Yes, you can effectively train your biceps with practically no equipment. You just have to simplify. Select exercises that train your biceps, brachialis/brachioradialis, and forearm muscles simultaneously. You just need two things:
- A towel.
- A heavy object – a kettlebell, heavy backpack, or even a water jug.
The strict pull-up is a staple in any effective program. Ever see a guy that could crush pull-ups with skinny arms? Didn't think so.
While the towel pull-up could be considered a lat exercise, you'll actually feel it the most in your biceps, forearms, and hands.
There's no real need for a pull-up bar. Just hang a towel over any sturdy anchor point (a gymnastic ring, a roof truss, or even a tree limb), and away you go. I prefer the gymnastic ring variation so your head doesn't have to dodge the bar every rep. Train for 3-5 sets of 5-10 reps, adding weight when needed.
It's a criminally underrated exercise. If you're serious about maximizing your grip strength and want better-looking arms, try it.
Wrap your hands around the towel, including the thumb. Forcefully squeeze the towel throughout the entirety of the set. During the concentric or lifting phase, curl the weight both up and out to maximize both the biceps and forearm contractions.
Use a moderate to heavy weight for 3-4 sets of 10-plus reps. Go to muscular failure.
This will present a unique challenge for lifters who only do barbell or dumbbell curls.
Expect your biceps, forearms, and grip to fatigue like never before. The beauty lies in the isometric hold. The arms are kept under constant tension by holding the weight up at the top for the set's duration. That extra time under tension will mean more strength and hypertrophy.
Rather than doing this exercise for reps, perform gun walks for total distance or total time. Keep your hands apart by not letting your knuckles ever touch together. This will keep constant tension on the arms.
Try 4-6 sets of 30-40 meters.
Combine both the towel curl and towel gun walk for a lethal combo to really polish off your biceps. For example, do a 40-meter gun walk, but stop every 10 meters and do 5 towel curls.