Inspiratory Muscle Training Affects Proprioceptive Use and Low Back Pain

Purpose We have shown that individuals with recurrent nonspecific low back pain (LBP) and healthy individuals breathing against an inspiratory load decrease their reliance on back proprioceptive signals in upright standing. Because individuals with LBP show greater susceptibility to diaphragm fatigue, it is reasonable to hypothesize that LBP, diaphragm dysfunction, and proprioceptive use may be interrelated. The purpose of this study was to investigate whether inspiratory muscle training (IMT) affects proprioceptive use during postural control in individuals with LBP. Methods Twenty-eight individuals with LBP were assigned randomly into a high-intensity IMT group (high IMT) and low-intensity IMT group (low IMT). The use of proprioception in upright standing was evaluated by measuring center of pressure displacement during local muscle vibration (ankle, back, and ankle-back). Secondary outcomes were inspiratory muscle strength, severity of LBP, and disability. Results After high IMT, individuals showed smaller responses to ankle muscle vibration, larger responses to back muscle vibration, higher inspiratory muscle strength, and reduced LBP severity (P < 0.05). These changes were not seen after low IMT (P > 0.05). No changes in disability were observed in either group (P > 0.05). Conclusions After 8 wk of high IMT, individuals with LBP showed an increased reliance on back proprioceptive signals during postural control and improved inspiratory muscle strength and severity of LBP, not seen after low IMT. Hence, IMT may facilitate the proprioceptive involvement of the trunk in postural control in individuals with LBP and thus might be a useful rehabilitation tool for these patients.