<?xml version="1.0" encoding="utf8"?>
 <!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Publishing DTD v1.0 20120330//EN" "http://jats.nlm.nih.gov/publishing/1.0/JATS-journalpublishing1.dtd"> <article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" article-type="research-article" dtd-version="1.0" xml:lang="en">
  <front>
    <journal-meta>
      <journal-id journal-id-type="publisher-id">JPMC</journal-id>
      <journal-title-group>
        <journal-title>Journal of Preventive Medicine And Care</journal-title>
      </journal-title-group>
      <issn pub-type="epub">2474-3585</issn>
      <publisher>
        <publisher-name>Open Access Pub</publisher-name>
        <publisher-loc>United States</publisher-loc>
      </publisher>
    </journal-meta>
    <article-meta>
      <article-id pub-id-type="publisher-id">JPMC-18-2178</article-id>
      <article-id pub-id-type="doi">10.14302/issn.2474-3585.jpmc-18-2178</article-id>
      <article-categories>
        <subj-group>
          <subject>research-article</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title>Neck, Shoulder and Low Back Musculoskeletal Pain in Greek Physical Education University Students:   A Series of Three Cross-Sectional Studies</article-title>
        <alt-title alt-title-type="running-head">musculoskeletal pain in greek physical education university students</alt-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <name>
            <surname>Analina</surname>
            <given-names>A. Emmanouil</given-names>
          </name>
          <xref ref-type="aff" rid="idm1850735844">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Elissavet</surname>
            <given-names>N. Rousanoglou</given-names>
          </name>
          <xref ref-type="aff" rid="idm1850735844">1</xref>
          <xref ref-type="aff" rid="idm1850733396">*</xref>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Konstantinos</surname>
            <given-names>D. Boudolos</given-names>
          </name>
          <xref ref-type="aff" rid="idm1850735844">1</xref>
        </contrib>
      </contrib-group>
      <aff id="idm1850735844">
        <label>1</label>
        <addr-line>Sports Biomechanics Lab, Section of Sport Medicine &amp; Biology of Exercise, School of Physical Education &amp; Sport  Science, National &amp; Kapodistrian University of Athens, Greece.</addr-line>
      </aff>
      <aff id="idm1850733396">
        <label>*</label>
        <addr-line>corresponding author</addr-line>
      </aff>
      <contrib-group>
        <contrib contrib-type="editor">
          <name>
            <surname>Subita</surname>
            <given-names>Patil</given-names>
          </name>
          <xref ref-type="aff" rid="idm1850862164">1</xref>
        </contrib>
      </contrib-group>
      <aff id="idm1850862164">
        <label>1</label>
        <addr-line>Assistant Professor, Department of Community Medicine, India.</addr-line>
      </aff>
      <author-notes>
        <corresp>
    
    Elissavet Rousanoglou, <addr-line>Sports Biomechanics Lab, Section of Sport Medicine &amp; Biology of Exercise, School of Physical Education &amp; Sport Science, National &amp; </addr-line><addr-line>Kapodistrian</addr-line><addr-line>University of Athens, Greece.</addr-line>                 Tel/fax: <phone>00302107276158</phone>. Email: <email>erousan@phed.uoa.gr</email></corresp>
        <fn fn-type="conflict" id="idm1842394276">
          <p>The authors have declared that no competing interests exist.</p>
        </fn>
      </author-notes>
      <pub-date pub-type="epub" iso-8601-date="2018-08-08">
        <day>08</day>
        <month>08</month>
        <year>2018</year>
      </pub-date>
      <volume>2</volume>
      <issue>2</issue>
      <fpage>32</fpage>
      <lpage>42</lpage>
      <history>
        <date date-type="received">
          <day>21</day>
          <month>06</month>
          <year>2018</year>
        </date>
        <date date-type="accepted">
          <day>31</day>
          <month>07</month>
          <year>2018</year>
        </date>
        <date date-type="online">
          <day>08</day>
          <month>08</month>
          <year>2018</year>
        </date>
      </history>
      <permissions>
        <copyright-statement>© </copyright-statement>
        <copyright-year>2018</copyright-year>
        <copyright-holder>Analina A. Emmanouil, et al.</copyright-holder>
        <license xlink:href="http://creativecommons.org/licenses/by/4.0/" xlink:type="simple">
          <license-p>This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.</license-p>
        </license>
      </permissions>
      <self-uri xlink:href="http://openaccesspub.org/jpmc/article/804">This article is available from http://openaccesspub.org/jpmc/article/804</self-uri>
      <abstract>
        <p>Several studies examine the musculoskeletal pain (MSP) in university students sustaining physical load as part of their compulsory learning. However, only two somewhat outdated cross-sectional studies examine the physical education teacher (PET) students. This study aimed to explore the neck, shoulder and low back MSP prevalence in Greek PET students in a series of academic years. The Nordic Musculoskeletal Questionnaire was used to record the past 12-month neck, shoulder and, low back pain, across three academic years (<italic>n</italic> = 479). The year association to MSP prevalence was examined with the cross-tabulation analysis (using the column proportion test for the year comparison) and, the gender association to MSP prevalence with the <italic>χ</italic><sup>2</sup> test (SPSS 22.0, <italic>p</italic> ≤ 0.05). The year association to MSP prevalence was not significant (<italic>p </italic>&gt; 0.05). The overall prevalence was 67.6%, with multiple pain at 25.7% and, the low back presenting the highest prevalence (40.9%). Women reported a higher prevalence of neck (36%) and low back (47%) pain (<italic>p  </italic>≤  0.05). The majority of pain and time loss duration was 1-7 days. The low back required higher medical attention (19.0%) than the neck (9.2%) and the shoulder (12.9%). The recurrent pain was at 30%, with the previous injury/accident rate at 5.8%, 14.4% and 14.6% for the neck, shoulder and low back. Our PET students present an alarming MSP prevalence. Due to their distinct work demands as PE teachers, entering working life with the healthiest possible musculoskeletal system is of critical importance. Thus, university authorities should consider strategies for the prevention of MSP risk.</p>
      </abstract>
      <kwd-group>
        <kwd>Musculoskeletal</kwd>
        <kwd>Youth</kwd>
        <kwd>Injury Prevention</kwd>
      </kwd-group>
      <counts>
        <fig-count count="1"/>
        <table-count count="3"/>
        <page-count count="11"/>
      </counts>
    </article-meta>
  </front>
  <body>
    <sec id="idm1850596724" sec-type="intro">
      <title>Introduction</title>
      <p>Musculoskeletal pain (MSP) is a highly prevalent and disabling condition that affects people of all ages, gender and socio-demographic characteristics, with subsequent increased health care utilization <xref ref-type="bibr" rid="ridm1842964700">1</xref><xref ref-type="bibr" rid="ridm1842976268">2</xref>. In spite of the different social and cultural substrate of the studied populations, the MSP prevalence in the general population rises approximately to 30% (range                   13.5–47%) <xref ref-type="bibr" rid="ridm1842964700">1</xref>. Epidemiological surveys document a worrying MSP prevalence in young populations and underline the need for early prevention and                detection <xref ref-type="bibr" rid="ridm1843067508">3</xref>. The MSP development in university students is of particular interest as it may affect their daily life <xref ref-type="bibr" rid="ridm1842821532">4</xref> and academic success <xref ref-type="bibr" rid="ridm1842807516">5</xref>. The MSP may also have a significant impact on their future musculoskeletal health <xref ref-type="bibr" rid="ridm1842813708">6</xref>. Pain tends to persist <xref ref-type="bibr" rid="ridm1842798884">7</xref><xref ref-type="bibr" rid="ridm1842801620">8</xref> and predisposes to a higher risk of future MSP <xref ref-type="bibr" rid="ridm1842801620">8</xref><xref ref-type="bibr" rid="ridm1842770604">9</xref>.</p>
