---
_id: '53785'
abstract:
- lang: eng
  text: |-
    <jats:title>Abstract</jats:title><jats:p>Due to the lockdown of schools as one of the COVID-19 control measures, adolescents have had the opportunity to re-organise their daily lives; e.g. some of them have adapted their bedtimes to the new situation during the lockdown in favour of their own chronotype. Hence, we investigated differences in chronobiological characteristics (e.g., the midpoint of sleep, sleep duration or social jetlag (SJL); i.e., a discrepancy between biological and social timing) before and during the pandemic lockdown to examine potential changes. We asked participants from the ongoing open cohort Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) study to fill out the Munich Chronotype Questionnaire during the COVID-19 lockdown and received the information of participants (<jats:italic>n</jats:italic> = 66) during the pandemic. A reference group matched for age, season, and sex was randomly selected from the DONALD study to assess participants’ chronobiological characteristics prior to (<jats:italic>n</jats:italic> = 132) the pandemic. Analyses of covariance were applied to examine differences between the two groups reflecting the situation before and during the COVID-19 pandemic. Participants were aged 9–18 years (52% males). In the current examination, average sleep duration across the week was higher among adolescents during the pandemic (<jats:italic>β</jats:italic> = 00:30; <jats:italic>p</jats:italic> = 0.0006) and social jetlag was significantly lower (<jats:italic>β</jats:italic> =  −00:39; <jats:italic>p</jats:italic> &lt; 0.0001).</jats:p><jats:p><jats:italic>  Conclusion</jats:italic>: Our results showed that the COVID-19 lockdown enabled adolescents to adapt their sleeping habits according to their naturally late chronotype, which led to a significant reduction in SJL. These observations are likely to be explained by the effect of school closure.<jats:table-wrap><jats:table><jats:tbody>
                        <jats:tr>
                          <jats:td colspan="2"><jats:bold>What is Known:</jats:bold><jats:italic>• Under ‘normal conditions’ without pandemic lockdowns, adolescents accumulate a lack of sleep due to social obligations such as school starts, resulting in social jetlag.</jats:italic>• <jats:italic>A late chronotype or exposure to social jetlag is a known risk factor for the development of chronic diseases.</jats:italic></jats:td>
                        </jats:tr>
                        <jats:tr>
                          <jats:td colspan="2"><jats:bold>What is New:</jats:bold><jats:italic>• </jats:italic><jats:italic>The COVID-19 lockdown represents a ‘natural experiment’ that enables adolescents to adhere to their internal biological clock. Without the usual social obligations, social jetlag can be significantly reduced.</jats:italic></jats:td>
                        </jats:tr>
                      </jats:tbody></jats:table></jats:table-wrap></jats:p>
author:
- first_name: Ines
  full_name: Perrar, Ines
  last_name: Perrar
- first_name: Ute
  full_name: Alexy, Ute
  last_name: Alexy
- first_name: Nicole
  full_name: Jankovic, Nicole
  last_name: Jankovic
citation:
  ama: Perrar I, Alexy U, Jankovic N. Chronobiological changes due to school closures
    during the COVID-19 pandemic among adolescents in the DOrtmund Nutritional and
    Anthropometric Longitudinally Designed cohort study. <i>European Journal of Pediatrics</i>.
