Why Can’t I Straighten My Arm After Working Out, & How Can I Prevent It?

After a challenging workout, have you ever felt that achy, stiff sensation in your arm? Whether you pushed yourself too hard in a strength training session or ramped up the reps in your favorite yoga class, that soreness can be a drag when recovering and returning to your next workout. For many, the discomfort goes beyond soreness and can lead to more serious issues, like not being able to straighten the arm properly. If this sounds familiar, you may wonder, "Why can't I straighten my arm after working out?" In this article, we'll cover some common causes of this problem, such as how to quickly relieve arm stiffness and prevent it from recurring, so you can recover comfortably and keep progressing in your workouts without unnecessary pain or setbacks. We’ll also touch on how to measure flexibility to better understand your current range of motion and track improvements over time.
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Why Can't I Straighten My Arm After Working Out?

Sore arms and biceps after a challenging upper-body workout are standard, maybe even to be expected. After all, aching muscles are a part of the natural muscle-repair process that ultimately makes you stronger.

But some people experience a strange post-exercise phenomenon beyond basic aches and pains. They find they can't straighten their arms after lifting weights, usually a hefty dose of biceps and pulling exercises. Their elbows just won't do it.

Here's Why

Experiencing lasting biceps pain, especially when you can't straighten your arm, is generally rooted in extra inflammation and damage (typically the result of new stress placed on your biceps muscles).

But what can you do to relieve the discomfort? And how do you prevent it in the future? Below, find out why you might not be able to straighten your arms after a workout and what you can do to resolve the issue.

Delayed-Onset Muscle Soreness

A tough workout causes micro-tears within your muscle fibers, leading to delayed-onset muscle soreness, or DOMS, a day or two after intense exercise.

‍"To repair the damage done to the neuromuscular system, blood flow to the area increases," says Todd Buckingham, PhD, lead exercise physiologist for the Mary Free Bed Sports Performance Lab. "This creates inflammation and edema, or swelling."

How Inflammation Affects Muscle Recovery and Pain

The increase in circulation is good because your blood carries nutrients that aid in healing. "It regenerates muscle tissue, increasing performance and overall strength," says Jonathan Mike, PhD, a professor of exercise science and sports performance at Grand Canyon University.

But it can also have some less-than-pleasant side effects. Buckingham says the inflammation from extra blood flow pushes on your nerves, which is why your muscles feel tender.

Why Your Arm Won’t Straighten After a Workout

The pain and swelling in your arms, in turn, can prevent you from fully straightening your elbow joint. Once you reach a certain point, the pressure against your nerve fibers is so intense that your brain tells your arm not to straighten any more.

This all happens in your autonomic nervous system, so it's not something you can consciously control. Buckingham says inflammation can physically limit your range of motion by several degrees. "The inflammation acts like a blockade preventing you from full extension."

Cellular Damage

Another potential cause of being unable to extend your elbow is damage to the structures supporting your biceps muscles. "Each of your muscle cells has a net-like structure surrounding it, called the sarcoplasmic reticulum [SR]," Buckingham says. The SR is vital in allowing you to contract and relax your muscles.

It releases calcium into your muscle cells, acting like the key that unlocks your muscles and allows them to move. "But if you damage your SR during heavy exercise, it won't release calcium, and so there won't be any relaxation of the muscle," Buckingham says. "This can lead to stiffness and pain and can prevent you from straightening out the muscle."

Workout Habits That Lead to Biceps Pain

Experiencing lasting biceps pain, especially when you can't straighten your arm, is generally rooted in the inflammation and damage detailed above. But it's often the result of a few common scenarios you may encounter during your workout:

1. You Pushed Too Hard

Overdoing it during a workout increases the chance of being unable to elongate your muscles afterward. "If a muscle is stressed past its limits due to repeated contractions against a heavy load, it causes neuromuscular injury," Buckingham says.

‍"This is an indication that you went too hard, so back off a bit next time." Upping the intensity little by little will lead to better long-term results. Moving forward, be sure to increase the intensity of exercise stepwise, so that you're not loading on more than you can handle.