      <p>In university students, the MSP is usually associated with the physical load that they must sustain to meet the demands of their learning compulsory activities <xref ref-type="bibr" rid="ridm1842765276">10</xref>. The studies on university students examine either a variety of disciplines <xref ref-type="bibr" rid="ridm1842821532">4</xref><xref ref-type="bibr" rid="ridm1842778740">11</xref> or distinct disciplines as dental hygiene <xref ref-type="bibr" rid="ridm1842746636">12</xref>, medicine <xref ref-type="bibr" rid="ridm1842740228">13</xref>, nursing <xref ref-type="bibr" rid="ridm1842752540">14</xref>, physiotherapy <xref ref-type="bibr" rid="ridm1842748076">15</xref> and, physical education teacher <xref ref-type="bibr" rid="ridm1842813708">6</xref><xref ref-type="bibr" rid="ridm1842717020">17</xref>. The physical education teacher (PET) students constitute a distinct university discipline because of the inherent injury risk associated to the physical load of the compulsory sports participation required by their study curriculum. Cross-sectional studies examined the injury prevalence in PET students a long time ago <xref ref-type="bibr" rid="ridm1842712412">18</xref>, with an ongoing research            interest <xref ref-type="bibr" rid="ridm1842681076">19</xref><xref ref-type="bibr" rid="ridm1842676612">20</xref><xref ref-type="bibr" rid="ridm1842673948">21</xref>. However, to the best of our knowledge, only two outdated studies appear to examine the MSP prevalence in PET students <xref ref-type="bibr" rid="ridm1842722204">16</xref><xref ref-type="bibr" rid="ridm1842717020">17</xref>,  indicating the lack of research during the last decade. In particular, Brennan et al. <xref ref-type="bibr" rid="ridm1842722204">16</xref> reported a 30% prevalence of low back pain, using a past 12-month retrospective questionnaire to examine a single only site of pain. Fliciński <xref ref-type="bibr" rid="ridm1842717020">17</xref> examined a variety of pain sites and reported an almost 50% prevalence in their PET students, who claimed as most frequent the knee, shoulder, and ankle pain. In the study of Fliciński <xref ref-type="bibr" rid="ridm1842717020">17</xref>, sports injuries were the most critical risk factor for MSP (42.4% and 50.5% of women and men, respectively reported a total of 1065 casualties) with participation in specific sports identified as the primary injury risk factor. </p>
      <p>The pain prevalence in PET students is of particular interest due to the physical load and injury susceptibility associated not only to their academic but also to their future working life as Physical Education (PE) teachers <xref ref-type="bibr" rid="ridm1842683740">22</xref><xref ref-type="bibr" rid="ridm1842654828">23</xref>. In fact, the PE teachers claim their rather high prevalence of musculoskeletal disorders as a limiting factor of their working capacity <xref ref-type="bibr" rid="ridm1842683740">22</xref><xref ref-type="bibr" rid="ridm1842654828">23</xref><xref ref-type="bibr" rid="ridm1842653172">24</xref>. The prospective studies about multiple MSP in university students <xref ref-type="bibr" rid="ridm1842798884">7</xref><xref ref-type="bibr" rid="ridm1842801620">8</xref><xref ref-type="bibr" rid="ridm1842778740">11</xref> conclude that the average sites of pain appear to be settled by age 20, and little variation occurs thereafter <xref ref-type="bibr" rid="ridm1842801620">8</xref>. Thus, PET students with multisite pain will most probably enter their working life as PE teachers already suffering from multiple MSP. However, there appear no prospective data regarding the MSP prevalence in PET students. The lack of prospective or serial cross-sectional research on MSP prevalence in PET students highlights the necessity for more and up to date studies. Such studies may contribute to MSP prevention and management during their physically demanding academic years. Thus, this study aimed to explore the prevalence of neck, shoulder and low back pain in a series of academic years in Greek PET students. </p>
    </sec>
    <sec id="idm1850595788" sec-type="methods">
      <title>Methods</title>
      <sec id="idm1850602340">
        <title>Study Design &amp; Sample</title>
        <p>A total of 479 students of the School of Physical Education and Sports Science of National and Kapodistrian University of Athens, Greece, participated in the study after signing an informed consent. Participants derived from three academic years (Y1: 2011-2012, Y2: 2015-2016 and Y3: 2017-2018). All students in Y1, Y2 and Y3 were eligible to participate in the study, In Y1, Y2 and Y3, respectively, the participants (n=123, n=160, and n=196) correspond to 17.6%, 22.9%, and 28.0% of the active students, and 12.3%, 16.0% and 19.6% of the officially registered students.  Among the officially registered students, the percentage of active students rises to about 70%. Thus, the total of 479 students corresponds to 22.8% and 16.0%, respectively, of the active and the officially registered students. The protocol of the study was submitted to and approved by an institutional review board for testing of human subjects.</p>
      </sec>
      <sec id="idm1850603060">
        <title>Study Instruments </title>
        <p>The Standardized Nordic Questionnaire  (SNQ) <xref ref-type="bibr" rid="ridm1842647988">25</xref>, which is a validated measure of musculoskeletal pain, was selected to assess MSP complaints. The questionnaire, translated into the Greek language and adapted for PET students, was pretested on forty students to ensure understandability of the questions. The responses provided in the pretest questionnaire showed a good understanding and a clear comprehension. Respondents were instructed to report whether they had experienced any pain or discomfort in 3 body regions over the past 12 months, naming the neck, shoulder and low back. The questionnaire was also supplemented by a ‘‘pain-site drawing” to illustrate the body regions of interest pictorially. The questionnaire also sought information about the sociodemographic characteristics (gender, age, body mass index, spine disorders, weekly coursework hours and daily computer use hours), as well as, general (pain prevalence and medical attention required) and specific (days of pain duration and days of time loss). Additional information regarding the time before the past 12 months was also sought (previous pain incidence and previous injury/accident regarding the reported site of pain). The same questionnaire was delivered at the beginning of the winter semester in all three academic years, with the single exception of the computer use hours that was not included in Y1 of data collection. The questionnaire was delivered during auditorium lectures regarding compulsory courses. The timetable of the auditorium lectures is usually constant across academic years for all study years, thus this sampling approach allowed us to contact a large number of students at a similar time period of the winter semester across the years of the study. Students are not obliged to present themselves in the auditorium lectures; however, it is typical that a large number of students attend these courses at the beginning of each semester. Practical constraints did not allow to deliver  the questionnaire in consecutive academic years or at academic years with even Intervals between them.</p>
