The effects of the COVID-19 pandemic on mental health have not been fully inspected among the young adults’ population. The objectives of the present study were: (1) to examine differences in emotional reactivity and emotion regulation between, both gender and sports engagement level during the first 2 weeks of the lockdown; and (2) to examine the possible impact of emotion regulation on emotional reactivity, and possible significant roles of gender and sports engagement level as moderators. This cross-sectional study included 315 Serbian young adults (aged 18–26 years old) during COVID-19 lockdown. Respondents answered socio-demographic questions and the Serbian version of the Multidimensional Emotion Questionnaire (MEQ). The results of confirmatory factor analysis indicated good fit for both positive and negative reactivity scales (SRMR = 0.037; CFI = 0.984, RMSEA = 0.046, and SRMR = 0.055; CFI = 0.964, RMSEA = 0.064, respectively). Gender differences were found in both positive (p = 0.039; d = 0.28) and negative emotional reactivity scales (p < 0.001; d = 0.60), with females reported lower and higher values, respectively. Professional athletes presented higher scores in positive reactivity scale in comparison to non-athletes (p < 0.001; d = 0.78) and recreational athletes (p = 0.034; d = 0.34) during 2 weeks of COVID-19 lockdown. Conversely, professional athletes scored lower in negative emotional reactivity scale in comparison to non-athletes (p < 0.001; d = 0.85) and recreational athletes (p = 0.006; d = 0.42). Both gender and sports engagement level differences were found for negative, but not for positive emotion regulation scale. Furthermore, results showed that engagement in sports level plays a significant role as moderator in relationship between negative regulation and negative reactivity, where professional athletes presented significant interaction effect and predicted lower negative reactivity scores compared to non-athletes and recreational athletes. However, gender does not moderate the influence of emotion regulation on emotional reactivity either positive or negative. Engagement in sports as a lifestyle may contribute to better emotional harmony especially in the crisis situation as COVID-19 lockdown.
