I dedicate this for BradG. It might help that third set of yours. I got this info from Max-OT and even though I don't still do Max-OT, I still do these warmup techniques.-
How NOT to warm-up
Let's use the Bench Press as an example here. For sake of description we'll say that 275 is the maximum for 3 reps. Here is how most people do a bench workout.
They load the bar with 135 pounds and do about 10 or 15 reps. They'll rest a few minutes and then go to 185 pounds. Here they do another 10 reps. Then they go to 205 pounds and do about 10 reps. After a little rest, they go to 225 pounds and do 7 or 8 reps depending on how good they feel.
So far that is 4 sets. Now throw on 20 pounds to 245 and do about 7 reps. That's set number 6 and they haven't even started to build muscle yet. From here they take the 10's off and put on some 25's. At 275 pounds the barely knock out 3 reps.
Can you point out the mistakes here? They warmed up. No question about that, but they did so at the expense of strength and overload. In other words, their technique for warming up resulted in poor or inadequate muscle fiber stimulation and overload due to premature muscle fatigue.
Here we are going to take the Bench Press and show you a proper warm-up technique that will allow you to lift more weight on your heavy sets. Remember, more weight - more overload - more muscle.
Again well use 275 as your heavy weight. If you typically warm-up and train like I pointed out earlier the 275 will feel a lot lighter this time.
135 x 12 reps (warm-up)
These should be good smooth reps. Not too slow and not to fast. Your main goal is to increase blood flow and get the feel of the movement and the weight. After this first set you should rest about 2 minutes.
135 x 10 reps (warm-up)
Same weight as before. Rhythm should be a little faster this time. Not much faster. Rest about 2 minutes.
185 x 6 reps (warm-up)
This should be a deliberate set done at a moderate pace. This is the next step in weight acclimation. It should feel light and 4 reps should be very easy. Rest about 2 to 3 minutes before the next set.
225 x 3 reps (weight acclimation)
You should follow the same rhythm as in the last set. 3 strong reps. Rest 2 minutes before next set.
255 x 1 rep (weight acclimation)
That's right, just 1 rep. The purpose here is weight acclimation. This should be a strong, powerful and deliberate rep.
Sixth, Seventh, and Eighth Sets:
285 x ??? reps (muscle-building)
These are the muscle building sets. Very important. These are the only sets that produce muscle growth. All the sets leading up to these heavy sets are merely warm-up sets and are treated as just that and nothing more.
"Do Not" Specifics:
1. Do not pyramid unnecessarily.
One of the worst training methods ever introduced is pyramid training. This is where you start out light and then add small increments of weight with each set - going to failure each set until you get to your heaviest set. After the heavy set you then lighten the weight just opposite to how you increased it on the way up. Then you complete reps to failure for each set on the way down.
As I said, this is probably the least efficient way possible to build muscle yet it is the most common training approach used today. So if you are training this way the first thing you should ask yourself is - Why do I do this?
When you structure your sets like this, for whatever muscle group you are training, you deprive them of not only the overload they are capable of, but also the overload needed to induce efficient muscle growth.
2. Never go to failure on a warm-up set.
This is the ultimate training sin. Never, ever, ever, ever, go to failure with a warm-up set. This is the perfect way to sabotage a workout and stop muscle growth dead in its tracks.
3. Do not warm-up the same muscle group twice.
Never re-warm a muscle group just because you have proceeded to a different exercise.
Examples: There is no need to warm-up on the Leg Press after a squat routine. There is no need to start out light on Barbell Curls after finishing Dumbbell Curls. Likewise, there is no need to start out light on Cable Rows after Barbell Rows.