2. You Tried New Exercises

Along those lines, if you haven't worked out in a while or you do a different type of workout than usual (say, you go to your first barre class, or lift weights for the first time in ages), you're also at greater risk of inner elbow pain. "When you are unaccustomed to the activity, you will experience more micro-tears in your muscles than if it's something you do routinely," Buckingham says.

‍"The reason is that your muscles have to build themselves up stronger so that the next time you do the same activity, they won't have as much damage." There's no reason to avoid new exercises (unless they aggravate a current injury or lead to a new one). Just ease into them.

3. You Worked Your Muscles Eccentrically

Pain and difficulty extending your arms are also more likely to happen after exercises that involve eccentric actions. "Eccentric contraction is the forced lengthening of a muscle," Buckingham says. For instance, during hammer curls, raising your hand to your shoulder is a concentric action or contraction; your biceps muscle is getting shorter.

Holding the dumbbell at the top of the lift is an isometric contraction, meaning there is no change in muscle length. When you lower your hand back down, this is an eccentric contraction, elongating your muscle. "Eccentric contractions produce the most muscle damage, because you are working against gravity," Buckingham says.

How to Safely Use Eccentric Exercises for Muscle Growth

"Instead of simply letting your hand fall down to my side, you have to control the descent." Eccentric exercises are great for building muscle, so don't feel like you have to avoid them. Instead, limit how many eccentric exercises you do in a given workout. Try limiting yourself to one per workout before increasing further.

4. Lactic Acid and Inflammation

The inflammation theory of DOMS started with lactic acid being causal, but has evolved over the years. Initially, it was thought that lactate (often called lactic acid) levels went up during anaerobic exercise like lifting weights, damaging the muscle fiber itself, or stimulating specific nerves in the muscle that transmit signals that are often associated with pain.

This theory has been disproven several times. First, lactate levels return to baseline minutes after exercise has been completed and thus do not correlate with the timeline of DOMS. Second, concentric-only exercise generates even more lactate than eccentric-only exercise but does not produce DOMS.

Inflammation Theory and DOMS Uncertainty

The theory later morphed into exercise-induced inflammation, which leads to DOMS by signaling various immune system cells, chemical mediators, and other factors that ultimately generate pain, swelling, and discomfort. While this is more plausible than the lactate theory, there’s a lot of uncertainty around it.

For example, it is unclear whether muscle or connective tissue generates the immune responses documented after training. We also don’t know if they’re related to DOMS per se or part of the muscle’s adaptation process in response to exercise.

Muscle Biopsy Limitations and Controversial Theories on DOMS

Several of these studies use muscle biopsies to investigate inflammatory responses and immune function after a workout. Still, few use a control group to rule out the effect of the biopsy itself, which would also cause inflammation.

Other inflammation-related theories, such as muscle swelling (Tissue Fluid Theory), suggest that peak DOMS correlates with peak muscle swelling. Even so, this hasn’t been reliably shown across studies of DOMS, making it and related mechanisms controversial.

5. Neural Mechanisms

Several neural mechanisms surrounding DOMS have been proposed. One is an evolutionary theory, in which DOMS is a pain signal that we experience to protect us against severe disability. The other is a physical compression of specialized nerve endings within the muscle spindle during exercise.

Concerning evolution, it seems unlikely that DOMS would be useful at protecting us from overexertion during an activity since it crops up days later.

DOMS, Fatigue, and Post-Workout Performance Challenges

It also wouldn’t seem to do an excellent job at preventing overexertion after a workout, as the time of peak DOMS often correlates with a return of maximal force production in dynamic movements.

As an aside, it’s difficult to separate the effects of fatigue from DOMS on subsequent muscle performance. A few studies have shown that when performing exercise with one arm or leg, the performance of the other non-exercised arm or leg decreases due to fatigue.

