Conceptual Design of a Massaging Device to Mitigate Exercise Associated Calf Muscle Cramps

Exercise-associated muscle-cramping (EAMC) is a-common-condition, experienced by recreational and competitive-athletes, which can potentially-endanger their-health, as-well-as professional-career. This paper reports the-synopsis of a-conceptual-design, simulation, and analysis of a-massaging-device to-mitigate paraphysiologic-EAMC, in-the-calf-area. Document-analysis was utilized as one of the-study-instruments (including published-research on the-concepts of cramps and their-treatments; selected-relevant Internationalpatents; the-use of anthropometric-data in product-design; prior-art on massaging-devices, and selected-devices, currently available at the-market, with their-respective-limitations). The-study applied fundamental-Engineeringprinciples of product design, and was-carried-out in-compliance with ISO7250: 1996 (Basic-human-bodymeasurements for technological-design). The-best-ranked-design (out of the 3 design-alternatives, made) was chosen, via Engineering-Design Weighted-Decision-Matrix, and confirmed by the ‘Drop and Re-vote’ (D & R) method. 2D-drawings, of the-best-design-alternative, were created by computer-aided-design (CAD) AutoCADsoftware, while 50 percentile, adult-male was selected, as a design-target. Relevant-leg and hand-dimensions (one-dimensional measurements), were obtained from published-anthropometric-data-tables. Simulation of StressAnalysis/Single-Point Static-Analysis (to-detect and eliminate rigid-body-modes; and separate stresses across contact-surfaces) was done by Autodesk Inventor-Version: 2016 (Build 200138000, 138). Conceptual-design of the-massaging-device was optimized according-to results of simulations, calculations, and fundamental engineering-product design principles. The-study also revealed that the-patho-physiology, causing EAMC, is most-likely multi factorial and complex. Overall, the-results of this-concise-study are rather-positive, providing agood starting-point for advanced-exploration on the-same. Further-improvements and trials, however, are necessary. The-study, hence, recommended: (i) Further-studies, to-optimize the-dimensions of the-device, toaccommodate different-shapes of calf-muscles; (ii) More-advanced-methods, such-as PuCC; AHP, and TRIZ should be considered in-selection of the-best-design-alternative; (iii) Comprehensive-materials-selection should be detailed via Ashby-charts; (iv) To-carry-out a-detail-design; (v) To-fabricate a-prototype; (vi) To-conduct additional-tests (e.g., FEA/FEM) and explorative-use-ability-trials, in-collaboration-with the-department of Medical-Engineering, School of Medicine, MU; and (vii) To-analyze the-marketing-aspect of the-final-device. The-device is potentially-beneficial to sports-health-care-providers, coaches, and athletes; moreover, it could be included into-First-Aid Sport-kit (subject-to satisfactory-trails).

Muscle-spasm can easily-bring even highly-fit-athlete to their-knees, especially if the-muscle-spasm or cramp, occurs during the-active-state (e.g., while-running or performing other-physical activities).These-muscle-spasms, occurring during such-activities are known as Exercise-Associated Muscle-Cramps (EAMC), which is the-subject of this-study.
Schwellnus and his-colleagues provided a-definition of EAMC (Schwellnus et al., 1997), as: "Skeletal muscle cramps that occur during, or shortly-following exercise, in healthy individuals, with no underlying metabolic, neurological, or endocrine pathology".This-definition is adopted by the-current-study.
Although some-EAMC do manifest only in-mild-discomfort and do not appear to-affect athletic performance (Schwellnus et al., 2007;Maughan, 1986), other-times, EAMC are extremely-painful and can be completelydebilitating (Miller et al., 2010;Brubaker et al., 1985;Moss, 1923), leading-to muscle-injury, and temporarilyloss of mobility, and, hence, can potentially-damage, or even, ruin the-carrier of a-sport man or a-woman.
Paraphysiologic-cramps develop in-healthy-people and are linked-to certain-circumstances and conditions, such-as exercise or pregnancy.In-idiopathic-cramps, the-muscular-problem is the-main symptom of a-generaldisease; these can-be sporadic, are sometimes inherited, and usually are not associated with cognitive, pyramidal, cerebellar, or sensory-abnormalities.A-central, neuronal-origin, at the moto-neuron-level has generally been hypothesized for these-cases.Symptomatic-cramps are manifestations of an-underlying-disease.The-scope of this-study is limited to paraphysiologic-cramps.
Calf-muscle (the-focus of this-study) is a-bilateral-muscle.Figure 1 shows the-anatomical-position and depiction of the-calf-muscle, which is the-focus of this-research.

Dehydration theory
According to the-dehydration-theory, excessive-sweating is the-primary-cause of EAMC (Braulick et al., 2013;Bergeron, 2008;Jung et al., 2005;Stone et al, 2003;Schwellnus et al., 1997).This-theory is propagated, becauseof the-association of heat-illness with cramps.However, Armstrong & Cross (2013) pointed-out, that thedehydration-theory is based-on anecdotal-observations, with no actual-measures of hydration-status reported.In the-more-recent-studies by Drew (2006);and Sulzer et al. (2005), in-which calculated-body-weight-changes and volume of blood or plasma, were used as-indicators of hydration status, the-hypothesis of a-direct-relationship, between dehydration and muscle-cramping, was not supported.

