Build strong, defined back and arm muscles with this 20-minute back and arm workout. This rep drop arm workout is designed to strengthen the upper body, improve posture and build functional strength for everyday life.
This is Day 7 of my Max 20 Program, and this workout is focused on building a strong back (the largest muscle group in your upper body) while also strengthening your arms, shoulders and grip.
As a mom and a trainer who is passionate about strength training, I’ve learned how important it is to build a strong upper body – especially your back muscles. This workout targets your back and arms for a reason. The back and arm muscles work together to create balance and stability through the upper body, which translates into better movement patterns in your daily life. Carrying kids, lifting groceries, pulling yourself up, even just standing tall – all of it becomes easier when the back is strong and activated.
One of the biggest benefits of training your back is improved posture. So many of us spend hours sitting, scrolling or hunched over screens, which leads to rounded shoulders and “tech neck.”
Strengthening the back helps pull your shoulders back into alignment, opening up your chest and supporting better movement patterns. Pair that with strong arms and grip, and you’re not just building definition; you’re building strength that actually shows up in your everyday life.
And yes – this workout includes a lot of pull-ups (I’m a big believer in them!). They’re tough and humbling, but I believe everyone should strive for them. Pull-ups are one of the most empowering strength exercises because they require full-body coordination, grip strength and core control. Even if you start with band-assisted or inverted rows, the process of training toward a pull-up will completely transform your upper-body strength and confidence.
We also hit the shoulders, biceps and triceps in this workout. Lateral raises help strengthen and stabilize the shoulders (one of the most mobile joints in your body). Hammer curls build forearm and grip strength, which is strongly linked to overall strength and longevity. Overhead tricep extensions target the long head of the triceps, helping build stronger, more defined arms while also supporting shoulder function.
When it’s time to grab your dumbbells today, don’t be shy with the weight. This is a rep drop workout, so as the reps go down, your weight or your effort should go up. Those last 2-3 reps should feel hard. That’s where the change happens.

This strength-focused upper body workout is designed to challenge every arm muscle, with extra emphasis on your back muscles.
I recommend incorporating 1-2 upper-body dumbbell workouts into your weekly workout routine, alternating with lower-body workouts, full-body workouts and rest days.
Medium-to-Heavy Dumbbells. I’m using 15-30 lbs. Optional pull-up bar and pull-up assist band (long loop resistance band) if needed (discount code: NML).
Follow along with the guided 20-Minute Arms and Back Workout on YouTube, led by me — your certified personal trainer, Lindsey Bomgren.
Your Workout Looks Like This:
Targets: Lats, rhomboids, trapezius, deltoids, rear deltoids, rotator cuff muscles, biceps, triceps, abdominals and obliques.

Modification: Option to perform narrow back rows from a standing position.
Targets: The lateral deltoid (also engages the anterior deltoid and posterior deltoid).

Modification: Option to perform alternating lateral raises, lifting just one arm at a time.
Targets: Latissimus dorsi (lats), erector spinae, trapezius (traps), biceps, pectoralis major and minor (chest) and core.

Modification: Option to perform assisted pull-ups with a long loop resistance band. Or perform reverse grip back rows.
Targets: The long head of the bicep as well as the brachialis (another muscle in the upper arm located at the elbow joint) and the brachioradialis (a forearm muscle).

Modification: Option to perform hammer curls from a standing position.
Targets: The long head of the triceps and all the stabilizing muscles in the shoulders, core, glutes and lower back muscles.

Modification: Option to perform overhead tricep extentsions from a standing position.
The back is the largest muscle group in the upper body, but you often use other arm muscles, like the biceps and shoulders, to assist with back exercises. Training these muscle groups together is an effective way to build muscle in the upper body as a whole.
Progressive overload and protein are the 2 most important things you should prioritize if you want to see muscle growth and definition in your upper body. Progressive overload means gradually increasing the intensity and difficulty of your workouts over time. You can do this by using heavier weights, increasing rep range or sets or increasing time under tension. Additionally, I aim for 30 grams of protein at each meal.
When it comes to arm day, I like to start with some of the basics. Some of the best arm exercises are back rows, pull-ups, push-ups, hammer curls, lateral raises, chest presses and triceps extensions. These upper body exercises are classics for a reason – they each hit the upper body pull muscles and push muscles, so you get a well-rounded workout by combining them.

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