Trunk flexors endurance test: Participants will be positioned with trunk flexed to 60º, knees and hips to 90º flexion. The evaluator fixes the feet on the ground by supporting them from the toes. When the 60º trunk flexion is broken, the test will be terminated and the time it maintains this position will be recorded in seconds.

Modified "Biering-Sorensen" test: With this test, the endurance of trunk extensors is evaluated. The subjects are positioned in the prone position with the pelvis, hips and knees on the bed. The subjects are asked to extend their upper body straight forward from the edge of the table and the time they maintain this position will be recorded in seconds.

Lateral bridge test: During the test, the subjects were asked to lie on their side, raise their bodies on their forearms and toes and maintain this position, and the time they held the position would be recorded in seconds. The test will be done on both sides.

"Fatigue Severity Scale" was used to evaluate the fatigue level of the participants. This scale consists of a 7-point Likert scale. 1 point means strongly disagree, 7 means strongly agree. High scores are associated with increased fatigue. Evaluates the effects of fatigue on physical function, motivation, family and social life. Turkish validity and reliability was established.

The "Roland Moris Scale" will be used to evaluate the participants for low back pain assessment. The Roland Morris Inquiry Form was designed to evaluate the functional disability of the patient. The total score ranges from 0 (no disability) to 24 (severe disability). The higher the total score, the lower the patient's functionality. It is a questionnaire filled by the patient, which evaluates the functionality of 24 items questioning the patient's mobility, self-care and sleep status. Each item marked as 'Yes' is given 1 point, and answers marked as 'No' are given 0 points. Turkish validity and reliability was established.

Trunk flexors endurance test: Participants will be positioned with trunk flexed to 60º, knees and hips to 90º flexion. The evaluator fixes the feet on the ground by supporting them from the toes. When the 60º trunk flexion is broken, the test will be terminated and the time it maintains this position will be recorded in seconds.

Modified "Biering-Sorensen" test: With this test, the endurance of trunk extensors is evaluated. The subjects are positioned in the prone position with the pelvis, hips and knees on the bed. The subjects are asked to extend their upper body straight forward from the edge of the table and the time they maintain this position will be recorded in seconds.

Lateral bridge test: During the test, the subjects were asked to lie on their side, raise their bodies on their forearms and toes and maintain this position, and the time they held the position would be recorded in seconds. The test will be done on both sides.

The "Roland Moris Scale" will be used to evaluate the participants for low back pain assessment. The Roland Morris Inquiry Form was designed to evaluate the functional disability of the patient. The total score ranges from 0 (no disability) to 24 (severe disability). The higher the total score, the lower the patient's functionality. It is a questionnaire filled by the patient, which evaluates the functionality of 24 items questioning the patient's mobility, self-care and sleep status. Each item marked as 'Yes' is given 1 point, and answers marked as 'No' are given 0 points. Turkish validity and reliability was established.