    2023;182(6):2801-2805. doi:<a href="https://doi.org/10.1007/s00431-023-04963-9">10.1007/s00431-023-04963-9</a>
  apa: Perrar, I., Alexy, U., &#38; Jankovic, N. (2023). Chronobiological changes
    due to school closures during the COVID-19 pandemic among adolescents in the DOrtmund
    Nutritional and Anthropometric Longitudinally Designed cohort study. <i>European
    Journal of Pediatrics</i>, <i>182</i>(6), 2801–2805. <a href="https://doi.org/10.1007/s00431-023-04963-9">https://doi.org/10.1007/s00431-023-04963-9</a>
  bibtex: '@article{Perrar_Alexy_Jankovic_2023, title={Chronobiological changes due
    to school closures during the COVID-19 pandemic among adolescents in the DOrtmund
    Nutritional and Anthropometric Longitudinally Designed cohort study}, volume={182},
    DOI={<a href="https://doi.org/10.1007/s00431-023-04963-9">10.1007/s00431-023-04963-9</a>},
    number={6}, journal={European Journal of Pediatrics}, publisher={Springer Science
    and Business Media LLC}, author={Perrar, Ines and Alexy, Ute and Jankovic, Nicole},
    year={2023}, pages={2801–2805} }'
  chicago: 'Perrar, Ines, Ute Alexy, and Nicole Jankovic. “Chronobiological Changes
    Due to School Closures during the COVID-19 Pandemic among Adolescents in the DOrtmund
    Nutritional and Anthropometric Longitudinally Designed Cohort Study.” <i>European
    Journal of Pediatrics</i> 182, no. 6 (2023): 2801–5. <a href="https://doi.org/10.1007/s00431-023-04963-9">https://doi.org/10.1007/s00431-023-04963-9</a>.'
  ieee: 'I. Perrar, U. Alexy, and N. Jankovic, “Chronobiological changes due to school
    closures during the COVID-19 pandemic among adolescents in the DOrtmund Nutritional
    and Anthropometric Longitudinally Designed cohort study,” <i>European Journal
    of Pediatrics</i>, vol. 182, no. 6, pp. 2801–2805, 2023, doi: <a href="https://doi.org/10.1007/s00431-023-04963-9">10.1007/s00431-023-04963-9</a>.'
  mla: Perrar, Ines, et al. “Chronobiological Changes Due to School Closures during
    the COVID-19 Pandemic among Adolescents in the DOrtmund Nutritional and Anthropometric
    Longitudinally Designed Cohort Study.” <i>European Journal of Pediatrics</i>,
    vol. 182, no. 6, Springer Science and Business Media LLC, 2023, pp. 2801–05, doi:<a
    href="https://doi.org/10.1007/s00431-023-04963-9">10.1007/s00431-023-04963-9</a>.
  short: I. Perrar, U. Alexy, N. Jankovic, European Journal of Pediatrics 182 (2023)
    2801–2805.
date_created: 2024-04-29T11:44:15Z
date_updated: 2024-06-17T09:00:04Z
doi: 10.1007/s00431-023-04963-9
intvolume: '       182'
issue: '6'
language:
- iso: eng
page: 2801-2805
publication: European Journal of Pediatrics
publication_identifier:
  issn:
  - 1432-1076
publication_status: published
publisher: Springer Science and Business Media LLC
status: public
title: Chronobiological changes due to school closures during the COVID-19 pandemic
  among adolescents in the DOrtmund Nutritional and Anthropometric Longitudinally
  Designed cohort study
type: journal_article
user_id: '105192'
volume: 182
year: '2023'
...
---
_id: '60095'
abstract:
- lang: eng
  text: "<jats:title>Abstract</jats:title><jats:p>Endurance training has been shown
    to be effective in treating adolescents with major depressive disorder (MDD).
    To integrate endurance training into the therapeutic setting and the adolescents'
    daily lives, the current performance status of the adolescents should be accurately
    assessed. This study aims to examine adolescents with MDD concerning exhaustion
    criteria during a cardiopulmonary exercise test (CPET), as well as to compare
    the values obtained thereon with sex- and age-related control values. The study
    included a retrospective examination of exhaustion criteria ((i) oxygen consumption
    (V̇O<jats:sub>2</jats:sub>) plateau, (ii) peak respiratory exchange ratio (RER<jats:sub>peak</jats:sub>) &gt; 1.0,
    (iii) peak heart rate (HR<jats:sub>peak</jats:sub>) ≥ 95% of the age-predicted
    maximal HR, and (iv) peak blood lactate concentration (BLC<jats:sub>peak</jats:sub>) &gt; 8.0 mmol⋅L<jats:sup>−1</jats:sup>)
    during a graded CPET on a cycle ergometer in adolescents with MDD (n = 57). Subsequently,
    maximal V̇O<jats:sub>2</jats:sub>, peak minute ventilation, V̇O<jats:sub>2</jats:sub>
    at the first ventilatory threshold, and peak work rate of participants who met
    at least two of four criteria were compared with published control values using
    an independent-sample t-test. Thirty-three percent of the total population achieved
    a V̇O<jats:sub>2</jats:sub> plateau and 75% a RER<jats:sub>peak</jats:sub> &gt; 1.0.
