Role of Vigorous Physical Activity in Mental Health: A Narrative Review.

Physical activity (PA) is widely associated with favorable mental health outcomes. However, much of the literature has examined PA as a broad exposure, usually in terms of total volume, participation status, or combined moderate-to-vigorous PA. This approach may neglect the potential importance of activity intensity. Vigorous physical activity (VPA) differs from lower-intensity activity in physiological demands, subjective effort, affective responses, and behavioral contexts and may, therefore, represent a distinct dimension of PA behavior. This narrative review aims to examine whether VPA should be considered a distinct dimension of PA behavior in mental health research by synthesizing mechanistic rationale, intervention evidence, and observational findings, while clarifying how differences in VPA definition, measurement approach, study design, population, and outcome selection contribute to inconsistent findings across the literature. The available evidence suggests that VPA is relevant to mental health, although the strength of evidence differs across outcomes. Findings are most developed for depressive symptoms, where both intervention and observational studies generally support favorable associations. Structured VPA may reduce depressive symptoms in some populations, while habitual VPA has been associated with lower depressive symptom burden in observational research. Evidence for other outcomes, including anxiety, perceived stress, psychological distress, sleep quality, and mental well-being, is more limited but suggests that the relevance of VPA may extend beyond depression alone. However, these findings remain less directly comparable because studies differ in outcome measures, populations, and study designs. Interpretation is complicated by the inconsistent definition of VPA across the literature. Prescribed VPA, habitual VPA, frequency of VPA, and the proportion of VPA within total PA are related but distinct constructs. High-intensity interval training is also a relevant, structured form of VPA, but it should not be treated as equivalent to all forms of VPA. These definitional differences, together with variation in measurement methods, populations, and mental health outcomes, help explain why findings remain inconsistent. Overall, VPA deserves consideration as a distinct feature of PA behavior in mental health research. Future studies should define VPA more precisely, distinguish absolute from proportion-based measures, account for total PA volume, and examine specific mental health outcomes separately.