Maximal strength, number of repetitions, and total volume are differently affected by static-, ballistic-, and proprioceptive neuromuscular facilitation stretching.
Most strength and conditioning professionals agree that proprioceptive neuromuscular facilitation (PNF) stretching would not be a wise choice for warming up before a lifting or practice session. Although proven to acutely increase range of motion (ROM), PNF stretching has also been shown to significantly reduce musculotendionus stiffness and decreased motor unit activation. In other words, athletes are able to generate less force after PNF stretching.
However, a recent study in the Journal of Strength and Conditioning Research evaluated the difference in not only PNF stretching but also static stretching (SS) and ballistic stretching (BS) in maximal strength output, number of repetitions and total volume. The findings show that the varying stretching techniques affect strength output differently.
The study took 12 strength trained men through 8 testing days, each spaced 72 hours apart, to determine how the different stretching techniques affected either their maximal strength, or strength endurance in the leg press.
Their experimental design:
The study supported that all forms of stretching acutely increased ROM with PNF increasing ROM the most. More importantly, not only PNF and SS decreased the number of repetitions and total volume lifted, but so did BS. In addition, the findings show that only PNF stretching significantly decreased maximal strength test results.
Despite previous evidence that shows BS does not affect max strength and may improve sprinting and jumping performance, this study was the first to investigate the acute effect of BS on the number of repetitions performed. The finding showed a significant reduction in the number of repetitions performed in the leg-press exercise at 80% of the subjects 1RM.
Readers, your dynamic warm up is essential because it elevates your heart rate and core body temperature, improves your flexibility and mobility as an athlete which will help keep you healthy, and it allows you time to get mentally focused for the days session. However, if you are going for a 1RM or a test till failure, say a max repetition bench press of 225 like at the NFL combine, it may be better to skip the stretching. Instead, perform a few warm up sets of that same exercise to warm up your nervous system while keeping the stiffness in your muscles that will help you set a new PR (personal record).
Barroso,R; Tricoli, V; Santos, G; Ugrinowitsch, C; Roschel, H. Maximal Strength, number of repetitions, and total volume are differently affected by static-, ballistic-, and proprioceptive neuromuscular facilitation stretching. Journal of Strength and Conditioning Research. 2012 Sept;26(9):2432-7