By Elena Voropay

Do you belong to the “no pain – no gain” club and feel sore every time you leave the gym? Sometimes your muscles hurt right after you put the weights down. But there are days when the pain is unbearable for almost a week. You probably think that if you don't feel sore the next day after the workout, then you actually haven't trained hard enough and will not grow or become stronger.

Muscle soreness is so common among beginners and professional trainees, that myths surrounding its cause and prevention have confused just about everything we know about weight training. Firstly, it is important to differentiate between the two kinds of muscle soreness - acute and delayed, both having very diverse mechanisms.

Acute Muscle Soreness

Pain felt during and immediately after exercise is called Acute Muscle Soreness (AMS). The main cause is the build-up of lactic acid. In simple terms, lactic acid is the by-product of glucose metabolism in your body, whether it is ingested sugar or glycogen stored in the muscles and liver. During exercise, your muscles use stored glycogen and produce lactic acid.

Normally, your body system produces and disposes of lactic acid all the time. Blood and muscle lactate levels typically return to normal values after 30-60 minutes of recovery. But when it builds up faster than it can be cleared away, lactic acid stops muscles from any further action causing fatigue and pain.

Interestingly, your muscles will generate more lactic acid after weight training and sprinting than after marathon running or cycling for a long time. For example, when you train with resistance with rest periods lasting less than 1-2 minutes between sets, your blood lactate will rise reducing your strength and muscle working potential. Unless you rest and restore your power, your muscles will not be able to perform with the same output. That makes lactic acid the main reason you can't finish one more repetition of a weight training set with a correct form.

Delayed-Onset Muscle Soreness

If you can feel pain in your muscles during the next couple of days after a workout, you've got DOMS. Also known as Delayed-Onset Muscle Soreness, it is not a new discovery, and research investigating the cause of DOMS dates back to the early 1900s with theories generating up to this day.

Probably one of the most popular and the most incorrect explanations of DOMS is the accumulation of lactic acid in the muscles confusing it with AMS. The real reason for DOMS is the actual muscle tissue damage caused by intense overload of resistance training. Microscopic tears or ruptures of individual muscle fibers cause structural damage resulting in pain, tenderness, and inflammation of muscle fibers. Tissue damage results in inflammation which puts pressure on pain receptors in the lean tissue causing the sensation of pain.

Main Causes of DOMS

Even though the subject of DOMS is not fully understood and more research is needed, a lot of current theories acknowledge that DOMS result primarily from eccentric, or negative, contraction. In a concentric, or positive, contraction the muscle shortens as it overcomes the resistance, as in an upward bicep curl with a weight. Lowering the weight, as the muscle acts to oppose gravity, lengthens the muscle and this is an eccentric, also known as negative contraction. Eccentric contractions occur in activities such as descending stairs, running downhill, lowering weights, and performing the downward movements of squats and push-ups.

The eccentric contraction is the major contributor to the muscle injury, it plays the key role in building muscle tissue. The more significant the damage inflicted on the muscle, the greater is the muscle soreness, the greater the potential of constructing muscle tissue, and the more rest is needed to generate recuperation and growth. But the sensation of pain is very perceptive and the lack of it does not necessarily mean that the muscle is not growing.

Does Soreness Mean Growth?

It is true that muscle soreness caused by resistance training may stimulate muscles to grow, but only if enough recuperation and fuel is provided. Research shows that extreme muscle soreness can lead to a decreased performance and limit the ability to train for as long as three weeks. For that reason, many professional athletes don't exercise to the point of complete failure thus hardly ever experience muscle soreness keeping their training schedules regular without skipping planned workouts.

Pain is a poor indicator whether or not any increase in size or strength actually occurs. Muscle and body aches may happen as a result of things other than strength training, such as virus or stress. When you are under pressure of work or social life, under-eating or under-sleeping, your body goes into a stress mode and muscles hold a lot of tension. If you put additional load of weight training on your muscular-skeletal system, you may inflict increased muscle soreness that lasts longer even if intensity of training is reduced.

The only way you may cause muscle breakdown is through overloading muscles. This can be achieved by increasing the intensity of training either through load or volume of exercises. Constant muscle soreness means that you are overtraining, or breaking down lean tissue further and further reducing the size and strength of exercising muscles.

Who Is susceptible to muscle soreness?

Muscle soreness can happen to anyone, be it an athletic virgin or a bodybuilding pro. It happens every time you overload muscles excessively, change from one activity to another, or work the same set of muscles in a new and different way. In most cases, the sensation of pain occurs only for the first one or two times you perform a new exercise or a different kind of activity. Thankfully, the body has a great ability to adjust and adapt to the new exercises allowing you to find different challenges and progress toward your goals.

According to the American Council on Exercise, delayed onset muscle soreness cannot be triggered twice for the same exercise and at the same intensity due to a rapid adaptation response of the muscles. Therefore, unless the intensity of exercise is increased, DOMS won't occur. The exception to that would be detraining prior to repeating the same exercise routine. Also, each time you provide your body with a new stimulus - whether it's a higher intensity, more weight, a new exercise or technique - you can expect the soreness to return.

Should you train if you're still sore from your previous workout?

It depends. If the soreness is very minor, then yes, go ahead and work your muscles through it. As blood gets into the area and your body temperature increases, the remaining soreness will dissipate. It is also good to do any kind of aerobic activity to increase blood flow to the affected areas and provide more oxygen and nutrients to growing muscles.

