The aim of the study was to investigate the effects of functional respiratory muscle training on diaphragm function, core stabilization, respiratory muscle strength, pain, functional status and quality of life in patients with chronic non-specific low back pain.

Patients with chronic non-specific low back pain (CNSBP) have imbalances in postural control and kinetic chain. Postural control and respiratory function are mechanically and neuromuscularly interdependent. The diaphragm is the primary muscle in active inspiration with a vital role in contributing to spinal stability by modulating intra-abdominal pressure. The attachment of the diaphragm to the lumbar spine creates a synergistic working pattern with the transversus abdominis muscle. Altered activation patterns of the diaphragm and transversus abdominis have been observed in patients with chronic low back pain. Therefore, diaphragm function and respiratory pattern play a critical role in achieving and maintaining core stabilization. Studies have supported that different respiratory exercise programs are effective in reducing pain intensity, improving respiratory function and quality of life in CNSBP. These studies suggest a possible link between respiratory function, respiratory pattern, core stability and low back pain.

Inspiratory muscle training (IMT) is a technique used to increase the strength or endurance of the diaphragm and auxiliary respiratory muscles with a pressure threshold device. IMT consists of exercises involving breathing against resistance to improve respiratory muscle strength and aerobic capacity in healthy and sick populations. Respiratory muscles are also trunk muscles and their performance cannot be sufficiently optimized when respiratory muscle training is performed in isolation. Furthermore, if the load on the diaphragm, which has inspiratory, postural control and trunk stabilization tasks, increases, the muscle prefers breathing over these tasks. Functional training of the respiratory muscles is therefore recommended for optimal performance of the respiratory muscles. Functional inspiratory muscle training (FIMT) is defined as inspiratory respiratory muscle training during exercises in specific body positions. FIMT stimulates both the respiratory system and the core stabilization muscles as it consists of trunk and lumbopelvic exercises with stabilization of the spinal region during inspiratory load. Compared to traditional inspiratory muscle training, FIMT has a greater effect because it improves two roles of respiratory muscles (ventilation and spinal stabilization).

This study will investigate the effects of functional inspiratory muscle training (FIMT) on diaphragm thickness and mobility, respiratory muscle strength, core stabilization, pain, quality of life and functional status in patients with CNSLBP.

Inclusion Criteria:

• Low back pain lasting at least 3 months
• Being between the ages of 18 and 55
• Scoring 4 or more on the Numeric Pain Scale for the severity of low back pain
• Having a non-specific origin (not caused by a specific pathology such as -Infection, osteoporosis, fracture, structural deformity, inflammatory disorder, radicular syndrome)
• Individuals with inspiratory muscle strength ≥80 mmHg
• Individuals with a forced expiratory volume (FEV1) of 80% or more

Exclusion Criteria:

• Tumor history
• Spine surgery in the last 12 months
• Spinal pathology (spondylolysis or spondylolisthesis) or concomitant neurological disease or neurological findings in the leg
• Having a chronic systemic disease
• Pregnancy
• Having a disease that affects the lungs and causes breathing problems
• Participation in a physiotherapy program in the last 6 months