• Group I (control) will receive advices only.

• Group II (experimental) will receive a suggested functional exercise program plus advises

The following advice will be given to the patients :

1. Walking as flexibly (normally) as possible

2. Advise when lifting ;

   • avoid twisting and bending.
   • for heavy objects use thighs with a vertical back.
   • at other times, use the back and flex it.

3. Heat application for 20 mins twice /day .

4. Avoid sitting or standing for prolonged period and change position every 15 mins.

5. Sitting: Sit with a back support

6. Driving: Use a back support (lumbar roll) at the curve of your back.

7. Sleeping and lying down: Select a firm mattress and box spring set that does not sag. If necessary, place a board under your mattress. You can also place the mattress on the floor temporarily if necessary.

will be measured by The Numeric Pain Rating Scale (NPRS). it consists of The 11-point numeric scale ranges from '0' representing one pain extreme (e.g., "no pain") to '10' representing the other pain extreme (e.g., "pain as bad as you can imagine" or "worst pain imaginable .patients are asked to indicate the point along the line that best reflect their pain intensity .

will be measured by Arabic version of Oswestry Disability Index (ODI) is a self-reported questionnaire consisting of 10 questions related to back function . Each question is answered on a 6-item Likert scale and is scored from 0 (minimum degree of difficulty in that activity) to 5 (maximum degree of difficulty). These questions assess the activities of daily living in patients with LBP. The questions in the index include pain intensity, personal care, lifting, walking, sitting, standing, sleeping, sex life, social life and travelling.

The validity of Arabic version of ODI is good intra-observer reliability was excellent . The correlations of the ODI with the VAS pain scale, the Roland-Morris Low Back Pain Disability and the Quebec Back Pain Disability.

The researcher will conduct a series of core stability tests before and after the core training program. Core stability tests has been reported to be highly reliable (ICC ≥ 0.98) and showed moderate to high correlation with one another (correation coefficient ranged from 0.4 to 0.8) , The following core tests will be used: trunk flexion test (McGill's test) , Trunk extension (Sorenson Test) , Side plank test and prone plank test .

will measured by Functional assessment using one legged hops test The most commonly used functional tests are a series of one-legged hops described by Noyes et al. (1991). The sensitivity of the single (49%), triple (50%), crossover (58%), and timed (52%) hop tests were reported by Noyes et al. (1991). The specificity was 97% and 94% for the timed and single hops, respectively