Is it bad to do static stretches while being sore? Say, a day after your workout.
I would, but don't force it. It always decreases the soreness for me.
Stretching is VERY important! Keep it up, but yeah, don't force it! relax and exhale slow. It'll help the soreness a lot as well help build muscle, belive it or not! Flexability is the number one overlooked and arguably most important aspect of training.
I wouldn't reccomend static stretching personally, since it has the potential to damage muscle fibers; and even decrease performance! It also does little to prevent injury since you are not doing movements you are likely to replicate in your sporting activity, which is why; if your movements should be dynamic. Search for the DVD "Magnificent Mobility" By T-nations own Mike Robertson and Eric Cressey.
I know many people that never stretch, besides what they doing during exercise, it is definitely not the most important aspect of training. If you have muscle imbalances and you are trying to stretch a short/tight muscle because of a postural fault, or something along those lines, that is another matter. Besides that, I would definitely not recommend static stretching....
How does stretching build muscle?
Without a convincing explanation, I don't believe it!
Here's a quote from The Stretching Roundtable.
Shugart: Okay, Don, you've written articles about stretching for size gains. How does that work?
Alessi: There are several ways this occurs. For one, stretching increases joint range of motion, which increases the distance that a load is moved thereby increasing the work performed. Also, specific methods like PNF stretching increases isometric and dynamic strength, muscular endurance, and functional flexibility.
Additionally, specific stretching conditions the stretch reflexes that are involved in weight training, thus shutting off these protective mechanisms. This allows the trainee to train at a higher percentage of his rep maximum more often. That means a greater force traveling over a greater distance.
Finally, stretching of the parallel elastic components (PEC) immediately after resistance training increases muscle hypertrophy by stretching the limiting ?sheaths? that encapsulate the muscle belly. In protective response to this unstable change, the stretched muscle sheets trigger an increase in protein splitting, muscle cell division, and collagen breakdown and repair. The result is hypertrophy or "thickening" for survival.