    The HR and BLC criteria were met by 19% and 22%, respectively. T-test results
    revealed significant differences between adolescents with MDD and control values
    for all outcomes. Adolescents with MDD achieved between 56% and 83% of control
    values.</jats:p><jats:p><jats:italic>   Conclusions</jats:italic>: The study shows
    that compared with control values, fewer adolescents with MDD achieve the exhaustion
    criteria on a CPET and adolescents with MDD have significantly lower cardiorespiratory
    fitness.</jats:p><jats:p><jats:italic>   Clinical trial registration</jats:italic>:
    No. U1111-1145–1854.</jats:p><jats:p><jats:table-wrap><jats:table><jats:tbody>\r\n
    \                   <jats:tr>\r\n                      <jats:td colspan=\"2\"><jats:bold>What
    is Known:</jats:bold><jats:italic>• It is already known that endurance training
    has a positive effect on depressive symptoms.</jats:italic></jats:td>\r\n                    </jats:tr>\r\n
    \                   <jats:tr>\r\n                      <jats:td colspan=\"2\"><jats:bold>What
    is New:</jats:bold><jats:italic>• A relevant proportion of adolescents with major
    depressive disorder do not achieve their V̇O2max during a graded cardiopulmonary
    exercise test.</jats:italic><jats:italic>• Adolescents with major depressive disorder
    have significantly lower cardiorespiratory fitness compared to sex- and age-related
    control values.</jats:italic></jats:td>\r\n                    </jats:tr>\r\n
    \                 </jats:tbody></jats:table></jats:table-wrap></jats:p>"
author:
- first_name: Charlotte
  full_name: Wenzel, Charlotte
  last_name: Wenzel
- first_name: Bart Chateau
  full_name: Bongers, Bart Chateau
  last_name: Bongers
- first_name: Marit Lea
  full_name: Schlagheck, Marit Lea
  id: '117661'
  last_name: Schlagheck
  orcid: '0000-0002-8913-6080 '
- first_name: Daniela
  full_name: Reis, Daniela
  last_name: Reis
- first_name: Franziska
  full_name: Reinhard, Franziska
  last_name: Reinhard
- first_name: Peter
  full_name: Schmidt, Peter
  last_name: Schmidt
- first_name: Stefan
  full_name: Bernitzki, Stefan
  last_name: Bernitzki
- first_name: Max
  full_name: Oberste, Max
  last_name: Oberste
- first_name: Heidrun Lioba
  full_name: Wunram, Heidrun Lioba
  last_name: Wunram
- first_name: Philipp
  full_name: Zimmer, Philipp
  last_name: Zimmer
- first_name: Oliver
  full_name: Fricke, Oliver
  last_name: Fricke
citation:
  ama: Wenzel C, Bongers BC, Schlagheck ML, et al. Validation of the maximal cardiopulmonary
    exercise test in adolescents with major depressive disorder and comparison of
    cardiorespiratory fitness with sex- and age-related control values. <i>European
    Journal of Pediatrics</i>. 2023;183(1):379-388. doi:<a href="https://doi.org/10.1007/s00431-023-05304-6">10.1007/s00431-023-05304-6</a>
  apa: Wenzel, C., Bongers, B. C., Schlagheck, M. L., Reis, D., Reinhard, F., Schmidt,
    P., Bernitzki, S., Oberste, M., Wunram, H. L., Zimmer, P., &#38; Fricke, O. (2023).