Other Possible Explanations for DOMS

While this theory is a popular one, there are a few more explanations as to why DOMS occurs, including:

• Enzyme efflux
• High Temperature
• Muscle spasms 

Most researchers agree that a single theory cannot explain DOMS, and there is still much uncertainty. Knowing the mechanisms behind why DOMS happens is interesting from an academic standpoint, but DOMS typically resolves on its own within days and is relatively benign.

A related medical condition is often associated with extreme muscle soreness after a workout, which can be dangerous if not treated: exertional rhabdomyolysis. 

Exertional Rhabdomyolysis

Rhabdomyolysis is a complex medical condition involving the rapid breakdown of damaged or injured skeletal muscle tissue, directly releasing intracellular muscle contents. Torres 2015 Clinically, rhabdomyolysis is characterized by myalgias, muscle weakness, and red-to-brown urine due to myoglobinuria. <10% of cases have this triad, and over half of the patients do not report muscle pain or weakness.

In general, rhabdomyolysis results from a specific “insult” to the muscle that ultimately leads to large amounts of muscle damage and subsequent breakdown from direct causes like a crushing injury, surgery with prolonged immobilization, burn or electrical injury, or prolonged, strenuous physical exertion, particularly to new exercises. There are other indirect causes like heat illness, seizures, myopathy, certain drugs, blood disorders, and even infections such as COVID-19.

Muscle Damage and Myoglobin Release in Rhabdomyolysis

After the insult to the muscle, the ion channels that typically maintain low levels of sodium and calcium and high levels of potassium within the muscle fibers no longer work appropriately. This causes a massive shift of sodium and calcium into the muscle fiber, causing further damage, swelling, and muscle breakdown. This perpetuates a self-sustaining muscle breakdown cycle and muscle fiber death or necrosis, releasing the muscle’s contents into the bloodstream.

First is myoglobin, an iron-containing protein that delivers oxygen to working muscle. When the muscle fiber breaks down, myoglobin is rapidly released in the urine due to its relatively small size, often producing red to brown urine. The kidneys filter High levels of myoglobin in the blood. They can cause Acute Kidney Injury (AKI) due to tubular obstruction and damage from the iron-containing proteins.

Electrolyte Imbalance and Creatine Kinase in Rhabdomyolysis

AKI is also a risk due to hypovolemia, as a substantial amount of the body’s water can enter the damaged tissue and not stay in the blood vessels, a process called “third spacing.” Other components within the muscle, such as potassium, phosphate, and calcium, are also released, causing electrolyte abnormalities and, potentially, cardiac arrhythmias.

Creatine kinase (CK) is also released from damaged muscle, as it plays a role in energy production within the muscle cells. In rhabdomyolysis, serum CK levels at presentation of rhabdomyolysis are usually at least five times the upper limit of normal but can vary significantly. In contrast to rhabdomyolysis, where the muscle cell is breaking down, the muscle cell remains intact in DOMS. CK is also not reliably correlated to DOMS, which is almost pathognomonic for rhabdomyolysis.

HyperCKemia and Rhabdomyolysis Treatment Overview

There’s also a condition called “hyperCKemia,” which has high elevated serum CK and myoglobinuria but no severe muscle symptoms or organ damage (e.g., AKI). This has been shown in both military personnel and D1 American football players, who occasionally have CK levels > 5x the Upper limit, with myoglobin in the urine but no other signs or symptoms of rhabdomyolysis.

Upon diagnosis, rhabdomyolysis is typically treated with fluid administration while the patient is admitted to the hospital. The patient is expected to recover with no lasting side effects. If there isn’t an apparent reason for the patient's rhabdomyolysis, the treatment team will typically investigate other, rare causes.

When to Talk to a Doctor

Should you be worried about not being able to straighten your arms? Not necessarily, it's normal to be a little sore after a workout. You should be fine if it clears up within 48 hours or so. That said, it means you pushed yourself too much. After all, if you're so sore or your movement is inhibited to the point where you can't work out for days, you're missing out on the benefits of regular exercise.

