Effect of Knee Extensor Training on the Lumbar Spine

The goal of this clinical trial is to learn if knee extensor training with different protocols works to treat LBP in adults.. The main questions it aims to answer are:

What are the comparative effects of open and closed kinetic chain knee extensor strengthening exercises versus lumbar stabilization exercises on lumbar curvature, postural control, and disability in individuals with non-specific low back pain? 1.4.2. How does open kinetic chain knee extensor strengthening affect pain, functional capacity, and lumbar spine stability compared to closed kinetic chain exercises in individuals with non-specific low back pain? 1.4.3 What is the effect of open kinetic chain knee extensor strengthening on pain, functional capacity, and lumbar spine stability compared to conventional lumbar muscle exercises in individuals with non-specific low back pain? 1.4.4 What is the effect of closed kinetic chain knee extensor strengthening on pain, functional capacity, and lumbar spine stability compared to conventional lumbar muscle exercises in individuals with non-specific low back pain? 1.4.5 What is the effect of open kinetic chain knee extensor strengthening on pain, functional capacity, and lumbar spine stability in individuals with non-specific low back pain? 1.4.6 What is the effect of close kinetic chain knee extensor strengthening on pain, functional capacity, and lumbar spine stability in individuals with non-specific low back pain? 1.4.7 What is the effect of conventional lumbar extensor strengthening on pain, functional capacity, and lumbar spine stability in individuals with non-specific low back pain Researchers will compare three different exercise protocols to a control group (will not receive exercise) to see if knee extensor training has an effect on problems associated with LBP.

Participants will:

* Exercise three times per week for 8 weeks * Be assessed before, 4 weeks after, and 8 weeks after intervention