that require large amounts of total energy applied to skin electrodes.

[0047] In some embodiments, a topical analgesic and/or anesthetic is utilized in conjunction with surface electrodes to decrease discomfort related to excitation of superficial sensory nerves. In one implementation, a lidocaine (or similar, ex. capsaicin or other NSAID) paste or gel is manufactured into or layered below (skin contact side) of the hydrogel contact layer of the surface electrodes utilized during LAMES. Thus, when electrodes make contact with the skin, the analgesic/anesthetic is automatically applied without extra steps for the operator. In variation embodiments, the topical analgesic/anesthetic is applied in discrete locations by an operator prior to placement of stimulation electrodes or a stimulation pad. In some embodiments using analgesics/anesthetics, additional safety features (such as thermistors, thermocouples, or other mechanisms aimed at burn prevention) are implemented to account for use of LAMES over areas of insensate skin.

[0048] The methods described herein can be utilized effectively with any of the embodiments or variations of the devices and systems described above, as well as with other embodiments and variations not described explicitly in this document.

DESCRIPTION OF THE FIGURES

[0049] FIG. 1 illustrates an existing technique to stimulate contraction in a deep muscle tissue without eliciting contraction in more superficial muscle tissues. As shown in the cross-sectional view, the energy from two separate pairs or groups of surface electrodes is combined in a coordinated fashion at depth. Each pair or group applies an energy level that is presumably too weak to cause contraction on its own. However, when the two energy deposits overlap in the target region, they combine in a way to produce an energy level that surpasses the threshold for muscle contraction in that region. Also, because current density is reduced in the region of superficial sensory nerves, comfort can also be improved using this method.

[0050] FIG. 2(a) illustrates an existing technique and illustrates why the technique is not sufficient to optimally reduce the energy requirements of stimulation. FIG. 2(a) shows a bird's eye view of region of stimulation using two electrode pairs (labeled 201 and 202, respectively). As energy travels between the two electrodes in a pair, energy spreads in three dimensions. In this two-dimensional sketch, the lateral spread of energy is represented by field lines (203). As shown, energy traveling between electrodes with moderate separation distances can spread significantly laterally, with an appreciable percentage of the original energy traveling along a pathway where it cannot combine synergistically with energy from the other electrode pair. In FIG. 2(a), the region inside the bold outline (204) indicates where energy from the two pairs of electrodes overlap.

[0051] FIG. 2(b) illustrates an exemplary embodiment where a mechanism (205) is implemented to reduce the outward direction lateral spreading of energy. As shown, a greater percentage of energy from the two pairs of electrodes now may combine synergistically. Additionally, even the portion of energy from a given electrode pair that still spreads laterally beyond the region where it can synergistically combine with energy from the other electrode pair will now be more focused in the desired stimulation region than it was without the use of mechanism 205, further improving muscle contraction efficiency. These improvements in efficiency will allow for the original energy amplitude provided by each electrode pair to be reduced without decreasing the degree of muscle contraction achieved, thus reducing current density in superficial regions of tissue and improving comfort. FIG. 2(b) therefore illustrates an exemplary embodiment which overcomes shortcomings of the design shown in FIG. 2(a)

[0052] As shown in FIGS. 3(a)-(g), a number of possible arrangements for surface electrodes (301) that may be desirable for use to implement the methods, systems, and devices disclosed in this document. Electrodes may be placed individually or may be combined into a larger structure which I refer to as a stimulation pad (302). The electrode arrangements illustrated in FIGS. 3(a)-(g) are provided by way of example only, and it will be obvious to those skilled in the art that many other electrode arrangements are feasible for use.

[0053] FIGS. 4(a)-(c) illustrate methods, devices, and systems to improve comfort during LAMES using two or more pairs or groups of electrodes with rapidly switching polarity. FIG. 4(a) provides an overview of the functionality of an exemplary embodiment of the method and systems. A stimulation pad (401) includes two groups of three surface electrodes (402 and 403), labeled 1, 2, and 3 for group 1 and a, b, and c from group 2. In a preferable implementation of the method, an early step involves having electrodes 1 and a simultaneously or near-simultaneously take on positive voltages relative to electrodes 2 and b, respectively, while electrodes 3 and c remain neutral. After a very short period of time, electrodes 1 and a take on a neutral polarity, while electrodes 2 and b become positive relative to electrodes 3 and c, respectively. Without wishing to be bound by any theory, it is believed that when polarity switches are precisely and properly timed, a current field such as that shown in FIG. 4(a) will result. This process may be repeated many times per second to deliver a series of guided stimulation pulses to tissue.

[0054] As shown in FIG. 4(b), one implementation of an exemplary system includes a stimulation pad positioned on a body of a user (405), in communication with a control unit via a wired connection. FIG. 4(c) shows four example electrode configurations to be used as part of a system implementing the rapid polarity switching embodiment described herein. These configurations are provided only by way of example, and other similar electrode arrangements will now be obvious to those skilled in the art.

