Body Posture, Joint Mobility, and Trunk Muscle Endurance Related to Lower Back Pain in Tennis Players

Hip range of motion

The hip range of motion was measured using a digital inclinometer. During hip rotation measurement, the subject lay prone with the pelvis stabilized by a strap. The tested hip was in a neutral position with the knee flexed to 90 degrees. The inclinometer was zeroed along the tibial axis when the tibial plateau was parallel to the ground. The range of motion was the angular difference between the initial and final positions. For flexion, the subject lay supine with the non-tested lower limb stabilized. The inclinometer was zeroed parallel to the ground. The final position was where the thigh could no longer move further into flexion. For extension, the subject .lay supine with the pelvis at the edge of the table. The subject maximally flexed both hips. The subject held the non-tested lower limb with both hands. On the tested side, the lower limb hung freely off the table. The inclinometer was zeroed on a surface parallel to the ground, and in the final position of the test.

Time frame: Baseline

Spine range of motion

The measurement was conducted using a Baseline bubble inclinometer. For flexion, the patient stood in a relaxed position. The spinous processes of Th12 and S1 were palpated and marked. The inclinometer was zeroed at Th12, and the patient executed a full forward bend. The same was repeated at S1. The lumbar flexion range was the difference between readings at Th12 and S1. For extension, the patient also stood relaxed. Before measuring, the patient performed three maximum lumbar extensions. The inclinometer was zeroed at Th12, and the patient executed a maximum extension. The same procedure was repeated at S1. The lumbar extension range was the difference between readings at Th12 and S1. For lateral trunk flexion, the measurement was the distance between a point on the lateral thigh, where the tip of the third finger reached in a relaxed standing position, and a point on the thigh/shin after performing maximum lateral flexion.

Time frame: Baseline

Modified sit and reach test

To perform the test, the subject sat on the examination table in such a way that one lower limb rested on the floor with the knee flexed at 90 degrees, while the other limb was placed on the table with the knee joint extended. The subject positioned their hands in front of them, thumbs joined and palms facing down. With elbows fully extended, the subject reached as far forward as possible, placing their hands on the table. The distance from the tip of the third finger to the heel line was measured. Positive results indicated that the tip of the third finger extended beyond the heel line, while negative results indicated that it was positioned before the heel line.