Alonso Martínez, AliciaRamírez Vélez, RobinsonGarcía Alonso, YeseniaIzquierdo Redín, MikelGarcía Hermoso, Antonio2021-06-162021-06-1620211660-4601 (Electronic)10.3390/ijerph18020693https://academica-e.unavarra.es/handle/2454/39943Background: A better understanding of the effects of the lockdown on lifestyle behaviors may help to guide the public health response to COVID-19 at a national level and to update the global strategy to respond COVID-19 pandemic. The aim of the study was to examine the effects of the COVID-19 lockdown on device-measured physical activity (PA), sedentary time, sleep and self-regulation; and to determine whether PA and sleep are related to self-regulation problems during the lockdown. Methods: PA, sedentary time and sleep were assessed using accelerometry in the week in which the Spanish national state of alarm was declared (n = 21). Parents reported preschooler’s self-regulation difficulties (internalizing and externalizing) before (n = 268) and during the lockdown (n = 157) by a validated questionnaire. Results: Preschoolers showed a decrease in total PA (mean difference [MD] = -43.3 min per day, 95% CI -68.1 to -18.5), sleep efficiency (MD = -2.09%, 95% CI -4.12 to -0.05), an increase in sedentary time (MD = 50.2 min per day, 95% CI 17.1 to 83.3) internalizing (MD = 0.17, 95% CI 0.06 to 0.28) and externalizing (MD = 0.33, 95% CI 0.23 to 0.44) problems. Preschoolers who met the World Health Organization recommendations for PA had lower internalizing scores than non-active peers (MD = -1.28, 95% CI -2.53 to -0.03). Conclusions: Our findings highlight the importance of meeting PA recommendations to reduce psychosocial difficulties during a lockdown situation.8 p.application/pdfeng© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.CoronavirusHealthy lifestyleMental healthQuarantineinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/openAccess