Electrodermal activity measurement shows athletes new information

Different kinds of physiological measurement systems have been used for a long time in top sports. Wearable devices have made exercise tracking easy for everyone.

Heart rate monitoring is the most used measurement in sports. It was developed by an Australian physician Robert Treffene for swim exercising. In Finland hear rate monitor was invented by the Polar Electro founder, professor Seppo Säynäjäkangas in 1975.

Today there is a huge variety of equipment for hear rate monitoring. The most accurate ones still measure from chest, either with a band or with taped sensors. Wrist worn trackers are comfortable to wear and they have largely displaced chest bands especially with non-professional exercisers. The accuracy of wrist worn trackers has been improved in past years, but it suffers especially at high heart rates.

Heart rate, heart rate variability (HRV) and electrodermal activity (EDA)

Analysing heart rate gives a good view of physical strain. With different algorithms it is possible to understands also recovery, sleep and stress.

Heart rate variability (HRV) has been lately brought up especially in measuring non-physical load. There are challenges, as at high heart rates the algorithms struggle to understand what happens: is the person physically at rest, but nervous (e.g. about a soon-to-start exam), or is it now about physical exercise? Here the accelerometers, present in all of the trackers, are of help. These components can detect whether a person is moving or is at rest, and much more about movement directions and pace.

The electrodermal activity (EDA) measurement brings interesting new information to analyse performance of an athlete. This does not tell about heart, but about sympathetic nervous system activation through sweat gland reactions of skin. Skin is the only organ that is purely innervated by the sympathetic nervous system. The EDA measurement is very sensitive to emotional and cognitive stress, and it has been used in psychological research already for over 100 years. Only lately it has become available for consumers.

The Moodmetric smart ring measures electrodermal activity. The ring is comfortable to wear and it is thus well suited for continuous, long term measurement. Only a sufficiently long measurement period gives a full picture on stress, how it is generated and how recovery happens during weeks, months and even years.

Both top sports, and going after personal goals in exercising benefit of stress load related information. It is good to understand what sources of stress or recovery might affect the performance. For instance, cognitive load of a professional athlete might be less than for someone who need to have a day job to finance the sports career. The professional athlete can probably exercise more, as there is more time for recovery. The results and performance are affected by emotional and cognitive load, if there is no time to unwind.

Read more: Moodmetric-measurement in research

Moodmetric will participate SMASH-sports event in Helsinki the 28-29th November, come to meet us and test the smart ring!

Contact:
Niina Venho
[email protected]
+358 40 710 4087

Moodmetric data analytics tool

The Moodmetric data analytics tool is created to support research and development projects related to EDA (electrodermal activity) measurements.

The tool enables researchers and developers to quickly process and visualize large Moodmetric data sets in uniform manner. It generates both group and individual level reports based on input data from wearable devices. The tool is released as open source for anyone to benefit of the Moodmetric measurement data in various use cases.

Download the Moodmetric data visualization tool instruction here.

For more information, contact
Jari Jussila
[email protected]
+358 40 717 8345

Electrodermal activity measured by the Moodmetric ring

Electrodermal activity

With any sympathetic nervous system activation, skin reacts and becomes a better conductor of electricity. This can result from emotional, cognitive or other psychological origin. The phenomenon is known as electrodermal activity (EDA) and it is widely adopted in psychological research (1). Other commonly used terms for this phenomenon are skin conductance response and galvanic skin response.

EDA is generated by the activity of the sweat glands.  Moodmetric measures the palmar skin on your finger. The palmar skin is the recommended EDA measurement location, since it has the highest eccrine sweat gland density (2). You can measure EDA elsewhere as well but the reliability is not as high or as easily achieved.

The unconscious actions of the human body are regulated by the autonomic nervous system. It consists of the sympathetic part and the parasympathetic part. The parasympathetic part controls the body’s rest-and-digest functions and the sympathetic part controls the fight-or-flight reactions. With EDA, we can examine the latter.