[0055] FIGS. 5(a)-(e) illustrate several exemplary embodiments comprising at least one impedance modification element to increase NMES efficiency by reducing lateral energy spreading between pairs or groups of electrodes. The embodiments in FIGS. 5(a)-(e) utilize athermal gradient to increase NMES efficiency by reducing lateral energy spreading between pairs or groups of electrodes. In FIG. 5(a), three pairs of individually-placed stimulation electrodes (501) are placed on a body part, while chemical or gel-based cooling elements (502), which are not integral with one another, are placed laterally in a region adjacent to the electrodes. The cooling elements are positioned laterally on both sides of the electrodes. In FIG. 5(a), the system cooling element comprises two cooling elements 502 that do not extend across an entire width of any of the electrodes. While the cooling element to the left in FIG. 5(a) extends partially across a width dimension of the left electrode without any hash marks, it does not extend across an entire width dimension of the electrode. And while the cooling element to the right in FIG. 5(a) partially extends across a width dimension of one of the electrodes, it does not extend an entire width of the electrode. In FIG. 5(b) two pairs of individually-placed electrodes are separated by a fluid-filled lumen (503) that is continuously infused with a chilled fluid (ex. water, saline) by a pump system (504). In FIG. 5(c), two pairs of electrodes are saddled by two cooling elements (505), shown as pouches containing an ice bath. The cooling element to the right in Figure (c) is positioned solely laterally to both sets of electrodes, while the cooling element on the left is positioned such that is extends partially across a width of one of the sets of electrodes, but is positioned solely laterally to the other set of electrodes. In FIG. 5(d), three groups of stimulation electrodes are integrated into a larger stimulation pad (506) which includes a specialized zone that interfaces with thermoelectric element (507). A control unit (508) controls temperatures in the thermoelectric element. In FIG. 5(e), a stimulation pad comprising stimulation electrodes includes both regions for tissue cooling (509) and tissue warming (510). The cooling elements in FIG. 5(e) are positioned solely laterally to the electrodes and do not extend across a width of any of them. It should be noted that several of the implementations shown in FIG. 5 (for example, 5(b) and 5(d)) would not only limit lateral spreading of electrical energy but may also provide increased penetration of energy to deep-lying muscle tissues.

[0056] FIGS. 6(a)-6(d) illustrate various aspects of phase delay timing between multiple electrode channels and provides an example system that implements the timing method described in the specification above. In FIG. 6(a), three electrode pairs (601) are placed and respective stimulation pulses are timed ideally, and maximum energy coordination and synergy at a deep focal point is achieved. In FIG. 6(b), the electrodes are misaligned (for example, an operator places a stimulation pad on in a crooked fashion). Thus, a new phase delay profile between the stimulation pulses delivered by the three electrode pairs is required in order to maintain maximum energy coordination at depth. This illustrates explicitly why a single pre-programmed phase delay is inadequate for optimal performance. As visualized in FIG. 6(c), varying body geometries between users and/or patients will also change the ideal phase delay combination for maximum coordination, further illustrating the need for devices, systems, and methods to optimize phase delays on the per-use basis.

[0057] FIG. 6(d) illustrates an exemplary embodiment of a system that implements an adaptive optimization of phase delays between stimulation pulses applied by different pairs or groups of electrodes. Control unit (602) with internal processing and data input/output capabilities is in communication with stimulation pad (603) housing surface stimulation electrodes and with sensor system (604) capable of detecting the relative degree of muscle contraction. This sensor system may be based upon EMG, accelerometers, or other custom sensors known to those skilled in the art. The control unit initiates a sequence of stimulation events using a default series of phase delay profiles. Based upon sensor data resulting from these default stimulation events and custom signal processing, a phase delay profile is selected for use during the NMES treatment session.

[0058] FIGS. 7(a)-(c) illustrate example embodiments of systems, devices, and methods that utilize simultaneous or near-simultaneous delivery of more than one type of energy waveform. In FIG. 7(a), stimulation pad (701) including two pairs of stimulation electrodes (702) is in electrical communication with control unit (703). Each of these electrodes multiplexes an output between both pain-relieving and muscle-stimulation electrical waveforms. By way of example, two preferable multiplexing embodiments are shown in FIG. 7(b). Both embodiments shown contain both muscle-activating (704) pulses and relatively lower-amplitude (but higher repetition frequency) pain-relief pulses (705).

[0059] A variation of the embodiment that utilizes more than one type of energy waveform is shown in FIG. 7(c). In this example, separate electrodes are used to deliver pain-relieving and muscle-activating energy. A control unit (703) communicates with a stimulation pad (706) containing both muscle-activating (707) and pain-relief (708) electrodes. By positioning the pain-relief electrodes in specific positions, muscle contraction can be induced with minimal discomfort to the user.

[0060] While an impedance modification element is primarily described herein as a cooling element to induce a temperature change in tissue, alternative types of impedance modification elements can be used in place of a cooling element or in conjunction with a cooling element. For example, topical or injected chemical substances may be utilized to create impedance gradients similar to those created with strategically-induced thermal gradients in tissue. For example, an aerosol or similar spray can be applied to skin that temporarily changes its conductive properties. Alternatively, an electric/magnetic/electro-magnetic field generation device that electrically polarizes cells is used to alter their natural conductance. Alternatively, a pressure-generating device can be used to compress cells and/or move excess edematous fluid away from the region of interest.

[0061] Additionally, while the devices and methods of use herein are primarily described for muscle stimulation, the devices may be used in other applications. For example, the systems may be used with, for example without limitation, deep brain stimulation, or other targeted stimulation systems where it would be desirable to use a minimal amount of energy.

[0062] While preferable embodiments have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from that which is disclosed herein. It should be understood that various alternatives to the embodiments of the disclosure may be employed.