However, take it easy if you have hard time going up the stairs or doing a push up. That is a sign that the damage inflicted on the muscles is quite substantial and you have not completely recovered yet. It's your body's way of telling you it needs rest and is still "healing." If you keep breaking down muscle before it has a chance to recover, the effect will be the opposite of what you want. It is extremely important to give your muscles time to adapt to your activity in order to incorporate progression and see results. One suggestion would be to take a very hard workout on one day, go easy for one to seven days afterward, and then take a hard workout again.

How long does the pain usually last?

Acute Muscle Soreness occurs as the blood and muscle lactate levels rise which usually dissipate in a few hours after the workout.

Delayed Onset Muscle Soreness begins 8-24 hours after exercise and peaks 24-72 hours postexercise and will go away in 3 to 7 days with no special treatment, but it can also last as long as several weeks. If you already feel the pain, there is not much you can do to make it go away immediately. However, there are some things you can do that may reduce the soreness and speed your recovery to some extent.

DOMS: Myth vs. Reality

Myth: Muscle soreness is caused by lactic acid.

Reality: DOMS result from the actual muscle tissue damage caused by intense overload of resistance training.

Myth: All training causes Delayed Onset Muscle Soreness

Reality: DOMS result primarily from eccentric, or negative, contractions when lowering the weight as the muscle opposes gravity. Examples include descending stairs, running downhill, lowering weights, and performing the downward movements of squats and push-ups.

Myth: Muscles grow only when they are sore

Reality: Reconstruction of broken muscle tissue causes muscle to grow in size and strength. Regardless whether or not you feel sore the next day, muscle breakdown occurs when you overload with resistance. The mechanism of the pain sensation is very complex, and muscle and body aches may happen as a result of things other than strength training, such as virus or stress.

Myth: Muscle soreness is experienced only by professional athletes

Reality: Delayed Onset Muscle Soreness happens to novice and professional trainees alike. It is common to experience soreness after trying a new activity, overloading muscles excessively, changing from one activity to another, or work the same set of muscles in a new and different way.

Myth: If your muscles are sore, you should train through the pain in order to speed up the healing process.

Reality: Depending on the severity of pain, rest and light exercise is advisable in most cases. Exercise gets more blood into the affected areas increasing the supply of oxygen and nutrients to growing muscles. Increase in body temperature also diminishes the feeling of pain assisting recuperation.

What you can do

• Increase the intensity gradually if you want to minimize muscle soreness and still grow muscles. But if you stop getting sore altogether because you never vary your workouts, you will also stop making progress. That's one of the reasons you need to change routines frequently. Shocking your body through progressive overload, even slightly, is the key to muscle growth.

• Since the eccentric contraction is the major contributor to the muscle injury and DOMS, reducing the negative portion of the movement, and giving special attention to the positive, or concentric, part may lessen the pain. But it is not possible with most sports and may diminish training gains.

• Proper warm-up before exercise is the best known-to-date way to minimize soreness without compromising potential growth. Just five minutes of cardio, followed by specific dynamic flexibility exercises such as walking lunges, backward runs and light sprints will increase blood circulation, muscle temperature and elasticity and build higher resistance to future damage.

• Stretching and cooling down may help in reducing Acute Muscle Soreness caused by build up of lactic acid, but has very little effect on inflammation-induced Delayed Muscle Soreness. Aerobic exercise such as biking or walking at a very low pace after vigorous training session will increase blood supply to all tissues of your body, and this in turn will speed up the removal of lactic acid, boost nutrient and oxygen supply to starving muscles, may help shorten the duration of pain by a few hours and stimulate better recuperation.

• Hot showers, saunas, whirlpools, baths, application of ice (cryotherapy), massage, proper nutrition may reduce the soreness temporarily, though they won't actually speed healing. These techniques can help you feel better, but the soreness will take several days to disappear and the muscles to fully recover.

• A study at Tufts University indicates that Vitamin E supplements (800 IU) taken every day for 7 days before a bout of strenuous exercise may reduce muscle soreness, inflammation and weakness. The vitamin acts as an antioxidant to protect cells from free radicals generated during a workout. Other tests support that supplementing with vitamin E even after the workout will help to deal with undesired effects, but professional lifters will benefit less than weekend warriors.

• Since muscle soreness comes from inflammation of damaged muscle tissue, adding anti-inflammatory foods to your diet may lessen the pain and promote recuperation. These foods will encourage the production of prostaglandins in your body that are responsible for inflammation response. In addition to cutting down on simple sugar and saturated fats, eat more fish, nuts, seeds, fruit, especially pineapples and apples, and green vegetables. Use olive and flaxseed oils as your primary fat source and spice up your dishes with protective onions, garlic and ginger. Liberal consumption of these anti-inflammatory foods may also boost your anti-oxidant, vitamin and mineral intake.

• A recent study carried out in Greece lends support to the use of anti-inflammatory drug Ibuprofen for reducing the perception of DOMS painful effects. Taking the drug may get you back on the training schedule sooner, but will have no effects in restoring muscle function. In fact, you may find yourself overtraining and performing progressively worse. Many scientists indicate that ibuprofen can strip you off the muscle gains provoked by intense training and muscle soreness.

Regardless whether you are experiencing the pain sensation or not, stay focused and concentrated on the proper technique of exercises, think about the muscles you are training, maintain a strict form and remember to let your body recover before you hit the gym again.

NOTE: If you experience sudden pain, severe pain, or pain that lasts more than 4 days or increases despite these measures, you may have injured yourself and should consult a doctor.

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