If you're already strength training and you suddenly do more than 50% extra workouts per week, your biceps and triceps might grow a bit more—but if you only increase a little or even cut back, you won't see a big difference in muscle size compared to those who ramped it up a lot.

If you're someone who regularly lifts weights, doing more triceps exercises each week might help your triceps muscles get a little bigger—but only a little, and not as much as it helps your biceps.

If you're lifting weights regularly, doing more reps and sets might make your biceps grow bigger, but it doesn't seem to help your triceps grow as much—your arms might just respond differently to extra work.

If you're already strength training and you do more sets of bicep exercises each week, your biceps tend to get thicker — and this link isn't just luck, it's a real pattern.

Two different weightlifting styles—one focused on heavy weights with long breaks, the other on lighter weights with short breaks—both grew arm muscles about the same amount when people lifted the same total amount over 8 weeks.

If a woman who's already fit does strength training, doing 5 to 10 sets per muscle each week might build more muscle than doing even more sets—like 15 or 20. Sometimes, more isn't better when it comes to muscle growth.