
The quest for bigger guns...it is never-ending. As someone who has struggled for years, if not almost 2 decades (sad), with building decent arm size, I feel I can make somewhat of a contribution here.
In no particular order, here are my top 11 arm-building lessons. I learned them over time, and learned them the hard way.
Train seated. It makes a difference in terms of muscle control, especially when it comes to curls of all kind and triceps extensions.
Get pumped. No, a muscle pump will not stretch the fascia. But at least you'll know that you hit the muscle correctly, and it will look great for 20 minutes.
Do pull ups. Lots of them. Nothing builds better biceps and forearms. If you do not believe me look at gymnasts or free climbers.
Some of my best results came during a period where I performed 80 pull ups before each workout. I did this for 4 weeks straight.
Lesson #4 - Try 150% EccentricsGo 2 for 1. This is one of my favorites.
Load up 150% of your regular weight for a single arm exercise, then use both arms to do the concentric portion of the movement. But only one arm to do the eccentric (negative) portion.
Examples would be barbell curls, triceps pushdowns or pull ups.
Isometrics, as such, are not all that useful for bodybuilding. They are tough to estimate progress because you're not pushing or pulling per se. With that said, there is a certain benefit in terms of hypertrophy.
For that to happen you need to cross the 30 second threshold. Ideally, you should use isometrics at every point of the strength curve. So it's a good idea to finish one set with a static hold at mid-point, a hold at the point of contraction, and a hold in the stretch position.
Use resistance bands when curling and pressing. Resistance bands (or chains) make the exercise much harder during the part of an exercise where your muscle is the strongest. It also aids in establishing a better mind muscle connection.
Train arms more often. I have had some decent success by spreading my arm workouts out over a period of 5 training days. I would add 4 sets of biceps and triceps to each training day of the week, as opposed to having just one designated arm day.
Use the small barbells...for one arm. As an example, try doing preacher or spider curls with one small barbell only.
The biceps and forearms will work much harder just to help you maintain balance. The soreness the next day is out of this world.

"Doing traditional pre-exhaustion was one of the hardest workouts I ever performed... I could hardly breathe... but I did not feel it gave me optimum muscle stimulation. I had to vary the method and rest sufficiently." - Dorian Yates
Use pre or post-exhaustion sets. This is an oldie but a goodie. Arnold Schwarzenegger used this practice a lot and it works great.
Simply do an isolation exercise before the compound movement. For example, perform curls before pull ups or press downs before close grip bench press.
This approach can also be reversed for a post-exhaustion set. Simply rep out via a single joint movement after performing the big one.
You must work all 3 positions of the strength curve. I have written about this before, but most people neglect this aspect of training.
Each workout should contain one exercise for each of the following positions:
If in a hurry, you can do all 3 positions by using the cable for press downs, curls and taking one big step back every 8 reps, thereby covering all positions.
Use nootropics, or academic steroids. No, you did not read that right. It says "academic steroids," sorry.
I want to focus on an overlooked aspect of performance: cognitive abilities. Very often, attention is paid to stimulants and anabolic steroids as ergogenic; aids which lead to a surge (and abuse) of pre-workout stimulants.
What are nootropics? They can be put into two categories:
Before I get into the details, here is huge disclaimer: nootropics will not change your body the way illegal drugs do, But over the course of several months they will contribute to a significant improvement in your workouts and overall quality of life.
Brain foods such as choline are the base for acetyl choline, the most used neurotransmitter. Remember when your mom mixed lecithin in your granola before a big exam so you could focus better? She was right.
So you can be smarter and have 18" guns.