Watch for Signs of Rhabdo

"Consistency is key if you want to see improvements in fitness," Buckingham says. If your symptoms linger longer than two days, you should get checked out by a doctor to rule out more serious conditions like rhabdomyolysis (often nicknamed "rhabdo").

‍"Rhabdomyolysis is when you have extreme damage to the muscle," Buckingham says. "It breaks down and releases proteins into the blood, which can harm your heart and kidneys, and is potentially life-threatening." Signs of rhabdomyolysis include dark red or brown urine, severe muscle aches, and weakness.

Inner Elbow Pain? It Might Be a Tendon Injury or Tennis Elbow

Also, consider talking to your doctor if you have severe or long-lasting inner elbow pain. Buckingham says this may indicate a tendon injury. You may have strained the tendon that attaches your biceps muscle to the bones. Luckily, this usually resolves on its own.

"It could also be a condition called tennis elbow," Mike says. "It is often due to overuse of the forearm muscle and is extremely treatable." According to the American Academy of Orthopedic Surgeons, most people with tennis elbow feel better with rest, over-the-counter pain meds, and physical therapy.

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What You Can Do to Relieve Muscle Tension

It’s common to experience soreness after working out, especially if you've ramped up your exercise routine or changed your training. This muscle tension and stiffness can interfere with your standard movement patterns and make it difficult to perform daily activities. If you're dealing with soreness in your arms and have ruled out any injuries, give your muscles time to recover before returning to your regular workouts.

Doing too much too soon is a common cause of muscle soreness and stiffness (especially for beginners). So, the best long-term solution is to back off on your exercise intensity. Lower the weights you're lifting and/or lower your number of sets and reps.

A Good Rule of Thumb

The last two reps of each set should feel comfortably challenging. Then, over time, slowly progress so your muscles can adapt, recover, and grow stronger between each lifting session. Generally, according to the National Academy of Sports Medicine, you shouldn't increase your training volume by more than 10 percent each week.

Move and Stretch to Reduce Arm Discomfort

Should you work out while you're sore? Don't jump right into another training session, but it's OK to keep moving. "Doing gentle range-of-motion movements will increase blood flow to the affected area and aid in recovery," Buckingham says. He suggests repeating the same type of movements that caused the issue, only without weights. So if you can't straighten my arm, try the following:

• Biceps curls
• Triceps extensions
• Arm circles
• Shoulder presses
• Y raises

According to the American Council on Exercise (ACE), stretching can also help relieve post-workout aches and pains. Running through a few dynamic arm stretches (like the moves below) can help promote blood flow and recovery to sore muscles. 

Refuel for Recovery

According to the ACE, your muscles use stored carbohydrates for energy when you strength train. So, it's essential to prioritize nutrient-dense carb sources (like oats or sweet potatoes) to replenish your sore muscles. You also want to make sure you're getting enough protein. Protein helps repair exercise-induced muscle damage, which is how you get stronger.

How much protein should I eat? Aim for 1.4 to 2 grams of protein per 2.2 pounds daily. Here's how to calculate that benchmark:

• Divide your weight in pounds by 2.2
• Multiply that number by 1.4. That's the low end of your protein intake range
• Divide your weight in pounds by 2.2
• Multiply that number by 2. That's the high end of your protein intake range
  

For example, if you weigh 180 pounds, you'd aim for 114 to 164 grams of protein daily. For more straightforward math, many people plan to eat 1 gram of protein for every pound of their body weight daily.

Apply Heat or Cold Therapy to Soothe Arm Soreness

You can use heat or cold packs to reduce pain and increase recovery. A heat pack relaxes tight muscles, while a cold pack reduces inflammation and pain in excessively sore areas. 

Rest & Recovery Are Essential

This should be obvious, but if your muscles are sore, they need to rest and recover. The very fact that your high-intensity bicep workout has left you with the inability to stretch out your arms tells you everything you need to know. Plus, don’t forget that your muscle fibres now have tiny tears that require healing time.

As I’ve mentioned, as your muscle fibres heal, they will generally grow back bigger and stronger. So, it’s important to remember that your muscles don’t grow while you’re working out, but rather when you’re not in the gym. Give it some time; it won’t be long before everything returns to normal.

