Why Are Muscles Sore After a Workout?

Delayed-onset muscle soreness (DOMS) is the pain and stiffness felt in muscles several hours to days after unaccustomed or strenuous exercise.


When we push ourselves through a challenging physical workout, our muscles are put under stress. These stresses can leave us feeling sore and uncomfortable. But why? In order to understand why muscles become sore after exercise, it is important to have an understanding of muscle physiology. When muscles are put under strain during exercise, tiny microscopic tears can occur in the muscle fibers. As they heal, the area around the tear is often inflamed and filled with fluid which causes swelling and pain, known as Delayed Onset Muscle Soreness (DOMS). This sensation can last anywhere from 1-3 days following a strenuous activity and is especially common among those new to fitness or those who have drastically increased their intensity or volume of work. The good news is that this pain will usually subside after a few days as the muscles heal.

What Causes Muscle Soreness?

Have you ever experienced that pleasant yet uncomfortable feeling after a good workout? That feeling is muscle soreness, also known as “delayed onset muscle soreness” (DOMS). It’s caused by a number of factors, such as lactic acid build-up, inflammation, and direct muscle trauma. In this article, we’ll discuss what causes muscle soreness and how to alleviate it.

Delayed Onset Muscle Soreness (DOMS)

Delayed Onset Muscle Soreness (DOMS) is the soreness that you feel in your muscles 24 to 48 hours after a physical activity or exercise routine that your muscles are not used to. It is a normal response to working out and usually means the exercise was effective. Symptoms of DOMS can include muscle tenderness, swelling, and stiffness. The discomfort is usually most noticeable 24-48 hours after you’ve worked out, but can last up to 72 hours. The exact cause of DOMS is not known; however it is thought to be due to small tears in the muscle fibers as a result of eccentric exercise that results from muscular tension beyond what it is used to – microscopic tears occur, which causes inflammation and pain when the muscles contract and relax.

Muscle Damage

Muscle damage is one of the major causes of muscle soreness after a workout. When muscles are exercised or strained beyond their current level of fitness, microscopic tears occur in the muscle fibers which triggers an inflammatory reaction. This localized inflammation is what causes the muscles to feel sore and tender when you press on them, and it also reduces strength and mobility as your body works to heal itself.

In addition to muscle damage, excess lactic acid buildup in the muscles can contribute to post-workout soreness as well. Lactic acid is a byproduct of anaerobic exercise that forms when the body demands more energy than can be delivered through aerobic means. High intensity strength training and sprinting are just two examples of exercises that involve a higher than normal production of lactic acid, resulting in greater fatigue and delayed onset muscle soreness.

Furthermore, overtraining can lead to prolonged muscle pain due to chronic inflammation from frequently working out at high intensities without giving adequate time for rest and recovery between workouts which exhausts muscles as well as connective tissues associated with muscle movement such as tendons and ligaments. To avoid overtraining, it is important to monitor your progress by including periods of rest into your exercise routine so that you can give your body time to heal before pushing too hard again.


One of the main causes of muscle soreness after exercise is inflammation. When you participate in high-intensity physical activity, your muscles experience microscopic tears. This can happen due to fatigue, overuse or not warming up prior to exercising. The resulting inflammation in your muscles can produce pain, swelling and tenderness. As your body repairs the microtears, it brings oxygen-rich blood to the affected area, which promotes healing and prevents further injury. It’s important to note that although inflammation is necessary for proper healing and repair processes, too much of it can cause unnecessary discomfort. To reduce muscle soreness after a workout, you should practice safe post-workout habits like stretching and foam rolling or using a massage stick that help encourage circulation and reduce inflammation.

How to Reduce Muscle Soreness

Muscle soreness is a common side effect after a strenuous workout. The soreness usually appears a few hours after the workout and can last for a day or two. Fortunately, there are many ways to reduce muscle soreness and get back to your normal routine quickly. In this article, we’ll discuss the various methods you can use to reduce muscle soreness after a workout.

Warm Up Before Exercise

Warming up before exercise is key to reducing your risk of possibly experiencing muscle soreness after a workout. The purpose of a warm-up is to slowly boost the heart rate, increase blood flow and make your muscles more flexible so you can work out safely and comfortably. It’s important to note that if you begin exercising without warming up, you are more likely to experience aches and pains from tight muscles afterwards.

The warm up should be specific to the upcoming exercise and focus on dynamic stretching, which involves movements such as an arm circles, leg swings or torso twists. Dynamic movements promote muscle flexibility while preparing them for movement during the workout. Additionally, you can also do light cardio exercises like jogging in place or skipping rope before engaging in high intensity workout activities.

