Let’s be honest: we’ve all sneaked a quick look in the gym mirror after a set of curls. It’s fine, you’re among friends here. But while “mirror muscles” are a nice perk, building stronger, more defined arms is about far more than just filling out a T-shirt.
Whether you’re aiming to carry all the shopping bags in one go (the ultimate flex) or you’re at a HYROX plan race where your grip strength is the only thing between you and a very long day, your arms are your primary tools. Think of them as your body’s Swiss Army knife: versatile, essential, and hopefully, razor-sharp.
Meet the cast: your arm anatomy
Before we start flinging weights around, let’s get to know the squad. It’s not just “the bicep.” Your arm is a well-coordinated team:
The Bicep: The headline act. Located at the front, it handles the “heavy lifting” of bending your elbow and rotating your forearm (like when you’re turning a door handle).
The Tricep: The unsung hero. It sits on the back of your arm and actually makes up about 60-70% of your upper arm’s mass. If you want “big” arms, you need to work the triceps. They’re responsible for elbow extension, crucial for those HYROX sled pushes.
Brachialis & Brachioradialis: The supporting cast. These help with movement and give your arms that “thick” look. They’re your best mates during a Farmer’s Carry.
The HYROX plan: quality over ego
We’ve all seen that person in the gym using their whole body to swing a 23kg dumbbell for one “bicep curl.” Don’t be that person.
For real progress without knackering your joints, aim for 3 to 5 sets per exercise in the 8 to 12 rep range. You want a weight that makes those last two reps feel like you’re trying to lift a literal boulder, but without losing your form. This “sweet spot” builds both muscle size and the endurance needed to survive the 1,000 metres of rowing you’ll face on race day.
A “gun show” workout
To keep things balanced, you need to hit the front, the back, and the grip. Here’s how to break it down:
1. For the biceps (the classics)
Barbell Curls: The staple. Keep your elbows tucked in by your sides, no “cheating” by swinging!
Hammer Curls: Hold the dumbbells like a hammer (neutral grip). This hits the forearms and the brachialis, making your arms look wider from the side.
Cable Curls: These keep constant tension on the muscle. Unlike dumbbells, where the “top” of the move is easy, cables keep those biceps grafting the whole time.
2. For the triceps (the powerhouse)
Cable Pushdowns: Great for isolation. Keep your shoulders down and focus on the “squeeze” at the bottom.
Overhead Extensions: These target the “long head” of the tricep. If you want that horseshoe look, this is the way.
Dips: Use a bench or parallel bars. These are brilliant for functional strength, basically a vertical version of the pushing power you need for a HYROX sledge drive.
3. Forearms (the Grip of steel)
Ever seen someone’s grip go during a Farmer’s Carry? It’s not a pretty sight. Don’t skip wrist curls or dead hangs. Strengthening your grip is the secret weapon for performing when you’re knackered.
Not all arms are created equal
It’s worth noting that biology plays a bit of a part in how we progress. According to various fitness studies and physiological data:
Men generally have higher upper-body muscle mass, with studies showing women have about 40% less muscle in that area on average, which leads to greater strength and size in men.
Women often possess greater muscular endurance and flexibility, meaning they can typically manage a higher training volume (more sets/reps) and recover slightly faster between sessions.
For perspective: Average upper arm circumference for men is about 33–36cm, while women average 30–33cm. But hey, we’re not here to be average, are we?
Don’t skip the “boring” stuff
I know, I know. You want to crack straight on with the lifting. But a quick warm-up of arm circles and dynamic stretches is the difference between a top session and a pulled muscle.
And when you’re done? Stretch. Your future self, the one who isn’t waking up with arms as stiff as planks, will thank you.
In a race, your arms are under constant tension. Whether you’re pulling a sledge or throwing a Wall Ball, your “arm day” is what keeps your pace from falling apart.
So, grab those weights, keep your form sharp, and remember: we’re building arms that are as functional as they are pleasing to the eye. Ready to flex?
