The alignment of respiration to sensory-motor events is shaped by expected effort

Humans often align their respiration with external events, which may optimize neural resources for perception and action. This may adjust neurophysiological processes related to neural excitation, attention, or arousal to optimize task performance. However, it remains unclear whether this alignment is a passive entrainment to a task's overall rhythm or an active process selectively aligning respiration more to highly demanding events. We tested this by recording respiration during three visual discrimination experiments that manipulated the importance of individual trials by imposing response deadlines or manipulating trial value and difficulty. We found that participants align their respiration more consistently for trials with short deadlines or trials presenting high-value and high-difficulty. This demonstrates that respiratory alignment is dynamically modulated on a trial-by-trial basis according to anticipated effort or task demands. Hence, respiration serves as an active tool to strategically allocate cognitive resources for sensory-motor challenges.