The Open Biomedical Engineering Journal




ISSN: 1874-1207 ― Volume 13, 2019
RESEARCH ARTICLE

Reliability and Validity of the Feedback Sensor for Activating the Transversus Abdominis Muscle



Duangruedee Dissanguan1, Patraporn Sitilertpisan1, *, Suchart Kiatwattanacharoen2, Leonard H. Joseph3, Pinyo Puangmali4, Aatit Paungmali1, *
1 Department of Physical Therapy, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand
2 Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand
3 School of Health Science, University of Brighton, East, Sussex, United Kingdom
4 Department of Mechanical Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand

Abstract

Background:

Core muscle activation is an effective intervention for the management of Low Back Pain (LBP). This study developed new feedback for detecting activation of the transversus abdominis muscle in the lumbar spine. The purpose of this study was to examine the validity and reliability of the feedback device for transversus abdominis muscle contraction.

Methods:

The participants in this study were 20 healthy males and females (aged 24.1 ± 6.8 years). The feedback sensor was attached to the lumbar support at the front of the trunk. The participants performed an abdominal drawing-in maneuver in order to activate the transversus abdominis muscle, and values from the feedback sensor were collected at the same time. Ultrasound imaging of the transversus abdominis muscle was also collected simultaneously. The feedback sensor collected values at different clinical levels of the pressure biofeedback unit at 64, 66, 68, and 70 mmHg. The protocol was repeated with a 24-hr interval. Intra-class correlation coefficient, coefficient of variation and standard error of measurements were used to examine reliability. The validity of the values obtained from the relationship between the feedback sensor and transversus abdominis muscle thickness was analyzed using Pearson’s correlation coefficients.

Results:

Test–retest reliability of the feedback sensor was excellent (ICC = 0.946, CV = 2.6%, SEMs = 0.54%). Values of the feedback sensor reported a significantly moderate correlation with the gold standard ultrasound measurement (r = - 0.514, p < 0.001).

Conclusion:

The feedback device demonstrated potential reliability and validity for clinical use by indicating activation of the transversus abdominis muscle.

Keywords: Validity, Reliability, Transversus abdominis, Feedback, Sensor, Core muscles, Ultrasound.


Article Information


Identifiers and Pagination:

Year: 2019
Volume: 13
First Page: 67
Last Page: 73
Publisher Id: TOBEJ-13-67
DOI: 10.2174/1874120701913010067

Article History:

Received Date: 03/01/2019
Revision Received Date: 23/03/2019
Acceptance Date: 05/04/2019
Electronic publication date: 30/04/2019
Collection year: 2019

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© 2019 Dissanguan et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: (https://creativecommons.org/licenses/by/4.0/legalcode). This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


* Address correspondence to these authors at the Department of Physical Therapy, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand; Tel: +66089422366; Fax: +66 053946042;
E-mails: aatit.p@cmu.ac.th, patraporn.s@cmu.ac.th





1. INTRODUCTION

The Transversus Abdominis (TrA) muscle has been considered an important component of lumbopelvic stability [1P.W. Hodges, and C.A. Richardson, "Delayed postural contraction of transversus abdominis in low back pain associated with movement of the lower limb", J. Spinal Disord., vol. 11, no. 1, pp. 46-56.[http://dx.doi.org/10.1097/00002517-199802000-00008] [PMID: 949 3770] , 2V. Akuthota, A. Ferreiro, T. Moore, and M. Fredericson, "Core stability exercise principles", Curr. Sports Med. Rep., vol. 7, no. 1, pp. 39-44.[http://dx.doi.org/10.1097/01.CSMR.0000308663.13278.69] [PMID: 18296944] ]. Previous studies [1P.W. Hodges, and C.A. Richardson, "Delayed postural contraction of transversus abdominis in low back pain associated with movement of the lower limb", J. Spinal Disord., vol. 11, no. 1, pp. 46-56.[http://dx.doi.org/10.1097/00002517-199802000-00008] [PMID: 949 3770] , 3P.W. Hodges, and C.A. Richardson, "Contraction of the abdominal muscles associated with movement of the lower limb", Phys. Ther., vol. 77, no. 2, pp. 132-142.[http://dx.doi.org/10.1093/ptj/77.2.132] [PMID: 9037214] -5T. Miura, M. Yamanaka, K. Ukishiro, H. Tohyama, H. Saito, M. Samukawa, T. Kobayashi, T. Ino, and N. Takeda, "Individuals with chronic low back pain do not modulate the level of transversus abdominis muscle contraction across different postures", Man. Ther., vol. 19, no. 6, pp. 534-540.[http://dx.doi.org/10.1016/j.math.2014.05.010] [PMID: 25009124] ] demonstrated that the TrA was activated prior to limb movement, and its automatic contraction occurred during postural changes, which increased spinal stability in asymptomatic individuals. Adults with Low Back Pain (LBP) showed a delayed contraction of the TrA during limb movement and less activation of it while performing postural changes [5T. Miura, M. Yamanaka, K. Ukishiro, H. Tohyama, H. Saito, M. Samukawa, T. Kobayashi, T. Ino, and N. Takeda, "Individuals with chronic low back pain do not modulate the level of transversus abdominis muscle contraction across different postures", Man. Ther., vol. 19, no. 6, pp. 534-540.[http://dx.doi.org/10.1016/j.math.2014.05.010] [PMID: 25009124] ]. The presence of LBP suggested an impaired neuromuscular system for controlling and protecting the spine [6E. Lederman, "The myth of core stability", J. Bodyw. Mov. Ther., vol. 14, no. 1, pp. 84-98.[http://dx.doi.org/10.1016/j.jbmt.2009.08.001] [PMID: 20006294] ]. Therefore, TrA muscle training is suitable for preventing and managing LBP.

