When to and How Much Warm-Up?

I’ve been doing a 6x5 program (basically the 5x5 with an added rep) for some time now, and I’ve found that most of my time is spent simply warming up for these exercises. I’ve been especially focused on preventative action and technique ever since I herniated a disc last year, but how much do you guys think is really needed and when is it needed?

I have been adhering to Rippetoe’s “Starting Strength” protocols with four warm up sets. Roughly, I do the motion of the bar for the max number of reps I’ll be doing (6), then 25% of the weight of the weight for 6 reps, 50% of the weight for four reps, and 75% of the weight for 2 reps–then I’ll do my sets. However, this sucks up a fair amount of time with the switching of weights and the short rests in between. Ultimately it adds up to 9 sets per exercise. Not hard, but it takes awhile (before people start commenting, I don’t take a long break between warm-up sets, but I don’t jump on immediately–maybe 15 sec).

So is it always necessary to warm up with that many sets? Also do I have to warm up on every one? For instance, I feel like if I have done squats prior, I shouldn’t need to bother warming up with the deadlift, since they are close to the same movements and utilize similar muscles.

I would just use as many work up sets as you feel you need. A lot depends on the amount of weight you will use. If you are working up to a 500 squat, it will take more work up sets than working up to 135.