Many of us have been there—that post-workout soreness that makes lifting a cup of coffee feel like a feat of strength. This is especially common after training the biceps, a frequently targeted muscle in most upper body and arm workouts. The soreness can sometimes feel so extreme that you might even have trouble straightening out your arms for a few days.
So, why does this happen, and what’s the fix?
If you can’t straighten your arms after an exercise, the reason is likely delayed onset muscle soreness. However, there are other potential causes, like an injury or an extreme form of delayed onset muscle soreness called rhabdomyolysis, that we’ll also discuss in this article, along with helpful tips on how to prevent or alleviate the symptoms of these conditions.
Why Can’t I Straighten My Arms After A Workout?
While there may be other reasons, the most common is delayed onset muscle soreness or DOMS.
Delayed Onset Muscle Soreness
Delayed Onset Muscle Soreness (DOMS) can be defined as discomfort in the active muscles following physical exertion that increases in intensity over the initial 24 hours, peaking at around 24 to 72 hours post-workout and then gradually subsiding. The severity of DOMS can range from mild to severe and is often associated with muscle stiffness and tenderness to the touch.
DOMS is most commonly experienced after exposure to new exercises and/or higher-volume workouts that involve eccentric muscle contractions. Eccentric muscle contractions are those where the muscle produces force while it lengthens, such as in the downward phase of the squat or bench press. Heydayatpour 2015
Whether or not DOMS is a muscle injury is an area of `active research, though most of the different international muscle injury classification systems do classify DOMS as an injury. For example, the Munich consensus statement classifies DOMS as a Grade 1B muscle injury, where ‘Grade 1’ refers to a functional (not structural) muscle disorder, and the ‘B’ designation differentiates DOMS from plain ol’ muscle fatigue. Mueller-Wohlfahrt 2013
In this view, muscle fatigue occurs during the workout and immediately after, leading to declines in muscular force production, which generally returns to baseline within days. DOMS, on the other hand, is not present during a workout or immediately after but gradually develops in the days following a workout and, as we’ll see, is not necessarily associated with decreased force production. Armstrong 1984 Hough 1902
Delayed onset muscle soreness (DOMS) is nothing new for those familiar with the inside of the gym, but what causes it and what to do about it are both still areas of controversy. Let’s explore the potential causes first. Wilke 2021 Nosaka 2002
Why Does DOMS Occur?
There is no consensus on what causes DOMS, though a number of theories have emerged relating to muscle damage, inflammation, temperature, and neural mechanisms. Let’s briefly review each of these potential mechanisms.
Muscle Damage
Despite the Munich consensus defining DOMS as non-structural muscle injury, there’s ample evidence that DOMS can be correlated with small ruptures to muscle fibers near the Z-disk, which anchors one end of the thin muscle fiber known as actin. Research has also shown that connective tissue elements surrounding muscle fibers can also be affected. Both of these changes in tissue are observed after exercise with an eccentric component. Ironically, stretching is often recommended to combat DOMS, but if performed, would also affect the Z-band integrity.
It is thought that during an eccentric contraction, less muscle mass is used to create force compared to a concentric contraction, which places the active muscle fibers under more tension and causes mechanical disruption of the muscle and connective tissue.
While various markers of muscle and connective tissue breakdown can be observed in the blood and urine after a workout, these findings do not reliably correlate with the severity of DOMS or subsequent strength performance. Additionally, there are discrepancies between when these markers peak and the experience of DOMS, suggesting damage is, at best, a partial explanation.
Lactic Acid and Inflammation
The inflammation theory of DOMS seems to have 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 and then either damaged the muscle fiber itself or stimulated specific nerves in the muscle that transmit signals that are often associated with pain.
However, this theory has been disproven a number of 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. Cheung 2003 Armstrong 1984
The theory later morphed into exercise-induced inflammation leading to DOMS by signaling various immune system cells, chemical mediators, and other factors that ultimately generate pain, swelling, and discomfort. Malm 2001 Yanagisawa 2015
While this is more plausible than the lactate theory, there’s a lot of uncertainty around this theory. For example, it’s not clear whether or not the immune responses that have been documented after training are generated by the muscle or connective tissue. We also don’t know if they’re related to DOMS per se or if they’re just part of the muscle’s adaptation process in response to exercise. Finally, a number of these studies use muscle biopsies to investigate inflammatory responses and immune function after a workout, but few use a control group to rule out the effect of the biopsy itself…which would also cause inflammation.
Other theories related to inflammation also exist, such as muscle swelling (Tissue Fluid Theory), which suggests that peak DOMS correlates with peak muscle swelling. However, this hasn’t been reliably shown across studies looking at DOMS, making it and related mechanisms controversial. Cheung 2003
Neural Mechanisms
Finally, a number of neural mechanisms surrounding DOMS have been put forth. One has to do with an evolutionary theory, where DOMS is a pain signal that we experience to protect us against severe disability. The other has to do with a physical compression of specialized nerve endings within the muscle spindle that takes place during exercise. Sonkodi 2020
With respect to evolution, it seems unlikely that DOMS would be terribly useful at protecting us from overexertion during an activity since it crops up days later. It also wouldn’t seem to do an awesome 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 also decreases due to fatigue. Newham 1983 Jarvinen 2013
Other Possible Explanations for DOMS
While this theory is a popular one, there are a few more explanations as to why DOMS occurs, including:
Overall, most researchers agree that DOMS cannot be explained by a single theory, 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.