Environmental theory
The-environmental-theory suggests that exercising in hot-conditions and the-subsequent-electrolyte-loss and dehydration, results in-EAMC (Bergeron, 2003;Schwellnus et al., 1997;Armstrong & Maresh, 1993).However, Armstrong & Cross (2013), have argued that EAMC is not directly-related to an-increased core temperature.Atrest, however, passive-heating does not result in skeletal-muscle-cramping and cooling does not relieve it, so it-is unlikely that exercising in hot-conditions causes secondary physiological changes, which can cause EAMC.Altered neuromuscular control theory During sports-competition, training, and a-variety of other-intense-physical-activities, repeated or extended-loading, on selected-muscles can lead-to localized-muscle-fatigue.The-altered-neuro-muscular control-theory suggests that muscle-fatigue disrupts the-normal-functioning of peripheral-muscle-receptors, causing an-increase in excitatory afferent-activity, within-the-muscle-spindle, and a-decrease in-inhibitory afferent-activity, within the-Golgi-tendon-organ, both of which then lead-to an-increase in-alpha motor neuron-discharge to the-musclefibers, producing a localized-muscle-cramp (Miller, 2015;Schwellnus et al., 1997;Ruff, 1996).
The-Altered-neuromuscular-control-theory seems to-be the-most scientifically-acceptable-theory, suggesting that EAMC are caused by an-imbalance, between increased-afferent-activity (e.g., muscle spindle), and decreasedinhibitory afferent-activity (e.g., Golgi-tendon-organs), which leads-to increased motor neuron-activity and muscle-cramping, especially with muscle-contraction in a-shortened-position.This is also supported by alaboratory-based exercise-protocol, specifically-designed to-cause premature-fatigue, of the-calf-muscles, has been shown to-result in a-high-incidence of muscle-cramping, during exercise (Jung et al., 2005).(Miller & Layzer, 2005).Among other-theories, that have been-proposed for the-etiology of EAMC, are an-inadequate-intake of carbohydrate, glycogen-depletion, poor-biomechanics or running-gait, hilly-terrain, and lack of adequate massage, before and during-a-game (Schwellnus et al., 2008).Cramp-discharges may-also be attributed to the-fact that terminal-branches of motor-axons are exposed-to increased-concentrations of excitatory extracellular-substances, such-as acetylcholine or electrolytes (i.e., sodium and potassium) (Ruff, 1996;Layzer, 1994;Sjogaard et al., 1985).
The-electrolyte-imbalance-and-dehydration-theory suggests that EAMC is related to the-decreased concentration of serum-electrolytes, particularly sodium and chloride, resulting-from excessive-sweating or overconsumption of water (Schwellnus et al., 1997;Armstrong & Maresh, 1993;Ladell & Camb, 1949).On-the-other-hand, according-to Armstrong & Cross (2013):"muscle fatigue is now acknowledged as the principal predisposing factor in the development of EAMC".This-study, however, supported Miller and his colleagues, who pointed-out, that (Miller et al., 2010): Because EAMC occur in a variety of situations, environmental conditions, and populations, it is unlikely that a single factor (e.g., dehydration, electrolyte imbalance, or neuromuscular factors) is responsible for causing them directly.It is more likely that EAMC are due to a combination of factors that simultaneously occur under specific physiological circumstances in each athlete.Muscle-cramping can-also-occur as-a-symptom for a-variety of medical-conditions, including: Hypothyroidism, vascular-disorders, metabolic-myopathy (caused by glucose-metabolism-defects), radiculoneuropathy, serum-deficit of magnesium, Parkinson's disease, diabetes mellitus, peripheral-neuropathy, electrolyte-disorders, venous-insufficiency, or chronic-obstructive arterial-disease of the-lower-limb (Parisi et al., 2003;Tarnopolsky, 2002).Muscle-cramps are also part of certain-conditions such-as: Compression of nerve; kidney disorder, hypo-glycemia; and anemia (Qiu & Kang, 2017).
Massage-therapy as therapeutic-treatment of EAMC is the-primary-focus of this-study.Massage therapy is designed to-stretch, calm, revitalize, and loosen the-affected-muscles, improve blood flow, facilitate the-removal of metabolic-wastes, resulting-from exercise, or inactivity, and increase the-flow of oxygen and nutrients to thecells.In-addition, massage stimulates the-release of endorphins (the-body's natural-painkiller) into the-brain and nervous-system (Zainuddin et al., 2005;Robertson, 2004;Hilbert et al., 2003;Hemmings et al., 2000).
Massage, and associated-soft-tissue-treatment, is an-important-component of the-training-process for manyelite-athletes, as muscle-tightness interferes with the-nerve-feedback-mechanisms, which ensure efficient and smooth-control of movement, so necessary in-competitive-sport. Indeed, according-to Bergeron (2008) and Jönhagen et al. (2004), the-request for sports-massage, among competitive-athletes, has seemed to-increase during the-past-years.Many-top-level-athletes consider this-treatment as-enhancing their-recovery, after training and competitions, as-protection from overuse-injuries, and as reducing the-risk of delayed-onset-muscle-soreness (DOMS) (see Thomson et al., 2015).DOMS normally follows unaccustomed-eccentric-exercise, and the-peak of muscle-soreness is seen 24 to 72 hours (Stone et al., 2003;Friden & Lieber, 2001;Byrne et al., 2001;Angus, 2001;Armstrong et al., 1991), after-exercise.
In-addition, it has-been-proposed that the-mechanical-pressure, during-massage, alters neural excitability, and these-neural-changes may-reduce the-potential for cramping (Nelson & Churilla, 2016;Behm et al., 2013;Lee, 2009).Sefton et al. (2012) discovered a-reduction in the-Hoffman (H)-reflex, which was-used to-measure the-excitability of the-motor-neuron-pool, in-study-participants, who received a 1-hour full-body-massage.Analogous, Behm et al. (2013) found that massage decreased spinal-reflex excitability, with significant-reductions, in-subjects, who received 30 seconds of a percussive-massage stroke.They, however, pointed-out, that furtherinvestigation is warranted to-determine whether treatment variables, such-as the-relative-timing of massage, depths of pressure, speed of stroke, and type of massage stroke, influence EAMC, without negatively-impactingperformance.

