EMG & Beyond
05 August 2024

What is the Ideal Slope in Downhill Running?

Combining Trigno EMG and VO₂

Introduction

Combining critically important physiological data enables clinicians and researchers to assess an individual’s performance and wellbeing like never before. Link serves as a bridge between the worlds of electromyography and performance physiology. For instance, VO₂, an indicator of cardiorespiratory fitness.

Using the Link, we can now ask the question: what are the benefits of combining VO₂ with EMG? This question is explored in the research project by Thomas Lapole and Gabriel Idda, from the Laboratory of Human Movement Biology (LIBM) at Jean Monnet University at Saint-Etienne.

What is VO2 Master?

VO2 Master is a portable metabolic analyzer.

Why combine EMG and VO2 Master?

By combining EMG and VO2 data, Lapole and Idda explore the energy costs of downhill running in their paper, What is the ideal slope in downhill running? A laboratory and field study to get insights into biomechanical and physiological determinants of cost of running.

How can EMG and VO2 Master be integrated?

Trigno Link is the future of integration and offers a combined platform for measuring Trigno EMG and VO₂ from VO2 Master alongside other physiological measures, including muscle oxygenation, heart rate, and hand dynamometry.

Background

VO₂ is a commonly used tool within sports science, physiology, and human performance assessments. It measures the maximum amount of oxygen an individual can utilize during exercise. VO₂ is a measure of aerobic capacity and is commonly used to assess an individual’s fitness level, to establish resting metabolic rates, examine ventilatory thresholds and provide information on the time spent in different training zones during a protocol.

VO2 Master is the first and only true portable VO₂ analyzer on the market. It provides a new platform to analyze performance and, through the cable free design, allows for metabolic performance to be monitored on the go.

EMG is an experimental technique, typically used within human movement assessments and performance monitoring, that involves the recording and analysis of the electrical signals that emanate from the muscles during contractions and force production. By gaining insight into the status of muscular excitation, researchers, clinicians, sports practitioners, and engineers have been able to determine:

The level of muscular effort involved –gained from assessing the overall EMG signal amplitude.
Coordination between muscles – assessed by the activation timings of muscles.
The effects of muscle fatigue – an exploration of the frequency component of the EMG signal.
Neural control strategies – how the brain is adapting to training or external stimuli

Combining EMG and VO₂ measurements offer several benefits, including:

Improved Accuracy

By combining EMG and VO₂ measurements, researchers can obtain more accurate and comprehensive data on muscle activity, energy expenditure, and metabolic demand during physical activities.

Better Insight into Muscle Function

The simultaneous measurement of EMG and VO₂ allows for a more detailed understanding of how muscles function during exercise, as well as how they respond to changes in workload, intensity, and duration.

Enhanced Treatment Planning

Healthcare professionals can use the information obtained from EMG and VO₂ measurements to develop more effective treatment plans for patients with muscle and metabolic disorders, such as neuromuscular diseases and diabetes.

Increased Efficiency of Training Programs

Combining EMG and VO₂ measurements can help coaches and athletes optimize training programs by identifying the most effective exercises, intensity levels, and recovery periods needed to improve performance and reduce the risk of injury.

Overall, the integration of EMG and VO₂ measurements can provide valuable insights into the physiological processes that underlie physical activity, which can be useful for a range of applications, from sports performance training to rehabilitation and medical treatment planning.

To see how a real Delsys user takes advantage of Trigno Link to conduct research in the field of exercise science, read the story below:

What is the ideal slope in downhill running? A laboratory and field study to get insights into biomechanical and physiological determinants of cost of running.

Despite extensive literature on the energy cost (Cr) of level running, there has been a noticeable lack of research done on downhill running, which differs from level running both mechanically and in terms of energy expenditure. While existing research has established an estimate of the optimal downhill slope for minimizing Cr during running, the causes of this optimal slope are yet to be determined. The research by Lapole and Idda aims to evaluate the muscular and biomechanical determinants of this optimal slope by collecting EMG and accelerometer data. Using Trigno Link, they will simultaneously record VO₂ to measure the metabolic costs of running at different negative slopes.

Experiment Equipment

Equipment Type	Equipment Name
Software	Trigno Discover 1.7.0
System	Trigno Lite
Hardware	Trigno Link
Sensor	Trigno Avanti
Biofeedback Device	VO2 Master
Other	Instrumented Treadmill
	Isokinetic Dynamometer

Experiment Protocol

The experiment was conducted over 2 sessions. The first session began with a data collection on an Isokinetic dynamometer to record EMG MVC data for normalization. After a rest period, Subjects ran a randomly ordered conditions of 5 slopes over 2 speeds (0,-5,-10, -15, and –20% slopes; 10 and 12 km/hr velocities). The second session involved a similar normalization session, with the same slope and speed conditions anda slight change in the duration of the trials. EMG data was collected from the Gastroc Lateralis (GL) and the Vastus Lateralis (VL), while Peak Propulsive Force (PPF) and Peak Braking Force (PBF) were collected from the Instrumented Treadmill.

Acquisition and Analysis

Trigno Lite was used to collect EMG data and the Trigno Link was used to synchronously collect VO₂ data. This data was recorded in Trigno Discover 1.7.0. Third-party software programs were used to collect data from the instrumented treadmill. The team at LIBM explored the relationship between EMG, VO₂, and ground reaction forces detected by the instrumented treadmill.

Results and Discussion

The lowest cost of running within the tested conditions was seen at a ~13.7% decline when the speed was set to 10 km/hr and at ~14.3% decline when the speed was set to 12 km/hr. As treadmill angle decreased, GL muscle activity decreased, VO₂ decreased, and PPF increased. Since GL is a primarily propulsive muscle, there are strong relationships between PPF, VO₂, and GL muscle activity as a product of treadmill angle.

When examining the VL, a slightly different view of the data is seen. PBF displays a positive correlation with the severity of the decline. VL muscle activity increases alongside PBF, implying that the VL plays a larger role in braking strategies the steeper the decline gets. However, VL muscle activity and VO₂ consumption are slightly negatively correlated. This relationship between muscles involved in braking and VO₂ consumption leads to further avenues of investigation on VO₂ and braking strategies in downhill running.

Expanding with Link

Lapole and Idda intend to broaden their research further by taking it out of the lab and into the field, an area lacking in prior research. By comparing the costs of running between the lab and the field, they hope to develop a more holistic understanding of Cr during downhill running.

To learn more about Trigno Link and to explore how it can be used for studying exercise science, please visit Link Webpage.

References

Sports Performance

Read Article

Exoskeleton Development

Read Article

Muscle Function

Read Article

FAQs

Do I need to use Trigno EMG sensors with my Trigno Link?

Yes, the Trigno Link is designed to integrate third-party biofeedback data with EMG. Therefore, the Link cannot be used without pairing a Trigno EMG sensor.

Can Trigno Link be used with other software? What about third-party software?

Currently, the Trigno Link can be only utilized within our Trigno Discover software. However, additional metrics can be brought into Trigno Discover via the use of our analog adapter or trigger module.

Trigno Link connects to both Bluetooth and ANT+ wireless devices; can it connect to both at the same time?

The Link can only connect to either Bluetooth or ANT+ at any given time. Refer to the following table for a full wireless connection compatibility guide to all our third-party devices:

ANT+	Bluetooth
Polar Heart Rate	Polar Heart Rate
Moxy NIRS Sensor	Moxy NIRS Sensor
Wahoo Cadence Sensor	Wahoo Cadence Sensor
Wahoo Bike Ergometer	VO2 Master
	Jamar Hand Dynamometer