The purpose of this research was to examine the effects of a premovement silent period (PSP), and an involuntary small amplitude countermovement (CM) on the maximal height of the squat jump (SJ). Fifteen elite male volleyball players (20.6 ± 1.6 yrs) and thirteen untrained males (20.2 ± 1.7 yrs) performed ten maximal effort SJs from identical starting positions. The electromyographic activity of the vastus lateralis and biceps femoris was measured in conjunction with the vertical ground reaction force, and the vertical displacement measured by a cable-extension transducer. The presence of a PSP or small amplitude CM did not increase maximal SJ height significantly (p > 0.05). These findings indicate that in the SJ, facilitation effects of the PSP and small amplitude CM are minimal. This is important to past and future studies utilizing the SJ, as it is often difficult for individuals to perform SJs with no detectable CM.