The aim of this research is to compare the effects of post-facilitation stretch and dry needling on hamstring flexibility, pain, lumbar range of motion, pelvic tilt, and functional status in patients with chronic low back pain. This randomized clinical trial will be conducted at Spine Care Physical Therapy and Rehabilitation Centre (SPRC), Peshawar. The sample size will be 36 participants, who will be randomly divided into two groups: 18 participants in the post-facilitation stretch group and 18 participants in the dry needling group. The study duration will be 3 weeks, with interventions applied three times per week. The sampling technique used will be non-probability purposive sampling, followed by random allocation using the sealed opaque envelope method. Participants aged 20-50 years diagnosed with chronic nonspecific low back pain and having hamstring tightness will be included. Outcome measures used in the study will be Active Knee Extension Test (goniometer) for hamstring flexibility, Numeric Pain Rating Scale (NPRS) for pain, goniometer for lumbar flexion and extension, pelvic inclinometer for pelvic tilt, and Modified Oswestry Disability Index (MODI) for functional disability.

Chronic low back pain (CLBP), defined as pain persisting for more than 12 weeks, represents one of the leading causes of long-term disability worldwide. In the absence of a clearly identifiable structural pathology, the majority of cases are classified as chronic non-specific low back pain, which poses significant challenges for accurate diagnosis and targeted management. The Global Burden of Disease (2023) report highlights low back pain as the highest-ranking musculoskeletal condition in terms of disability, affecting approximately 7.5% of the global population, with lifetime prevalence estimates reaching up to 80% and projected to rise further by 2050.Chronic low back pain is closely associated with musculoskeletal dysfunctions, including impaired trunk muscle control, altered pelvic mechanics, and compensatory movement strategies involving the hip and lower extremities. Disruption of normal movement patterns and muscle imbalances contributes to abnormal load distribution across the lumbar spine, thereby perpetuating pain and functional limitation. In particular, restricted pelvic mobility during trunk flexion and extension results in excessive lumbar spine motion, increasing mechanical stress on spinal structures.Lifestyle and behavioral factors play an important role in the development and progression of CLBP. Emerging evidence suggests that regular moderate physical activity has a protective effect against chronicity. A recent prospective cohort study (2025) demonstrated that individuals engaging in more than 100 minutes of daily walking exhibited a significantly lower risk of developing chronic low back pain. In contrast, psychosocial factors such as depression have been shown to negatively influence pain severity, disability levels, and recovery outcomes, emphasizing the multifactorial nature of CLBP.

Hamstring muscle tightness is a commonly observed impairment in individuals with CLBP and has been identified as a key contributor to altered lumbopelvic rhythm. The hamstring muscle group comprising the semitendinosus, semimembranosus, and long head of the biceps femoris originates from the ischial tuberosity and plays a crucial role in regulating hip and knee mechanics. Reduced hamstring flexibility limits anterior pelvic tilt during forward bending, leading to compensatory lumbar spine motion and increased repetitive loading. Chronic hamstring tightness is frequently accompanied by weakness of the gluteus maximus and deep core stabilizers, resulting in posterior chain imbalance and reliance on superficial stabilizers such as the erector spinae, further aggravating pain persistence.Improving hamstring flexibility is therefore considered an important therapeutic target in the management of chronic non-specific low back pain. Various stretching techniques, including static stretching, have demonstrated effectiveness in increasing range of motion and reducing musculotendinous stiffness. Improved flexibility has been associated with favorable changes in muscle activation patterns and a more balanced distribution of movement between the pelvis and lumbar spine, potentially reducing mechanical strain.

Among manual therapy interventions, Dry Needling (DN) has gained increasing attention as an invasive technique designed to deactivate myofascial trigger points, normalize muscle tone, and reduce nociceptive input. DN has shown effectiveness in reducing pain sensitivity, relieving muscle tightness, and improving functional movement, particularly when combined with exercise-based rehabilitation. Evidence from systematic reviews and meta-analyses supports its short- to mid-term benefits in reducing pain and disability in individuals with CLBP.Similarly, Muscle Energy Technique (MET), particularly in the form of post-facilitation stretch (PFS), has demonstrated strong efficacy in improving hamstring flexibility. PFS utilizes a maximal voluntary contraction followed by an immediate stretch to enhance muscle extensibility through neuromuscular mechanisms such as post-isometric relaxation and reciprocal inhibition. Compared to conventional stretching, MET has been shown to produce superior improvements in range of motion, reduce muscle stiffness, and enhance functional performance.Although both DN and PFS are effective in reducing pain and improving flexibility, they operate through distinct physiological mechanisms. PFS primarily modulates neuromuscular tone through voluntary contraction and reflex inhibition, whereas DN directly targets localized myofascial dysfunction to interrupt pain cycles and restore tissue perfusion. Despite their individual benefits, limited evidence exists directly comparing these two interventions within a standardized rehabilitation framework for chronic non-specific low back pain associated with hamstring tightness.However, no evidence exists comparing post-facilitation stretch and dry needling when combined with conventional physiotherapy in chronic non-specific low back pain associated with hamstring tightness.Therefore, the present randomized clinical trial aims to compare the effects of post-facilitation stretch and dry needling, each combined with conventional physiotherapy treatment, in individuals with chronic non-specific low back pain accompanied by hamstring tightness. The primary objective of the study is to determine which intervention leads to greater improvement in hamstring flexibility. Secondary objectives include comparison of lumbar range of motion, pelvic tilt, pain intensity, and functional disability between the two intervention groups.

Inclusion Criteria:

• Diagnosed with chronic non-specific low back pain of more than 12 weeks' duration.
• Positive Straight Leg Raise (SLR) test or Active Knee Extension Test showing hamstring tightness (<80° hip flexion with knee extended).

Exclusion Criteria:

• History of spinal surgery, fracture, or neurological deficit.
• Radiculopathy or red flag signs (tumor, infection, inflammatory disorders).
• Recent steroid injection therapy for low back pain (within 3 months).
• Contraindications to dry needling (bleeding disorders, infection at site, needle phobia).
• Pregnancy.
• Severe needle phobia (for DN group).