Research-purpose.
EAMC can be severe, reguiring immidiate-medical-attention.According-to Venable (2009), the-most effectiveway of muscle-spasm-relieve, is by the-use of drugs, which reduce the-firing-effect of the motor neurons, or act to the-central-nervous-system, to-reduce pain-sensitivity.One of these-drugs is Quinine-Sulfate; however this-drug causes the-feeling of nausea, dizziness, partial-blindness, and even death; these-side-effects being greater-than theadvantages, therefore, this-drug is rarely-used (Timothy, 2005).In other-severe-situations, the-patient is advised to-undergo a-surgery, known as-orthopedic-surgery, to-correct the-muscle-situation.
On-the-other-hand, massaging-devises are relatively-effective and harmless, in-mitigating EAMC.Preliminary-assessment showed, that the-majority of massaging-devices rely on external-power (such-as batteries, electricity), this power-requirement, however, could be a-big-disadvantage, when such-sources do fail.Forexample, athletes may experience EAMC, at the-middle of the-field, where there is no electric-source, which endangers their-mobility and even their-career.
In-addition, the-author was not able to-trace freely-available-published-literature on the-design of massagingdevices; with-exception of one-article, by Kamat et al. (2017), who described a-design a-manual calf-massager for prolonged-standing-workers.Hence, there is a-gap, to-be-filled.
Considering the-above-limitations, the-aim of the-current-research was to-design a-manual, simple, costeffective massaging-device, that can-be-used to-manage EAMC, in the-field.

Concepts of Engineering-design and Conceptual-design.
Design can-be-described as a-set of decisions, taken to-solve a-particular-set of product-requirements. Design is part of a-human problem-solving-activity, beginning with a-perception of a-gap in a-user-experience, leading-to a-plan for a-new-artifact, and resulting in the-production of that artifact.Product design is conceiving and giving form to goods and services that address needs (Burdekin, 2007).Within the product-development-process there are several-phases: idea-generation, product-definition (also-called product-planning), conceptual-design, detaildesign, and embodiment-design (Timings, 2000).
The-conceptual-design-phase is the-most-important-phase in concurrent-engineering, after the-project planning-phase or product-definition.Approximately 80% a-product's life-cycle costs are committed through design-choices, such-as materials and manufacturing-process-selections in this-phase.Conceptual-design comprises concept-definition, exploration, evaluation, and selection (Allen & Carlson-Skalak, 1998).The-inputs, into-the-design-process, are shown in-Figure 3.

