The field investigating the relationship between physical activity and cognition has considerably evolved in recent years. This has led to an increasingly differentiated view on this phenomenon, challenging the notion of overall cognitive and academic benefits of regular physical activity for school-aged children, with renewed questioning of whether, to what extent, and under which circumstances regular physical activity shapes cognitive and academic development. The current lack of consensus may weaken the advocacy among relevant stakeholders (e.g., policymakers and teachers) for intensified efforts to promote physical activity in educational settings in which the value of planned and structured forms of physical activity (e.g., physical education lessons) for broader academic achievement is often questioned in the crowded school curriculum. To generate more robust evidence, we propose that the relationships between regular physical activity and cognitive performance should be elucidated by considering both sides of the coin, namely the influence of increased and reduced levels of regular physical activity. In this article, we show how investigating the consequences of reduced levels of regular physical activity can provide a novel perspective that will complement our understanding of how regular physical activity in school-aged children shapes cognitive and academic performance. Furthermore, such a novel perspective will help advance the research practice and knowledge generation in educational psychology and related research fields, probably yielding evidence with practically highly relevant implications for curriculum design and equity-focused interventions. To that end, we critically reflect on observational and intervention research designs that can be used for this purpose and identify and discuss the role of the summer break as an ecologically valid scenario in which a 'natural' reduction of regular physical activity levels and the phenomenon of summer learning loss occur. Lastly, we provide methodological recommendations for future studies in which we consider reduced levels of physical activity not as a mere reduction of the metabolic demands of physical activity but also as an absence of broader challenges in the school physical education context.