      </sec>
      <sec id="idm1850603348">
        <title>Statistical Analysis</title>
        <p>The cross-tabulation analysis was used to test the academic year association to MSP prevalence. The column proportion comparison test included in the        cross-tabulation analysis was used to test the difference of MSP prevalence between academic years. This option computes pairwise comparisons of column proportions and indicates which pairs of columns (for a given row, with columns indicating the academic years) are significantly different. In the column proportions comparison, the Bonferroni correction was used to adjust the p-values for multiple comparisons. Chi-Square tests (χ2) were applied to test the gender association to pain prevalence. All statistical analyses were conducted using the SPSS statistical software version 22 (IBM Corp., Armonk, NY, USA), with the level of significance set at p ≤ 0.05.</p>
      </sec>
    </sec>
    <sec id="idm1850602700" sec-type="results">
      <title>Results </title>
      <p>The characteristics of the 479 students (Men: 48%, Women: 52%) who completed the questionnaire along the three years are presented in <xref ref-type="table" rid="idm1842409492">Table 1</xref>. Across all three years, 67.6% of the students reported MSP symptoms, with 25.7% of them reporting more than one pain site (<xref ref-type="table" rid="idm1842241900">Table 2</xref>). The gender association to the neck and low back pain was significant (<xref ref-type="fig" rid="idm1842284036">Figure 1</xref>), with women demonstrating a significantly higher pain prevalence in almost all three years (p ≤ 0.05), whereas the gender association to shoulder pain was not significant (p &gt; 0.05). Association of the other demographics to pain (age, body mass index, coursework hours, computer use, and spine disorders) was not examined as their distribution was predominantly in a single category.</p>
      <table-wrap id="idm1842409492">
        <label>Table 1.</label>
        <caption>
          <title> Characteristics of the participants. Values indicate the percentage and count of the year total % (n).</title>
        </caption>
        <table rules="all" frame="box">
          <tbody>
            <tr>
              <td colspan="2"> </td>
              <td>Y12011-2012</td>
              <td>Y22015-2016</td>
              <td>Y32017-2018</td>
              <td>All Years</td>
              <td>Year association</td>
            </tr>
            <tr>
              <td colspan="2">Total respondents</td>
              <td>(n = 123)</td>
              <td>(n = 160)</td>
              <td>(n = 196)</td>
              <td>(n = 479)</td>
              <td><xref ref-type="table-fn" rid="idm1850477284">*</xref><italic>p </italic>≤ 0.05</td>
            </tr>
            <tr>
              <td colspan="2">  </td>
              <td> </td>
              <td>    % (n)</td>
              <td>  % (n)</td>
              <td>% (n)</td>
              <td> </td>
            </tr>
            <tr>
              <td>Gender</td>
              <td>Men</td>
              <td>45.5 (56)</td>
              <td>52.5 (84)</td>
              <td>45.9 (90)</td>
              <td>48.0 (230)</td>
              <td><italic>χ</italic>2 = 1.939</td>
            </tr>
            <tr>
              <td> </td>
              <td>Women</td>
              <td>54.5 (67)</td>
              <td>47.5 (76)</td>
              <td>54.1 (106)</td>
              <td>52.0 (249)</td>
              <td>
                <italic>p = </italic>
                <italic>0.379</italic>
              </td>
            </tr>
            <tr>
              <td>Age (years)</td>
              <td>18-25</td>
              <td>95.9 (118)</td>
              <td>91.9 (147)</td>
              <td>93.2 (179)</td>
              <td>93.7 (445)</td>
              <td><italic>χ</italic>2 = 1.911</td>
            </tr>
            <tr>
              <td> </td>
              <td>26-33</td>
              <td>4.1 (5)</td>
              <td>8.1 (13)</td>
              <td>6.8 (13)</td>
              <td>6.3 (30)</td>
              <td>
                <italic>p = 0.385</italic>
              </td>
            </tr>
            <tr>
              <td>Body Mass Index</td>
              <td>&lt; 18.5</td>
              <td>4.1 (5)</td>
              <td>2.5 (4)</td>
              <td>5.6 (11)</td>
              <td>4.2 (20)</td>
              <td> </td>
            </tr>
            <tr>
              <td>(kg / m<sup>2</sup>)</td>
              <td>18.5-24.9</td>
              <td>88.6 (109)</td>
              <td>86.9 (139)</td>
              <td>88.2 (172)</td>
              <td>87.9 (420)</td>
              <td><italic>χ</italic>2 = 5.578</td>
            </tr>
            <tr>
              <td> </td>
              <td>25.0-29.9</td>
              <td>7.3 (9)</td>
              <td>10 (16)</td>
              <td>6.2 (12)</td>
              <td>7.7 (37)</td>
              <td><italic>p = </italic>0.444</td>
            </tr>
            <tr>
              <td> </td>
              <td>&lt; 30.0</td>
              <td>0 (0)</td>
              <td>0.6 (1)</td>
              <td>0 (0)</td>
              <td>0.2 (1)</td>
              <td> </td>
            </tr>
            <tr>
              <td>Spine disorder <xref ref-type="table-fn" rid="idm1850479000">†</xref></td>
              <td>Normal</td>
              <td>77.2 (95)</td>
              <td>73.8 (118)</td>
              <td>80.0 (156)</td>
              <td>82.2 (393)</td>
              <td><italic>χ</italic>2 = 1.950</td>
            </tr>
            <tr>
              <td> </td>
              <td>Disorder</td>
              <td>22.8 (28)</td>
              <td>26.3 (42)</td>
              <td>20 (39)</td>
              <td>17.8 (85)</td>
              <td><italic>p </italic>= 0.381</td>
            </tr>
            <tr>
              <td>Coursework</td>
              <td>&lt; 20</td>
              <td>96.7 (119)</td>
              <td>67.5 (108)</td>
              <td>59.6 (109)</td>
              <td>72.1 (336)</td>
              <td><italic>χ</italic>2 = 53.133</td>
            </tr>
            <tr>
              <td> (h / week)</td>
              <td>≥ 20</td>
              <td>3.3 (4)</td>
              <td>32.5 (52)</td>
              <td>40.4 (74)</td>
              <td>27.9 (130)</td>
              <td><italic>p = </italic>0.000*</td>
            </tr>
            <tr>
              <td>Computer use</td>
              <td>&lt; 10</td>
              <td>na</td>
              <td>91.3 (146)</td>
              <td>98.4 (186)</td>
              <td>95.1 (332)</td>
              <td><italic>χ</italic>2 = 9.593</td>
            </tr>
            <tr>
              <td>(h / day)</td>
              <td>≥ 10</td>
              <td>na</td>
              <td>8.8 (14)</td>
              <td>1.6 (3)</td>
              <td>4.9 (17)</td>
              <td><italic>  p </italic>= 0.002<xref ref-type="table-fn" rid="idm1850477284">*</xref></td>
            </tr>
          </tbody>
        </table>
        <table-wrap-foot>
          <fn id="idm1850479000">
            <label>†</label>
            <p>Scoliosis (14%), Kyphosis (4.8%), Lordosis (1.3%), multiple spine disorders (2.7%).</p>
          </fn>
          <fn id="idm1850477788">
            <label/>
