Inspiratory muscle loading with dyspnea limits simulated driving performance in young adults

Dyspnea is a neurophysiological experience that imposes cognitive load by activating cortical areas responsible for attention, emotional regulation, and motor planning. Consequently, it may compromise multi-tasking activities like driving. This study investigated whether inspiratory threshold loading (ITL) and associated dyspnea impairs simulated driving performance in young healthy adults.

28 healthy adults (mean age 24 ± 1 years) completed the Depression Anxiety Stress Scale 21 (DASS-21), and performed maximal inspiratory pressures (MIP) and spirometry. Using a repeated measures design, they completed 3 tasks in randomized and counterbalanced order: single-task ITL against a 20 cmH₂O load (ITL), single-task Driving (Drv), and dual-task Drv + ITL. Simulated driving was performed using a computer-based software where preplanned routes of comparable length and difficulty were provided. Driving error, dyspnea intensity (Borg Dyspnea Scale), ventilatory outcomes and affect (Self-Assessment Manikin [SAM]), and qualitative dyspnea descriptors were assessed at baseline and immediately after each task.

Two categories of driving error, vehicle control and signal infractions, were significantly higher during dual task Drv + ITL compared to single-task Drv (p ≤ 0.048). Tidal volume, respiratory rate and minute ventilation were more variable during Drv + ITL than ITL (p ≤ 0.010). SAM affective responses indicated significantly lower sense of control (p= 0.018) and greater chest pressure (p = 0.010) during Drv + ITL versus single-task Drv. Greater MIP (inspiratory muscle strength) was correlated with lower Borg Dyspnea scores during Drv + ITL (r=- 0.336, p = 0.040).

Inspiratory muscle loading and associated dyspnea decreased sense of control and impaired simulated driving performance. Participants with higher inspiratory muscle strength experienced lower dyspnea intensity during dual task Drv + ITL.