Drink Water to Boost Recovery 

The human body is made up of approximately 55-60% water. So, this in itself should tell you why it’s so important to drink water daily. Drinking water can also help to alleviate the pain of DOMS. Firstly, your muscle cells require water to function normally, and water can aid the process of protein synthesis.

Furthermore, drinking water helps to improve blood circulation. This also means you can flood your muscles with blood, aiding healing. Finally, water helps to flush the vital organs and body of waste products, which can help to alleviate some of the soreness in your muscles. So, water is essential whether you’re working out or not.

Massage for Active Recovery

Once again, massage will help flush lactic acid and other waste products out of the body. It increases blood flow, which you now know is good for relieving the soreness of DOMS. Plus, it can help with stiffness and flexibility, in much the same way as stretching does.

Sleep for Sore Muscle Recovery

Okay, I’ve spoken of rest and recovery, and in addition to this, getting a good night’s sleep can do wonders for muscle soreness. Most adults should aim for 7-9 hours of sleep a night. The beauty of getting a great night’s sleep when you have DOMS is to do with the hormones that are released.

During one of the stages of deep sleep, the body secretes the Human Growth Hormone. As the name suggests, this hormone is responsible for helping your muscles to grow. And this occurs as the damaged muscle fibres are repaired and essential hormones and nutrients are passed through the muscle tissues.

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How to Prevent Stiff, Sore Arms In Your Next Workout

If you can't straighten your arms after a workout, only so much can be done after the damage is there. But there are some strategies for preventing it from occurring. Of course, you can always reduce the intensity of your workout, but here are some better options.

Prime Your Muscles for New Movements

As a more proactive approach, I strongly recommend priming your muscles for new movements as a novice or someone returning after a training hiatus. You would do this by spending one week or so moving your body in the range of motion you wish, but using very, very light weights. 

You should focus on just moving for the sake of moving without the goal of hitting any high intensities. What this will do is, in essence, wake up your muscles in a gentler way so that when you go in the next week and do a more challenging set, the muscles aren’t caught off guard, and the recovery systems are in place.

Spread Out Weekly Volume Goals

For those experiencing soreness because they have overdone the volume for a specific muscle group, it may be wise to split up your weekly volume throughout a few days. You could try several bicep exercises across two to three days rather than doing a monster bicep workout in one day. This will be a more sustainable, long-term approach for most because it will help you avoid extreme soreness while allowing you to complete the same volume per week. 

How Long Will It Take For Your Arms To Return To Normal?

Delayed Onset Muscle Soreness (DOMS) will peak about 48 hours after a workout and progressively improve in the following days. If you are still feeling pain after a week, consider seeing a doctor to ensure you don't have bicep tendinitis.

In some cases, you may feel stiff just a couple of hours after a workout, but then have no delayed onset muscle soreness the next day because you have recovered overnight. In other cases, you may feel perfectly fine the same day of your workout, but wake up immobile and stiff.

Delayed Soreness After Workouts

This is the classic case of DOMS, when the soreness comes later and typically peaks two days after the workout. Novices and those who have been away from the gym for a long time may find their soreness lasting more than two days. This will not persist beyond the first two weeks of returning to the gym and exercise.

Related Reading

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Improve Your Flexibility with Our Mobility App Today | Get 7 Days for Free on Any Platform

When your arm won't straighten after working out, it's often due to stiffness or soreness in the muscles or tendons around the elbow. The fix is simple, give it time to heal, then ease back into activity. If you have recently increased your workout intensity, the stiffness will likely resolve with a few days of rest and gentle stretching.

Sometimes, it might indicate a more serious injury, especially if the elbow is swollen or painful. A thorough assessment of your range of motion will help to identify the issue. See a doctor if you experience a significant loss of range of motion after exercises that target the elbow or arm. You might have a tendon injury, like tendonitis, or damage to the muscles or ligaments that requires rehabilitation.

Building Pliability to Improve Arm Mobility

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