Steps and tools involved in the-current-study.
This-study was focused on product-design, where several-tools have to-be-applied.Design-tools enable productdesigners, to-structure and formalize parts of their-design-steps (Jangager, 2005).In-particular, this study is basedon the-bottom-up-approach, where the-design starts-with specifying-requirements and capabilities of individualcomponents (see Crespi et al., 2011).
In-particular, to-achieve the-study objectives, the-following-steps were conducted: (1) formulate designproblem with target-specifications; (2) prepare and analyze design-alternatives; (3) conduct design simulation and analysis; and (4) establish optimum-conceptual-design, based on the-analysis of results.Romer et al. (2001) stated, that traditional-tools, such-as sketches and simple-physical-models are very-useful and cost-efficient, in-generating design-solutions, in early-phase of design-process.Besides, most of the-times (this-study included) design-problems, are open-ended; they do not have a-unique, or the only-one correct-solution, though some-solutions will, clearly, be-better, than others.In-this-regard, three design-alternatives, is to-be handsketched.
Product-designers utilize a-wide-variety of design-tools, ranging from sophisticated-computerized information support-systems, such-as CAD-systems, to inexpensive-memory-aids, such-as pencil and paper (Love, 2003).This-study, for-example, used a-pencil and paper, as tools, for free-hand-sketching, of three alternativedesigns; and a-database, as a-tool for information-storage and retrieval.The-design also applied fundamental-Engineering-principles of product-design.Besides, this-study was-carried-out in-compliance with ISO7250: 1996 (Basic-human-body-measurements for technological-design).
2D-drawing, of the-best-design-alternative, was created via computer-aided-design (CAD) AutoCADsoftware.Furthermore, identification of specific-anthropometric-dimensions and the-design target-population was identified and specified.These-dimensions were used for the-preliminary-design.
Simulation of Stress-Analysis/Single-Point Static-Analysis (to detect and eliminate rigid-body-modes; and separate stresses across contact-Surfaces) was done by Autodesk-Inventor-Version: 2016 (Build 200138000, 138).
According-to Ashby (2004), first-consideration, in materials selection, is on the-functionality of the material, the-main-goal here is being-able to-produce products that function effectively, safely, at acceptable-cost.Thisstudy adopted the-interaction of function, materials, shape, and manufacturing-processes from Asbhy (1999), and the-interaction of use, function, materials, and shape, from Roozenburg & Eekels (1995).The-following-limitations were identified in the-specified-patents: (i) In-the-Patent US 6027434 (2010), the-major-limitation is the-rigidity of the-design, as the-device cannot be used universally (e.g., for athletes of different-hight).Second-limitation is that the-device only utilizes stretching-function; no massaging.Third, the-device tends to-pinch the-sides of the-users-feet, as tension is applied to-pull the-leg.Besides, this-device may only be limited to-handle the-cramps of the quadriceps, and can hardly-be-used for the hamstrings, since the-stretching-direction cannot be changed.
(ii) In-the-Patent US 7223251 B1 ( 2007), most-people, using rollers to-relieve muscle-spasms agree that they are quite-effective, but it requires technique, especially if the-roller lies on the-ground, as suggested in this-design.
(iii) In-the-Patent US 6027434 ( 2005), the-spherical-shape of the-roller does not bring-about adequatemassaging-action and it's generally more-difficult to-bring such-balls to-rotate.The-manner, in-which theserollers are attached at the-end of the-handle, is not clear whether massaging of the-leg occurs when the-rollerarrangement is intact, or that they have to-be-detached.Usually, one needs a-closer contact with the-massagingrollers of which this-massaging-system entirely-depends-on the-amount of pressure the-user applies.
The-study also examined selected-examples of available, on the-market, devices.Figure 5 shows someexamples of the available-devices.
Most-of the-available-devices, reviewed, utilize the-principle of electrotherapy, which are powered electrically, used transducers to-produce a-vibration-motion.Some of the-electrotherapy-devices are the FES (Functional-Electrical-Simulation), which mainly-stimulates the-muscles of the-ankle and the-foot, when one is walking (Bailey, 2011).The-FES-pad is attached on the-particular-foot-muscle and triggers it, during-walking.TENS (Trans-cutaneous Electrical-Nerve-stimulation) is a-pad, attached to-the-muscle, and generally affects thepathway of pain to the-brain, hence eases the-pain.TENS-devices, however, could cause some-skin-irritation with use (Bailey, 2011).So-many-devices have-been invented and currently being-sold, however, these-devices are quite-expensive, for any-developing-country, Kenya is not an-exception.(i) In-Calf-Braces-device, calf-compression-brace is designed to-support the-calf and shin in-case of a muscle-strain or a-muscle-pull, they are used to-provide-compression to the-affected-calf-area (Mathews, 2016); (ii) Power-massage-device (by Brick, 2017), has a 12V battery and makes 2000 strokes per-minute and costs $399 which is quite-high.Another-limitation is that the-speed of the-device is constant, giving no room for adjusting (Brick, 2017), and again the-noise, it produces, is quite-high, especially when it has to-be-used tomassage areas near the-ear (Matt, 2018); (iii) Lumitherapy-Device infrared-Light-device uses infrared-light to-reduce muscle-pain, joint-pain and stiffness, with the-light, emitted ensuring proper-blood-circulation and also relieves muscle-cramps.The-device can have 4 pods or 8 pods, going at $512 and $712 respectively, at the-Amazon.One-user, in their-chart-reviewsite commented that the-device was not powering properly, other-users claim that this-device produces anannoying buzzing-sound; and (iv) Laser-pain-relief-device consists of a-flex-pad, on-which a 60 LED (Light Emitting Diodes) infrared and red-light, arranged in an-array.The-infrared-light supposes to-stimulate blood-circulation, enables musclerelaxation, and relieve muscle-spasms, pains, aches, sprains, strains, carpal-tunnel Syndrome, and other-physicalailments.Going at $180.99, this-device can be used for therapeutic purposes, and claimed to-cause faster-healing of tissues.A-disappointed-user, however, explains how the-product stopped working, just after six-months of using it, and the-pad and the-LED separated for other-cases (Grainge, 2016).Another-complains is that the-LEDS are too-bright, and one would-require to-buy safety glasses, while using them.