Core stability exercise is an effective intervention for reducing pain and recurrence in LBP patients [7G.E. Hicks, J.M. Fritz, A. Delitto, and S.M. McGill, "Preliminary development of a clinical prediction rule for determining which patients with low back pain will respond to a stabilization exercise program", Arch. Phys. Med. Rehabil., vol. 86, no. 9, pp. 1753-1762.[http://dx.doi.org/10.1016/j.apmr.2005.03.033] [PMID: 16181938] , 8C. Demoulin, V. Distrée, M. Tomasella, J-M. Crielaard, and M. Vanderthommen, "Lumbar functional instability: A critical appraisal of the literature", Ann. Readapt. Med. Phys., vol. 50, no. 8, pp. 677-684, 669-676.[http://dx.doi.org/10.1016/j.annrmp.2007.05.007] [PMID: 17597247] ]. Abdominal Drawing in Maneuver (ADIM) is a technique that promotes co-contraction of the TrA and lumbar multifidus muscle [9D.S. Teyhen, C.E. Miltenberger, H.M. Deiters, Y.M. Del Toro, J.N. Pulliam, J.D. Childs, R.E. Boyles, and T.W. Flynn, "The use of ultrasound imaging of the abdominal drawing-in maneuver in subjects with low back pain", J. Orthop. Sports Phys. Ther., vol. 35, no. 6, pp. 346-355.[http://dx.doi.org/10.2519/jospt.2005.35.6.346] [PMID: 16001906] ]. It was proved that activation of the TrA muscle increased the stability of the spine, due to improved motor control, increased abdominal pressure and tightened thoracolumbar fascia [10P.W. Hodges, "Is there a role for transversus abdominis in lumbo-pelvic stability?", Man. Ther., vol. 4, no. 2, pp. 74-86.[http://dx.doi.org/10.1054/math.1999.0169] [PMID: 10509061] -12A.G. Cresswell, L. Oddsson, and A. Thorstensson, "The influence of sudden perturbations on trunk muscle activity and intra-abdominal pressure while standing", Exp. Brain Res., vol. 98, no. 2, pp. 336-341.[http://dx.doi.org/10.1007/BF00228421] [PMID: 8050518] ]. LBP patients, who were prescribed core stability exercise, demonstrated improvement of pain and disability associated with their condition [13J.A. Hides, G.A. Jull, and C.A. Richardson, "Long-term effects of specific stabilizing exercises for first-episode low back pain", Spine, vol. 26, no. 11, pp. E243-E248.[http://dx.doi.org/10.1097/00007632-200106010-00004] [PMID: 1138 9408] , 14X-Q. Wang, J-J. Zheng, Z-W. Yu, X. Bi, S-J. Lou, J. Liu, B. Cai, Y.H. Hua, M. Wu, M.L. Wei, H.M. Shen, Y. Chen, Y.J. Pan, G.H. Xu, and P.J. Chen, "A meta-analysis of core stability exercise versus general exercise for chronic low back pain", PLoS One, vol. 7, no. 12, p. e52082.[http://dx.doi.org/10.1371/journal.pone.0052082] [PMID: 23284879] ].

