Trunk endurance tests are widely used in physical medicine to assess the muscle status of people affected by low back pain. Nevertheless, traditional evaluation procedures suffer from practical limitations, which can lead to potential misdiagnoses. This work presents mDurance, a novel mobile health system aimed at supporting specialists in the functional assessment of trunk endurance by using wearable and mobile devices. The system makes use of a wearable inertial sensor to track the patient trunk posture, while portable electromyography sensors are employed to seamlessly measure the electrical activity produced by the trunk muscles. The information registered by the sensors is processed and managed by a mobile application that facilitates the expert normal routine, while reducing the impact of human errors and expediting the analysis of the test results. The reliability and usability of mDurance is proved through a case study, thus demonstrating its potential interest for regular physical therapy routines.

1. Facilitating Trunk Endurance
Assessment by means of Mobile
Health Technologies
Oresti Banos, Jaehun Bang, Donguk Kang,
Choong Seon Hong, Sungyoung Lee
Ubiquitous Computing Lab, Department of Computer
Engineering, Kyung Hee University, Korea
oresti@oslab.khu.ac.kr
Trunk endurance tests are widely used in physical medicine to assess the muscle status of people affected by low back pain. Nevertheless,
traditional evaluation procedures suffer from practical limitations, which can lead to potential misdiagnoses. This work presents mDurance,
a novel mobile health system aimed at supporting specialists in the functional assessment of trunk endurance by using wearable and mobile
devices. The system makes use of a wearable inertial sensor to track the patient trunk posture, while portable electromyography sensors are
employed to seamlessly measure the electrical activity produced by the trunk muscles. The information registered by the sensors is
processed and managed by a mobile application that facilitates the expert normal routine, while reducing the impact of human errors and
expediting the analysis of the test results. The reliability and usability of mDurance is proved through a case study, thus demonstrating its
potential interest for regular physical therapy routines.
Keywords: Mobile Health; Physical Therapy; Trunk Endurance; Inertial Sensors; EMG Sensors
Abstract
Trunk Endurance Assessment - TEA
The system consists of a wearable inertial sensor to estimate the trunk position
and an attachable electromyography sensor to measure the activity of the
skeletal muscles of the trunk. The sensor data is transmitted to a mobile
application for the data processing and analysis. The app automatically estimates
the duration of the test, presents the physiological responses of the patient and
generates reports summarizing the patient status and evolution.
mDurance: a Novel Mobile Health System for TEA
This work was supported by the Industrial Core Technology Development Program (10049079,
Development of mining core technology exploiting personal big data) funded by the Korean Ministry
of Trade, Industry and Energy. This work was also supported by the Junta de Andalucia Project P12-
TIC-2082 and FPU Spanish Grant AP2012-1789.
Jose Antonio Moral Munoz, Ignacio Diaz Reyes,
Manuel Arroyo Morales, Miguel Damas, Hector
Pomares, Ignacio Rojas, Claudia Villalonga
Research Centre for Information and
Communications Technology,
University of Granada, Spain
mDurance
App
mDurance
Sensors
mDurance
Core
Technology
ACC, GYR, MAG, EMG
Ten volunteers (8 males and 2 females, 21-37 years old) were recruited to be
evaluated by three external physical therapists using both mDurance and
traditional procedures:
• In the traditional approach experts had to visually determine the start and end of
each test and time it using a stopwatch  ΔTtraditional
• When using mDurance these processes were automated  ΔTmDurance
Evaluation
Inter-rater reliability
• Measures the agreement between
both methods (ΔTtraditional –
ΔTmDurance)
• All the differences fall within the
limits of agreement, thus
confirming that both methods can
be used interchangeably
Usability
• Experts appreciate the practicality of
the automatic angle measurement
to determine the user start position
and to estimate the end-of-test
• They also value the EMG online
representation to observe the
muscle contraction during the test
• System Usability Scale (SUS) scores
indicated high levels of acceptability,
ease of use and confidence when
utilizing mDurance
Acknowledgements
TEA consists in the measurement of the time a person can hold a
specific posture involving the trunk muscles:
• The Sorensen test is the most common medical procedure for TEA
• The subject has to hold a horizontal unsupported posture while extending the
upper body beyond the edge of a bench
• The timing begins when the posture is horizontal and unsupported, and the
test ends when a) the position is held 240s or b) the trunk position drops >10°
High
Subjectivity
Limitations of traditional TEA:
• The human expert has to estimate the start and end visually
• The expert has to supervise various aspects simultaneously,
such as time, position, and possible abnormalities during the
test
• Specialists elaborate their diagnosis on the recorded time, and
that is the only information to compare with in future tests