Identification of target-specifications/objectives of the-massaging-device.
Document-analysis revealed that the-selected-reviewed-devices have a-number of limitations.For-example, some of them: (1) are lacking massaging and stretching capability; (2) cannot be used universally; (3) are bulky and heavy; ( 5) are expensive to-buy and to-maintain; (6) are not effective in-severe-cases of EAMC; (7) produce extreme-vibrations and make a-buzzing-sound; (8) use power (e.g., electricity; inverter; battery) and use potentially-harmful infrared-light, for operation; and ( 9) can have side-effects, e.g., skin irritations, and generaldiscomfort, among-others.
In-particular, the 3 major-utility-characteristics of the-device are: functional-efficiency, adjustability, and thermal-comfort-ability.It also should-be portable, easy to-store, and to-transport.Bio-compatibility was alsotaken into-consideration as a-constraint; the-device must not irritate the-skin, or result in a-higher surfacetemperature.With proper-material-choice, that incorporates sweat-wicking or a reasonably-high thermalconductivity, the-body-heat can-be-dissipated, easily, to-prevent profuse-sweating and, hence, discomfort.
Besides, a-device usually comprises of various-parts.The-utilitarian or functional-part is the-one that trulyperforms basic-task, which prompts the-execution of the-segment.The-non-functional-part does not have realwork in-segment-presence, but rather it needs to-do-with support, spreads, examination, and aesthetical-worth, and therefore, the-number of non-functional-parts should-be-reduced to-cut the-cost (Juvinall & Marshek, 2012;Budynas-Nisbet, 2008).
To-achieve these-criteria, structurally, all-the-components should: (a) be symmetrical (and have polargeometry-mark), if possible, as this also-helps in-manufacturing; (b) have consistency, in the-dimensions, used for feeding, orientation, and location; (c) have location-points; and (d) be functional, hence, components which are not important/functional should-be-eliminated.

Free-hand-sketches of design-alternatives.
The-study limited to three-design-alternatives, developed, by the-design-team, which are shown in-Figure 6. Some-preliminary-calculations were done, at the-same-time, which might-be-required to-substantiate ideas and to-establish approximate-sizes.The-design-alternative (#1 in Figure 6) is an-electro-mechanical system, it-is to-be-composed of a-coil, alight-magnet, and a-diaphragm, as the-basic-components, with a-stretchable-covering-material.The device can fit both; on the-calf and on the-thigh-muscles.The-electrical-system involves the-supply of Alternating-Current (AC) to the-coil, which is within the-magnetic-field, of the-light-magnet.As the magnet's magnetic-field and theinduced-magnetic-field on the-coil interacts, the-coil moves-inwards, pushing the-diaphragm.This-enables thedevice to-give a-pressing-action, on the-affected-muscle, supposedly relieving the-pain.
The-second-design is made-up of a-wrap-round-piece, on-which massage-wheels are mounted, so-as toenhance the-massaging-action. Mounting gives the-rollers better-massaging, since the-pressure is applied on themuscle the-wrap-round-piece. The-massaging-wheels transverse the-muscle by the-use of a-handle that is attached to the-axle of the-wheels, and the-motion is guided by a-rail.The-interior of the-device is made of a-layer of protrusions, which give a-finger-like-massage, by smoothly-penetrating to the affected-muscle, this with the-wheel massaging-rollers give a-double-action-massage.
The-third-proposed-device will be using primarily a-stretching-function, while massaging is secondary.Theinner-part of the-device will-be-spiked, hence, on stretching it will produce some-close-skin-contact.The-device is to-be adjustable, to-accommodate several-sizes.

Preliminary selection of material-groups.
In-preliminary-selection of material-groups, Engineering-materials are sorted into the-family-groups, such-as: polymers, metals, ceramics, glasses, natural-materials, composites, and hybrids; each of these families/ groups has a-set of attributes (property-profile), which can be plotted in a-material-property-chart (e.g., Ashby-Materials Selection-Charts (see Ashby, 2005).
Besides, according-to Jerz (2014), the-selection of materials goes-through four-steps: translation, screening, ranking, and support-information.Translation-stage involves establishing the-constrains on material-properties and the-process-attributes.The-properties for consideration, in-this-study, were-limited to: (i) technical-properties of materials (e.g., density, conductivity, strength, etc.); (ii) manufacturing of materials (e.g., easy to manufacture with existing-manufacturing-facilities); (iii) economic-properties of materials (availability and cost for material and production); and (iv) ecological-properties of materials (recycle-ability, sustainability, etc.).Besides, materials, which come in-contact-with the-human-skin, should-be carefully-selected; this is due-to some-skin-diseases, suchas Eczema (recurrent-skin inflammation) (Mason, 2009), therefore, the-materials-bio-comparability will be also under-consideration.
Natural-chrome-tanned-leather has excellent-mechanical-properties of bursting, and thermal-resistant properties (Yu, 2013); however it-is expensive, and the-chrome-tanned-leather may not be compatible-with some people's skin, especially those suffering-from the-eczema-disease of the-skin (Mason, 2009).Synthetic-leather is, hence, to-be used, due to its-flexibility, comparability, availability, and price.The handle is to-be-made of wood, due to its-specific-gravity, of which the-general-substance that make it up is 1.5 regardless of the wood-type (Green, 1999).Galvanized-steel-sheets, which do not easily-rust, will be used for rails.3.6.Design-target and Anthropometric-measurements, to be used in the-design.50 th percentile (covering 90% of the-population) adult-male, was selected, as most-appropriate design targetpopulation.Figure 7 shows the-relevant-anthropometric-dimensions, needed for the-design.International-Standards, for Anthropometric-Assessment by Marfell-Jones (2001) and Anthropometrical-data from Fryar (2012), were used, to-obtain one-dimensional-values for these-dimensions.