There are various feedback methods used to indicate TrA activation in research and clinical settings such as Electromyography (EMG), ultrasonography, Pressure Biofeedback Unit (PBU) and palpation [15S. Lee, S. Han, and D. Lee, "Comparison of abdominal muscle thickness according to feedback method used during abdominal hollowing exercise", J. Phys. Ther. Sci., vol. 28, no. 9, pp. 2519-2521.[http://dx.doi.org/10.1589/jpts.28.2519] [PMID: 27799683] -18S.M. Henry, and K.C. Westervelt, "The use of real-time ultrasound feedback in teaching abdominal hollowing exercises to healthy subjects", J. Orthop. Sports Phys. Ther., vol. 35, no. 6, pp. 338-345.[http://dx.doi.org/10.2519/jospt.2005.35.6.338] [PMID: 16001905] ]. EMG is an invasive method that is limited in its adoption [19J.M. McMeeken, I.D. Beith, D.J. Newham, P. Milligan, and D.J. Critchley, "The relationship between EMG and change in thickness of transversus abdominis", Clin. Biomech. (Bristol, Avon), vol. 19, no. 4, pp. 337-342.[http://dx.doi.org/10.1016/j.clinbiomech.2004.01.007] [PMID: 15109 752] ]. Lee and colleagues [15S. Lee, S. Han, and D. Lee, "Comparison of abdominal muscle thickness according to feedback method used during abdominal hollowing exercise", J. Phys. Ther. Sci., vol. 28, no. 9, pp. 2519-2521.[http://dx.doi.org/10.1589/jpts.28.2519] [PMID: 27799683] ] compared the effectiveness of three feedback methods (i.e. ultrasonography, PBU, and palpation) for contracting the TrA muscle and found that using visual feedback was more effective than only palpation. However, there was a limitation in using visual feedback methods while performing functional tasks or during activity of daily living. Therefore, clinicians need an affordable, reliable, and valid alternative tool to deal with TrA activation during functional positions. This study intended to develop a sensor tool for the detection and feedback of core muscle activation while wearing lumbar support, which is portable and easy to use. However, this new device needed to be proven for its reliability and validity.

Therefore, the purpose of this study was to determine the validity and reliability of a Feedback Sensor (FS) device for detecting TrA muscle contraction using real-time ultrasound imaging as a gold standard comparative tool.

2. MATERIALS AND METHODS

The protocol was approved by the Institutional Ethics Committee according to the Declaration of Helsinki principles. All participants gave written informed consent before the study began.

2.1. Participants

Twenty healthy male and female subjects (aged 24.1 ± 6.8 years; 7 males, 13 females, height 164.5 ± 9.1 cm. and weight 64.2 ± 8 kg.) participated in this study. They were recruited from the university and areas of the community from December 2017 to January 2018. Those with a history of LBP during the previous three months, lumbar surgery, pregnancy, neuromuscular or joint disease or neurological conditions affecting the trunk were excluded.

2.2. Development of the Feedback Sensor (FS) Unit

The FS unit was designed and developed using a pressure sensor. Once built, it was attached to the inner site of the lumbar support. Decreased value of FS pressure was interpreted as increased activation of the TrA.

2.3. Procedure

All of the participants were instructed to perform the ADIM using the PBU (Chattanooga Group Inc., USA) as a feedback tool.

The FS was applied at the front of the TrA muscle [1 inch above the Anterior Superior Iliac Spine (ASIS) and 4 inches lateral to the umbilicus], but underneath the lumbar support. One PBU was placed centrally between the umbilicus and the lumbar support and another between the lumbopelvic region (upper border at the L2 level) and lumbar support. The lumbar support was worn firmly, and the PBU at the front was pumped to 70 mmHg, and that at the back to 40 mmHg. The participants were positioned standing upright, with the trunk stabilized by the wall. They achieved core muscle activation in the functional standing position by performing the ADIM at various levels of pressure (i.e., 70, 68, 66, and 64 mmHg, consecutively). Pressure of the PBU at the back was maintained at 40 mmHg for controlling the neutral spinal position. Values from the FS and images of the TrA muscle were collected simultaneously while the ADIM was performed at each level. Decreased sensor values indicated the amount of TrA muscle activation. The participants were allowed to rest for 1 minute between each trial. Each level of pressure and the image were collected three times. The average value was calculated. The participants were also scheduled for two sessions of reliability study with a 24-hour interval between them.

