Mariposas
Best Arms Exercises
By Zachary, builder of Mariposas · Reviewed against published exercise-science sources (references)
· Last updated June 2026
Arms training has a reputation for being the most ego-driven part of a gym program, and that reputation is mostly earned. Curling whatever weight lets you swing your torso, or doing tricep pushdowns with half the stack because it looks impressive, produces a pump but not much else. What actually builds upper arm size and strength is a combination of tension across a full range of motion, enough frequency to practice the movement patterns consistently, and honest load selection. If you want to track what's working, logging your sets in Mariposas is free and you'll collect pets along the way, which is a genuinely fun reason to stay consistent.
How to train your arms
The biceps and triceps respond well to moderate rep ranges, typically somewhere in the 8 to 15 range, because both muscles contain a meaningful mix of fiber types and fatigue relatively quickly under load. Most experienced lifters train arms two to three times per week, either in dedicated sessions or tacked onto pulling days for biceps and pushing days for triceps. Getting the elbow fully extended at the bottom of a curl, or fully locked out at the top of a pressdown, is where many people lose real stimulus by cutting the range short. Varying the angle of the upper arm, like incline curls versus standing curls, changes which portion of the biceps is most challenged, so rotating through a few exercises over a training week tends to produce better development than hammering one movement every session.
FAQ
- How much direct arm work do you actually need if you already do rows and pressing?
- Compound movements do load the arms, but the degree varies a lot by exercise and individual mechanics. Rows train the biceps heavily through elbow flexion, but the load is usually limited by back fatigue long before the biceps are near failure. Overhead pressing and dips load the triceps, but again the chest and shoulders often give out first. Most people who rely entirely on compounds find their arms lag relative to their torso development. A handful of direct sets per session, even just two or three, tends to close that gap over several months.
- Why do my biceps feel nothing during curls but my forearms fatigue immediately?
- This usually points to two things: grip fatigue cutting the set short before the biceps are challenged, and a range of motion issue where the wrist is doing compensatory work. Using a slightly thicker grip or wrist wraps for heavier sets can isolate the problem. Also check whether your pinky side of the hand is drifting outward during the curl, which shifts more load onto the brachioradialis in the forearm rather than the biceps brachii. Supinating fully at the top, turning the palm up and slightly outward, creates a harder biceps contraction that many people have never actually felt.
- What's the actual difference between a hammer curl and a regular curl for arm development?
- The forearm position changes which muscles do the most work. In a standard supinated curl, the biceps brachii is the primary mover. In a hammer curl with the thumb pointing up, the brachialis and brachioradialis take on more of the load. The brachialis sits underneath the biceps and, when developed, actually pushes the biceps up and makes the arm look thicker from the front. So hammer curls aren't a substitute for regular curls but they do build a different part of the upper arm that contributes meaningfully to overall size.
- Is there a point where adding more tricep volume stops helping?
- Yes, and the triceps tend to hit that ceiling faster than people expect because they're already working during all pressing movements. The long head of the triceps, the one that makes up the bulk of upper arm mass from behind, is best loaded in a stretched position, like overhead extensions. If someone is already doing bench press and close-grip work, adding overhead extension volume targets something those movements don't fully address. But stacking in more pushdowns on top of an already pressing-heavy program often just adds fatigue without adding stimulus, especially if technique starts to break down late in a session.