            <p>na: the Y1 questionnaire did not include this question.</p>
          </fn>
          <fn id="idm1850477284">
            <label>*</label>
            <p>Coursework &lt; 20 h/week: Y1 &gt; Y2 &amp; Y3 (<italic>p </italic>≤ 0.05). Computer use &lt; 10 h/day: Y3 &gt; Y2 (<italic>p </italic>≤ 0.05). </p>
          </fn>
          <fn id="idm1850475124">
            <label/>
            <p>Note: The Fisher’s Exact test was used for Body Mass Index because 3 cells (25%) had expected count &lt; 5.</p>
          </fn>
        </table-wrap-foot>
      </table-wrap>
      <fig id="idm1842284036">
        <label>Figure 1.</label>
        <caption>
          <title> Gender association to pain prevalence in neck, shoulder and low back. *significant gender difference at p ≤ 0.05.</title>
        </caption>
        <graphic xlink:href="images/image1.jpg" mime-subtype="jpg"/>
      </fig>
      <sec id="idm1850475484">
        <title>Pain General Characteristics</title>
        <p>Overall for gender and across all three years (<xref ref-type="table" rid="idm1842241900">Table 2</xref>), the low back was the site with the highest past 12-month prevalence followed by the shoulder and the neck. The low back pain required medical attention at a higher percentage (19.0%) than the neck (9.2%) and the shoulder (12.9%) MSP (<xref ref-type="table" rid="idm1842241900">Table 2</xref>). More than 30% of the participants reported their pain as a recurrent incidence (neck: 32.4%, shoulder: 33.6%, low back: 44.1%) (<xref ref-type="table" rid="idm1842241900">Table 2</xref>). The percentage of students with previous injury/accident at the site of pain raised to 5.8%, 14.4% and 14.6% for the neck, shoulder and low back, respectively (<xref ref-type="table" rid="idm1842241900">Table 2</xref>). About 4% of those with low back pain reported a hospitalization due to a pain incidence before the past-12 month period (<xref ref-type="table" rid="idm1842241900">Table 2</xref>). A significant year association, indicating a decreasing trend, was found for the low back past 12-month and recurrent pain (p ≤ 0.05) (<xref ref-type="table" rid="idm1842241900">Table 2</xref>). A significant year association, indicating a decreasing trend, was found for the shoulder previous injury/accident (p ≤ 0.05)               (<xref ref-type="table" rid="idm1842241900">Table 2</xref>). In specific, Y3 demonstrated a significantly lower prevalence (p ≤ 0.05) of low back past 12-month and recurrent pain, as well as, of shoulder previous injury/accident.</p>
        <table-wrap id="idm1842241900">
          <label>Table 2.</label>
          <caption>
            <title> MSP prevalence and pain characteristics in the three years (Y1, Y2, Y3). Values indicate the              percentage and count of the year total % (n) for the “YES” responses in each category.</title>
          </caption>
          <table rules="all" frame="box">
            <tbody>
              <tr>
                <td colspan="2"> </td>
                <td>Y12011-2012</td>
                <td>Y22015-2016</td>
                <td>Y32017-2018</td>
                <td>   All Years</td>
                <td>Year association</td>
              </tr>
              <tr>
                <td colspan="2">Total                     respondents</td>
                <td>(n = 123)</td>
                <td>(n = 160)</td>
                <td>(n = 196)</td>
                <td>  (n = 479)</td>
                <td><xref ref-type="table-fn" rid="idm1850431548">*</xref><italic> p </italic>≤ 0.05</td>
              </tr>
              <tr>
                <td colspan="2"> </td>
                <td>% (n)</td>
                <td>% (n)</td>
                <td>% (n)</td>
                <td>% (n)</td>
                <td> </td>
              </tr>
              <tr>
                <td colspan="7">Number of pain sites</td>
              </tr>
              <tr>
                <td>No pain</td>
                <td colspan="2">24.4 (30)</td>
                <td>31.3 (50)</td>
                <td>38.3 (75)</td>
                <td>32.4 (155)</td>
                <td> </td>
              </tr>
              <tr>
                <td>1 site</td>
                <td colspan="2">42.7 (58)</td>
                <td>41.3 (66)</td>
                <td>39.3 (77)</td>
                <td>42.0 (201)</td>
                <td><italic>χ</italic>2 = 11.122</td>
              </tr>
              <tr>
                <td>2 sites</td>
                <td colspan="2">17.9 (22)</td>
                <td>22.5 (36)</td>
                <td>16.8 (33)</td>
                <td>19.0 (91)</td>
                <td><italic>p </italic>= 0.085</td>
              </tr>
              <tr>
                <td>3 sites</td>
                <td colspan="2">10.6 (13)</td>
                <td>5.0 (8)</td>
                <td>5.6 (11)</td>
                <td>6.7 (32)</td>
                <td> </td>
              </tr>
              <tr>
                <td colspan="7">Past 12-month pain</td>
              </tr>
              <tr>
                <td>Neck</td>
                <td colspan="2">48.0 (59)</td>
                <td>30.6 (49)</td>
                <td>30.6 (60)</td>
                <td>35.1 (168)</td>
                <td><italic>χ</italic>2 = 0.387,   <italic>p </italic>= 0.824</td>
              </tr>
              <tr>
                <td>Shoulder</td>
                <td colspan="2">33.3 (41)</td>
                <td>32.5 (52)</td>
                <td>31.1 (61)</td>
                <td>32.2 (154)</td>
                <td><italic>χ</italic>2 = 2.039,  <italic>p </italic>= 0.361</td>
              </tr>
              <tr>
                <td>Low back</td>
                <td colspan="2">55.3 (68)</td>
                <td>40.0 (64)</td>
                <td>32.7 (64)</td>
                <td>40.9 (196)</td>
                <td><italic>χ</italic>2 = 14.062, <italic>p </italic>= 0.001<xref ref-type="table-fn" rid="idm1850431548">*</xref></td>
              </tr>
              <tr>
                <td colspan="7">Medical attention</td>
              </tr>
              <tr>
                <td>Neck</td>
                <td colspan="2">8.9 (11)</td>
                <td>10.6 (17)</td>
                <td>8.2 (16)</td>
                <td>9.2 (44)</td>
                <td><italic>χ</italic>2 = 2.777,  <italic>p </italic>= 0.249</td>
              </tr>
              <tr>
                <td>Shoulder</td>
                <td colspan="2">15.4 (19)</td>
                <td>12.5 (20)</td>
                <td>11.7 (23)</td>
                <td>12.9 (62)</td>
                <td><italic>χ</italic>2 = 0.956,  <italic>p </italic>= 0.620</td>
              </tr>
              <tr>
                <td>Low back</td>
                <td colspan="2">25.2 (31)</td>
                <td>18.8 (30)</td>
                <td>15.3 (30)</td>
                <td>19.0 (91)</td>
                <td><italic>χ</italic>2 = 0.507,  <italic>p </italic>=0.776</td>
              </tr>
              <tr>
                <td colspan="7">Recurrent pain</td>
              </tr>
              <tr>
                <td>Neck</td>
                <td colspan="2">32.5 (40)</td>
                <td>31.9 (51)</td>
                <td>32.7 (64)</td>
                <td>32.4 (155)</td>
                <td><italic>χ</italic>2 = 2.085,  <italic>p </italic>= 0.353</td>
              </tr>
              <tr>
                <td>Shoulder</td>
                <td colspan="2">35.8 (44)</td>
                <td>33.8 (54)</td>
                <td>32.1 (63)</td>
                <td>33.6 (161) </td>
                <td><italic>χ</italic>2 = 3.417,  <italic>p </italic>= 0.181</td>