However, there is a related medical condition that is often associated with extreme muscle soreness after a workout, which can be very 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, leading to the direct release of intracellular muscle contents. Torres 2015
Clinically, rhabdomyolysis is characterized by the combination of myalgias, muscle weakness, and red-to-brown urine due to myoglobinuria. However, <10% of cases have this triad, and over half of 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. Bawor 2022
After the insult to the muscle, the ion channels that normally 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, thereby causing further damage, swelling, and breakdown of the muscle—perpetuating a sort of self-sustaining muscle breakdown cycle and muscle fiber death or necrosis, thereby releasing the muscle’s contents into the bloodstream.
First up, is myoglobin, an iron-containing protein, that is responsible for delivering oxygen to working muscle. When the muscle fiber breaks down, myoglobin is rapidly released in the urine due to its relatively small size, often resulting in the production of red to brown urine. High levels of myoglobin in the blood get filtered by the kidney and can cause Acute Kidney Injury (AKI) due to tubular obstruction and tubular damage from the iron-containing proteins. AKI is also a risk due to hypovolemia, as a substantial amount of the body’s water can enter into the damaged tissue and not stay in the blood vessels, called “third spacing”.
Other components within the muscle such as potassium, phosphate, and calcium are also released, causing electrolyte abnormalities and, potentially, cardiac arrhythmias. Gallagher 1997
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, where it is almost pathognomonic for rhabdomyolysis. 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, where they occasionally have CK levels > 5x the Upper limit, with presence of myoglobin in the urine, but no other signs or symptoms of rhabdomyolysis. Gemelli 2022
Upon diagnosis, rhabdomyolysis is typically treated with fluid administration while a person is admitted to the hospital and people are expected to make a full recovery with no lasting side effects or sequelae. If there isn’t a clear reason for the person to have rhabdomyolysis, the treatment team will typically investigate for other, rare causes of rhabdomyolysis
Assuming someone does not have exertional rhabdomyolysis, let’s turn our attention back to DOMS and look at the known risk factors for getting it and what we can do about them.
Risk Factors for DOMS
As mentioned above, exposure to novel, eccentric exercise at higher-than-normal training volumes seems to be the biggest risk factor for experiencing DOMS. Gradual exposure to new exercises and increased training volumes is good practice for both DOMS and training results.
A few other unique risk factors have also been investigated with respect to DOMS:
How-to Manage DOMS
A number of potential DOMS-modifying interventions have also been looked at:
- Soft tissue work: Limb compression, stretching, massage, and heat and cold therapy have variable (and potentially negligible) changes in DOMS pain but do not reliably correlate with perceived fatigue or objective performance Mizuno 2016 Dupuy 2018 Lund 1998
- Training: Exercise appears to reduce DOMS severity via Exercise-Induced Analgesia (EIA) and prevent future DOMS through the Repeated Bout Effect (RBE) Sakamoto 2010 Zainuddin 2006 Zourdos 2015 Chen 2019
- Protein: Seemingly little to no impact on DOMS based on multiple studies, provided adequate protein intake of ~ 1.4 to 1.6 grams of protein per kilogram of body weight per day. Pearson 2022 Pasaikos 2014 Kersick 2018
If you’d like to learn more about programming and/or nutrition, reach out to us. We provide personalized coaching, and if you’re struggling with constant DOMS, injuries, or just aren’t getting the results you want, we’d be happy to help you out.
Final Thoughts…
Delayed Onset Muscle Soreness (DOMS) is pain, stiffness, and tenderness in the muscles that start in the hours following a workout and peak within 24 to 72 hours before gradually subsiding. There is still a lot of uncertainty around the mechanisms of DOMS, though it’s pretty clear that loaded eccentric exercise is required. New exercises and/or higher training loads likely increase the risk and severity of DOMS, though age and sex don’t seem to be related.
Yes, we know that feeling like you can’t straighten out your arms can be a bother, but it is also highly likely that anyone who is serious about training will experience DOMS. If it’s happening all the time, that suggests the training load—likely volume, proximity to failure, and/or intensity—are too great for the individual. If someone never experiences DOMS, however, it’s likely their training load isn’t high enough. Perhaps paradoxically, continued training— even when sore—can reduce the severity of DOMS and the risk of future DOMS.
If you’re experiencing trouble straightening out your arms, consider the following tips:
- Assess programming, specifically total training volume for the arms (reps and sets) and proximity to failure (RPE). Consider reducing volume and increasing proximity to failure, e.g., leave more reps in the tank
- Keep exercising, even if it has to be lighter. Additional exercise seems to help reduce soreness the best.
- Practice progressive loading and avoid big leaps in intensity.
- Make sure you’re consuming enough protein.
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