Whether you’re someone who enjoys a regular gym session, or you’ve just begun a new fitness journey, you have likely experienced muscle soreness after a vigorous work out at some point. While some enjoy the feeling of sore muscles the next day and may feel more accomplished, others may dread that feeling. No matter your feelings on post work out soreness, you may be wondering why do muscles get so sore after a strenuous work out? Is it good or bad and what can you do to prevent it?
You may have heard the term delayed onset muscle soreness; this is the soreness you experience 24–48 hours after exercise. When we talk about muscle soreness, we’re typically referring to delayed onset muscle soreness.
Exercise of any type is a stressor on your body. Physical stress from exercising is a different type of stress then mental worrying and is considered to be a good for you. However, when the stress is of a higher intensity than normal, your muscles respond to it. That response is often muscle soreness.
Strength training, for example, breaks down the small proteins within your muscles, prompting your body to generate inflammatory proteins known as cytokines. The inflammation creates swelling of the muscles, which can sometimes lead to tightness and soreness, as well as damaged tissue.
Similarly, cardio exercises such as running can create micro-tears or breakage in muscle tissues, especially if you’re a new runner, have recently increased the mileage or intensity of your run, or are just getting back into training after some time off. What we’re actually doing every time our foot lands is slowing the downward motion of support, preventing it from falling down to the ground. In essence, you’re controlling the rate at which your muscles lengthen, this is what creates those micro-tears within the tissues.
Your muscles perform three different types of actions: eccentric, concentric and isometric. Eccentric refers to the lengthening phase of muscle contraction, or the lowering portion of an exercise. For example, sitting back into a squat, uncurling your arm during a biceps curl or running downhill. Concentric refers to the shortening phase of muscle contraction, where you curl that dumbbell or stand up from a squat. Finally, isometric refers to holding a position, like when you hold a plank or wall-sit. Eccentric training can lead to greater post-workout soreness.
One reason eccentric training can cause greater soreness is because you exert more control on descent, as opposed to when gravity is doing all the work for you. This damages the muscle fibers, which leads to the after work out soreness. The good news is your body is intelligent and able to easily adapt to the stresses of eccentric exercise. You’ll notice you experience much less strain when you repeat the same workout a week later, according to studies. One such study published, reveals it only takes one workout for your immune system to adapt so it’s better able to respond to your next round of exercise.
Muscle soreness following exercise is a good thing: It means that you’ve created a stimulus for which your body is going to adapt and become stronger. However, you want to be able to go about your normal daily routine without being in too much discomfort. Ideally, you should not be experiencing pain or soreness for more than 2 days post work out or you have pushed your body too far. Whether you’re sore or not, make sure you’re doing things to help your body recover between workouts. Your best recovery tools are sleep, hydration and nutrition. The best way to rest your muscles and recover is sleep. We experience the greatest boost in muscle protein synthesis during non-REM sleep phase.
You have likely heard muscle soreness comes from a buildup of lactic acid, which is produced in your muscles during intense exercise. In actuality, this theory was debunked back in the 80’s. When lactic acid builds up in your muscles during exercise, it can create a feeling of pain or discomfort during the workout. However, following an intense workout, blood lactate levels drop significantly within 20 minutes of working out. Your body metabolizes the lactic acid quickly and uses it for energy.