From physiological workload to motivation during a prolonged trail run: the mediating role of affective valence and...

Motivation is critical for sustaining effort during prolonged exercise, yet the mechanisms underlying in-task fluctuations remain unclear. Affective responses may contribute to these fluctuations given their links with exercise intensity and motivation. This exploratory study investigated the relationship between physiological workload relative to speed and motivation, and the mediating role of affective responses.

Fourteen trained male trail-runners completed two 90 min runs on a 2 km loop while maintaining an RPE of 14 on Borg's 6-20 scale. Heart rate and running speed were continuously recorded, and RPE, affective responses (valence and arousal), and motivation were assessed each lap. Physiological workload was indexed via the HR:Speed ratio. Bayesian mediation models quantified direct and indirect effects of physiological workload on motivation through valence and arousal.

A 1-unit increase in HR:Speed from the mean was associated with a 0.19-unit decrease in motivation. Higher physiological load was associated with 3.2 greater odds of lower valence, while evidence for changes in arousal was weaker. Higher valence and arousal tended to be associated with greater motivation. Mediation analysis suggested that 32% of the association between HR:Speed and motivation operated through affective responses with valence contributing most of the indirect effect. This indirect pathway appeared workload-dependant, with higher valence associated with greater motivation at lower intensity, but lower valence associated with reduced motivation at higher intensity.

These finding provide preliminary evidence for a potential role of affective valence in motivational regulation during prolonged run. Further research is needed to clarify the robustness of these relationships and to determine whether intervention targeting affective responses may influence performance.