Static Stretches
Good point. Static Stretches dampen the Stretch Reflex, decreasing Power Output.
Weaken Nor Improve
I doubt that impede you kicks or knee strike that much, providing you don't go crazy with them.
However, static stretches prior don't do that much to improve them either.
Research shows the greatest training effect with static stretches is when they are preformed after your workout, rather than prior.
This take us back to...
String Cheese
To reiterate, you're connective tissue is similar to string cheese. When it is cold, it has very little elasticity; more likely to snap apart.
When string cheese is warmed up, it is very elastic and flexible. Thus, static stretching post training produce elicits a greater degree of flexibility.
Dynamic Stretching
Dynamic Stretching prior to training is a much more effective method to employ prior to training. It primes the Stretch Reflex and the Central Nervous System displaying/producing greater Power Output.
Neural Charge
Chris Thibaudeau, Strength Coach, uses Dynamic Movements prior to training as a means of providing what he terms as a, Neural Charge; priming your training movement to be more explosive.
Beyond Stretching
Pavel "explained that since preceding a strength movement with a similar, explosive plyometric movement allows for a greater weight to be used during a strength movement, a greater training effect is elicited. He gave the example of Dr Fred Hatfield would, during competition, precede his squat with a verticle jump and his deadlift with a depth jump." [
Building Strength and Power With Complex Training - World Class Bodybuilding Forum]
The Size Principle
The firing sequence of muscle fiber is...
Slow Twitch Type I > Fast Type IIa > "Super" Fast Type IIb/x.
However, when explosive movements like Dynamic Stretching is preformed, the "Super" Fast and Fast Twitch Muscle Fiber are innervated quickly, learn to fire faster
Car Type of Muscle Fiber
Slow Twitch: Think of them a small 4 cylinder car.
Fast Twitch: Think of them as a 6 cylinder car.
"Super" Fast Twitch: Think of them as a fuel injected 8 cylinder car.
The Muscle Fiber Car Race
In this Muscle Fiber Car Race, the "Muscle Fiber Cars" have staggered starts.
The Slow 4 cylinder car is given a heard start.
Then the Fast 6 cylinder car follows behind the Slow 4 cylinder car.
Finally, the "Super" Fast fuel injected 8 cylinder car follows behind the Slow 4 cylinder and 6 cylinder Fast Twitch.
Race Results
The Fast 6 cylinder car quickly overtakes the Slow cylinder car.
The "Super" Fast fuel injected car then passes the Fast 6 cylinder car.
Summary
1) Static Stretch prior to exercise in dampen Power Output to some degree.
2) Connective Tissue is more pliable when heated up; post Static Stretching is more effective.
3) Dynamic Stretching primes the Stretch Reflex, Central Nervous System, engaging the Fast and "Super" Fast Muscle Fiber.
4) Research show that up to 18% more power is produced with the Stretch Reflex. The only way to develop the Stretch Reflex is to train it.
Kenny Croxdale