## 2 Materials and Methods
### Procedures  
A preliminary session was used to determine the 1 RM in the concentric-only PBP variant through a standard incremental loading test [22]. Body mass (Tanita BC 418 segmental, Tokyo, Japan) and stature (Seca 202 Stadiometer, Seca Ltd., Hamburg, Germany) were measured at the beginning of the first session. The warm-up consisted of jogging, dynamic stretching, and upper-body joint mobilisation exercises, followed by two sets of five repetitions of the concentric-only PBP variant against 20 and 30 kg. The initial external load of the incremental loading test was set at 40 kg and was progressively increased in 10 kg increments until the mean velocity was lower than 0.80 m\(\cdot\)s\({}^{-1}\). Thereafter, the load was increased by five to one kg until the 1 RM was directly determined. Two repetitions were performed with light-moderate loads (mean velocity \(\geq\) 0.80 m\(\cdot\)s\({}^{-1}\)) and one repetition with heavier loads (mean velocity \(<\) 0.80 m\(\cdot\)s\({}^{-1}\)). Recovery time was set to three minutes for light-moderate loads (i.e., those \(>\) 0.80 m\(\cdot\)s\({}^{-1}\)) and five minutes for heavier loads (i.e., those \(\geq\) 0.80 m\(\cdot\)s\({}^{-1}\)). Subjects verbally received mean velocity performance feedback immediately after completing each repetition to encourage maximal effort.  
The general warm-up specified for the preparatory session was used to begin each experimental session. The specific warm-up consisted of one set of ten, five, and two repetitions at 40, 60, and 80% of 1 RM, determined during the preliminary session, respectively. In a sequential order, subjects then performed three repetitions against the 14 kg load (L1; the lightest load), two repetitions against 85% of the 1 RM load (L4 = 72.0 \(\pm\) 10.9 kg; the heaviest load), three repetitions against an equidistant intermediate light load (L2 = 33.2 \(\pm\) 3.6 kg), two repetitions against an equidistant intermediate heavy load (L3 = 51.9 \(\pm\) 7.5 kg), and one to five 1 RM attempts (2.3 \(\pm\) 1.9). The inter-repetition rest was set at ten seconds and the inter-set rest was fixed at three minutes for submaximal loads and at five minutes for 1 RM attempts.  
The PBP was performed in a Smith machine (Multipower Fitness Line, Peroga, Murcia, Spain) using bumper-calibrated plates (RusterFitness, Jaen, Spain). The PBP technique involved the subjects lying down in a prone position with the chin in contact with the bench and the legs held with a rigid strap on the calves [17]. There was 11 cm between the underside of the bench and the subjects' chests. The repetition was deemed invalid when the barbell failed to contact the bench's underside. To guarantee safety, there were two spotters on either side of the barbell. The two PBP variants' distinct characteristics are outlined below.  
_Concentric-only PBP_. The assignment was started with the subjects holding the barbell with their elbows completely extended using a self-selected grip breadth. Note that the barbell was supported by the two telescopic holders of the Smith machine. From that position, subjects were instructed to pull the barbell as fast as possible until it made contact with the underside of the bench. The range of motion was individually measured and kept constant throughout all sessions using the two telescopic holders of the Smith machine.  
_Eccentric-concentric PBP_. With the assistance of two spotters, subjects started the assignment by holding the barbell at a self-determined grip width and flexing their elbows to keep the barbell in contact with the bench's underside. From that position, subjects lowered the barbell in a controlled manner until contact was made with the two telescopic holders of the Smith machine. At that point, they pulled the barbell as fast as possible until it made contact with the underside of the bench.