Soccer Players' Sleep Quality and Training Load Were Affected by the COVID-19 Lockdown: An International Survey

Background: The effect of the 2020 COVID-19 lockdown on athlete sleep and training behavior is documented, albeit without a worldwide soccer-specific focus. Method: Soccer (football) players (N = 1639; 30 countries; age 22.5 [5.7] y; 81% ≤25 y; 56% male; 30% elite; 66% Muslim) answered a retrospective, cross-sectional questionnaire related to their behavioral habits before and during COVID-19 lockdown (survey period July to September 2020), including (1) Pittsburgh Sleep Quality Index PSQI, (2) Insomnia Severity Index (ISI), (3) bespoke questions about training behaviors, and (4) Muslim player focused sleep and training behavior questions. Results: During lockdown (compared to prelockdown), PSQI (P < .001; moderate effect size [ES]) and ISI (P < .001; moderate ES) scores were higher in the overall sample and in elite versus nonelite (PSQI: P < .05; small ES and ISI: P < .001; small ES), >25 years versus ≤25 years (PSQI: P < .01; small ES and ISI: P < .001; moderate ES), females versus males (PSQI: P < .001; small ES), <1 month versus >1 month lockdown (PSQI: P < .05; small ES and ISI: P < .05; small ES), and players maintaining versus reducing training intensity (PSQI: P < .001; moderate ES and ISI: P < .001; small ES). Muslim players (41%) reported unfavorable sleep and/or training behaviors during Ramadan in lockdown compared to lockdown outside of Ramadan. Conclusions: Specific subgroups appear more vulnerable to lockdown effects, with training-intensity maintenance moderating negative effects relative to sleep. Policy and support (respectful of subgroup nuances) during lockdown-like challenges that facilitate training (including intensity) appear prudent, given their favorable relationship with sleep, mental health, and physical health, in the present data and elsewhere.