The aim of this randomized controlled trial is to find the effectiveness of low load blood restriction training on improving hamstring muscle strength, alleviating pain and reducing functional disability in nonspecific low back pain patients

Low back pain (LBP)-related disability and the related socioeconomic burden remain high despite the many treatment options and health care resources available for LBP. LBP can be caused by a specific pathology or trauma; however, in >90% of cases, an underlying disease is absent. The clinical course of this called as nonspecific LBP which is the most common type of low back pain and, some patients recover within weeks, and others experience persistent disabling symptoms leading to chronic LBP. Chronic low back pain (CLBP, pain lasting more than 12 weeks duration) is one of the most common chronic musculoskeletal disorders with high prevalence rates worldwide. Patients with CLBP have varying degrees of pain in the lumbar region of the spine, generally located between the lower ribs and the gluteal region.

Approximately 85% of patients have chronic non-specific low back pain (CNLBP) who do not have a specific patho-anatomical cause attributable to their pain in clinical examination. More than 50% of people in the United States are affected by CLBP. 90% adults will experience LBP in their lifetime, and the recurrence of LBP following chronic episode ranges from 24 to 87 %. The prevalence of LBP in children and adolescents has reaching around 39% of LBP lifetime prevalence in adults at 18 years of age. The prevalence of low back pain was 55.51% in Lahore, Pakistan.

Common nonspecific LBP symptoms include paravertebral muscle spasms, tight hamstrings, trigger points in the muscles, limited spinal range of motion, discomfort and pain. CNLBP is the most common musculoskeletal condition impacting performance leads to functional disability. Various factors associated with CLBP, including smoking, excessive BMI, poor muscle endurance, occupational ergonomic factors, poor posture, altered muscle firing rates, muscular imbalance, psychological factors as depression, inflexibility of the lower extremities, and leg length discrepancies.

Muscle tightness linked to postural disturbances and reduced extensibility resulting from increased hamstring stiffness could be a possible contributing factor to low back pain. Tight hamstring draws the pelvic into posterior rotation with greater flattening of lumbar lordosis which increase mechanical stress on the spinal soft tissues and altered hip biomechanics and lumbopelvic rhythm. If hamstrings are tight, then blood supply will be squeezed out of them leads to decreased muscle capacity, deconditioning and reduced strength which may cause abnormal changes in the bodily posture lead to lumbar hypo-lordosis causing LBP.

Chronic low back pain involves complex interaction of neuromuscular, inflammatory and neurophysiological processes that leads to constant pain. Long-term alterations in movement patterns due to muscular tightness result in structural changes within muscle fibers. The mechanism involved behind is arthrogenous muscle inhibition that inhibits alpha-motor neurons leading to decreased activation of stabilizing muscles. At molecular level, Peripheral and central sensitization contribute to LBP by releasing inflammatory mediators (substance P, bradykinin, cytokines and histamine) and by enhancing the excitability of spinal neurons respectively. Impaired neural drives alter proprioceptive feedback signals linked with increased adipose infiltration, reduced muscle quality, and diminished muscle efficiency.

In 1966, Yoshiaki Sato began developing the Kaatsu training method that has led to the current BFR training techniques that partially restrict arterial inflow. The physiologic effects of BFR at cellular level leads to activation of fast twitch muscle fibers increase in glycogen stores and protein synthesis that stimulates hypertrophy. On the molecular level, a state of localized metabolic stress due to hypoxic environment, causes an increase in growth hormone, stress-related upregulation of signaling factors and Insulin growth factor (IGF)-1 levels that improves vascular functions at low load training.

Conventional Physical Therapy leads to restoration or augmentation of the ability of neuromuscular system which is the most effective rehabilitation strategies for chronic LBP tackle the maladaptive changes in hamstring muscle morphology and function, and ranked third for improving LBP. It plays a major role in stabilizing the pelvis during trunk rotation, or when the center of gravity is grossly shifted as in CLBP. The main focus is on retraining the function of back and hip muscles by integration of exercise resulting in the fine-tuning of intersegmental motion of the spine.

Hamstring tightness leads to posterior rotation of pelvis that alters the lumbopelvic rhythm or flattening of lumbar curve subsequently increased stress on the spinal soft tissues and it may be the reason for dysfunctions that may cause CLBP. Recent literature focused on different manual and therapeutic modalities with their short-term effects on non-specific low back pain. BFR induces muscle hypertrophy and improves strength and endurance, moreover serve as a stimulus to promote protein synthesis leading to the muscle activation and integration of hamstring. BFR has been identified as an alternative when high-load resistance training is not allowed and has been extensively documented in quadriceps and upper limb muscles in literature, however its effect on hamstring remains scarcely investigated as evidence linking hamstring tightness to altered lumbopelvic mechanics and an increased risk of low back pain. This study aims to find the effect of low load blood flow restriction training on improving hamstring strength, alleviating pain and decreasing functional disability in nonspecific low back pain patients

Inclusion Criteria:

Participants falling in this category would be recruited into the study.

1. Both gender
2. Age is between 18-45 years
3. Individuals with pain localized posteriorly below the costal margin and above the inferior gluteal folds for more than 12 weeks
4. A score greater than or equal to 4/10 on Numeric Pain Rating Scale (NPRS)
5. Hamstring muscle strength graded between (3- to 4) on MMT
6. Proximal thigh circumference between (27.0 cm to 56.0 cm), measured 10cm below the inguinal crease
7. Eligible for BFR training as per the Blood Flow Restriction Blood Flow Training Questionnaire

Exclusion Criteria:

Participants falling in this category would be excluded from the study.

1. Patients of spinal stenosis, disc herniation spondylolisthesis, spondylosis or osteoporosis will be excluded
2. Participants had a history of hip or lower extremity pathology requiring medical or surgical intervention.
3. History of venous thromboembolism (VTE), clotting or other hematologic disorder
4. Peripheral arterial disease, hypertension (blood pressure >140/90 mm Hg), coronary artery disease
5. Current Pregnancy
6. Patients who had difficulties in exercise performance due to mental problems.
7. Spinal cord infection like Cauda equina syndrome