Background. Stay-home orders and the shutdown of university campuses and fitness centers have greatly influenced health behaviors, resulting in a widespread reduction in physical activity. This study aimed to identify factors associated with maintaining physical activity among Jazan University medical students during the COVID-19 shutdown. Methods. An official Arabic short form of the International Physical Activity Questionnaire was used to assess physical activity before and during the COVID-19 home quarantine. Differences between groups were examined using chi-square analyses and the Mann–Whitney U test. Multinomial logistic regression was used to test whether certain demographic and exercise-related variables were significant predictors of maintaining physical activity levels during the COVID-19 pandemic. Results. More than half of the participants (53%) reported no change or increased physical activity level. Several factors were significantly related to physical activity heterogeneity including income (p = 0.04), fitness center membership (p < 0.01), usage of fitness tracker devices (p < 0.01), and the purchase of physical activity equipment during the COVID-19 pandemic (p < 0.01). The odds of maintaining physical activity were higher among those who tracked their physical activity (AOR = 6.160; 95% CI = 3.782–10.032, p < 0.001). Similarly, the odds of maintaining physical activity were higher among those who purchased home-exercise equipment during the pandemic (AOR = 2.243; 95% CI = 1.386–3.632, p = 0.001). Conclusions. Understanding the factors affecting physical activity behaviors is an essential step toward addressing the reduction in physical activity. This could help maintain physical activity levels during a potential future pandemic-related shutdown.