## 2 Materials and Methods
### Electromyography  
To perform sEMG analysis, the bold skin was abraded and cleaned to avoid impedance artifacts. The sEMG electrodes were applied to 4 muscles of the dominant leg of each subject (rectus femoris (RF), vastus medialis (VM), biceps femori (BF) and medial hamstrings (MH)) [29]. The electrodes were placed following the recommendations of the European Surface EMG project [29] for the non-invasive evaluation of the muscles (see Figure 2). The RF electrodes were placed at 50% on the line from the superior anterior iliac spine to the superior part of the patella, VM at 80% on the line between the superior anterior iliac spine and the joint space in front of the anterior border of the medial ligament. The MH electrodes were placed over the muscle belly half-way between the ischial tuberosity and the tibial insertion point, at least 5 cm proximal to the musculotendinous junction.  
Figure 1: Squat with ball on two legs stance on balance board.  
The BF electrodes were placed over the biceps femoris muscle halfway between the ischial tuberosity and the fibular insertion site [29].  
The pre-activation time of knee stabilizer muscles is calculated as the interval lasting between the onset of muscle activation and the ground contact, assessed by surface electromyography (sEMG) (FREE EMG 1000; BTS Bioengineering Spa, Garbagnate M.se--Milano, ITA). The sampling frequency was 1000 Hz. Furthermore, signals were band-pass filtered with a high- and low-pass Hamming filter with cutoff frequencies of, respectively, 10 and 500 Hz, and an additional 50 Hz 80 dB/decade notch filter. We rectified the signals and calculated the linear envelope.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Type of Exercise** & **Classic** & **Neuromuscular** \\  & **Warm-Up** & **Warm-Up** \\ \hline _Mobility exercises (5 min)_ & & \\ Joint mobility & ✓ & ✓ \\ Dynamic stretching & ✓ & ✓ \\ _Agility drills(30 s per exercise)_ & & \\ Light run & ✓ & ✓ \\ Knee lift and heel kicks run & ✓ & ✓ \\ Backward running with sidesteps & ✓ & ✓ \\ Parde sideway running with raised arms & ✓ & ✓ \\ Carioca sideway crossover foot running & ✓ & ✓ \\ Intermittent stops forward running & ✓ & ✓ \\ Trunk rotations forward running & ✓ & ✓ \\ Cutting movements & ✓ & ✓ \\ Sprint run & ✓ & ✓ \\ _Balance exercises (4 min) on balance board_ & & \\ Squts (with the ball on one or two legs) & & ✓ \\ Pushing each other of balance (pair exercise) & & ✓ \\ Single-limb dead lift & & ✓ \\ Side-steps with resistance band & & ✓ \\ _Strength and power exercises (5 min)_ & & ✓ \\ Squats (to 80\({}^{\circ}\) of flexion) & ✓ & ✓ \\ Bulgarian split squat & & ✓ \\ Bounding strides & & ✓ \\ “Nordic hamstring lowers” & & ✓ \\ Forward jumping & & ✓ \\ \hline \hline \end{tabular}
\end{table}
Table 1: Exercise for the two different warm-up protocols.  
Figure 2: Graphic demonstration of sEMG electrodes placement.  
Kinematic data were captured using an inertial measurement unit (IMU, G-sensor; BTS Bioengineering Spa, Garbagnate M.se--Milano, ITA). Wireless IMU was positioned to the trunk with an elastic belt. It was used to define the ground contact time and therefore calculate the pre-activation time, as the interval between the onset of sEMG signal and ground contact.  
The sEMG and IMU signals were elaborated utilizing the software called sEMG Analyzer (BTS Bioengineering Spa, Garbagnate M.se--Milano, ITA) utilizing the \"drop fall\" protocol [9; 10; 11].  
Using a 32 cm platform, each athlete had to position himself on the platform edge with his foot suspended. Each subject had to get off the platform, simply by moving their weight forward, as vertically as possible without jumping or moving the body. Upon landing, the subject had to stop in position for 5 s on the foot.