If you’ve been training for a while, then I’m sure you’ve been in a situation that went something like this: You got to the gym late, and with only about 45 minutes before closing time you’re in a hurry. Naturally, you prefer to go through your whole workout, so you opt to leave out a few of your usual warmup sets to save time. Instead of first adding a couple of 10kg plates on each side like you usually do, you put on the 20kg plates straight away. Upon lifting the bar from the rack, the weight feels crazily heavy, and you’re slow as hell. You finish the set, and after a minute of panic you decide to try your luck and go for the usual +5kg follow up anyway, to only find out that this one feels totally smooth and even a little easy. Sounds familiar?
“Skip out on too many preparatory sets, and you’re left with less-than-ideal strength.”
This struggle to lift a heavy weight without a proper warmup has to do with your nervous system needing to potentiate a certain neural pathway. Think of it as your body needing to grease the groove before it can fire full force. Skip out on too many preparatory sets, and you’re left with less-than-ideal strength (and speed), which will hurt your results. You also want to be careful to not do too many though, because then you might end up fatiguing and losing steam before you get to your important working sets.
The obvious question then is: where is the sweet spot? In order to be able to come up with an advice regarding the amount of warmup sets, you first need to estimate what percentage of your one rep max weight (1RM) you are planning to lift. If you have no idea what your 1RM is, and are clueless as to what repetition ranges typically correspond with percentages of that max; here are common averages: 15 reps at 65% (of 1RM), 12 reps at 70%, 8 reps at 80%, 5 reps at 85%, 3 reps at 90%, and of course 1 rep at 100%. Remember, these are estimates, so these values might vary depending on the person.
When warming up to about 60% of 1RM, tension is pretty low, so jumps in weight can be quite big without them affecting your performance. However, as the weights go up and you enter the heavy stuff (a.k.a. maximal activation territory), jumps should be progressively smaller in order to be prepared for the next step. Take a build up to a 1 rep max, for example, I have found this to be a proper warmup sequence: 10×20%, 5×40%, 3×60%, 3×75%, 1×85%, 1×92.5%, 1×97.5%, 1×100%. That’s 7 warmup steps. When building up to a lower range instead, like 70% (+- your 12 rep max), I recommend going through the same steps as when building up to 100%, but jumping out at your desired working percentage for the day (in this case: 20%, 40%, 60% as warmups, and then lifting 70% as the working weight). So please note: the higher your working percentage of the day, the more warmup sets you’ll need.
“The higher your working percentage, the more warmup sets you need.”
After deciding on the amount of warmup sets, the question then is: should you perform the same amount of reps on your warmup sets as you do on your working sets? This depends on the goal of your session. If you are planning to lift earlier mentioned 70% for a classical 4×12, then just do 12 reps on your warmup sets as well. If you’re trying to see how many reps you can get with 70% in one set however, then you’d ideally keep the repetitions during your warmup lower in order to save as much juice for your one money set. In that case, I recommend taking the regular steps working up to 70%, as stated in the 1 rep max example (10×20%, 5×40%, 3×60%).
Of course nobody is exactly alike, and we’re not talking exact science here, so maybe you perform better with either a bit more or a bit less warmup volume. I encourage you to experiment. But if you’ve never given it an honest thought, you might have been leaving something on the table.