              </tr>
              <tr>
                <td>Low back</td>
                <td colspan="2">59.3 (73)</td>
                <td>40 (64)</td>
                <td>37.8 (74)</td>
                <td>44.1 (211)</td>
                <td><italic>χ</italic>2 = 23.067,  <italic>p </italic>= 0.000<xref ref-type="table-fn" rid="idm1850431548">*</xref></td>
              </tr>
              <tr>
                <td colspan="7">Previous Injury/Accident</td>
              </tr>
              <tr>
                <td>Neck</td>
                <td colspan="2">6.5 (8)</td>
                <td>5.6 (9)</td>
                <td>5.6 (11)</td>
                <td>5.8 (28)</td>
                <td><italic>χ</italic>2 = 0.232,  <italic>p </italic>= 0.891</td>
              </tr>
              <tr>
                <td>Shoulder</td>
                <td colspan="2">22.8 (28)</td>
                <td>13.8 (22)</td>
                <td>9.7 (19)</td>
                <td>14.4 (69)</td>
                <td><italic>χ</italic>2 = 8.997,  <italic>p </italic>= 0.011<xref ref-type="table-fn" rid="idm1850431548">*</xref></td>
              </tr>
              <tr>
                <td><xref ref-type="table-fn" rid="idm1850432988">†</xref> Low back </td>
                <td colspan="2">21.1 (26)</td>
                <td>13.8 (22)</td>
                <td>11.2 (22)</td>
                <td>14.6 (70)</td>
                <td><italic>χ</italic>2 = 0.389,  <italic>p </italic>= 0.823</td>
              </tr>
            </tbody>
          </table>
          <table-wrap-foot>
            <fn id="idm1850431548">
              <label>*</label>
              <p> Low back pain prevalence and recurrent pain (<italic>p </italic>≤ 0.05): Y1 &gt; Y2 &amp; Y3, Shoulder previous injury/accident: Y1 &gt; Y3.</p>
            </fn>
            <fn id="idm1850432988">
              <label>†</label>
              <p> Hospitalization due to low back pain was reported as <sup>% (n)</sup>: Y1: 8.8 (6), Y2: 14.1 (9), Y3: 4.7 (3), All years: 9.2 (18) with no significant year association (<italic>χ</italic>2 = 4.212, <italic>p</italic> = 0.122).</p>
            </fn>
          </table-wrap-foot>
        </table-wrap>
      </sec>
      <sec id="idm1850431116">
        <title>Pain and Time Loss Duration</title>
        <p>The majority of the pain symptoms lasted from 1 - 7 days (neck: 73.8%, shoulder: 49.4%, low back: 57.7%), except the similar shoulder pain duration in Y2 for both 1-7 days (36.5%) and 8-30 days (34.6%) (<xref ref-type="table" rid="idm1842143740">Table 3</xref>). The year association to pain duration was significant for all three pain sites (p ≤ 0.05), with significant year differences indicating a pain site and pain duration specificity (<xref ref-type="table" rid="idm1842143740">Table 3</xref>). For the neck, in Y3 there was an increase of pain lasting 1-7 days with a concomitant decrease of pain lasting &gt;30 days but not every day, both significantly different from Y2, p ≤ 0.05. Regarding the shoulder, in Y3 there was also an increase of pain lasting 1-7 days but with a concomitant decrease of pain lasting 8-30 days, both significantly different from Y1 (p ≤ 0.05). In Y3 compared to Y2, there was a significant decrease (p ≤ 0.05) of the low back pain lasting for more than 30 days but not every day. Course time loss raised to 37.5%, 66.9% and 57.1% for the neck, shoulder and low back respectively (<xref ref-type="table" rid="idm1842143740">Table 3</xref>) with the majority of time loss lasting from 1 - 7 days                   (<xref ref-type="table" rid="idm1842143740">Table 3</xref>). The year association to time loss duration was significant only for the low back pain, with the year comparison indicating a decrease of the overall time loss in Y3 than Y1 and Y2 (<xref ref-type="table" rid="idm1842143740">Table 3</xref>).</p>
        <table-wrap id="idm1842143740">
          <label>Table 3.</label>
          <caption>
            <title> Pain and time loss duration across the three years (Y1, Y2, Y3) % (n).</title>
          </caption>
          <table rules="all" frame="box">
            <tbody>
              <tr>
                <td>  </td>
                <td>Y1</td>
                <td>Y2</td>
                <td>Y3</td>
                <td>All Years</td>
                <td>Year association *<italic>p </italic>≤ 0.05</td>
              </tr>
              <tr>
                <td> </td>
                <td>2011-2012</td>
                <td>2015-2016</td>
                <td>2017-2018</td>
                <td/>
                <td/>
              </tr>
              <tr>
                <td> </td>
                <td>(n = 59)</td>
                <td>(n = 49)</td>
                <td>(n = 60)</td>
                <td>(n = 168)</td>
                <td/>
              </tr>
              <tr>
                <td> </td>
                <td>% (n)</td>
                <td>% (n)</td>
                <td>% (n)</td>
                <td>% (n)</td>
                <td> </td>
              </tr>
              <tr>
                <td>Pain duration</td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
              </tr>
              <tr>
                <td>Neck</td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
              </tr>
              <tr>
                <td>1-7 days<xref ref-type="table-fn" rid="idm1850264100">PD</xref></td>
                <td>76.3 (45)</td>
                <td>57.1 (28)</td>
                <td>85.0 (51)</td>
                <td>73.8 (124)</td>
                <td> </td>
              </tr>
              <tr>
                <td>8-30 days</td>
                <td>11.9 (7)</td>
                <td>12.2 (6)</td>
                <td>11.7 (7)</td>
                <td>11.9 (20)</td>
                <td><italic>χ</italic>2 = 25.870</td>
              </tr>
              <tr>
                <td>&gt;30 days - not every day</td>
                <td>10.2 (6)</td>
                <td>24.5 (12)</td>
                <td>3.3 (2)</td>
                <td>11.9 (20)</td>
                <td><italic>p </italic>= 0.000*</td>
              </tr>
              <tr>
                <td>Every day<xref ref-type="table-fn" rid="idm1850264100">PD</xref></td>
                <td>1.7 (1)</td>
                <td>6.1 (3)</td>
                <td>0 (0)</td>
                <td>2.4 (4)</td>
                <td> </td>
              </tr>
              <tr>
                <td>Shoulder</td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
              </tr>
              <tr>
                <td>1-7 days<xref ref-type="table-fn" rid="idm1850264100">PD</xref></td>
                <td>41.5 (17)</td>
                <td>36.5 (19)</td>
                <td>65.6 (40)</td>
                <td>49.4 (76)</td>
                <td> </td>
              </tr>
              <tr>
                <td>8-30 days</td>
                <td>22.0 (9)</td>
                <td>34.6 (18)</td>
                <td>23.0 (14)</td>
                <td>26.6 (41)</td>
                <td><italic>χ</italic>2 =15.245</td>
              </tr>
              <tr>
                <td>&gt;30 days - not every day<xref ref-type="table-fn" rid="idm1850264100">PD</xref></td>
                <td>24.4 (10)</td>
                <td>21.2 (11)</td>
                <td>6.6 (4)</td>
                <td>16.2 (25)</td>
                <td><italic>p </italic>= 0.015*</td>
              </tr>
              <tr>
                <td>Every day</td>
                <td>12.2 (5)</td>
                <td>7.7 (4)</td>
                <td>4.9 (3)</td>
                <td>7.8 (12)</td>
                <td> </td>
              </tr>
              <tr>
