Effects of diaphragmatic manual therapy on respiratory function in patients with non-specific low back pain: A randomized control trial

Abstract

Background: Non-specific low back pain (NSLBP) is common and often resistant to conventional physiotherapy. The diaphragm, given its dual role in posture and respiration, may be a therapeutic target.

Objective: To determine whether diaphragm manual therapy plus conventional physiotherapy improves thoracic expansion and pulmonary function in NSLBP.

Methods: A single-blind randomized controlled trial included 46 adults with NSLBP (mean age 46.0 ± 16.2 years; 43 % female; BMI 27.2 ± 5.4 kg/m²). Participants were randomized to an experimental group (n = 20) receiving diaphragm manual therapy plus physiotherapy or a control group (n = 26) receiving physiotherapy alone. Outcomes were inspiratory thoracic expansion, forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV1), measured at baseline, post-treatment, and 10- and 30-day follow-ups. Repeated-measures ANOVA and Spearman correlation were used (α = 0.05).

Results: The experimental group showed greater improvements in thoracic expansion (mean difference = 3.31 cm; 95 % CI 2.69-3.93; p < 0.001; η² = 0.78), FVC (Δ = 1.24 L; 95 % CI 1.11-1.37; p < 0.001; η² = 0.76), and FEV1 (mean difference = 1.25 L; 95 % CI 1.12-1.38; p < 0.001; η² = 0.77) compared with controls. Thoracic expansion correlated with FVC (ρ = 0.731) and FEV1 (ρ = 0.751) at 30 days (both p < 0.001).

Conclusions: Diaphragm manual therapy improved thoracic expansion and pulmonary function in NSLBP, supporting its role as an adjunct to physiotherapy. The trial has been registered under the name of "DIAFRAGMA" and number NCT06069388.

Keywords: Diaphragm; Low back pain; Physical therapy modalities; Randomized controlled trial; Respiratory function tests; Spirometry.