i personally don't like any form of static stretching prior to strength/power/agility training.
i've learned that AIS (active isolated stretching) & loaded stretching can actually improve power/strength scores. i would use AIS on problem areas.
for example: general warmup, mobility warmup, AIS stretching, specific warmup / activation exericses, go!
i think forms of PNF do help prior to training, but not with 30 second stretch holds.. for example contract-hold ~5-15 seconds, relax stretch hold ~2 seconds.
there exists hundreds of studies, where they concluded static stretching reduced force in the muscles stretched.. some studies say the effect lasts 15 minutes, some say 2 hours.
a couple of examples:
An Acute Bout of Static Stretching: Effects on Force and Jumping Performance.
Results: After SS (STATIC STRETCHING), there were significant overall 9.5% and 5.4% decrements in the torque or force of the quadriceps for MVC and ITT, respectively. Force remained significantly decreased for 120 min (10.4%), paralleling significant percentage increases (6%) in sit and reach ROM (120 min). After SS, there were no significant changes in jump performance or PF measures.
Effect of Acute Static Stretching on Force, Balance, Reaction Time, and Movement Time.
Conclusion: In conclusion, it appears that an acute bout of stretching impaired the warm-up effect achieved under control conditions with balance and reaction/movement time.
Acute Effects of Static and Proprioceptive Neuromuscular Facilitation Stretching on Muscle Strength and Power Output
Conclusions: Both static and proprioceptive neuromuscular facilitation stretching caused similar deficits in strength, power output, and muscle activation at both slow (60Â°Â·sï¿½??1) and fast (300Â°Â·sï¿½??1) velocities. The effect sizes, however, corresponding to these stretching-induced changes were small, which suggests the need for practitioners to consider a risk-to-benefit ratio when incorporating static or proprioceptive neuromuscular facilitation stretching.
Should static stretching be used during a warm-up for strength and power activities