Can't Grab Your Arms Behind Your Back? Here's What Your Body Is Trying to Tell You

You may not realize it, but you reach behind your back for a lot of things — tucking in a shirt or shirt tag, putting on a backpack or coat, doing the clasp on a bra or reaching behind the seat in the car.

If you can't reach that far, it could mean you're struggling with your upper body flexibility and mobility, which doesn't just make your workouts harder but daily movements as well.

"Most people are sitting hunched all day and this tends to be the biggest culprit for lack of mobility," Leada Malek, DPT, CSCS, board-certified sports physical therapist, tells LIVESTRONG.com. "Without this area to extend and retract, the shoulder adapts to sitting in front and reaching behind gets tougher."

According to a May 2021 study in ‌Pe‌er‌J‌, the risk of injury increases with low flexibility and low-quality movement patterns. By improving flexibility, focusing on high-quality movement patterns, and promoting a full recovery from previous injuries, you can help reduce your future injury risk.

"Once you get to the root of your issue, though, you can work on a few stretches and drills that can help increase mobility and flexibility," Malek says. Here are a few reasons why you can't reach behind your back as well as stretches that target those muscles, courtesy of Malek.

If you're at a desk all day, you might be prone to poor posture, where you're hunched in your chair with a rounded neck and back. This can create tension in the shoulder blades and lead to tightness as well as lack of flexibility and range of motion, Malek says.

You can work on your posture by checking in with yourself throughout the day and working on sitting upright with your chest popped outward a bit and your neck and spine straight and aligned. Or you can put a pillow behind your back on the chair to keep yourself upright and tall as you sit.

Or roll it out: "Foam rolling with thoracic extension mobilization is a great tool to open up the spine and come out of a hunched posture after a long day at the desk," Malek says. This helps prevent a build-up a tension so you can avoid chronic stress.

‌Foam Rolling With Thoracic Extension Mobilization‌

1. Lie on your back, knees bent with the foam roller horizontally at the top of your thoracic spine (bottom of shoulder blades).
2. Cradle your head with your hands so your neck is relaxed.
3. Breathe and let the upper back extend over the roller while keeping your hips down. You should feel a deep stretch in the upper back.
4. Do 3 sets of 40 seconds each.

The shoulder joint is made up of the humeral head of your upper arm and the scapula (shoulder blade). Both need to move well and move together for proper joint mobility.

"When the shoulder blade doesn't move back towards the spine, it can get in the way of the shoulder and cause pinching and lack of mobility," Malek says. And with time, soft tissue around it adapts to the available (or lack thereof) range of motion.

"Lack of shoulder mobility often stems from joint stiffness, as muscles tense up and can't find their regular range of motion and flexibility," Malek says. This can be a result of daily activities, like lifting heavy bags or being hunched over, and if you don't stretch these muscles enough, it'll create chronic tension.

"If the thoracic spine is stiff, the scapula doesn't move as well and it causes a risk for injury because it's in the way of the shoulder," Malek says. So it's best to do exercises that can improve range of motion in both areas.

One option is scapular controlled articular rotations (CARs). "This allows a controlled movement of the socket of the ball-in-socket that is your shoulder, and it's a great way to make sure the foundations are moving well, and can contribute to improved posture and reduced neck pain," she says.

‌Scapular Controlled Articular Rotation (CARs)‌

1. Start with your hands on your thighs, then shrug your shoulder up, back and down, then roll them around the front again. Start with small circles and arms rested.
2. As your mobility improves, you can place the arms in any position, which is a great way to progress the mobility, such as hands flat on the wall or on all fours on the ground.
3. Do 3 sets with 15 circles a set.

Unfortunately, the pectoral muscles are tight on a lot of people, Malek says, which can cause the shoulders to round forward.

"Additionally, most people spend a lot of time at the computer and desk work, which can predispose the chest muscles to shorten, thus limiting how far the arms can be pulled back," she says.

Plus, if you're doing more pushing exercises than pulling, or hold your phone down low and hunch over to see it, you might also be susceptible. "Even prolonged positions with the shoulders are both closed off, such as laying on one side, with arms curled in can contribute to this," she says.

‌Foam Roller Angel‌

1. Lie on a long foam roller so it's under your tailbone, upper back and head. Let the arms fall to your sides, palm facing upward.
2. Move them up toward your ears, then back down, as if you were making a snow angel.
3. Do 3 sets for 30 seconds a set.

Your biceps is a muscle with two heads: one on each side of your shoulder. "So sometimes, with biceps that are very developed but inflexible, they have the ability to contribute the shoulder tipping forward which can pose posture limitations," Malek says.

Because of where the biceps attach in the shoulder, if they're overly tight, it can cause the tip of the shoulder to round down and the shoulder blade to round forward. This then limits the ability for the shoulders to open up, allowing you to reach behind your back.

Strengthen the muscle opposite of your biceps — your triceps. And ease up on the biceps curls. Do the move below with arms next to side, with an emphasis on pulling the shoulder blades backward.

"This will allow the biceps to lengthen through a range that corresponds to the chest being open and having good posture, gaining flexibility through the muscle itself," Malek says.

‌Standing Triceps Kickback‌

1. Stand with your arms at your sides, a dumbbell in each hand.
2. Bend your elbows to 90 degrees, keeping the weights at your sides.
3. Draw the shoulder blades back and extend the weights back behind you.
4. Release back to the start.
5. Do 3 sets with 10 reps each.