                <td>Low Back</td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
              </tr>
              <tr>
                <td>1-7 days</td>
                <td>64.7 (44)</td>
                <td>43.8 (28)</td>
                <td>64.1 (41)</td>
                <td>57.7 (113)</td>
                <td> </td>
              </tr>
              <tr>
                <td>8-30 days</td>
                <td>11.8 (8)</td>
                <td>17.2 (11)</td>
                <td>15.6 (10)</td>
                <td>14.8 (29)</td>
                <td><italic>χ</italic>2 = 16.574</td>
              </tr>
              <tr>
                <td>&gt;30 days - not every day<xref ref-type="table-fn" rid="idm1850264100">PD</xref></td>
                <td>14.7 (10)</td>
                <td>32.8 (21)</td>
                <td>14.1 (9)</td>
                <td>20.4 (40)</td>
                <td><italic>p </italic>= 0.031*</td>
              </tr>
              <tr>
                <td>Every day</td>
                <td>8.8 (6)</td>
                <td>6.3 (4)</td>
                <td>6.3 (4)</td>
                <td>7.1 (14)</td>
                <td> </td>
              </tr>
              <tr>
                <td>Time loss duration</td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
              </tr>
              <tr>
                <td>Neck</td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
              </tr>
              <tr>
                <td>0 days</td>
                <td>69.5 (41)</td>
                <td>65.3 (32)</td>
                <td>53.3 (32)</td>
                <td>62.5 (105)</td>
                <td> </td>
              </tr>
              <tr>
                <td>1-7 days</td>
                <td>23.7 (14)</td>
                <td>30.6 (15)</td>
                <td>28.3 (17)</td>
                <td>27.4 (46)</td>
                <td><italic>χ</italic>2 = 9.826</td>
              </tr>
              <tr>
                <td>8-30 days<xref ref-type="table-fn" rid="idm1850264532">TLD</xref></td>
                <td>6.8 (4)</td>
                <td>4.1 (2)</td>
                <td>0 (0)</td>
                <td>3.6 (6)</td>
                <td><italic>p </italic>= 0.073</td>
              </tr>
              <tr>
                <td>&gt;30 days</td>
                <td>0 (0)</td>
                <td>0 (0)</td>
                <td>18.3 (11)</td>
                <td>6.5 (11)</td>
                <td> </td>
              </tr>
              <tr>
                <td>Shoulder</td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
              </tr>
              <tr>
                <td>0 days</td>
                <td>58.5 (24)</td>
                <td>59.6 (31)</td>
                <td>78.7 (48)</td>
                <td>66.9 (103)</td>
                <td> </td>
              </tr>
              <tr>
                <td>1-7 days</td>
                <td>31.7 (13)</td>
                <td>28.8 (15)</td>
                <td>14.8 (9)</td>
                <td>24.0 (37)</td>
                <td><italic>χ</italic>2 = 8.397</td>
              </tr>
              <tr>
                <td>8-30 days</td>
                <td>9.8 (4)</td>
                <td>9.6 (5)</td>
                <td>4.9 (3)</td>
                <td>7.8 (12)</td>
                <td><italic>p </italic>= 0.154</td>
              </tr>
              <tr>
                <td>&gt;30 days</td>
                <td>0 (0)</td>
                <td>1.9 (1)</td>
                <td>1.6 (1)</td>
                <td>1.3 (2)</td>
                <td> </td>
              </tr>
              <tr>
                <td>Low Back</td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
                <td> </td>
              </tr>
              <tr>
                <td>0 days<xref ref-type="table-fn" rid="idm1850264532">TLD</xref></td>
                <td>50.0 (34)</td>
                <td>50.0 (32)</td>
                <td>71.9 (46)</td>
                <td>57.1 (112)</td>
                <td> </td>
              </tr>
              <tr>
                <td>1-7 days</td>
                <td>32.4 (22)</td>
                <td>37.5 (24)</td>
                <td>23.4 (15)</td>
                <td>31.1 (61)</td>
                <td><italic>χ</italic>2 = 14.897</td>
              </tr>
              <tr>
                <td>8-30 days</td>
                <td>8.8 (6)</td>
                <td>4.7 (3)</td>
                <td>3.1 (2)</td>
                <td>5.6 (11)</td>
                <td><italic>p </italic>= 0.016*</td>
              </tr>
              <tr>
                <td>&gt;30 days</td>
                <td>8.8 (6)</td>
                <td>7.8 (5)</td>
                <td>1.6 (1)</td>
                <td>6.1 (12)</td>
                <td> </td>
              </tr>
            </tbody>
          </table>
          <table-wrap-foot>
            <fn id="idm1850264748">
              <label/>
              <p>The Fisher’s Exact test is reported because of cells with expected count less than 5 in Pain duration <sup>cells (%): 4 (26.7%)</sup><sup> 3 (25%)</sup><sup> and 3 (20%) in neck</sup><sup> shoulder and low back</sup><sup> respectively</sup> and in Time loss         duration <sup>6 cells (50%) in all three pain sites</sup>.</p>
            </fn>
            <fn id="idm1850264100">
              <label>PD</label>
              <p> (p ≤ 0.05): Neck: Y3&gt;Y2 for 1-7 days, Y3&lt;Y2 for more than 30 days but not every day, Shoulder: Y3&gt;Y1 &amp; Y2 for 1-7 days and Y3&lt;Y1 for more than 30 days but not every day, Low back: Y2 &gt; Y1 &amp; Y3 for more than 30 days but not every day. </p>
            </fn>
            <fn id="idm1850264532">
              <label>TLD</label>
              <p> (p ≤ 0.05):  Neck: Y1 &amp; Y2 &gt; Y3 for 8-30 days, Low back: Y3 &gt; Y1 &amp; Y2 for 0 days.</p>
            </fn>
          </table-wrap-foot>
        </table-wrap>
      </sec>
    </sec>
    <sec id="idm1850264316">
      <title> Discussion</title>
      <p>The study aimed to examine the neck, shoulder, and low back prevalence of MSP in Greek PET students across three academic years. The 67.6% overall MSP prevalence is higher than the prevalence of 32% and 50%, respectively, reported for PET students by Brennan et al. <xref ref-type="bibr" rid="ridm1842722204">16</xref> and Fliciński <xref ref-type="bibr" rid="ridm1842717020">17</xref>. However, it must be noted that Brennan et al. <xref ref-type="bibr" rid="ridm1842722204">16</xref> examined only the low back pain. Furthermore, despite their variety of pain sites (shoulder, elbow, wrist, hand, hip, knee, ankle, and foot), Fliciński <xref ref-type="bibr" rid="ridm1842717020">17</xref> did not include the neck and low back in their study. Sports injuries appear as the most critical risk factors for MSP <xref ref-type="bibr" rid="ridm1842717020">17</xref> with an ongoing research interest regarding interventions that could prevent the injury incidences in PET students <xref ref-type="bibr" rid="ridm1842681076">19</xref><xref ref-type="bibr" rid="ridm1842676612">20</xref><xref ref-type="bibr" rid="ridm1842673948">21</xref><xref ref-type="bibr" rid="ridm1842683740">22</xref>. When compared with other disciplines, the overall pain prevalence in the present study was within the range reported in studies including the neck, the shoulder, and the low back to examine the past 12-month pain. In specific, the overall pain prevalence was 64.3% for dental students <xref ref-type="bibr" rid="ridm1842746636">12</xref>, 75.8-89.3% for medical               students <xref ref-type="bibr" rid="ridm1842740228">13</xref>, 64% for nursing students <xref ref-type="bibr" rid="ridm1842752540">14</xref> and, 63% for physiotherapy students <xref ref-type="bibr" rid="ridm1842748076">15</xref>. When a variety of disciplines was included in the same study, the MSP prevalence ranged from 34% <xref ref-type="bibr" rid="ridm1842778740">11</xref> up to 92.7% <xref ref-type="bibr" rid="ridm1842821532">4</xref>. </p>
