Changes in hippocampal volume and affective functioning after a moderate intensity running intervention

This study examined the effects of a moderately intense seven-week running intervention on the hippocampal volume and depressive symptoms of young men (20-31 years of age) from the general population (N = 21). A within-subjects-design involving a two-week baseline period before the running intervention, and two subsequent intervention cycles was applied. At four time points of assessment (t₁: start of the study; t₂: end of baseline period/start of the intervention; t₃: end of the first intervention cycle; t₄: end of the 2nd intervention cycle/study end) magnetic resonance imaging was performed and symptoms related to depression were assessed employing the Center for Epidemiological Studies Depression (CES-D) Scale. The intervention resulted in a significant increase in the estimated maximum oxygen uptake (VO₂max), measured with a standardized walking test (average increase from 42.07 ml*kg^{- 1}*min^{- 1} to 46.07 ml*kg^{- 1}*min^{- 1}). The CES-D scores decreased significantly over the course of the running intervention (average decrease from 12.76 to 10.48 on a 20-point scale). Significant volumetric increases in the hippocampus were found, most notably after the first intervention cycle in the left (average increase from 613.41 mm³ to 620.55 mm³) and right hippocampal tail (average increase from 629.77 mm³ to 638.17 mm³). These findings provide new evidence regarding the temporal dynamics of hippocampal changes following engagement in physical activity.