2.4. Outcome Measurements

Real-time ultrasound imaging was used to investigate the amount of TrA muscle contraction during various levels of ADIM performed against the force production from the FS attached to the lumbar support. The ultrasound scanner (Toshiba, Famio 8, SSA-530A) in B-mode, with a 5-MHz curvilinear transducer, was used to assess TrA muscle thickness. The participants were positioned standing in an upright position. Ultrasonic gel was applied between the transducer and skin. The transducer was placed in the transverse plane at a point 2.5 cm anteromedial to the midpoint between the lower rib and iliac crest on the mid-axillary line [19J.M. McMeeken, I.D. Beith, D.J. Newham, P. Milligan, and D.J. Critchley, "The relationship between EMG and change in thickness of transversus abdominis", Clin. Biomech. (Bristol, Avon), vol. 19, no. 4, pp. 337-342.[http://dx.doi.org/10.1016/j.clinbiomech.2004.01.007] [PMID: 15109 752] ]. The image was captured at the end of exhalation. After that, muscle thickness was measured during TrA activation at each pressure level of the PBU. Thickness of the TrA was measured randomly on both sides. Images and measurements of the TrA were obtained using NIH (Bethesda, MD) Image J software (V 1.8). The mean thickness of three measurements on each side was calculated.

2.5. Statistical Analysis

The test-retest reliability of force production was determined using Intra-Class Correlation Coefficients (ICCs). Coefficient of Variation (CV) and Standard Error of Measurements (SEMs) were also included for determining variability of measurements. The measurements were determined as acceptably reliable if the ICC value was greater than 0.85, CV was less than 15%, and SEMs were less than 5% [20G. Atkinson, and A.M. Nevill, "Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine", Sports Med., vol. 26, no. 4, pp. 217-238.[http://dx.doi.org/10.2165/00007256-199826040-00002] [PMID: 982 0922] , 21L.G. Portney, Foundations of clinical research: Applications to practice 3th (third)., Edition, .]. The validity of the values obtained from the relationship between the FS and TrA thickness was analyzed using Pearson’s correlation coefficients. Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS).

3. RESULTS

Table 1 shows the ICCs, CV and SEMs for all measurements. The FS and measurement of TrA thickness were considered as being acceptably reliable (i.e. ICC > 0.9, CV < 10%, SEMs < 5%).

Table 1
The test – retest reliability results of the feedback sensor device and the real time ultrasound imaging of TrA thickness.


Table 2
Correlation between feedback sensor device and the thickness of transversus abdominis muscle.


Fig. (1)
Relationship between levels of the PBU and FS device.


Results of FS validity for activating the TrA muscle are presented in Table 2. There was a significant correlation (moderately positive) between the PBU and FS (r = 0.657, p < 0.001). Value of the FS at each level of the PBU is shown in Fig. (1). There was a strong negative correlation between the PBU and TrA thickness (r = - 0.793, p < 0.001). Thickness of the TrA at each level of the PBU is shown in Fig. (2). There was a significant correlation (moderately negative) between the FS and TrA thickness (r = - 0.514, p < 0.001). The correlation between the FS and TrA thickness is shown in Fig. (3).

4. DISCUSSION

The purpose of this study was to evaluate the reliability and validity of the feedback device compared with the ultrasound imaging for activating the TrA muscle, and report test–retest reliability of the device. This study found excellent reliability of the FS and measurement of the TrA thickness using ultrasound imaging in a standing position (ICC = 0.946 and 0.931, respectively). This suggested that the FS and measurement method of TrA thickness in this study were reliable methods. Previous studies [9D.S. Teyhen, C.E. Miltenberger, H.M. Deiters, Y.M. Del Toro, J.N. Pulliam, J.D. Childs, R.E. Boyles, and T.W. Flynn, "The use of ultrasound imaging of the abdominal drawing-in maneuver in subjects with low back pain", J. Orthop. Sports Phys. Ther., vol. 35, no. 6, pp. 346-355.[http://dx.doi.org/10.2519/jospt.2005.35.6.346] [PMID: 16001906] , 22J-R. Jeong, J.H. Han, J-E. Cho, and W-h. Lee, "Reliability and validity of a personal computer based muscle viewer for measuring upper trapezius and transverses abdominis muscle thickness", Phys. Ther. Rehabil. Sci., vol. 5, pp. 155-161.[http://dx.doi.org/10.14474/ptrs.2016.5.3.155] ] also found very high reliability in ultrasound measurement of the TrA muscle (ICC > 0.9) in supine position. The high Intra-Class Correlation of TrA thickness consistency in an upright position correlated with the result in this study of that in a standing position (ICC > 0.9) [23C.W. Hoppes, A.D. Sperier, C.F. Hopkins, B.D. Griffiths, M.F. Principe, B.L. Schnall, J.C. Bell, and S.L. Koppenhaver, "Ultrasound imaging measurement of the transversus abdominis in supine, standing, and under loading: A reliability study of novice examiners", Int. J. Sports Phys. Ther., vol. 10, no. 6, pp. 910-917.[PMID: 26618070] ].

