Study design and participants
This double-blind randomized controlled trial with parallel groups was conducted in the physiotherapy clinic of Kermanshah Sports Medicine Federation, Kermanshah, Iran.
After obtaining approval from the Ethics Committee of Shiraz University of Medical Sciences with the code of IR.SUMS.REHAB.REC.1397.017 and registration of the trial in the IRCT website under the code of IRCT20190130042556N1, sampling was conducted from January until April 2019.
The inclusion criteria allowed subjects aged 18-45 years, who had history of ACL reconstruction surgery in the last 6-12 months, those who were scared to move on the basis of the Tampa questionnaire > 37, were athlete on the basis of the Tegner questionnaire (scores > 5 from the Tegner questionnaire), had full range of motion of hips, knees and wrists and had normal gait.
Subjects with severe pain, swelling and range of motion limitation in the knees, dizziness and involvement of the vestibular system, limiting physical activity (e.g. major orthopedic, neurological or rheumatologic problems in the lower extremities, history of previous surgery in the lower extremity and difference in leg's length) were excluded. A trained physiotherapist interviewed the eligible participants for confirmation of the criteria.
As no related study on main outcomes was found; therefore, the sample size was estimated based on a pilot study. In the beginning of the study, pilot information (means and standard deviations of main outcomes) was obtained using a preliminary sample of participants. The sample size was calculated as 10 participants in each group to have a statistical power of 80%.
Eligible participants were randomly allocated to kinesio tape (n=10) and placebo kinesio tape groups (n=10) with randomized block procedure of block size two using the Random Allocation Software (RAS) version 1.0.0. Random allocation of participants was performed by a statistician not involved in the sampling process. The participants and assessor were blinded to the patients’ allocations (Figure 1).
Before any intervention, the study goals and the methods were explained for and written consents were obtained from all participants.
Treatment group: To apply the kinesio tapes in the intervention group, 5-centimeter kinesio tape length with 50% elongation was attached from the origin to the insertion of the quadriceps muscle, and then it has splited to two tails and comes down of two sides of the patella. Then we used a tape in (I) shape, which was sized to extend from the tuberosity of tibia up to 5-centimeter above the femoral condyles in order to modify knee movements and stimulate surface receptors. By flexing the knee at 80 to 90 degrees, we opened the tape from the middle and put on the tibia tuberosity in full tension. Then the stretch of the tails was reduced to about 50 percent to attach them to the femoral condyles (Figure 2).
Control group: In this group, taping was the same as the treatment group without tension in the tape (Figure 3).
All the outcome's measures were evaluated by a blinded assessor, at the baseline, ten minutes after the intervention and on the second KT treatment day. At each assessment point, Kinesiophobia (Primary outcome), balance, stability and functional performance were measured by Tampa scale, Y balance test (YBT), single leg hop and 10-yard extremity functional test (secondary outcomes), respectively.
Tampa Scale for Kinesiophobia (TSK)
Tampa scale was used to measure the degree of fear of movement (kinesiophobia). This scale was designed by Corey et al. in 1990. It consists of 17 items that every item was scored from 1 (strongly disagree), 2 (disagree), 3 (agree) to 4 (strongly agree). The overall scores were calculated between 17 to 68. The high score shows the greater fear of movement due to pain perception. In this calculation, the score of 37 is the border line of high and low scores. The Persian version of this questionnaire was developed and validated by Jafari et al. (2010 ) .
Y Balance Test (YBT)
This test which is a modified type of Star Excursion Balance Test (SEBT)  consists of three tapes in three directions for measurement; anterior, posterior-lateral and posterior-medial. They are stuck to the ground. The posterior tape is positioned 135 degrees from anterior one, and the two posterior tapes are positioned 90 degrees to each other. For evaluation, the subject was in standing position in the middle of these three lines on one leg without shoes. His foot positioned in the center of the intersection of three tapes, and the big toe positioned along the line drawn in the anterior direction. While maintaining single leg stance, the person was asked to move his foot forward as far as possible along these three directions in relation to the stance foot. The distance has been measured by reading the tip of the foot on the meter. The person repeated the process three times for each direction, and the highest score was recorded during the test. After three attempts, if the subject could not perform the test correctly, the test was repeated until could do it at least once. If the subject could not do the test properly with six attempts in each direction, it was rejected in that direction. The test results were normalized in all three directions by dividing the distance to the leg length in cm and then multiplied by 100 to obtain the percentile of the length of the lower limb.
See Formula 1 in supplementary information
Single Leg Hop Test
This test is one of the valid functional tests for evaluating the knee, which was used to evaluate the objective performance of the athletes. To perform this test, the subject was asked to stand behind a line then positioned both hands to the back of the body and while maintaining single leg stance, tried to jump and land on the same foot, as far as he could. The test was repeated three times for each foot and the distance from the tip of the toe in the start line to the base of the toe after landing was measured and recorded with one-millimeter precision. The maximum jump record was taken for each individual subject. Results were also normalized based on each person’s leg‘s length .
Level of Functional Activity
10-Yard Lower Extremity Functional Test
Starting was line A, subject sprinted ten yards forward to line B then back pedal to line A. Next, subject will side shuffle to line B then side shuffle back to line A. After than subject will carioca to line B and also carioca back to the line A. Finally, subject will sprint through the line B. The subject must make sure to touch each line with his foot (Figure 4). The administrator measured the time. Normal range of records for this test for males has reported 17-20. and for females has reported 19-23 seconds .
SPSS software version 23.0 (SPSS Inc., Chicago, IL, USA) was used for statistical analyses. Kolmogorov–Smirnov test was applied to determine normality of the distribution of the quantitative data.
Comparisons of baseline characteristics were performed using independent samples chi-squared test and t-test for qualitative and quantitative data, respectively.
The between-group differences for kinesiophobia, functional performance (Single Leg Hop and 10-Yard test and balance performance) throughout the study were assessed by analysis of Covariance (ANCOVA). Repeated measures ANOVA (RMANOVA) was used to compare differences in outcome measures before, ten minutes and two days after the intervention in each group. Mauchly's test was used to evaluation the assumption of sphericity. All significance was set at P < 0.05.