Considering Barnett wrote the book on dumbbells (literally!), she knows better than anyone what to consider before picking up a pair. Ahead, she explains how to find the right weight dumbbells for you and shares guidance on when to level up what you’re lifting:

Think about your fitness goals.

Lifting dumbbells is so much more than just picking up and putting down weights—you can achieve real strength goals over time by tweaking different variables, like weight, reps, and sets, Barnett says. Here are some guidelines to follow for different strength training goals.

If you want to…

• Sculpt muscle: Lift medium to heavy weights for six to 12 reps and three to six sets.
• Build stamina: Lift light weights for 12 or more reps and three sets.
• Lift heavy objects: Lift heavy weights for six or less reps and three to five sets.
• Lift heavy objects quickly: Lift heavy weights for one to two reps and three to five sets.

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Consider the specific exercise.

There’s a reason you can squat way more than you can curl. That’s because smaller muscles like your biceps, shoulders, and core are physically unable to lift as much as larger muscles like your back, chest, and legs. These latter muscles “can handle heavier weight because they’re designed to generate more power,” Barnett says.

That’s why it’s always good to have multiple sets of dumbbells by your side while you’re working out.

Use the light-to-medium set for these smaller muscle groups:

• Biceps
• Triceps
• Shoulders
• Core

Use the medium-to-heavy set for these larger muscle groups:

Perform a rep test.

With your fitness goal and muscle group in mind, grab a lighter weight than you think you can handle (so you don’t risk injury) and try to reach the rep count for each exercise. If your goal is building muscle stamina in your arms, for example, and you think you can handle lifting five-pound dumbbells for a minimum of 12 reps, you should conduct a rep test by lifting three-pound dumbbells for those 12 reps.

When you finish the rep test—even if you had to put your weight down before completing all the desired reps—ask yourself these questions:

• Am I maintaining proper form throughout all of my reps?
• Am I breathing properly and not holding my breath?
• Am I completing my reps, especially in my first set?

If the answer to any of these is “no,” decrease your weight. But if you said “yes” to those questions, then ask yourself these questions: