# Comparative Analysis of Performance in the High-Bar vs. Low-Bar Squat
## 2 Materials and Methods
### Procedures  
The mean propulsive velocity, mean force, and the load lifted were compared according to the technique used (high vs. low bar) and gender. To do this, the technique used in each case was controlled, considering also the angle of knee flexion to ensure that a parallel squat was performed.  
First, an explanatory video on the two squat exercise techniques was sent to the participants. In these videos, participants could observe how they must start from an upright position, with the knees and hips fully extended and both feet positioned flat on the floor in parallel, shoulder-width apart. From this position, they were to descend in a continuous motion until reaching their parallel position (thighs aligned with the floor and the hips aligned with the knees). All participants performed two assessments of the parallel squat exercise separated by 7 days to achieve a full recovery, at the same time of day, under the same experimental conditions (without strenuous exercise 24 h before, similar food intake, hydration, instructions during the test, etc.) and similar environmental conditions (550 m altitude, 22-25 \({}^{\circ}\)C, 35-40% relative humidity).  
Firstly, they performed a warm-up consisting of 10 min on a cycloergometer (Wattbike Trainer, Nottingham, UK) at a moderate intensity and then performed 5 min of joint mobility. Following this, the squat exercise force-velocity test was performed using free weights on a squat rack (Technogym\({}^{\oplus}\), Rack, Cesena, Italy). An Eleiko\({}^{\oplus}\) (Eleiko AB, Halmstad, Sweden) Olympic bar (20 kg) and Technogym\({}^{\oplus}\) Olympic discs (2.5 kg, 5 kg, 10 kg, 15 kg, 20 kg, 25 kg) were used for the testing. A linear position transducer (EV-PRO locomotor Dynamic, SDT, Madrid, Spain) and the corresponding software (Isocontrol Dynamic v. 6.0 for Windows) were used to measure the mean propulsive velocity [33] and mean force of each repetition. Knowing the mass (kg) of the load to be lifted and the acceleration, the device offers us the value of the force manifested, obtaining a value through the mean values of the propulsive phase, defined as the portion of the concentric phase during which the measured acceleration is greater than the acceleration due to gravity (9.81 m\(\cdot\)s\({}^{-2}\)). This transducer recorded the position and direction of the bar with an accuracy of 0.0002 m. This validated system has been used in other studies for similar measurements [34; 35]. A researcher controlled the correct performance of the squats according to the technique being studied. Also, three other participants offered safety and helped with execution if it was necessary.  
Each participant, with the supervision of one of the researchers, performed the parallel squat, controlling the descent velocity (as previously shown in [36]) until the thighs were parallel to the floor and the hips aligned with the knees. When the position was achieved, the researcher gave an audible signal to initiate the concentric phase of the movement, which was performed at the maximal intended velocity. The 1 RM test consisted of one repetition per load starting with 20 kg, with a gradual increase in load within 5-7 attempts to avoid fatigue. The test finished when the participant reached failure or when the recorded mean propulsive velocity was lower than 0.32 m/s [25]. The rest between loads was 4 min [37].  
In the second session, the participants performed the other technique and repeated the absolute loads from their first sessions. If they reached the 1 RM of the previous day without reaching failure or with a velocity greater than 0.32 m/s [25], they continued increasing the load based on the same criteria as in the first session. The recorded variables, that is, the mean force (N) and squat load (kg), were normalized to body weight.