Multiple Sclerosis (MS), a chronic inflammatory disease of the central nervous system, is a disease characterized by myelin, oligodendrocyte and axon damage [1]. Research continues on the autoimmune, infectious, environmental, vascular and genetic origins of this disease, which affects approximately 2.5 million people in the world and is seen 2-3 times more in women than in men. Although the signs and symptoms of the disease vary according to the location of the lesion; Loss of balance and strength, spasticity, sensory disturbances, fatigue, ataxia, autonomic dysfunction, and decreased visual acuity is frequently observed.

There are no studies in the literature investigating the validity and reliability of this test in individuals with MS. Reliability is population-specific and it is important to investigate the reliability of the L test in MS patients. Therefore, the aim of our study is to reveal the test-retest reliability and validity of the L test.

General Information about the Research, Rationale and Objectives:

Multiple Sclerosis (MS), a chronic inflammatory disease of the central nervous system, is a disease characterized by myelin, oligodendrocyte and axon damage [1]. Research continues on the autoimmune, infectious, environmental, vascular and genetic origins of this disease, which affects approximately 2.5 million people in the world and is seen 2-3 times more in women than in men [1, 2]. Although the signs and symptoms of the disease vary according to the location of the lesion; Loss of balance and strength, spasticity, sensory disturbances, fatigue, ataxia, autonomic dysfunction, and decreased visual acuity are frequently observed [1].

Abnormalities and losses in balance management are frequently seen in individuals with MS [3-6] . This abnormality, together with other risk factors, increases the risk of falling [7] and causes limitations in patients' activities of daily living. Studies on balance problems in elderly individuals are frequently investigated in the literature. However, the frequency of falls in this population was found to be 1.5 falls per year [8], while another study investigating individuals with MS found an average of 9 falls per year [7]. In order to develop fall prevention or reduction strategies, it is necessary to evaluate different aspects of motor impairment and to accurately identify factors contributing to falls [9-11]. Since falls among MS patients have a multifactorial etiology, multiple evaluations are necessary to explore the balance problem.

Although various scales have been developed to evaluate the functional level of MS patients [12, 13], the use of frequently applied scales in this patient group allows the results to be compared with other studies and other pathologies. In addition, the use of frequently applied scales does not require special training of raters. Previous studies have used the Berg Balance Scale, the Functional Reach Test, the Timed Get Up and Walk test, and general measures of fall risk (eg, questioning the date of fall) [14-16]. These tests primarily assess the ability to walk forward, turn back, and take a step.

The reliability of the TUG in people with MS has ranged from 'good' to 'excellent' [17,18], but the TUG is only an opportunity for unilateral disorders to turn in a preferred direction [19]. Thus, despite good reliability and validity, TUG currently has limitations in MS that can only be overcome by adding complex and potentially excessively expensive instrumentation. The L test is a modification of the TUG that extends the walking distance from 6 to 20 m and also requires participants to make both clockwise and counterclockwise turns. Therefore, it may have limited sensitivity and the potential to overcome ceiling effects. The L test was originally designed for individuals following lower limb amputation and has since been evaluated in stroke and hospitalized elderly subjects [19-21]. In all three studies, the L test showed good reliability and also showed good correlation with the TUG. The aim of this study is to evaluate the L test in terms of test/retest reliability and concurrent validity with TUG in individuals with MS. There are no studies in the literature investigating the validity and reliability of this test in individuals with MS. Reliability is population specific and it is important to investigate the reliability of the L test in MS patients. Therefore, the aim of our study is to reveal the test-retest reliability and validity of the L test.

10. Detailed Material and Methodology of the Research: The methodological model of the study is the validity and reliability study. Our study will include individuals who applied to Fırat University Training and Research Hospital after ethical approval and were diagnosed with Relapsin-Remitting MS by a neurologist. It is planned to collect the Helsinki Declaration on a voluntary basis from individuals whose data meet the inclusion criteria. As demographic characteristics; The age, gender, body weight, height, EDSS score, occupation and education level of the patients, the history of the disease, the number of falls in the last year and the type of MS will be recorded. Inclusion criteria for volunteers; Individuals with relapsing-remitting type MS, who are between 18-65, EDSS scores between 1 ≤ and ≤ 5.5, individuals who score 24 and above in Mini Mental State Examination and who can walk a minimum of 20 m independently will be included. In addition, exclusion criteria for volunteers; Severe spasticity of the lower extremities (Ashworth score 3 or 4), having an acute MS attack or a history of an attack in the last 1 month, having an orthopedic or systemic problem that would prevent participation in the tests, having another neuromuscular disorder other than MS, visual involvement or diplopia, and is that he has a cardio-pulmonary problem that will prevent him from participating in the tests.

Our study will be carried out as a "test-retest" design and the psychometric properties of the L test in MS patients will be examined. 3 m walk back test, Timed Up and Go, 4-Square Step Test test will be applied to the patients. All assessments will be done by the same physiotherapist. The second evaluation will be performed by the same physiotherapist two days after the first evaluation (test) to measure test-retest reliability. Data collection with the same rater will be preferred to avoid inter-rater variability and error rate between evaluations.

According to Lexell and Downham, 30-50 participants should be included in reliability studies [22]. Considering this recommendation, which defines the reliability of the L test, it is planned to include 50 individuals with MS in our study.

L Test; It is an expanded version of the TUG and is designed to assess advanced functional ambulation with more detail available elsewhere. It is recorded when the participant gets up from the chair, walks 3 m to a cone, turns 90° to the right, continues to walk 7 m to the next cone, turns 180° left around the cone, then returns to the chair the same way. The test duration is recorded, beginning with the word "go" and ending with the participant's back touching the back of the chair [23].

3-meter Walk Back Test; The 3-meter distance is marked with a black tape and participants are asked to align their heels with the black tape. Individuals are asked to walk backwards as soon as possible with the "walk" command and stop when they reach 3 meters. Meanwhile, the elapsed time is recorded in seconds. Evaluation will be done three times and the average time will be recorded [24].

Timed Get Up and Go Test; It is applied to assess the balance and fall risk of individuals. The patient is first asked to sit leaning on the chair. The patient is then asked to stand up, walk with regular steps for a predetermined distance of 3 meters, return at the end of 3 meters and sit in a chair. During the test, the patient's walking time is recorded in seconds with a stopwatch. The test was repeated three times and the mean value will be recorded [25].

Inclusion Criteria:

• Inclusion criteria for volunteers; Individuals with relapsing-remitting type MS, who are between 18-65, EDSS scores between 1 ≤ and ≤ 5.5, individuals who score 24 and above in Mini Mental State Examination and who can walk a minimum of 20 m independently will be included.

Exclusion Criteria:

• In addition, exclusion criteria for volunteers; Severe spasticity of the lower extremities (Ashworth score 3 or 4), having an acute MS attack or a history of an attack in the last 1 month, having an orthopedic or systemic problem that would prevent participation in the tests, having another neuromuscular disorder other than MS, visual involvement or diplopia, and is that he has a cardio-pulmonary problem that will prevent him from participating in the tests.

Individuals who applied to Fırat University Training and Research Hospital and were diagnosed with Relapsin-Remitting MS by a neurologist will be included in our study.