The sweat glands are exclusively innervated by the sympathetic nervous system. This makes EDA an ideal measure for sympathetic activation (2). Electrodermal activity correlates to general cognitive and emotional intensity, and high responses are caused by e.e. stress, enthusiasm, anxiety, joy, anger (1, 3).

Mobile EDA devices have been used by scientists for some time (2, 4). The Moodmetric ring is an unobtrusive option to follow EDA responses real-time and in long term.

Signal accuracy

The signal accuracy has been proven in a study of 24 people by the Finnish Institute of Occupational Health by J. Torniainen et al.. The accuracy against a laboratory grade reference was found to be 83 %. They conclude:

“Clearly the ring sensor can be used to measure a valid EDA signal as indicated by the similarity of both event-related responses and the calculated features. The accuracy of the Moodmetric EDA Ring is adequate for psychological and physiological research when weighted against the advantage of conducting ecologically valid experiments outside laboratory conditions.”

The results were accepted for publication in the 2015 conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2015, August 25-29).

The Moodmetric measurement has also been proven to be accurate by THe University of Tampere, Finland. The correlation with the reference equipment Nexus-10-MK II was good. Comparison details in charts below.

With skin conductance level (SCL) we refer here to raw measured skin conductance without any filtering. The figures below show the comparison of the two devices. 

References

1 Mendes, W.B. (2009). Assessing the autonomic nervous system. In: Harmon-Jones   E. ja Beer J.S. Methods in social neuroscience. New York: Guilford Press. p. 118-147.

2 Setz C., Arnrich B., Schumm J. and La R. (2010) Discriminating Stress From Cognitive Load Using a Wearable EDA Device. IEEE Trans. Inf. Technol. Biomed. 14(2). p. 410-417.

3 Nikula R. (1991) Psychological correlates of nonspecific skin conductance responses. Psychophysiology. 28(1). p.86-90.

4 Poh M.Z, Swenson N.C. and Picard R.W. (2010) A Wearable Sensor for Unobtrusive, Long-Term Assessment of Electrodermal Activity. IEEE Trans. Biomed. Eng. 57(4). p. 1243-1252.

 

 

Assembling the Rings

Emotion load indication through electrodermal activity or skin conductance measurement is a rising trend in the modern wearable technology. Most manufacturers use the word stress as a synonym for emotional load.
Wearables are typically forced to use dry skin electrodes in varying conditions, with movement present. Ideally the system should be able to detect, interpret and visualize underlying electrodermal activity changes caused by autonomous nervous system reactions.
Typically the following challenges are present:
• Dry and sweaty hands produce autonomic responses with significantly different amplitudes
• Different people produce significantly different response amplitudes
• Analysis is subject to constant motion artifacts
The Moodmetric algorithm is developed to produce higher lever emotional information of the wearer, based on the raw conductivity signal received.

 

The first Moodmetric rings have been produced. The ring is improved version of the beta sample, that has been in user testing since October 2014. The electronics manufacturing and 3D-printing of the covers of the new version was made in August 2015. The stone assembly could now be completed:

 

FullSizeRender4

The two steel rings with an insulation in between is the actual sensor needed to detect the changes in skin conductivity. The ring comes in four sizes: US (6.5, 8, 10 and 12.5), EU (17, 18,5, 20 and 22 mm). It is exchangeable which enables several users to the same stone. This reduces cost but note: excessive swapping causes the snaps to wear out.

ringit

The final product is small and lightweight. It connects with the Moodmetric app automatically and displays your emotional intensity real-time.

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Where to measure electrodermal activity?

This article explains the difference of using a wristband or a ring to measure your emotional intensity levels.

Moodmetric rings

Many things can get you emotionally activated. A close by situation with a colliding car can certainly light all the inner alarm systems, but milder things can also cause strong emotional reactions: seeing your children after a school day, a victory of you favourite basketball team or forgetting to buy paper for your printer.

