When it comes to arm day, it's easy to fall into a rut — or not even know where to begin. This 21-day dumbbell arm challenge, created by NASM-certified personal trainer Désirée Triolo [1], is designed to help you mix things up, pretty much guaranteeing that you'll feel stronger [2] by the end of the three weeks. Don't worry if you've never lifted a dumbbell in your life; this arm plan was crafted with everyone in mind, whether it's your first time working out or you exercise regularly.
This dumbbell arm challenge leverages a simple arm workout that consists of five basic dumbbell exercises. The moves target your biceps, triceps, back, and shoulders to build overall upper-body strength. Over the course of the challenge, you'll increase the number of reps you're doing of each exercise, eventually working up to three sets of 15 reps of each.
Ahead, you can find a detailed explanation of how to do each of the five arm exercises, followed by the three-week plan. The first step is choosing the appropriate weight [3] — Triolo says you want a dumbbell that fatigues your muscles by the end of the last two reps. She suggests beginners start with five-pound dumbbells and more advanced lifters go heavier at 15 to 25 pounds. If the challenge ever feels too easy (because you're gaining strength!), that's your cue to increase the weight of the dumbbells. Likewise, if you find your muscles are fatiguing too early or your form becomes compromised, decrease the amount of weight you're lifting.
This arm challenge incorporates two rest days per week — because even though it's a challenge, recovery days are always important. "My professional opinion is to alternate upper-body and lower-body training days to improve your overall fitness level and to avoid creating muscle imbalances," Triolo says, which is why you'll see "lower body" listed on the plan. On these days, you can do lower-body exercises (like this dumbbell butt workout [4]) or walk, run, bike, or hike.
3-Week Arm Workout Challenge
Equipment needed: Dumbbells
Directions: After warming up for a few minutes with some neck circles, Cat and Cow [5], and arm circles [6], perform all five of the dumbbell exercises listed below for the designated number of reps and sets. After each day's workout, run through these upper-body stretches [7].
- Bicep curl
- Bent-over row
- Overhead shoulder press
- Upright row
- Triceps kickback
Day 1
3 sets of 8 reps of each exercise
Day 2
Lower body
Day 3
Rest
Day 4
3 sets of 8 reps of each exercise
Day 5
Lower body
Day 6
Rest
Day 7
3 sets of 10 reps of each exercise
Day 8
Lower body
Day 9
Rest
Day 10
3 sets of 10 reps of each exercise
Day 11
Lower body
Day 12
Rest
Day 13
3 sets of 12 reps of each exercise
Day 14
Lower body
Day 15
Rest
Day 16
3 sets of 12 reps of each exercise
Day 17
Lower body
Day 18
Rest
Day 19
3 sets of 14 reps of each exercise
Day 20
Rest
Day 21
3 sets of 15 reps of each exercise
Keep reading for instructions on how to do the five different arm exercises.
— Additional reporting by Mirel Zaman
21-Day Arm Challenge Exercise 1: Bicep Curl
- Stand with your feet hip-distance apart, holding a dumbbell in each hand at the sides of your body.
- Keeping your elbows close to your ribs, bend your elbows and slowly raise the dumbbells to your shoulders.
- Moving with control, lower back to the starting position. That's one rep.
21-Day Arm Challenge Exercise 2: Bent-Over Row
- Stand with your feet hip-distance apart, holding a dumbbell in each hand at the sides of your body. Lean forward, bending both knees, keeping your back flat.
- Extend your arms in front of you so they're parallel with your thighs.
- Pull your elbows behind your back, raising the dumbbells toward the sides of your ribs, squeezing your shoulder blades together. Be sure to keep your elbows in and pointed upward, and don't arch your back.
- Slowly lower the weights back to the starting position. That's one rep.
21-Day Arm Challenge Exercise 3: Overhead Shoulder Press
- Stand with your feet hip-distance apart, holding a dumbbell in each hand just above your shoulders, palms facing in.
- Straighten your arms above you.
- Bend your elbows, coming back to the starting position. That's one rep.
21-Day Arm Challenge Exercise 4: Upright Row
- Stand with your feet hip-distance apart. Hold a dumbbell in each hand with your palms facing your body, shoulders over your pelvis, and a slight bend in your knees.
- Keeping the dumbbells close to your body, raise them toward your shoulders, bending your elbows out to the sides.
- Slowly lower them to the starting position. That's one rep.
21-Day Arm Challenge Exercise 5: Triceps Kickback
- Holding a dumbbell in each hand, hinge forward from your hips, bending your knees slightly. Bend your elbows behind you.
- Squeeze your triceps to straighten your arms behind you with your palms facing in. Try to keep your shoulders from shrugging up toward your ears.
- Lower the weights to return to the starting position. That's one rep.