High-level spinal cord injury (SCI) can result in spinal and supraspinal respiratory control deficits leading to insufficient ventilatory responses to exercise and training-related adaptations. We hypothesized a serotonin agonist, known to improve respiratory function in animal models, would improve adaptations to whole-body functional electrical stimulation (FES) exercise training in patients with acute high-level SCI.

We identified ten patients (<2 years of injury with SCI from C4-T3) in our program who had performed six months of FES-row training while on the Buspirone, a serotonin 1A agonist (29±17mg/day), between 2012 and 2018. We also identified well-matched individuals who trained for six months but not on Buspirone (n=11). A peak incremental FES-rowing exercise test and resting pulmonary function test had been performed before and after training.

Those on Buspirone demonstrated greater increases in peak oxygen consumption (VO₂peak: +0.24±0.23 vs. +0.10±0.13L/min, P=0.08) and peak ventilation (VEpeak: +6.5±8.1 vs. -0.7±6.9L/min, P<0.05) compared to control. In addition, changes in VO₂peak and VEpeak were correlated across all patients (r=0.63, P<0.01), but most strongly in those on Buspirone (r=0.85, P<0.01). Furthermore, changes in respiratory function correlated to increased peak tidal volume in the Buspirone group (r>0.66, P<0.05).

These results suggest Buspirone improves cardiorespiratory adaptations to FES-exercise training in individuals with acute, high-level SCI. The strong association between increases in ventilatory and aerobic capacities suggests improved respiratory function is a mechanism, however controlled studies are needed to determine if this preliminary finding is reproducible.