Postactivation potentiation (PAP) refers to increased muscular force generation after previous muscular activity. Various studies have used different squat variations as a PAP stimulus; however, different squat depths can have different mechanical and physiological demands that could yield different PAP levels and subsequent performance. The study aimed to compare the effects of the parallel (PS) and quarter (QS) squat on PAP. Twenty-seven, semiprofessional, male rugby union players (mean ± SD, 18 ± 2 years, 87.2 ± 5.4 kg, 180.7 ± 5.1 cm) performed a countermovement jump (BL-CMJ) followed by a 10-minute rest. Subsequently, they performed 3 PS or QS, at each squat's respective 3-repetition maximum load, in a randomized counterbalanced order. After a 5-minute rest, another countermovement jump (CMJ) was performed (POST-CMJ). Countermovement jump height (JH), peak power (PP), impulse (I), and flight time (FT) were recorded using a contact mat. BL-CMJ and POST-CMJ pairwise comparisons for all variables were conducted for each squat type to examine performance changes. Delta values were compared to examine whether one squat produced better CMJ results. Both squats induced PAP for all the variables (p < 0.05), although PS produced better results than QS (p < 0.05; JH, 4.6 ± 2 vs. 3.5 ± 2 cm; I, 15 ± 6 vs. 12 ± 5 N·s; PP, 285 ± 109 vs. 215 ± 96 W; FT, 34 ± 23 vs. 26 ± 11 milliseconds for PS vs. QS). This is the first study to demonstrate that different squat types can induce PAP and that PS is more beneficial for subsequent CMJ performance compared with QS. It is suggested that the deeper depth of PS, which increases gluteus maximum activation and work produced, is responsible for the increased CMJ performance.

History, where the phenomenon of acute enhancement is termed postactivation potentiation (PAP). Acute enhancement of dynamic activity has been observed when preceded by resistance exercises; however little information exists for plyometric activity as a conditioning stimulus. In addition, no study has examined PAP effects on more than one subsequent performance trial. The purpose of the present study was to determine whether countermovement jump (CMJ) performance could be enhanced if preceded by heavy-resistance exercise or by dynamic plyometric activity over 3 trials. Thirteen anaerobically trained male subjects (mean ± SD: age, 22 ± 3 years; height, 182.4 ± 4.3 cm; body mass, 82.7 ± 9.2 kg) performed in a counterbalanced order 3 half squats using a 3 repetition maximum loading (SQUAT), a set of 24 contacts of lower body plyometric exercises (PLYO), or a control of no activity (REST) 5 minutes before each CMJ. Three sets of each treatment and CMJ were performed in total and maximal displacement (dmax), peak power (Ppeak), and peak vertical force (Fpeak) were recorded, whereas rate of force development and relative force (F/body mass) were calculated for every trial. No significant differences were revealed for any of the other variables, but greater displacement was found for SQUAT compared to REST or PLYO, whereas no differences were revealed for any of the conditions for the repeated trials. Although heavy resistance-induced PAP seems to enhance jump height compared to REST or PLYO in repeated CMJ performance, it has no additional benefit on repeated trials....

Muscle contractions preceding an activity can result in increased force generation (postactivation potentiation [PAP]). Although the type of muscular contractions could affect subsequent strength and power performance, little information exists on their effects. The purpose of this study was to examine PAP effects produced by isometric (ISO), concentric (CON), eccentric (ECC), or concentric-eccentric (DYN) conditioning contractions on upper body force and power performance. Ten male, competitive rugby players (mean ± SD: age 20.4 ± 0.8 years, height 177.0 ± 8.1 cm, body mass 90.2 ± 13.8 kg) performed a ballistic bench press throw (BBPT) followed by a 10-minute rest and one of the conditioning contractions. After a 12-minute rest, the subjects performed another BBPT (post-BBPT). The conditioning contractions, applied on separate days and in counterbalanced randomized order, were a 7-second isometric barbell bench press for ISO and 1 set of 3 bench press repetitions at 3 repetition maximum for CON, ECC, and DYN (each repetition lasting 2 seconds for CON and ECC, overall execution time 0.05), and no significant differences existed in Fpeak, Dmax, and RFD for ISO, CON, ECC, and DYN (p > 0.05). Finally, EMG was not significantly different between pre- and post-BBPT for any of the conditioning contractions (p > 0.05). Isometric contractions appear to be the only conditioning contractions increasing upper body power output after long resting periods.

Postexercise hypotension (PEH) has been observed in males and females; however, the impact of menstrual cycle phase upon PEH has not been evaluated. We examined the pattern of PEH in the early follicular (EF), late follicular (LF), and midluteal (ML) phases of the menstrual cycle in eight eumenorrheic women following 30 min of exercise at 80% lactate threshold. Supine hemodynamic measurements were assessed at rest and then for 45 min following exercise. Blood pressure was measured with manual sphygmomanometry, calf vascular resistance (CVR) via venous occlusion plethysmography, and central hemodynamics with echocardiography. Cardiovascular parameters did not differ between menstrual phases at rest (P > 0.05). The pattern of PEH was unaffected by menstrual phase, but mean arterial and diastolic (DBP) pressures dropped to significantly lower levels across the recovery period in the EF phase than in the LF and ML phases (mean DBP EF: 69 +/- 4; LF 74 +/- 3; ML 72 +/- 5; P < 0.05). Postexercise cardiac output, stroke volume, ejection fraction, left ventricular dimensions, and heart rate did not differ across menstrual phases (P > 0.05). These parameters, except for left ventricular dimensions in systole and heart rate, varied with recovery time, increasing to a peak between 5 and 10 min postexercise (P < 0.05). CVR displayed a significant interaction between cycle phase and recovery time as resistance increased to greater values in the ML phase compared with the EF and LF phases following 30 min of postexercise recovery (P < 0.05). Buffering of PEH appears to be enhanced in the LF and ML phases of the cycle where estrogen concentrations are known to be elevated.