# Is Running Technique Important to Mitigate Hamstring Injuries in Football Players?
## 2 Materials and Methods
### Data Analysis  
Data processing was performed in Qualisys Track Manager software version 2023.2 (Qualisys AB, Goteborg, Sweden), visually identifying each lower limb touchdown and toe-off instants (defined as the first contact of the foot with the ground and the last frame of the foot in contact with the ground, respectively) [13; 42]. These specific instants in the gait cycle were selected because they are critical landmarks for analyzing running technique [36; 43] and hamstring injuries are known to occur frequently during the late swing or early stance phase of the running [44; 45]. Ground contact and flight times were determined as the periods between the touchdown and toe-off instants, and neither foot was in contact with the ground (respectively) [46].  
To evaluate the three-dimensional kinematic changes induced by the improving running technique protocol, data were exported to Theia 3D version 2023.1.0.3160.p0 software (Theia Markerless Inc., Kingston, ON, Canada) for markerless movement identification and  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Week**} & \multicolumn{2}{c}{**Day 1—Acceleration**} & \multicolumn{2}{c}{**Day 2—Maximal Velocity**} & \multicolumn{2}{c}{**Day 3—Maximal Velocity**} \\ \cline{2-6}  & **Running Drill** & **Wicket Sprints** & **Running Drill** & **Wicket Sprints** & **Running Drill** & **Wicket Sprints with Optimal Step Length** \\  & **Exercises** & **Step Frequency** & **Exercises** & **Step Length** & **Exercises** & **and Frequency** \\ \hline
1–2 & 10 min & 2 \(\times\) 30 m (a) & 5 min & 3 \(\times\) 35 m & 5 min & 3 \(\times\) 40 m \\
3–4 & 5 min & 4 \(\times\) 45 m & 5 min & 4 \(\times\) 45 m & 5 min & 4 \(\times\) 45 m \\
5–6 & 5 min & 4 \(\times\) 45 m (b) & 5 min & 4 \(\times\) 45 m (b) & 5 min & 4 \(\times\) 45 m (b) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Training contents performed by the intervention group.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{**Week**} & \multicolumn{1}{c}{**Days**} & \multicolumn{1}{c}{**Drill Exercises**} \\ \hline \multirow{3}{*}{1–2} & 1 & Ankle drill, high skipping, glue skipping, front lower limb extension marching, and straight lower limb running \\ \cline{2-3}  & 2 & High skipping, 3/3 high skipping, and straight lower limb running \\ \cline{2-3}  & 3 & High skipping, front lower limb extension marching, and straight lower limb running \\ \hline \multirow{3}{*}{3–4} & 1 & High skipping (with a bar over the head), 3/3 high skipping, and straight lower limb running \\ \cline{2-3}  & 2 & High skipping (front/back), front lower limb extension marching, and bounding \\ \cline{2-3}  & 3 & 3/3 high skipping, bounding, and straight lower limb running \\ \hline \multirow{3}{*}{5–6} & 1 & High skipping (with upper limbs above the head), straight lower limb running, and pelvic step progression for running \\ \cline{2-3}  & 2 & 3/3 high skipping, front lower limb extension marching, and bounding \\ \cline{2-3}  & 3 & High skipping (with upper limbs above the head), straight lower limb running, and pelvic step progression for running \\ \hline \hline \end{tabular}
\end{table}
Table 2: Running drill exercises performed by the experimental group (each task performed over a distance of 2 \(\times\) 20 m).  
creation of a 6\({}^{\circ}\) of freedom biomechanical model using the Qualisys Running Evaluation plugin (PAF v7.1.1+225). Afterwards, the sprint velocity and the lower limbs segments angles in relation to their proximal segment were analyzed. This analysis was conducted at both touchdown and toe-off instants during sprint cycle using the Visual 3D version 2021-11-3 (C-Motion, Washington, DC, USA) [37; 47]. A depiction of the segments' movement in each anatomical plane, along with the corresponding signal convention, is available in Figure 2.