A significant (moderate) relationship was found between the FS and thickness of the TrA. Utilizing the FS in this study could be considered in order to give information of TrA activation during the performance of ADIM in a functional upright position. The negative relationship between the FS and TrA thickness was as expected. The FS was put between the lumbar support and abdominal muscles. When performing the ADIM, the pressure values from the FS and PBU, which were located between the lumbar support and abdominal muscles, were decreased. At the same time, the TrA was activated by performing the ADIM, and presented in the increase of muscle thickness. This was supported by the study of McMeekan et al. [19J.M. McMeeken, I.D. Beith, D.J. Newham, P. Milligan, and D.J. Critchley, "The relationship between EMG and change in thickness of transversus abdominis", Clin. Biomech. (Bristol, Avon), vol. 19, no. 4, pp. 337-342.[http://dx.doi.org/10.1016/j.clinbiomech.2004.01.007] [PMID: 15109 752] ], which showed an excellent correlation between the activity and thickness of the TrA. In addition, Lee and colleagues [15S. Lee, S. Han, and D. Lee, "Comparison of abdominal muscle thickness according to feedback method used during abdominal hollowing exercise", J. Phys. Ther. Sci., vol. 28, no. 9, pp. 2519-2521.[http://dx.doi.org/10.1589/jpts.28.2519] [PMID: 27799683] ] reported that ADIM training with the feedback method (i.e. ultrasound imaging and PBU) for 15 minutes resulted in significantly thicker TrA muscle than using manual contact. They suggested that use of the feedback method may be more effective only in improving TrA muscle function than using manual contact. Therefore, the feedback device in this study may be useful as an indicator of TrA activation for patients with LBP, especially for self-training at home or the workplace because it is easy to use and affordable.

Fig. (2)
Relationship between levels of the PBU and thickness of the TrA muscle.


Fig. (3)
Relationship between the FS device and thickness of the TrA muscle.


CONCLUSION

This study demonstrated that the feedback device, which was developed in this study, is considered as a reliable and valid tool for providing information on TrA activation during performance of the ADIM. It could be a clinically useful device for simultaneous feedback in activating the TrA muscle and encouraging patients with LBP to perform precise core stability activation.

A limitation of this study was validity and reliability of the feedback device being evaluated in healthy subjects in a standing position. Further study may require various patient populations and different positions during activity of daily living.

LIST OF ABBREVIATIONS

LBP = Low Back Pain
FS = Feedback Sensor
TrA = Transversus Abdominis
ADIM = Abdominal Drawing-in Maneuver
EMG = Electromyography
PBU = Pressure Biofeedback Unit
ASIS = Anterior Superior Iliac Spine

ETHICS APPROVAL AND CONSENT TO PARTICIPATE

Ethical approval was obtained by the Institutional Ethics Committee with approval number AMSEC-60EX-028.

HUMAN AND ANIMAL RIGHTS

No animals were used in this research. All human research procedures followed were in accordance with the ethical standards of the committee responsible for human experimentation (institutional and national), and with the Helsinki Declaration of 1975, as revised in 2013.

CONSENT FOR PUBLICATION

All participants gave written informed consent.

AVAILABILITY OF DATA AND MATERIALS

Not applicable.

FUNDING

This study was supported by Thailand Research Fund, grant number TRF-RRi 59I0017.

CONFLICT OF INTEREST

The authors declare no conflict of interest, financial or otherwise.

ACKNOWLEDGEMENTS

The authors are pleased to acknowledge the support of Thailand Research Fund.

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Endorsements



"Open access will revolutionize 21st century knowledge work and accelerate the diffusion of ideas and evidence that support just in time learning and the evolution of thinking in a number of disciplines."


Daniel Pesut
(Indiana University School of Nursing, USA)

"It is important that students and researchers from all over the world can have easy access to relevant, high-standard and timely scientific information. This is exactly what Open Access Journals provide and this is the reason why I support this endeavor."