Description of the best-design-alternative.
Fundamentally, fatigue is occurring due-to the-Isometric-Contraction, with the-increasing lactic-acid accumulation.Influence of massage on Muscle-Blood-Volume (MBV) is particularly-important, in this designalternative, since according-to Imai et al. (2016);and Mori et al. (2004), the-effect is thought to help enhanceremoval of metabolic-waste by-products, such-as lactic-acid, thus enhancing recovery from muscle-fatigue.Therotating-roller will give superficial-massage and provide soft-tissue manipulation, towards the-calf-parts, achieving relaxations on-muscle-activity, and consequently improving blood-circulation in the-body.
Figure 8 shows the-ideation-diagram, which is the-general-plan-view of the-proposed-device.The yellow outer-lines represent the-synthetic-leather-part, to-wrap-around the-calf-muscles.It spans for 430mm, with theflaps, where the-Velcro-strips are attached, so as to-allow adjustment.The-blue-parts are the-rails, on which themassaging wheel-axel is to-move-through.The-part, represented in-green, is the massaging-system, made-up of the-massaging-wheels, the-axel, and the-handle.Lastly, the-part, represented in-pink is the-spiked-area, which surface, gives a-finger-like-massage to the-muscles.The-height of the-rail should be such, to-allow free-rotation of the-rollers, massage, as-well-as support on the-leather-surface by rivets.Positioning of four-Velcro-strips, for adjustability were calculated to be positioned in the-upper-side at 17, 21, 25, and 29cm, from the-centre and on both-sides, and at points 10, 13, 16, and 19cm (on the-lower-side).The-handle-dimensions was calculated, based on the design-target and arm-dimensions, at 25.45mm, and optimized (for ease of fabrication) to be 30mm.The-smallest-wheel, available, at the-time of thestudy, was used.
The-layout was analyzed for forces, stresses, etc., and calculations, necessary were made to-be-certain that the-parts can perform satisfactorily.Engineering Design Software --SolidWorks, 2013 (design and simulation tool) was used.

Simulation and Analysis.
By identifying the-loads, the-governing-failure-modes and tentatively selecting the-appropriate candidate material, the-failure-prediction-scenarios provide a-basis for choosing the optimal-combination of design parameters: geometry, material, and loads (Budynas-Nisbet, 2008).A-key-strategy in the-PDP (Product Development-Process) is to-avert failure of a machine/device/structure, by predicting and analyzing potential-failure-scenarios at thedesign-stage, before it-is built.Factor of safety (FoS), also-known-as (and used-interchangeably-with) safetyfactor (SF), and design-factor of safety (N), is a-term, describing the capacity of a-system, beyond the-expectedloads or actual-loads.According to Starovoytova & Njoroge (2016): "Essentially, the-factor of safety is howmuch-stronger the-system is than it usually needs to-be for an-intended-load'.Factor-Safety of 4 was chosen, tocarter for changes in-material-properties, due-to normal-use and possible-extreme-weather.The-force of 557 Newton (since it-is the-highest-value for 95 th percentile-male), was chosen for the-test (in-accordance with Schutte, 2007), where device ultimate tensile-strength at steady-loading is considered.
Operating-conditions for the-test are shown in   Figure 9 shows a non-uniform-displacement, along the-axel; besides the-Factor of Safety as-low-as 0.15Mn was reported, which is an-indication that the-axel could eventually fracture.Both-indicators necessitated corrective-measures, taken on the-handle.
Other-results, obtained from the-stress-analysis, include the-von-Misses-stress, the 1 st and 3 rd Principle-stress and strain, Equivalent-Strain and Contact-pressure.

Conceptual Design.
Conceptual-design of the-massaging-device was optimized, according-to results of simulations, calculations, and fundamental engineering-product-design-principles. Figure 10 shows the-functional-elements/parts of themassaging-device, while Figure 11 shows its-assembly.