With any emotional activation, your skin reacts and becomes a better conductor of electricity. This can be resulting from emotional or other psychological causes. The phenomenon is known as the skin conductance response or electrodermal activity (EDA). You may also run into an older term called galvanic skin response.

Based on the scientific research there are only a few places in your body where the EDA can be measured accurately and easily: the palms and the soles of your feet. These are the places where human body has the highest density of eccrine sweat glands that response to the emotional stimuli. You can measure the EDA elsewhere as well but the reliability is not as high or as easily achieved.

We want to bring to the market a very reliable and accurate measurement of emotional activation and intensity that is available for everybody. The choice for having a beautiful jewelry ring as the measurement form was an easy one.

It provides the best optimal measurement data that can be detected from the palm side of wearer’s hand. A ring is also a natural thing to wear and can be used daily as any other jewelry. It is easy to forget that this small, beautiful and non-intrusive jewelry detects your emotional levels and helps you in your life with its data.

What is moodtech? – Science behind Moodmetric

Moodmetric measures the electrodermal activity (EDA) of the skin, which is widely adopted in psychological research 1. EDA is generated by activity of the sweat glands.  Moodmetric measures the palmar skin on your finger. The palmar skin is the recommended EDA measurement location, since it has the highest sweat gland density2.

The unconscious actions of the human body are regulated by the autonomic nervous system. It consists of the sympathetic part and the parasympathetic part. The parasympathetic part controls the body’s rest-and-digest functions and the sympathetic part controls fight-or-flight reactions. When bodily functions are not of interest and the emotional side is, sympathetic nervous system is your choice.

The sweat glands are exclusively innervated by the sympathetic nervous system. This makes EDA an ideal measure for sympathetic activation.2 Electrodermal activity correlates to general emotional intensity, negative emotion, concern, and anxiety. 1, 3 These emotions cause almost similar electrodermal responses, which makes them very hard to differentiate. However, Moodmetric will tell you if certain parts of your day have brought up emotions or not. Inversely, Moodmetric tells you weather you are calm or not. This is particularly useful during your mindfulness, meditation and other calming exercises.

Mobile EDA devices have been used by scientists for some time2, 4, and now we bring this technology within everyone´s reach.

Signal accuracy

The signal accuracy has been proven in a study of 24 people by the Finnish Institute of Occupational Health by J. Torniainen et al.. The accuracy against a laboratory grade reference was found to be 83 %. They conclude:

“Clearly the ring sensor can be used to measure a valid EDA signal as indicated by the similarity of both event-related responses and the calculated features. The accuracy of the Moodmetric EDA Ring is adequate for psychological and physiological research when weighted against the advantage of conducting ecologically valid experiments outside laboratory conditions.”

The results have been accepted for publication in the 2015 conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2015, August 25-29).

Our measurement has been proven to be accurate also by University of Tampere, Finland. The correlation with the reference equipment Nexus-10-MK II was good. Comparison details in charts below.

image1 image2 image3 image4

1 Mendes, W.B. (2009). Assessing the autonomic nervous system. In: Harmon-Jones   E. ja Beer J.S. Methods in social neuroscience. New York: Guilford Press. p. 118-147.

2 Setz C., Arnrich B., Schumm J. and La R. (2010) Discriminating Stress From Cognitive Load Using a Wearable EDA Device. IEEE Trans. Inf. Technol. Biomed. 14(2). p. 410-417.

3 Nikula R. (1991) Psychological correlates of nonspecific skin conductance responses. Psychophysiology. 28(1). p.86-90.

4 Poh M.Z, Swenson N.C. and Picard R.W. (2010) A Wearable Sensor for Unobtrusive, Long-Term Assessment of Electrodermal Activity. IEEE Trans. Biomed. Eng. 57(4). p. 1243-1252.

 

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