Measuring muscle activity via wearable EMG – is it possible?

Finally we are able to get data on muscles, easily, and even in real-

time. This information provides us the most comprehensive insight in

human performance thus far.

Heart can be seen as a fuel pump of the human machine, delivering fuel to operating engine. It plays also major part in exhaust system transporting away the metabolic waste.

Our muscles, the engine, produce the power. Thus, the neouromuscular system - together with our joints, bones and ligaments – is the powertrain of the human machine, being responsible of power production, transmission & movement control.

Do we understand the “human machine”?

How are we able to measure the engine, our muscles?

Electromyography

Our muscles generate small electrical signals when contracting them. These signals can be detected using specific sensors and measurement devices.

The technique of measuring this electrical activity is called electromyography, EMG. Thus, by using EMG, we are able to analyze the function and performance of our muscular system, or to be precise, our neuromuscular system.

Signal = Volts (A-B)

muscle cell (muscle fiber)

Cell membrane

When muscle contracts, negative voltage, or action potential, travels along the cell

membrane. This can be detected and measured.

What are the key components in terms of muscle function?

Muscles, are composed of a mixture of different types of muscle fibers (or cells). There are two types of muscle fibers: slow (type I) and fast type (IIa, IIb, IIx) of muscle fibers.

Each muscle is innervated by several α-motor neurons. These neurons convey electrical signals from the central nervous system to muscle.

An α-motor neuron and all the muscle fibers it innervates forms muscle’s smallest functional unit, called motor unit (MU).

When a motor unit is activated, all of its fibers contract.

How do these motor units work?

Motor units are recruited according to “Size Principle” or “Orderly recruitment principle”. This means that

smaller loads requiring, low-force, fatigue-resistant, slow twitch MUs (i.e., slow twitch fibers) are activated first. These units are also smaller in size.

fast twitch, high-force, units with higher activation thresholds will follow when higher force is needed. These MUs are also bigger in size.

Motor uni t recrui tment:”SIZE” OR ”ORDERLY PRINCIPLE”

All muscle fibers in a motor unit are of the same fiber type.

The force in muscle is increased both via temporal and spatial recruitment. If muscle need to create more force:

More muscle fibers in action = more force..?

i) the same muscle fibers are stimulated more by the innervating α-motor neuron until the muscle twitches ”fuse”. I.e., same amount of MUs create greater force by firing more rapidly (temporal).

ii) more new MUs are being recruited (spatial). This follows the orderly or the size principle, presented before.

Forc

e (%

of M

VC)

MUs

MU activation

Light contraction

Strong contraction

Could we summarize this..?

EMG is about measuring the electric activity of muscles. The level of this activity is determined by the motor units: the higher the load the higher is the firing rate of MUs and also more MUs are being recruited in order to create greater force. Or inversely and simplified: the stronger the muscle contraction, the greater is the electrical activity.

This technique can be applied in many ways to evaluate the muscular work and function.

EMG can be used, for example, to evaluate the muscle function, capacity, fatigue, force production, or to analyze

activation patterns and biomechanics of human movement, or to detect problems, medical abnormalities or deviations

of neuromuscular system.

How have EMG been measured in practice?

Tradionally, tiny, needle-like sensors are placed straight into the muscle tissue to gain the muscle data. This method is still often used in clinical, diagnostic setups.

For more practical cases, non-invasive surface-EMG is used. In this method, disposable electrodes are being glued on skin.

Difficult and time-consuming preparation, and also issues with the reliability of the measurement procedure has hindered the applicability of EMG in habitual situations, especially during strenuous activities and exercises.

Can we measure EMG with wearables?

All the electronics, wiring and sensors are seamlessly integrated in high-quality compression sportswear.

Small, light-weight EMG unit with high frequency sampling rate, memory and wireless communication is being attached to the textile.

PROS+ no loose electrodes, snap

connectors, or loose wires nor cables

+ easy & quick preparation: “gear up and go”

+ motion artefact minimized + extremely good signal quality even during the most extreme and strenuous exercises

+ sensoring bigger area offers better reproducibility (reliability, stability), especially during exercises

+ fully machine washable+ price, simplicity, ease-of-use

CONS

- sensoring bigger area causes cross-talk & signal cancellation, leading diagnostic insensitivity in single motor unit level.

Myontec’s wearable system offers valid and reliable EMG data added with ease-of-use, convenience, and applicability in the field.

For what can we utilize this technology for?

field measurementperformance analysis

Sports & exercise

Fysio & rehabilitation

Health & wellbeing

Occupational health & ergonomics

Medical solutions

Entertainment, gaming

Possibilities for utilizing this technology in different areas are almost endless.

biofeedback

injury prevention

problem detection

training periodization

screening technique analysis

strain analysis

biomechanics analysisdiagnostics

education

The complete picture

better knowledgebetter training

better performancebetter results

Myontec is an innovator. It is an entrepreneurial company, taking the invention of muscle measurement to marketable products and applications

by integrating existing data and adding unique information to it

thereby creating an additional dimension to better understand and manage the human body & perfromance.

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Want to know more: www.myontec.com