    Validation of the maximal cardiopulmonary exercise test in adolescents with major
    depressive disorder and comparison of cardiorespiratory fitness with sex- and
    age-related control values. <i>European Journal of Pediatrics</i>, <i>183</i>(1),
    379–388. <a href="https://doi.org/10.1007/s00431-023-05304-6">https://doi.org/10.1007/s00431-023-05304-6</a>
  bibtex: '@article{Wenzel_Bongers_Schlagheck_Reis_Reinhard_Schmidt_Bernitzki_Oberste_Wunram_Zimmer_et
    al._2023, title={Validation of the maximal cardiopulmonary exercise test in adolescents
    with major depressive disorder and comparison of cardiorespiratory fitness with
    sex- and age-related control values}, volume={183}, DOI={<a href="https://doi.org/10.1007/s00431-023-05304-6">10.1007/s00431-023-05304-6</a>},
    number={1}, journal={European Journal of Pediatrics}, publisher={Springer Science
    and Business Media LLC}, author={Wenzel, Charlotte and Bongers, Bart Chateau and
    Schlagheck, Marit Lea and Reis, Daniela and Reinhard, Franziska and Schmidt, Peter
    and Bernitzki, Stefan and Oberste, Max and Wunram, Heidrun Lioba and Zimmer, Philipp
    and et al.}, year={2023}, pages={379–388} }'
  chicago: 'Wenzel, Charlotte, Bart Chateau Bongers, Marit Lea Schlagheck, Daniela
    Reis, Franziska Reinhard, Peter Schmidt, Stefan Bernitzki, et al. “Validation
    of the Maximal Cardiopulmonary Exercise Test in Adolescents with Major Depressive
    Disorder and Comparison of Cardiorespiratory Fitness with Sex- and Age-Related
    Control Values.” <i>European Journal of Pediatrics</i> 183, no. 1 (2023): 379–88.
    <a href="https://doi.org/10.1007/s00431-023-05304-6">https://doi.org/10.1007/s00431-023-05304-6</a>.'
  ieee: 'C. Wenzel <i>et al.</i>, “Validation of the maximal cardiopulmonary exercise
    test in adolescents with major depressive disorder and comparison of cardiorespiratory
    fitness with sex- and age-related control values,” <i>European Journal of Pediatrics</i>,
    vol. 183, no. 1, pp. 379–388, 2023, doi: <a href="https://doi.org/10.1007/s00431-023-05304-6">10.1007/s00431-023-05304-6</a>.'
  mla: Wenzel, Charlotte, et al. “Validation of the Maximal Cardiopulmonary Exercise
    Test in Adolescents with Major Depressive Disorder and Comparison of Cardiorespiratory
    Fitness with Sex- and Age-Related Control Values.” <i>European Journal of Pediatrics</i>,
    vol. 183, no. 1, Springer Science and Business Media LLC, 2023, pp. 379–88, doi:<a
    href="https://doi.org/10.1007/s00431-023-05304-6">10.1007/s00431-023-05304-6</a>.
  short: C. Wenzel, B.C. Bongers, M.L. Schlagheck, D. Reis, F. Reinhard, P. Schmidt,
    S. Bernitzki, M. Oberste, H.L. Wunram, P. Zimmer, O. Fricke, European Journal
    of Pediatrics 183 (2023) 379–388.
date_created: 2025-06-02T09:49:36Z
date_updated: 2025-06-02T09:52:44Z
doi: 10.1007/s00431-023-05304-6
extern: '1'
intvolume: '       183'
issue: '1'
language:
- iso: eng
page: 379-388
publication: European Journal of Pediatrics
publication_identifier:
  issn:
  - 1432-1076
publication_status: published
publisher: Springer Science and Business Media LLC
status: public
title: Validation of the maximal cardiopulmonary exercise test in adolescents with
  major depressive disorder and comparison of cardiorespiratory fitness with sex-
  and age-related control values
type: journal_article
user_id: '117661'
volume: 183
year: '2023'
...