      <p>In agreement with the majority of previous studies in university students <xref ref-type="bibr" rid="ridm1842778740">11</xref><xref ref-type="bibr" rid="ridm1842740228">13</xref><xref ref-type="bibr" rid="ridm1842717020">17</xref> as well as in general population <xref ref-type="bibr" rid="ridm1842964700">1</xref><xref ref-type="bibr" rid="ridm1842643092">26</xref> women had a higher MSP prevalence than men. The strong association of gender to MSP prevalence is broadly supported <xref ref-type="bibr" rid="ridm1842964700">1</xref><xref ref-type="bibr" rid="ridm1842643092">26</xref><xref ref-type="bibr" rid="ridm1842642948">27</xref><xref ref-type="bibr" rid="ridm1842637908">28</xref>. The purpose of this study was not to determine the factors of the gender related MSP differences. However, in general, the explanations for gender differences in MSP are categorized in three groups, in terms that women rather than men: (A) are more willing to report pain, (B) are more vulnerable to develop MSP because of gender-linked factors (hormones, physiology, pain sensitivity), and (C) may possibly sustain a greater accumulative exposure to MSP risk factors when one considers both the working (studying in the case of university students) and typical household-related activities (cleaning, laundry, etc.) <xref ref-type="bibr" rid="ridm1842643092">26</xref><xref ref-type="bibr" rid="ridm1842642948">27</xref><xref ref-type="bibr" rid="ridm1842637908">28</xref>. Some studies do not succeed in revealing any specific risk factors that could explain the higher prevalence of chronic musculoskeletal complaints in women than          men <xref ref-type="bibr" rid="ridm1842643092">26</xref>. As concluded by Andorsen et al. <xref ref-type="bibr" rid="ridm1842643092">26</xref> in their 13-year prospective study, unmeasured factors may also be contributing substantially to the MSP gender differences, which warrants further research focused on such factors.</p>
      <p>The increasing trend of MSP highlights a documented worldwide growing health problem that appears to affect people of all ages, gender and           socio-demographic characteristics <xref ref-type="bibr" rid="ridm1842964700">1</xref><xref ref-type="bibr" rid="ridm1842976268">2</xref>. In our study, the MSP prevalence did not reveal a significant year trend for the neck and the shoulder pain. However, it showed a decreasing year trend in the low back past           12-month pain, the recurrent pain, and the shoulder previous injury/accident. The pain and time loss duration did not show a specific year trend profile for the three pain sites, with both significantly increases and decreases in Y3 compared to the other years. The comparison to earlier data is not feasible due to the scarcity of previous serial cross-sectional or prospective studies on university students. To the best of our knowledge, the single MSP prospective study in university students is the nationwide study of Oksanen et al. <xref ref-type="bibr" rid="ridm1842778740">11</xref>. Oksanen et al. <xref ref-type="bibr" rid="ridm1842778740">11</xref>, using the previous week rather than the past 12-month symptoms, report an increasing trend of MSP from 2000 to 2012 in Finnish university students. Over a 6.5 year period, there was an increase in the number of pain sites in men but not in women young technical students entering their working life <xref ref-type="bibr" rid="ridm1842798884">7</xref>, indicating a gender specificity regarding the MSP risk factors. So far, a variety of psychosocial and lifestyle factors have been proposed for the increasing MSP in adolescents (sedentary activities and sleeping, physical activity level, body mass index, alcohol consumption, smoking, and emotional and behavioral factors) <xref ref-type="bibr" rid="ridm1842664692">29</xref>. However, the reasons for increasing MSP in young adults are not known, and there is still much uncertainty about the factors leading to pain.</p>
      <p>In university students, the MSP is associated with the physical load that they need sustain                      during their compulsory learning activities <xref ref-type="bibr" rid="ridm1842746636">12</xref><xref ref-type="bibr" rid="ridm1842740228">13</xref><xref ref-type="bibr" rid="ridm1842752540">14</xref><xref ref-type="bibr" rid="ridm1842748076">15</xref><xref ref-type="bibr" rid="ridm1842722204">16</xref><xref ref-type="bibr" rid="ridm1842717020">17</xref>.                               Oksanen et al. <xref ref-type="bibr" rid="ridm1842778740">11</xref> suggest that broad ergonomic information targeted to young people, together with the increase and widening of the preventive health care could lower the future MSP prevalence in university students. Ergonomic information may also regard the use of computers in university students as their daily hours of computer use are associated with musculoskeletal discomfort <xref ref-type="bibr" rid="ridm1842765276">10</xref>. However, in our study, the vast majority (95.1%) of PET students reported their computer use to be less than 10 hours per day, allowing us to disregard computer use as a factor for their MSP based on the data provided by Noack-Cooper et al. <xref ref-type="bibr" rid="ridm1842765276">10</xref>. It should not be ignored that, in university students, health complaints are also associated with perceived stress <xref ref-type="bibr" rid="ridm1842807516">5</xref><xref ref-type="bibr" rid="ridm1842662532">30</xref>. More specifically, Ekpenyong et al. <xref ref-type="bibr" rid="ridm1842807516">5</xref> suggest to particularly consider certain factors (i.e., demographics, reaction to stress) when developing interventions for stress-induced MSP among university students.</p>
      <p>Regardless of the reasons for their MSP development, the comparison of our PET students with previous PET students is limited to the somewhat outdated cross-sectional studies of Brennan et al. <xref ref-type="bibr" rid="ridm1842722204">16</xref> and Fliciński <xref ref-type="bibr" rid="ridm1842717020">17</xref> which both used a past-12 month questionnaire. Brennan et al. <xref ref-type="bibr" rid="ridm1842722204">16</xref> examined only the low back pain and report a higher (40.1%) than the present (30%) pain prevalence. Fliciński <xref ref-type="bibr" rid="ridm1842717020">17</xref> reported the shoulder prevalence about 30% (Men: 28%, Women: 29%) similar to the 30.1% pain prevalence of the present study; however, they did not include the neck and the low back in their study. In the survey of Fliciński <xref ref-type="bibr" rid="ridm1842717020">17</xref>, sports injuries were the most critical risk factors for MSP (42.4% and 50.5% of women and men, respectively reported a total of 1065 incidences) with participation in specific sports identified as the primary injury risk factor. The recurrent pain in our study is also worrying; more than one-third of the students reported their pain as a recurrent one (32.4%, 33.6% and 44.1% for the neck, shoulder, and low back, respectively). Besides the discomfort itself, pain, and particularly the recurrent one, may limit students’ daily and leisure time <xref ref-type="bibr" rid="ridm1842821532">4</xref><xref ref-type="bibr" rid="ridm1842752540">14</xref> and increase the psychical stress <xref ref-type="bibr" rid="ridm1842662532">30</xref>. Above all, MSP symptoms may impair study success <xref ref-type="bibr" rid="ridm1842807516">5</xref> and affect the students’ future musculoskeletal health <xref ref-type="bibr" rid="ridm1842813708">6</xref>.</p>
