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Why Do Muscles Get Sore After Working Out?

author image Jennifer Sukalo
A writer since 2007, Jennifer Sukalo has been an educator and presenter in the health and wellness industry since 1989. She has written for Rodale Inc. online and contributed to "Prevention" magazine. Sukalo is a Certified Health Education Specialist and holds a Master of Science in exercise and wellness from Arizona State University.
Why Do Muscles Get Sore After Working Out?
Any type of activity can cause muscle soreness. Photo Credit Comstock/Stockbyte/Getty Images

Some people avoid physical activity because of the associated soreness and pain. Slight muscle soreness comes with the territory when working out, and the benefits you gain from working out far exceed the discomfort you experience. A better understanding of what your muscles go through and how they respond to your workouts will help you see soreness in a whole new light.

Muscle Contractions

Muscular contraction is required to perform any type of physical activity. During your workout, your muscles go through a variety of contractions. At times, your muscles will contract concentrically, or shorten. At other times, they will contract eccentrically, or lengthen. During these contractions, other muscles will contract isometrically to provide stability. As your muscles adapt to the activity, lactate levels increase, and microscopic damage to the muscle fibers and connective tissue takes place. The soreness you feel after a workout is caused by your muscles naturally learning and responding to a new activity.

Types of Soreness

Muscle soreness can be acute or delayed-onset. Acute soreness takes place during and immediately following your workout. Delayed onset muscle soreness occurs 24 to 48 hours after your workout. Symptoms of both types can include mild swelling, stiffness, pain and reduced range of motion. If you see excessive swelling, discoloration or feel extremely severe pain, these may be signs of a more serious injury, and you should seek medical attention immediately.

What Soreness Means

The symptoms of typical muscle soreness, whether acute or delayed-onset, may last up to 10 days. The muscle soreness you experience does not mean simply that you are out of shape. On the contrary, your soreness is letting you know that your muscles are learning new activities and are responding exactly as they should be. Your muscle soreness is a normal and positive part of becoming healthier and getting into better shape. However, if your soreness persists or worsens, talk to your doctor.

Activities that Cause Soreness

Muscle soreness is most commonly linked with resistance or weight training. However, soreness can occur anytime you ask your muscles to do activities that they are not already used to. For example, you decide to go for a hike, having not hiked in months. Your muscles are not used to the work required to go up and down hills and must again adapt to the activity. This adaptation will result in muscle soreness following your hike.

Preventing Soreness

One session of walking down hills can prepare your muscles and decrease the severity of soreness from your upcoming hike. Performing a warm-up and ensuring that your workout type and intensity match your fitness level can also help lessen the occurrence of muscle soreness. Your warm-up should include five to 10 minutes of light activity followed by stretching. Talk to your fitness professional about your warm-up and the exact "map" of your workout. Additionally, keeping the muscles moving with light activity, stretching and massage are beneficial in reducing the symptoms of your soreness following a workout.

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