You just finished a grueling leg workout after not training for a couple of weeks. You chastise yourself for pushing so hard, but it felt so good to be back in the gym. Of course you’re going to be sore tomorrow anyway because of the time off, so you might as well make it really worth the pain by lifting as intense as you can. Then you wake up the next morning and can barely stand up out of bed. All day long you’ll be walking like you just got off a horse, if you can walk at all. Now you regret even stepping a foot into the gym! Why do muscles get so sore after long lay-offs, new exercises, or heavy workouts? Does the pain mean that the muscle is growing or that it is injured? Find out all there is to know about delayed onset muscle soreness (DOMS) and become an expert in the field of muscular pain management.

What Is Delayed Onset Muscle Soreness?
Delayed-onset muscular soreness (DOMS), is the sensation of pain and stiffness in the muscles that occurs from 1 to 5 days following unaccustomed exercise [1]. It affects muscular performance temporarily from both a voluntary reduction of effort (because the muscles are too sore to move), and from an actual loss of the muscle’s ability to produce force. Many studies have shown that strenuous and unaccustomed exercise damages muscle cells [2-4]. Eccentric exercises where muscles lengthen as they exert a force (like when slowly lowering a weight), cause more muscle damage than concentric exercises (shortening the muscle like when lifting a weight) [5]. It seems that the extent of injury is more related to change in muscular length than by the force generated by the muscle [6]. It was thought that DOMS was caused by lactic acid that accumulated in muscles after strenuous exercise, but research has shown that lactic acid dissipates quickly and eccentric exercise produces less lactic acid than concentric exercise [7].

Muscle Damage and Repair
A popular theory on DOMS states that the high tension associated with eccentric exercise disrupts the muscle cell membrane [1]. Extracellular calcium then enters into the muscle cell and disturbs the delicate balance of electrolytes. This results in tissue damage that peaks about two days post-exercise. When tissue damage occurs, inflammatory cells called neutrophils infiltrate the muscle and cause inflammation [8]. More inflammatory cells called macrophages move in to clean up and remove the cellular debris. A second wave of macrophages then comes in to assist the repair procedure, along with stress proteins [9]. Inflammation is a necessary process in the healing of tissue. As the inflammatory process runs its course, muscle fibers are repaired and become stronger. As the muscle becomes stronger, it may even prevent subsequent damage.

What’s Pain Got To Do With It?
The exact reason why pain is associated with DOMS is not known, but many scientific hypotheses try to explain the phenomenon. One theory is that the eccentric exercise causes damaged muscle fibers. These damaged fibers become inflamed and swollen [10] and this causes pain [11]. Another theory states that the inflammatory cells (phagocytes) that come to clean up the damaged tissue further damage the tissue and this leads to pain [12]. Still another theory surmises that the free radicals produced by the inflammatory cells aggravate the already existing mechanical damage and this causes pain [13]. But most likely, it is a combination of all of these factors that contributes to the pain of DOMS [5].

Consequences of DOMS
You probably know from personal experience that DOMS results in pain and stiffness, the loss of muscular strength, the loss of ability to generate force, and an increase in muscular fatigue. But you may not have known that the damage from DOMS prevents proteins that transport glycogen from entering the muscle [14]. This results in an impairment of glycogen resynthesis, which is crucial to muscle development [15]. Glycogen is the energy the muscle uses for work and to grow. When it is depleted after exercise, it makes it difficult for the muscle to heal and to store up energy for its next work assignment. Eccentric exercise also impairs muscle pH regulation and cellular function [16].

What Doesn’t Work For DOMS
Although the pain from DOMS may have something to do with inflammation, many studies have shown that common anti-inflammatory medications taken before and after eccentric exercise have not decreased that pain [17, 18]. It is possible that the soreness is not entirely related to the inflammation, or that the inflammation seen in DOMS is not the typical inflammation seen in other muscle injuries [19]. Regardless, it seems that taking anti-inflammatory medications may be harmful to the healing process and possibly even delay it. The same advice goes for massage, too. Currently there is little scientific evidence that massage can help decrease pain or increase function after DOMS [20]. Likewise, ultrasound [21], electrical stimulation [22], and ice [23] all fall to that same fate.

What Does Work For DOMS
So how do you avoid significant muscular damage in your training program? First and most importantly is to have a specific training plan and gradually acclimate to exercises and weights. You should never put yourself in the position of taking up where you last started if you have been away from the gym for sometime. Likewise, if you have never weight trained, starting slowly and light is more appropriate for muscular and joint health than fast and heavy. In addition, if you make yourself so sore that you don’t want to weight train anymore, you only succeeded in demotivating yourself. Secondly, make sure that you get sufficient rest and recovery. Muscles do get slightly damaged from weight training and need time for the inflammatory process to heal and repair them. Waiting at least 48 hours between weight sessions for the same muscle group or until the pain is gone is appropriate. Last, but not least, if you want to decrease the possibility of DOMS, limit exercises that focus on negatives and involve lengthening of the muscle for a prolonged period of time. Of course, weight training, sports activities, and everyday functional activities involve an eccentric component, so limiting these actions may be a little difficult. Realizing that DOMS is a normal part of life and may even be necessary for muscle growth, may make it easier to accept the pain.

References

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