Multi-marathoners, usually 100 Marathon Club members, have completed dozens or even hundreds of marathons. While physiological benefits of endurance running are established, the psychological impacts, particularly depression and anxiety, remain underexamined. This study compared depression and anxiety in multi-marathoners with population norms and examined differences by age, gender, and psychological subgroup.

A cross-sectional online survey collected data from 576 multi-marathoners (56 % men), mean age 53.4 years (SD 9.88), average marathon completions of 146 (SD 196.77). Depression and anxiety were assessed using CESD-8 and STAI-S-6, and compared to TILDA, an Irish longitudinal ageing study. Age and gender trends were analysed with linear regression. Latent Class Analysis identified subgroups, while t-tests and ANOVA explored group differences.

Compared to TILDA norms, multi-marathoners had higher depression and anxiety scores across demographics, though still below clinical thresholds (CESD-8 ≥ 8; STAI-S-6 ≥ 12). Women scored higher on depression than men. Older men had lower anxiety (slope = −0.35, p = 0.002), with a similar, non-significant trend in women. Depression scores were stable with minor, non-significant age-related shifts.

LCA identified four psychological profiles, mostly with minimal to moderate symptoms. Notably, 8 % of multi-marathoners fell into the Severe Depression & High Anxiety category, exceeding the highest clinical cut-offs.

Multi-marathoners did not consistently show lower depression or anxiety. While many exhibited low or subclinical symptoms, a subgroup showed clinically significant mental health issues. This highlights psychological variability and the limitations of group-level analysis, underscoring the need for targeted mental health assessments and individualised support.