Effects of inspiratory muscle training on posture and respiratory muscle performance in forward head posture: Randomized controlled trial

Background Forward head posture (FHP) alters spinal alignment, impairs core stability, and disrupts respiratory mechanics. Due to the link between respiration and postural control, inspiratory muscle training (IMT) may serve as a targeted intervention to enhance respiratory function and postural alignment. Purpose This study aimed to investigate the effects of IMT on posture, respiratory functions, respiratory muscle strength, and respiratory endurance in individuals with FHP. Materials and methods This prospective, randomized controlled trial was completed by 40 participants aged 18–35 years with a craniovertebral angle (CVA) ≤ 50°. Participants were allocated to the IMT or control group. The IMT group completed a structured 6-week IMT protocol with the PowerBreathe ® device, while the control group received no intervention. Postural assessments, pulmonary function tests, and respiratory muscle strength and endurance evaluations were conducted at baseline and after 6 weeks. Results Mixed-model ANOVA showed significant group × time interaction effects for postural parameters, including CVA (F = 13.975, p = 0.001), sagittal head angle (F = 8.105, p = 0.007), C7-wall distance (F = 16.330, p < 0.001), and thoracic kyphosis (F = 8.135, p = 0.006). Respiratory function parameters showed no significant group, time, or group × time interaction effects (all p > 0.05). In contrast, significant group × time interaction effects were observed for respiratory muscle strength and endurance, including maximal inspiratory pressure (F = 53.645, p < 0.001), maximal expiratory pressure (F = 40.399, p < 0.001), and endurance (F = 12.386, p = 0.001). Conclusion Inspiratory muscle training appears effective for improving postural alignment in individuals with FHP. The results indicate that IMT may be a valuable adjunct in the early conservative management of postural disorders.