Why Do Muscles Get Sore? - The Science Behind Muscle Pain

What is Muscle Soreness?

Muscle soreness refers to muscle aches, pain, or discomfort in muscle tissue. This can be a sharp pain or dull ache. It can be all over the body or in a specific muscle group. Sore muscles and muscle pain can be a sign of injury, infection, or disease. It is also common to have muscle soreness after starting a new workout routine.

Types of Muscle Soreness

Acute muscle soreness is a burning sensation that you feel in a muscle during a workout. This type of muscle pain is present when you’re exercising and disappears when you stop exercising. It occurs due to exercise-induced connective tissue and muscle damage.

Delayed onset muscle soreness (DOMS) is a type of muscle pain that occurs when you switch up your exercise routine or try new positions, forms, or techniques. It typically comes on 6 to 12 hours after exercising and can last for 48 to 72 hours.

Physiology of Muscle Soreness

Microtears in Muscle Fibers

Muscle soreness after a new exercise program or strenuous workout occurs due to structural damage to the muscles that were used during the workout.

Inflammatory Response

The damage to muscle fibers triggers an inflammatory response, which is the body’s way of healing the muscle injury.

Role of Exercise and Workouts

Muscle damage and inflammation triggered by exercise causes sore muscles. As you continue training, your body adapts to the exercises and you are able to perform them without experiencing pain or discomfort.

This is why you are sore the first few times you do a tough workout but feel fine after you’ve been doing the exercises for a few weeks. However, when you try another new workout, a different exercise technique or position, or an increased intensity of working out, you experience soreness again.

The soreness can develop right away (acute soreness) or slowly over the next few days (delayed onset muscle soreness or DOMS).

Misconceptions: Lactic Acid Buildup

When you push yourself through an intense workout, you “feel the burn” in your muscles. Experts previously thought this burning sensation or muscle pain was due to lactic acid buildup in the muscles during intense exercise. However, now the general consensus is that this isn’t true. So, just what happens?

During exercise, your body converts glucose into energy by using oxygen. During an intense workout, there isn’t enough oxygen to fuel this process. The body instead uses a substance called lactate (also called lactic acid) to produce energy in the absence of oxygen.

When you feel the characteristic burn associated with an intense workout such as high-intensity interval training (HIIT), you think it’s because of lactic acid buildup. However, it is not the lactic acid that is causing your muscle pain, but rather microscopic trauma (tiny tears in muscle fibers) and the resultant inflammation that occurs following physical activity. Therefore, lactic acid is actually an important fuel for your muscles and not the cause of your muscle soreness.

You can reduce muscle soreness after working out by taking your body through a proper cool-down consisting of 5-10 minutes of light aerobic activity. This provides oxygen to your muscles and helps eliminate the buildup of lactic acid.

Common Questions about Muscle Soreness

Why Do My Muscles Get Sore So Easily?

Your muscles may be getting sore easily if you’re not giving them adequate time to repair and recover from exercise. Overworking your muscles can lead to more severe soreness. Make sure you include rest days in your exercise routine. Also, don’t forget the importance of adequate sleep, a healthy diet, and hydration for muscle recovery.

What Causes Muscle Soreness If Not Lactic Acid?

Research has shown that rather than muscle enzymes like lactic acid, the burn you experience during vigorous exercise is due to microscopic trauma (tiny tears in muscle fibers). This triggers an inflammatory response that causes you to feel sore.

Why Do Muscles Get Sore After Lifting?

Muscles get sore after lifting because of structural damage to the muscle tissue, which triggers an inflammatory response. This happens when you lift at a level you haven’t done before or lift using a new form, position, or technique. It can cause soreness in your untrained muscles either right away or over the next few days. However, with continued training, your body adapts to the level and type of lifting you are doing, and you can lift without pain.

Do sore muscles mean you’re getting stronger?

Sore muscles indicate that your muscles have reached their capacity to handle load. In other words, you have pushed yourself to the limit. However, muscle soreness does not mean you are going to build muscle.

Is Muscle Soreness After Workouts A Good Thing?

It is normal to have slightly tired muscles after a workout. But your muscles should not be particularly sore if you are working out correctly. In other words, you should have minimal muscle soreness if you increase the frequency and intensity of your workouts gradually over time, warm up and cool down before and after exercise, and focus on healthy eating, hydration, and rest.

Preventing and Managing Muscle Soreness

Here are some tips to prevent or reduce muscle soreness:

Easing Into Workout Routines

It’s important to slowly increase the intensity and frequency of any new exercise program over several days to weeks. This gives your muscles time to adapt and can limit how much soreness you experience post-workout. An athletic trainer can develop a workout plan for you that includes gradually increasing the intensity and frequency of a variety of physical activities.

Warm-Up and Cool-Down Techniques

Warm-ups and cool-downs involve doing physical activity at a slower pace and reduced intensity compared to the main workout. They are important to get your body ready for and to help it recover from exercise. Warm-ups help to reduce muscle soreness and lower your risk of injuries. Cooling down helps to bring your heart rate and blood pressure to pre-exercise levels. However, more research is needed on whether cooling down reduces muscle stiffness and soreness.

Stretching Practices

Stretching exercises are another important part of any exercise program. They improve flexibility and the range of motion of your joints and bones. However, it’s unclear if stretching helps in preventing post-exercise muscle aches and injuries. It’s best to stretch after you have warmed up or cooled down.

Hydration and Nutrition

A protein-rich diet can supply your body with the raw materials it needs to rebuild damaged muscle fibers. Experts in sports medicine recommend a protein intake of 1.4 to 2 grams of protein per kilogram of body weight per day to build and maintain muscle mass.

It’s also important to eat an overall healthy, balanced diet to give your muscles all the nutrients they need.

Hydration is essential for muscle recovery after exercise. It’s especially important to drink plenty of water if you’re exercising in hot or humid conditions.

Lifestyle Measures

Rest days are important to give your muscles time to recover from workouts. Similarly, stress management and sleep play vital roles in supporting the healing process from exercise-induced muscle damage.

A good way to ensure adequate rest is to work on a different muscle group each day. For example, you could do legs one day and your upper body the next. This ensures you don’t overuse any one muscle group and give your muscles time to recover.

Remedies for Muscle Soreness

Massage and Foam Rolling

Studies suggest that massage and foam rolling can decrease delayed onset muscle soreness (DOMS) post-exercise. Massage reduces muscle tension. Foam rolling relieves muscle pain through myofascial release (breaking up of adhesions that form between your muscles and fascia).

Light Exercise

It’s important to keep moving your muscles even when you feel sore. You can accomplish this with stretching, yoga, or light cardio, such as walking.

Ice and Heat Therapy

Heat increases blood flow and helps to speed up muscle repair. Ice numbs the pain. Experts recommend alternating between heat and ice therapy throughout the day to aid active recovery from exercise-related muscle aches.

Epsom Salts

Soaking in an Epsom salt bath with warm water can relax sore and damaged muscles and relieve discomfort.

Over-the-Counter Pain Relievers

Over-the-counter pain medicines and anti-inflammatories do not speed up the muscle repair process after workouts. However, they can reduce the muscle aches and pains associated with post-exercise muscle soreness.

When to Seek Medical Attention for Sore Muscles

Exercise-induced muscle aches typically get better within a few days. You should contact your doctor if you experience severe muscle pain or the following other symptoms: