core stabilization exercise + motor imagery training group Participants will be given core stabilization exercises and motor imagery training 2 days a week, 60 minutes per session, for 2 months. Motor imagery training will be applied for 15 minutes immediately after the core stabilization exercisesAt the end of 2 months, the outcome measurements will be taken by the same evaluator physiotherapist who is not present during the treatment

McGill's core endurance tests: McGill's tests were Used to examine participants' core endurance. These tests consisted of four positions: the trunk anterior flexor test, the right and left lateral plank, and trunk posterior extensor test. Participants performed one practice trial that lasted a few seconds to confirm correct positioning and then one test trial was recorded per position where the maximum time (seconds) participants could maintain a static Position was measured. The same investigator visually determined the end of all tests to assure reliability of testing. This investigator used the commands 'start' and 'stop' to initiate and conclude the test while an assistant investigator recorded the times using a stopwatch. The order of the four test positions was randomly assigned.

The Modified Star Excursion Balance Test is reliable methods commonly used to clinically assess dynamic balance of the lower extremity.The 8 directions in the Star Excursion Balance Test are arranged as 3 directions in the Modified Star Excursion Balance Test.The tape measures were fixed by sticking them to the floor so that the angle between the anterior and posterolateral and posteromedial directions was 135ᵒ; the angle between the posteromedial-posterolateral directions was 90ᵒ. Then, they were asked to reach 3 times for all directions and the average was taken. The test score was calculated with the formula [Average reach distance (cm) / lower extremity length (cm) x 100]

A pressure biofeedback device (Chatanooga, Australia, 2005) was used to evaluate the activity of the TrA muscle. The pressure biofeedback device is a tool used in practice in the clinic to measure the pressure produced by the TrA muscle during activation, with an emphasis on segmental stabilization . Before the test, all participants were taught the abdominal wall pulling (abdominal hallowing) maneuver. The pressure biofeedback device was fixed at 70 mmHg. For the measurement of TrA muscle activity, the pressure biofeedback device was placed under the abdomen at the level of the anterior superior iliac spine while the patient was in a supine position. The participant was asked to perform the abdominal hallowing maneuver and continue the contraction for 10 seconds. The change in pressure was recorded, and the highest value from 3 trials was taken.

alternatives. Learn more Participants' lumbar flexion flexibility was evaluated with the Modified Schober Test. The researcher physiotherapist placed both thumbs on the participant's posterior superior iliac spine and marked the midpoint of the distance between the two points. Then, 10 cm above and 5 cm below this point were determined and marked. After the researcher physiotherapist told the participant to bend forward as much as possible with their knees straight, he measured and recorded the new distance between the lower and upper limit points. The distance difference between the new measurements is used to indicate the amount of lumbar flexion. A difference of 0-5 cm indicates that lumbar flexion flexibility has decreased, while a difference of 10 cm or more indicates that lumbar flexion flexibility has increased. Values between 5-10 cm are considered normal.

Participants' motor imagery ability was assessed using the Movement Imagery Questionnaire-3.. The survey consists of 3 sub-dimensions: internal visual imagery, external visual imagery and kinesthetic imagery, and includes 12 tasks. Participants were asked to perform these tasks in the visual and kinesthetic imagery type. Each task was first explained, physically performed, then the participant returned to the starting position and imagery was performed according to the visual/kinesthetic imagery type. The participant rated the ease or difficulty of creating an imagery on a 7-point scale. In this scale, 1 means "very difficult to see/feel" and 7 means "very easy to see/feel". The actions performed included the upper extremity, lower extremity and body. When calculating the score, the scores of all sub-dimensions were added separately and averaged by dividing by 4. A higher score indicates better mental imagery ability.

The Body Awareness Questionnaire is a scale that includes physical, emotional and social elements about a person's sensitivity to normal or abnormal body states and processes and questions their sensitivity to physical reactions.The questionnaire consists of four subscales. These are (1) estimation of body reactions, (2) sleep-wake cycle, (3) estimation of the onset of the disease, and (4) attention to changes and reactions in body processes. Participants were asked to score each of the 18 statements on a scale of 1 to 7 (1=Not true for me at all, 7=Very true for me). The maximum score that can be obtained from the questionnaire is 126, and the minimum score is 18. The higher the score, the better the level of body awareness.

Participants' anxiety levels were assessed using the Trait Anxiety Inventory.The Turkish validity and reliability study of the scale developed by Spielberger in 1964 was conducted by Öner and Le Compte in 1983. This inventory has two subscales, each consisting of 20 items, namely the trait anxiety level and the state anxiety level. While the State Anxiety Scale assesses the temporary anxiety level of the person under the circumstances they are currently in, the Trait Anxiety Scale assesses the anxiety levels that individuals generally feel and are not related to a specific cause and are not clearly understood by others. A high score on the 4-point Likert-type scale indicates a high level of anxiety. The Trait Anxiety Scale was used in our study. The reason for this was to determine the general level of anxiety felt by mothers of physically disabled children.

The International Physical Activity Questionnaire Short Form (IPAQ Short Form) was used to determine the physical activity levels of the participants. The Turkish validity and reliability of this questionnaire was conducted by Sağlam et al. (2010). The form, consisting of 7 items, provides data on the time spent by the individual in walking, moderate-intensity and vigorous activities. The form asks how many days in the last week and how long each day heavy physical activity, moderate-intensity physical activity and walking were performed. In addition, the time spent inactive (sitting, lying down, etc.) is determined.

The physical activity level is determined by the MET-minute score. 1 MET is accepted as 3.5 ml/kg/min. MET values are 8.0 MET for heavy activities, 4.0 MET for moderate-intensity activities and 3.3 MET for walking.

For example, the walking MET-min/week score of a person who walks 30 minutes, 4 days a week;

It is calculated as 3.3 X 4 X 30 = 396 MET-min/week.