Rarity:
Rare

After exceeding a certain frequency in pec bounce, the performer bounces so fast that he either can't (non-mastered control) or his pecs don't have the time (mastered control) to fully be restored at their relaxed position before the next contraction. This results in a vibration/shake effect, hence the term pec shake.

Many performers reach pec shake with an accelerating pec bounce (progressive pec shake) but there are a good deal of them who can instantly perform it (instant pec shake).

Instant pec shake performers are much more skilled and can shake at considerably higher frequencies than progressive pec shake performers.

The true masters of this performance can shake their pecs so fast that it seems that they simply hold their pecs contracted/flexed. A closer inspection, however, will reveal that their pecs shake at such high speed that the human eye / camera can't register the frames between the oscillation. Such rapid contractions are testing the physical limits of the muscle fibers and neurons, making them impressive even from a biological standpoint. They usually don't last for long, due to the extreme stress inflicted on the muscle. They are, however, documented and possible.

Our Youtube playlist of this control may be found here.