## 2 Materials and Methods
### Outcome Measures  
All assessments were performed by a physical therapist with more than five years of clinical experience with children with CP, and who was familiar with the scales and procedures. No extensive training was conducted to resemble the usual clinical practice in which the assessments would be used. However, to ensure to the methodological consistency, the entire research team held a meeting before starting the study, so then all procedures were clarified. The scales and instructions were included in the recording form so then the raters might refer to them. Each assessment was conducted pre (the prior hour) and post immediately (the hour that followed) for each of the sessions of each intervention. Following each session, the physiotherapist registered a brief narrative on the participants' experience. Spasticity of the knee flexors (hamstrings). The modified Ashworth scale (MAS) and the modified Tardieu scale (MTS) were used to assess spasticity. The interrater reliability of the MAS is ICC= 0.27-0.56, and for the MTS, the ICC is 0.55-0.74 [26]. Two scales have been used to minimize measurement errors. The MAS measures the response to passive movement at a constant speed. For assessing hamstrings spasticity, the child was positioned in prone position with the knee joint maximally flexed, and the leg was extended at a controlled speed, ideally completing the movement within approximately one second [27]. The movement should be performed smoothly and without excessive force, reaching the maximum movement that the joint allows us [28]. The MAS scores on a scale with 6 different grades, from 0 to 4, with an intermediate number between the value \"1\" and \"2\" called \"1+\". In order to perform an analysis of this scale, it is necessary to change the numbers of the levels of the scale, with the new numerical values being from 0 to 5, where the value \"1+\" will be level 2, level 2 will be 3 and so on (Table 1). The MTS also measures the response to passive movement at three moments: at the slowest possible speed (V1, described as slower than the natural drop of the limb segment under gravity) and the passive range of movement reached is recorded (R2); at the greatest possible speed (V3), described as faster than the rate of the natural drop of the limb segment under gravity) and the quality of movement is graded on a scale of 0-4; and again at the highest possible speed (V3) in order to record the first \"joint brake,\" called \"catch,\" which is described as R1 [28]. In order to minimize the levels of subjectivity in the scale, only the angle (\({}^{\circ}\)) of the first recorded catch (R1) will be measured at the fastest possible speed \begin{table}
\begin{tabular}{c c c} \hline \hline
**Score** & **Sposticity Grade** & **Numerical Value** \\ \hline
0 & No increase in muscle tone. & 0 \\  & Slight increase in muscle tone, with a catch & \\
1 & and release or minimal resistance at the end & 1 \\  & of the range of motion when an affected & \\  & part(s) is moved in flexion or extension. & \\  & Slight increase in muscle tone, manifested & \\
1+ & as a catch, followed by minimal resistance & 2 \\  & through the remainder (less than half) of the & \\  & range of motion. & \\  & A marked increase in muscle tone & \\
2 & throughout most of the range of motion, but & 3 \\  & the affected part(s) are still easily moved. & \\
3 & Considerable increase in muscle tone, & 4 \\  & passive movement difficult. & 5 \\
4 & Affected part(s) rigid in flexion or extension. & 5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Modified Ashworth scale scores and the numerical values used in the analysis. (V3) [29]. The participant was placed prone, and a digital goniometer was placed taped to his/her skin to minimize movement and obtain the most accurate value. Initially, the knee joint was fully flexed, and then the movement toward extension was performed at the fastest speed possible, stopping at the first noticeable resistance to movement (R1) and registering the angle at that moment.