Discussion.
As stated-earlier, the-scope of the-project was-limited-to the-conceptual-design.On the-other-hand, prototyping and testing-stages, if carried-out, can give a-real-picture of the device-functionality. The-author proposes furtherwork on prototyping and testing to-be-carried-out, leading-to detail-design and embodiment-design.
Besides, the-general-contouring, of the-calf-area, of the-leg, is different, length and the-circumference variesgreatly, hence fitting the-wrap-round-piece. For-instance, Figure 12 shows 9 combinations with different-length of leg (short, medium, and long), and varying-calves (small, medium, and big).The-study, hence, recommends further-studies, to-optimize the-dimensions of the-device, to-accommodate different shapes of calf-muscles; and the-use of stretchable-material (and also durable), which can easily take the-shape of the-leg.This-unfunded concise-study was preliminary, by nature; its-results, are largely, relatively-positive, providing a-good-starting-point, for further and much-deeper-study, on the-same.Next-logical-step, would be a-detaileddesign, which can-be-generated, using 3D-solid-modeling CAD-programs, such-as SolidWorks.CAD-models can-be created, for components and assemblies, to-check, for interference, before any-physical parts are made.
Also, the-Finite-Element-Analysis/Method (FEA/FEM) can-be used, to-conduct stress-strain investigations.The-most-characteristic-case is to-use FEA to-understand what stress will-develop, in-a-part, under certainloading-conditions. Besides, AUTODESK Simulation-Mechanical, can-be-used, to-perform Stress-Strainanalyses; the-same-package can-be-also-used to-perform heat-transfer-modeling.
In-addition, final trade-off of performances-test (see Masctelli, 2000), and FMEA-tests should-be conducted, as every-product has some-possible-failure-point, and it-is important to-identify such failure point(s) and thesubsequent-effect(s).Moreover, a-particular-component-failure is often identified, during the-use-ability-testingprocess, meaning that only that-component should-be redesigned, and not the entire product (see Starovoytova, 2018).
Moreover, it-is a-standard-procedure to-analyze the-marketing-aspect of any-newly-designed-device, and hence, it-is recommended.
Lastly, reviewing the-British-Standard for Workplace-First-Aid BS8599-1, for Professional-First-Aid-Kits (Sports), it was exposed that there is absolutely-nothing that it provided, for the-relieve of EAMC, under suchstandard.In-particular, according to the-standard, a-Standard-Sports First-Aid-Kit should provide the-treatmentsolutions for the-following-conditions: Bleeding, Asthmatic-attack, Broken-bone, Concussion, Diabetic-attack, Eye-injury, Fractured-bone, Hypothermia, Shock, Soft-tissue injury, and in addition, it should contain a-tweezers and a-paramedic-shears.Taking into-consideration that EAMC is rather-common, in-sports, the-study, therefore, recommends to-include into-first-aid Sport-kit, a-device, which could help in-managing EAMC, such-as for example, the-massaging-device, designed by this-study.

Conclusions and Recommendations.
The-current-study revealed that the-patho-physiology, causing EAMC, is most-likely multi-factorial and complex.
Besides, this-unfunded concise-study was preliminary, by nature; its-results, are largely, relatively positive, providing a-good-starting-point, for further and much-deeper-study, on the-same.The-study, hence, further recommends: i) More-advanced-methods, such-as PuCC; AHP, and TRIZ should be considered in-selection of the-best design-alternative; ii) Further-studies, to-optimize the-dimensions of the-device, to-accommodate differentshapes of calf-muscles; iii) To-conduct prototyping and a-detail-design; iv) Additional-tests, such-as FEA/FEM and the-use-ability-testing should be incorporated; v) Comprehensive materials-selection should be detailed via Ashby-charts; and vi) To-analyze the-marketing-aspect of the-final-device.Lastly, the-author would-like-to-emphasize that there is absolutely-nothing that can ever-be-perfect that is made by man, especially when it-is at its-initial-stages, and, thus, the-author would-like-to-welcome constructive expert-criticism from the-readers (if any).

Figure 4
shows selected-examples of most-recent-patents, reviewed.

Figure 4 :
Figure 4: Selected Patents, reviewed.Key: left -US 6027434 (2010); middle -US 7223251 B1 (2007); and right -US 6027434 (2005).The-following-limitations were identified in the-specified-patents:(i) In-the-Patent US 6027434 (2010), the-major-limitation is the-rigidity of the-design, as the-device cannot be used universally (e.g., for athletes of different-hight).Second-limitation is that the-device only utilizes stretching-function; no massaging.Third, the-device tends to-pinch the-sides of the-users-feet, as tension is applied to-pull the-leg.Besides, this-device may only be limited to-handle the-cramps of the quadriceps, and can hardly-be-used for the hamstrings, since the-stretching-direction cannot be changed.(ii)In-the-Patent US 7223251 B1 (2007), most-people, using rollers to-relieve muscle-spasms agree that they are quite-effective, but it requires technique, especially if the-roller lies on the-ground, as suggested in this-design.(iii)In-the-Patent US 6027434 (2005), the-spherical-shape of the-roller does not bring-about adequatemassaging-action and it's generally more-difficult to-bring such-balls to-rotate.The-manner, in-which theserollers are attached at the-end of the-handle, is not clear whether massaging of the-leg occurs when the-rollerarrangement is intact, or that they have to-be-detached.Usually, one needs a-closer contact with the-massagingrollers of which this-massaging-system entirely-depends-on the-amount of pressure the-user applies.The-study also examined selected-examples of available, on the-market, devices.Figure5shows someexamples of the available-devices.Most-of the-available-devices, reviewed, utilize the-principle of electrotherapy, which are powered electrically, used transducers to-produce a-vibration-motion.Some of the-electrotherapy-devices are the FES (Functional-Electrical-Simulation), which mainly-stimulates the-muscles of the-ankle and the-foot, when one is walking(Bailey, 2011).The-FES-pad is attached on the-particular-foot-muscle and triggers it, during-walking.TENS (Trans-cutaneous Electrical-Nerve-stimulation) is a-pad, attached to-the-muscle, and generally affects thepathway of pain to the-brain, hence eases the-pain.TENS-devices, however, could cause some-skin-irritation with use(Bailey, 2011).So-many-devices have-been invented and currently being-sold, however, these-devices are quite-expensive, for any-developing-country, Kenya is not an-exception.