      <p>The co-occurring MSP is also of particular interest. In the present study, about 36% of our PET students reported multiple pains. This percentage is almost triple than the 12.5% reported by                     Oksanen et al. <xref ref-type="bibr" rid="ridm1842778740">11</xref> in a variety of university students regarding four pain sites (neck-shoulder, low back, limb/joint, temporomandibular). The lower prevalence of multiple pains in Oksanen et al. <xref ref-type="bibr" rid="ridm1842778740">11</xref> may be attributed to the student population specificity, as PET students are exposed to a higher physical workload than general student population. However, our 36% multiple pain prevalence is lower than the multiple pain reported for Greek workers <xref ref-type="bibr" rid="ridm1842587316">31</xref>, young technical school students <xref ref-type="bibr" rid="ridm1842798884">7</xref>, and the general population <xref ref-type="bibr" rid="ridm1842801620">8</xref>. In specific,                        Solidaki et al. <xref ref-type="bibr" rid="ridm1842587316">31</xref> in their cross-sectional study, report a 67% multiple pain prevalence for a total of 6 body sites (neck, shoulder, elbow, wrist-hand, low back, and knee). Hanvold et al. <xref ref-type="bibr" rid="ridm1842798884">7</xref>, in their 6.5-year prospective study, report the baseline multiple pain at 69% for a total of 4 pain sites (neck-shoulder, low back, arm-hand-wrist,             hip-knee-leg). Kamaleri et al. <xref ref-type="bibr" rid="ridm1842801620">8</xref>, in their 14-year prospective site on general population, report the baseline multiple pain at 75% for a total of 10 pain sites (head, neck, shoulder, elbow, hand/wrist, upper back, lower back, hip, knee, and ankle/foot). The pattern of multiple pains has been found to be relatively stable over the years <xref ref-type="bibr" rid="ridm1842798884">7</xref><xref ref-type="bibr" rid="ridm1842801620">8</xref><xref ref-type="bibr" rid="ridm1842778740">11</xref> as the average sites of pain appears to be settled by age 20 and little variation occurs after that <xref ref-type="bibr" rid="ridm1842801620">8</xref>. Furthermore, the pattern of multiple pain sites is more strongly related to work disability <xref ref-type="bibr" rid="ridm1842582276">32</xref> and long-term sickness absence <xref ref-type="bibr" rid="ridm1842579612">33</xref>. Thus, even though the multiple pain prevalence in our Greek PET students is lower than in previous                  studies <xref ref-type="bibr" rid="ridm1842798884">7</xref><xref ref-type="bibr" rid="ridm1842801620">8</xref><xref ref-type="bibr" rid="ridm1842587316">31</xref>, it should not be overlooked; multisite pain may persist or reoccur, meaning that those students who report multisite pain will most probably continue to do so during their working life <xref ref-type="bibr" rid="ridm1842801620">8</xref>. Studies in European and worldwide populations suggest that it is vital to widen the preventive health care <xref ref-type="bibr" rid="ridm1843067508">3</xref><xref ref-type="bibr" rid="ridm1842778740">11</xref> and to identify the factors predicting the number of pain sites already at an early age <xref ref-type="bibr" rid="ridm1842813708">6</xref>. Furthermore, it is essential to provide the young population of students with specific preventive and informative programs including ergonomic, physiological, and psychosocial and lifestyle           aspects <xref ref-type="bibr" rid="ridm1842821532">4</xref><xref ref-type="bibr" rid="ridm1842807516">5</xref><xref ref-type="bibr" rid="ridm1842778740">11</xref><xref ref-type="bibr" rid="ridm1842717020">17</xref><xref ref-type="bibr" rid="ridm1842673948">21</xref><xref ref-type="bibr" rid="ridm1842662532">30</xref>.</p>
      <p>In the perspective of the physical load and musculoskeletal disorders associated to the upcoming working life of the PET students <xref ref-type="bibr" rid="ridm1842683740">22</xref><xref ref-type="bibr" rid="ridm1842654828">23</xref><xref ref-type="bibr" rid="ridm1842653172">24</xref><xref ref-type="bibr" rid="ridm1842574788">34</xref>, the pain prevalence is of particular interest as it may limit their future working ability <xref ref-type="bibr" rid="ridm1842653172">24</xref>. All over the world, PE teachers face similar essential duties demanding a rather high physical workload <xref ref-type="bibr" rid="ridm1842683740">22</xref><xref ref-type="bibr" rid="ridm1842654828">23</xref><xref ref-type="bibr" rid="ridm1842574788">34</xref>. The musculoskeletal risk due to their work duties justifies the consideration whether it is possible, or even reasonable, to work as a PE teacher after the age of 60 <xref ref-type="bibr" rid="ridm1842653172">24</xref>. Thus, it is of utmost importance to develop strategies that will allow PET students to enter their working life with the healthiest possible musculoskeletal system. Such strategies aim to prevent the risk factors associated with the study curriculum <xref ref-type="bibr" rid="ridm1842673948">21</xref>. </p>
      <p>When interpreting the results of the present study, one should consider the possible bias as the data was collected through questionnaires. Self-reports may be influenced by, for example, personality dimensions such as negative affectivity (common method bias) <xref ref-type="bibr" rid="ridm1842603732">35</xref>. Also, self-administered questionnaires tend to be answered primarily by those who perceive the questions to be relevant <xref ref-type="bibr" rid="ridm1842600060">36</xref>. The population of the study does not reflect a 'general' population due to the mean age and narrow age range limited to the academic years as well as the discipline specificities of the PET population. Furthermore, the physical workload induced by the study curriculum of the Greek PET students may be different than PET students from other countries. Thus, the results from this study cannot be generalized to all PET students. As stated in our introduction, the study was conducted to explore the prevalence of MSP among the Greek PET students rather than to study the risk factors. Nevertheless, the results are alarming, and careful attention should be given by school authorities to increase students’ awareness of MSP prevention and management.</p>
      <p>In conclusion, our series of three cross-sectional studies in Greek PET students is in agreement with previous studies among university disciplines when students must sustain a significant physical load as part of their compulsory learning activities (i.e., dental, medical, nursing, and physiotherapy students). Although an increasing trend was not revealed across the three academic years of 2011-2012, 2015-2016 and                    2017-2018, the overall pain prevalence in our PET students (67.6%) could be considered somewhat high compared to the general population (30%, ranging from 13.5 to 47%) <xref ref-type="bibr" rid="ridm1842964700">1</xref>. The reduction of MSP during their academic life is of critical importance, as in their future working life as PE teachers, the PET students will also be susceptible to increased physical load and injury risk due to their distinct work demands. Thus entering their working life with a healthy musculoskeletal system is of critical importance and underlines the need for PE university authorities to take initiatives (i.e., changes of physical curriculum load) for the reduction of MSP.</p>
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