Jacques Descotes
(Centre Antipoison-Centre de Pharmacovigilance, France)

"Publishing research articles is the key for future scientific progress. Open Access publishing is therefore of utmost importance for wider dissemination of information, and will help serving the best interest of the scientific community."


Patrice Talaga
(UCB S.A., Belgium)

"Open access journals are a novel concept in the medical literature. They offer accessible information to a wide variety of individuals, including physicians, medical students, clinical investigators, and the general public. They are an outstanding source of medical and scientific information."


Jeffrey M. Weinberg
(St. Luke's-Roosevelt Hospital Center, USA)

"Open access journals are extremely useful for graduate students, investigators and all other interested persons to read important scientific articles and subscribe scientific journals. Indeed, the research articles span a wide range of area and of high quality. This is specially a must for researchers belonging to institutions with limited library facility and funding to subscribe scientific journals."


Debomoy K. Lahiri
(Indiana University School of Medicine, USA)

"Open access journals represent a major break-through in publishing. They provide easy access to the latest research on a wide variety of issues. Relevant and timely articles are made available in a fraction of the time taken by more conventional publishers. Articles are of uniformly high quality and written by the world's leading authorities."


Robert Looney
(Naval Postgraduate School, USA)

"Open access journals have transformed the way scientific data is published and disseminated: particularly, whilst ensuring a high quality standard and transparency in the editorial process, they have increased the access to the scientific literature by those researchers that have limited library support or that are working on small budgets."


Richard Reithinger
(Westat, USA)

"Not only do open access journals greatly improve the access to high quality information for scientists in the developing world, it also provides extra exposure for our papers."


J. Ferwerda
(University of Oxford, UK)

"Open Access 'Chemistry' Journals allow the dissemination of knowledge at your finger tips without paying for the scientific content."


Sean L. Kitson
(Almac Sciences, Northern Ireland)

"In principle, all scientific journals should have open access, as should be science itself. Open access journals are very helpful for students, researchers and the general public including people from institutions which do not have library or cannot afford to subscribe scientific journals. The articles are high standard and cover a wide area."


Hubert Wolterbeek
(Delft University of Technology, The Netherlands)

"The widest possible diffusion of information is critical for the advancement of science. In this perspective, open access journals are instrumental in fostering researches and achievements."


Alessandro Laviano
(Sapienza - University of Rome, Italy)

"Open access journals are very useful for all scientists as they can have quick information in the different fields of science."


Philippe Hernigou
(Paris University, France)

"There are many scientists who can not afford the rather expensive subscriptions to scientific journals. Open access journals offer a good alternative for free access to good quality scientific information."


Fidel Toldrá
(Instituto de Agroquimica y Tecnologia de Alimentos, Spain)

"Open access journals have become a fundamental tool for students, researchers, patients and the general public. Many people from institutions which do not have library or cannot afford to subscribe scientific journals benefit of them on a daily basis. The articles are among the best and cover most scientific areas."


M. Bendandi
(University Clinic of Navarre, Spain)

"These journals provide researchers with a platform for rapid, open access scientific communication. The articles are of high quality and broad scope."


Peter Chiba
(University of Vienna, Austria)

"Open access journals are probably one of the most important contributions to promote and diffuse science worldwide."


Jaime Sampaio
(University of Trás-os-Montes e Alto Douro, Portugal)

"Open access journals make up a new and rather revolutionary way to scientific publication. This option opens several quite interesting possibilities to disseminate openly and freely new knowledge and even to facilitate interpersonal communication among scientists."


Eduardo A. Castro
(INIFTA, Argentina)

"Open access journals are freely available online throughout the world, for you to read, download, copy, distribute, and use. The articles published in the open access journals are high quality and cover a wide range of fields."


Kenji Hashimoto
(Chiba University, Japan)

"Open Access journals offer an innovative and efficient way of publication for academics and professionals in a wide range of disciplines. The papers published are of high quality after rigorous peer review and they are Indexed in: major international databases. I read Open Access journals to keep abreast of the recent development in my field of study."


Daniel Shek
(Chinese University of Hong Kong, Hong Kong)

"It is a modern trend for publishers to establish open access journals. Researchers, faculty members, and students will be greatly benefited by the new journals of Bentham Science Publishers Ltd. in this category."


Jih Ru Hwu
(National Central University, Taiwan)


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