Figure 6 :
Figure 6: Three design-alternatives.The-design-alternative (#1 in Figure6) is an-electro-mechanical system, it-is to-be-composed of a-coil, alight-magnet, and a-diaphragm, as the-basic-components, with a-stretchable-covering-material.The device can fit both; on the-calf and on the-thigh-muscles.The-electrical-system involves the-supply of Alternating-Current (AC) to the-coil, which is within the-magnetic-field, of the-light-magnet.As the magnet's magnetic-field and theinduced-magnetic-field on the-coil interacts, the-coil moves-inwards, pushing the-diaphragm.This-enables thedevice to-give a-pressing-action, on the-affected-muscle, supposedly relieving the-pain.The-second-design is made-up of a-wrap-round-piece, on-which massage-wheels are mounted, so-as toenhance the-massaging-action. Mounting gives the-rollers better-massaging, since the-pressure is applied on themuscle the-wrap-round-piece. The-massaging-wheels transverse the-muscle by the-use of a-handle that is attached to the-axle of the-wheels, and the-motion is guided by a-rail.The-interior of the-device is made of a-layer of protrusions, which give a-finger-like-massage, by smoothly-penetrating to the affected-muscle, this with the-wheel massaging-rollers give a-double-action-massage.The-third-proposed-device will be using primarily a-stretching-function, while massaging is secondary.Theinner-part of the-device will-be-spiked, hence, on stretching it will produce some-close-skin-contact.The-device is to-be adjustable, to-accommodate several-sizes.

Figure 7 :
Figure 7: Relevant Anthropometric-dimensions. Note: Dimensions B and H were not considered in this-design.

Figure 8 :
Figure 8: Ideation diagram.The-height of the-rail should be such, to-allow free-rotation of the-rollers, massage, as-well-as support on

Figure 12 :
Figure 12: Calf Shape and size Variety.This-unfunded concise-study was preliminary, by nature; its-results, are largely, relatively-positive, providing a-good-starting-point, for further and much-deeper-study, on the-same.Next-logical-step, would be a-detaileddesign, which can-be-generated, using 3D-solid-modeling CAD-programs, such-as SolidWorks.CAD-models can-be created, for components and assemblies, to-check, for interference, before any-physical parts are made.Also, the-Finite-Element-Analysis/Method (FEA/FEM) can-be used, to-conduct stress-strain investigations.The-most-characteristic-case is to-use FEA to-understand what stress will-develop, in-a-part, under certainloading-conditions. Besides, AUTODESK Simulation-Mechanical, can-be-used, to-perform Stress-Strainanalyses; the-same-package can-be-also-used to-perform heat-transfer-modeling.In-addition, final trade-off of performances-test (seeMasctelli, 2000), and FMEA-tests should-be conducted, as every-product has some-possible-failure-point, and it-is important to-identify such failure point(s) and thesubsequent-effect(s).Moreover, a-particular-component-failure is often identified, during the-use-ability-testingprocess, meaning that only that-component should-be redesigned, and not the entire product (seeStarovoytova, 2018).The-current (conceptual)-design is rather-uncomplicated, hence, EDWDM was considered to-be sufficient, during selection of best-design-alternative.At a-later (detail design-stage) additional-methods, such-as: PuCC; AHP (Analytic-Hierarchy-Process); and TRIZ (Theory of Inventive-Problem-Solving) should-be-applied (seeRenzi et al., 2017; Starovoytova , 2015; Starovoytova et al., 2015;Mansor et al., 2013; 2014).Moreover, it-is a-standard-procedure to-analyze the-marketing-aspect of any-newly-designed-device, and hence, it-is recommended.Lastly, reviewing the-British-Standard for Workplace-First-Aid BS8599-1, for Professional-First-Aid-Kits (Sports), it was exposed that there is absolutely-nothing that it provided, for the-relieve of EAMC, under suchstandard.In-particular, according to the-standard, a-Standard-Sports First-Aid-Kit should provide the-treatmentsolutions for the-following-conditions: Bleeding, Asthmatic-attack, Broken-bone, Concussion, Diabetic-attack, Eye-injury, Fractured-bone, Hypothermia, Shock, Soft-tissue injury, and in addition, it should contain a-tweezers and a-paramedic-shears.Taking into-consideration that EAMC is rather-common, in-sports, the-study, therefore, recommends to-include into-first-aid Sport-kit, a-device, which could help in-managing EAMC, such-as for example, the-massaging-device, designed by this-study.

Table 1 ,
while Table 2 specifies Reaction-Force and Moment, for Fixed-Constraint 1; and Table 3 details the-summary of results.