Greater diaphragm fatigability in individuals with recurrent low back pain

The diaphragm plays an important role in spinal control. Increased respiratory demand compromises spinal control, especially in individuals with low back pain (LBP). The objective was to determine whether individuals with LBP exhibit greater diaphragm fatigability compared to healthy controls. Transdiaphragmatic twitch pressures (TwPdi) were recorded in 10 LBP patients and 10 controls, before and 20 and 45 min after inspiratory muscle loading (IML). Individuals with LBP showed a significantly decreased potentiated TwPdi, 20 min (-20%) (p=0.002) and 45 min (-17%) (p=0.006) after IML. No significant decline was observed in healthy individuals, 20 min (-9%) (p=0.662) and 45 min (-5%) (p=0.972) after IML. Diaphragm fatigue (TwPdi fall ≥ 10%) was present in 80% (20 min after IML) and 70% (45 min after IML) of the LBP patients compared to 40% (p=0.010) and 30% (p=0.005) of the controls, respectively. Individuals with LBP exhibit propensity for diaphragm fatigue, which was not observed in controls. An association with reduced spinal control warrants further study.