A house won’t be much of a house without nails, screws, and cement. I would say the same goes for your training as well. Consider your main movement of the day (squat, bench, deadlift, overhead press, pull-ups) the building blocks of your house. With that first lift you have the makings of a giant mansion; now how will you hold it all together? This is where your “assistance” work or “supplemental” work comes in. The assistance work of your program act as the nails, screws, and cement that solidify the work you’ve put in with your main movement. They will provide your house the ability to stay strong and not crumble.
Before I go any further let me explain what qualifies as assistance work. If your main lift of the day is a squat then your assistance would be a variation thereof. This can be another bilateral movement or a unilateral movement; but almost always compound in nature and will mimic the movement pattern of your main lift. Examples of assistance work for a squat would be a box squat, front squat, split squat, BSS, etc. (these lifts can be used as a main movement but in this instance they would be considered assistance work). Your assistance work can be used for different reasons be it to reinforce the movement pattern of your main lift, bringing up weak points and imbalances, to make the main musculature stronger and bigger, etc. Regardless of the reason the main point becomes that assistance work will get you stronger and better at the main lifts which in the end will make you stronger overall. Plus it gives you yet another way to get your Hulk on and smash weight.
I’m not saying go out and work up to a heavy double on safety squat bar good mornings for an assistance lift, that would just be overkill. I believe you should still be moving some appreciable weight but the volume should be greater than your first lift (as long as your volume for your first lift wasn’t absurdly high). In order to work on your weaknesses or to get better at the movement pattern you need to practice. This would be the reason why it’s important to keep the volume higher; it provides a lot of practice.
How much volume are we talking here? You want to give yourself a rep range that is going to work on your specific goals. Is maximal strength your goal? Then I would probably keep the volume low (18-30 reps). Is hypertrophy your goal? Then I would probably keep the volume on the higher end (30-50 reps). Keep in mind I am speaking generally, there are many exceptions to what I just said based on a person’s strength level. One exception would be if you have a relatively young training age then I would stay at the low end and be focused on quality not quantity. What I like to do is pick a number of reps and flat load it over a few weeks. For example, if I picked 24 reps for my total volume then my sets/reps would go something like, week 1: 6x4, week 2: 5x5, and week 3: 4x6. This way I can stay at the same volume while hitting it in different ways each week. Mark Bell has talked about this before and I think it’s a great way to go about programming your assistance lifts.
The tricky part in all this is to keep from going overboard. As I stated before I feel you should be using heavy weight but that heavy weight should be appropriate for the volume you are working at. If your max deadlift is 315 then it’s probably not a good idea to try and do 300lbs RDL’s for 5X6. You would look awful doing it, if you could even do it at all. Good luck trying to groove a movement pattern using 95% of your deadlift max (yeah I did the math, what of it!). Have you ever read or heard a fitness professional say “just focus on your main movement; don’t worry so much about your assistance work?” The reason they say that is because if they told you to treat it with the same intensity as your main lift then you would probably load the bar as heavy as possible and the lift would look as ugly as this dog.
The problem with fitness professionals coaching that or writing that is now people seem to just go through the motions when it comes to assistance work; they feel it’s not important. Well I’m telling you now that it is. Just work hard and make the reps look smooth!
I know it can be challenging for people to get in their training session with their hectic schedule. Your main movement is primary and crucial but your assistance work is a close second. If you need to cut out anything then cut out your accessory work (accessory work would be something like tricep pushdowns, delt raises, facepulls; most of the time they are single joint movements done at a high volume, 30+ reps near the end of a training session). You really shouldn’t lose focus on anything while training. All your movements should be intense and deliberate. If you can’t devote the effort needed to an exercise then you shouldn’t do it at all. With that said, it’s time to show your assistance work some love, it has feelings too!