To help reduce post-workout soreness even further, it’s important to incorporate cool downs into every workout routine. After completing a session at the gym, it’s best practice to end with light stretching or yoga poses specific for the joint or muscle group most worked during that particular session. Hold each stretch for 30 seconds or longer but ensure maximum comfortability throughout the stretched hold period – if something hurts then stop immediately – because too much tension can disrupt proper muscle recovery and impair healing process overtime due to soreness buildup overtime.

Cool Down After Exercise

A key step to reducing post-exercise muscle soreness is to make sure you include an appropriate cool-down following your workout. A proper cool down should include a few minutes of light cardio activity like walking or jogging to lower your heart rate, followed by some stretches designed specifically for the muscles you worked out.

Stretching helps encourage muscle relaxation and reduce the overall effects of exercise on the body’s soft tissues. It can also help with circulation and reduce stiffness and pain. A static stretch — where you hold a stretch for 10 to 30 seconds at a time — can help boost circulation in your muscle tissue and increase range of motion in areas that became tight during exercise. Make sure to focus your stretching on the muscles that were used during exercise, particularly those that are sore after your workout is done.

Increase Intensity Gradually

A major contributing factor to sore muscles after a workout is performing the activity at an intensity which is too high for the current level of fitness. Intense workouts are more likely to lead to delayed-onset muscle soreness (DOMS) than those that are relatively low in intensity. Therefore, it is important for individuals to gradually increase the intensity of their workouts in order to avoid injury and excessive muscle soreness.

When gradually increasing intensity, it is also beneficial to begin with a five-minute warm-up period before starting the main workout, such as light jogging or cycling. This serves two purposes: firstly, it prepares your body for physical activity and increases blood flow; secondly, it reduces the risk of straining muscles during exercise. Once warmed up, perform a few stretching exercises in order to further reduce the risk of injury and optimize muscle performance.

Remember that it takes time for your body adapt to physical activity; introduce increases in intensity slowly in order to give your body time adjust and prevent excessive muscle soreness.

Eat Protein and Anti-Inflammatory Foods

Protein is an essential nutrient for muscle growth and recovery. Eating a source of protein after a workout can help to reduce muscle soreness and increase gains in strength. Protein-rich foods such as lean meats, fish, legumes, nuts, and protein shakes provide building blocks to rebuild damaged muscle tissue.

Eating anti-inflammatory foods can also be beneficial to reduce post-workout soreness. Anti-inflammatory foods are filled with antioxidants that help fight inflammation in the body and reduce damage caused by oxidative stress. Examples of anti-inflammatory foods include fatty fish, ginger, leafy greens, turmeric, garlic and berries. Eating a diet rich in these types of foods can result in a quicker recovery from your workout as well as reducing pain from muscle soreness.

Use Ice and Heat Therapy

The use of cold or ice therapy and heat therapy are both safe and effective treatments to help alleviate muscle soreness after a workout. Cold therapy is great for reducing inflammation and swelling while heat therapy is best suited for calming tense muscles prior to or after exercise.

Ice Therapy: Ice should be applied immediately following activity as it will reduce swelling, reduce pain, and also act as a numbing agent. When using ice as a form of muscle soreness relief, make sure that you wrap the ice in a wet towel (or store-bought wrap) and apply it for no more than 20 minutes at a time. If the area is too cold before the 20 minutes are up, you can take it off early. This can typically be done 3-5 times per day until the swelling has gone down or depending on how you feel afterwards.

Heat Therapy: Heat can provide temporary relief from muscle spasms and stiffness by improving circulation in the affected areas. Heat should be used post activity to warm up those cool down muscles without aggravating any inflammation issues. It’s best practice to use heat no longer than 10 minutes at a time with an hour in between treatments during which other forms of cool down can occur such as stretching, foam rolling, etc.. A hot tub could also be used if one is available. Make sure when using this type of treatment that the heat source isn’t too hot so that there is no chance of burning yourself during your session.


Overall, the soreness experienced after a workout can be attributed to microtrauma occurring to the muscles as they adapt and strengthen. This microtrauma triggers the inflammatory response, including pain, as the cells seek out repair and recovery in order to become stronger.

Although it can be uncomfortable, this pain is a sign of progress towards achieving your fitness goals. Of course, everyone has different levels of tolerance for pain and different recovery times – so be sure to take appropriate rest days in order to avoid injury or damage. A light post-workout stretch and/or massage after workouts can boost muscle recovery and help prevent soreness in the future. And remember – with every workout comes rewards!

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