Post-workout pain or injury — how to tell them apart?

Muscle pain after training, i.e. delayed onset muscle soreness (DOMS), usually appears 12–24 hours after exercise, is diffuse and on both sides of the body, eases within a few days, and movement often relieves it. An injury hurts suddenly, already during the activity, in one specific spot, often with swelling, bruising or difficulty putting weight on the limb.

In this post we describe the symptoms of both conditions, compare them in a table, list the situations that require a doctor and suggest what to do in the first few days.

Contents

What is muscle pain after training (DOMS)?

Delayed onset muscle soreness is tenderness and stiffness of the muscles after new, more intense or unusual exercise, especially with a lot of braking movements, e.g. going downstairs, squats or running downhill. It results from micro-damage to muscle fibres and the inflammatory reaction during their repair. It is the body’s normal response to a new training stimulus.

The pain usually affects whole groups of muscles that worked during training, often on both sides of the body – e.g. both thighs after your first leg workout. The muscles are tender to pressure and stretching, and the first movements in the morning can be stiff, but the pain usually eases once you warm up. The body adapts quickly, so after a few similar workouts the discomfort is less.

Which symptoms point to an injury?

An injury is suggested by pain that came on suddenly during activity, e.g. while sprinting, jumping or falling, and is clearly located in one spot. It is often accompanied by swelling, bruising, a feeling of something “snapping” or a “shot”, weakness, joint instability or difficulty putting weight on the leg or arm. Injury pain usually does not ease with movement, but gets worse.

Typical sports injuries are muscle strains (e.g. of the hamstrings or calf), ankle sprains, knee ligament injuries and tendon overload. The latter develops gradually, but causes pain in one spot around the tendon that gets worse with each workout, rather than easing like DOMS. One example is jumper’s knee. We describe what to do after an ankle injury in our post rehabilitation after an ankle sprain.

Post-workout pain or injury? A comparison of symptoms

The key differences concern when the pain appears, where it is and how it reacts to movement. Post-workout pain appears with a delay, is diffuse, symmetrical and eases after warming up. An injury hurts straight away, in one spot, often on one side only, with swelling or bruising, and movement makes it worse. The table below brings these criteria together, but it does not replace an examination.

Criterion	Post-workout pain (DOMS)	Injury
Onset	12–24 hours after exercise	sudden, during the activity or just after it
Location of pain	diffuse, in whole muscle groups, often on both sides	in one spot, usually on one side
Response to movement	eases after warming up	gets worse with movement or load
Swelling, bruising	usually absent	often present
Function	full, although movement feels “stiff”	limited, e.g. limping, instability, weakness
Course	gradual improvement over a few days	no improvement or getting worse
What to do	light movement, sleep, gradual return to training	offloading, assessment by a physiotherapist or doctor

What to do with post-workout pain and what to do with an injury?

With delayed onset muscle soreness, light movement, e.g. a walk or an easy bike ride, sleep and a gradual return to training are enough – the pain will go away on its own. If you suspect an injury, stop the activity, take the load off the painful area, raise the limb and watch the symptoms. If the pain is severe or does not ease, see a physiotherapist or a doctor.

In the first days after a soft-tissue injury, the principle of gradual loading helps: a short period of offloading, raising the limb, possibly compression, and then a return to movement within the limits of pain. Contrary to popular advice, you do not always need to reach for anti-inflammatory medicines straight away – it is worth discussing their use with a doctor or pharmacist. With DOMS, on the other hand, avoid intense training of the same muscles until the tenderness has clearly eased.

Physiotherapy consultationassessment of an injury or overload, plan for returning to training180 PLN Manual therapyfor pain and limited movement after overload and injuries180 PLN

Prices valid from 08.2026. We write more about injuries of individual joints in our guide joint pain and injuries.

Summary

Post-workout pain appears with a delay of 12–24 hours, is diffuse and goes away on its own within a few days, whereas an injury hurts suddenly, in one spot and often with swelling or bruising. With a deformity, inability to put weight on a limb or dark urine after exercise, see a doctor urgently; with persistent pain, book a physiotherapy consultation (PLN 180).

Frequently asked questions

Is muscle soreness caused by lactic acid?

No. Lactate is produced during intense exercise, but it is cleared from the muscles within a short time after training and is not responsible for the pain that appears the next day. Delayed onset muscle soreness results from micro-damage to muscle fibres and the process of their repair. That is why the popular Polish name “zakwasy” (literally “souring”), which links soreness to acid, is misleading, even though it is widely used.

Can I train with sore muscles after a workout?

With mild delayed onset muscle soreness you can do light training, e.g. walking, swimming or exercises for other muscle groups. Light movement often reduces stiffness. It is better to postpone intense training of the same muscles until the tenderness has clearly eased. If the pain is in one spot and gets worse with movement, stop training.

Does stretching prevent muscle soreness?

Research shows that stretching before or after training has very little effect on delayed onset muscle soreness. Gradually increasing training loads is more effective, especially with new exercises. You can stretch for comfort and to maintain your range of movement, but it should not be treated as a way of preventing muscle soreness.

Ice or heat after an injury?

For a fresh injury with swelling, cooling is traditionally used and may reduce pain, although its effect on healing is debatable. Heat is usually avoided in the first days after an injury with swelling. Always wrap ice in a cloth so as not to cause frostbite to the skin. With chronic muscle tension, heat often feels more pleasant.

Does massage help with muscle soreness after training?

Massage may reduce the sensation of delayed onset muscle soreness and give pleasant relaxation, although it does not clearly speed up the recovery of the muscles themselves. Massage is not performed on a freshly injured area with swelling or bruising. At the clinic in Rydułtowy a partial classic massage costs PLN 110 and a full-body massage PLN 190.

When should I see a physiotherapist with an injury?

It is worth seeing a physiotherapist when pain after an injury persists despite rest, comes back with every workout, limits movement or strength, or when you want to return to sport safely. With warning signs such as deformity or being unable to put weight on a limb, see a doctor first. A consultation at the clinic costs PLN 180.

Sources

• Cheung K., Hume P., Maxwell L., Delayed onset muscle soreness: treatment strategies and performance factors, Sports Medicine, 2003.
• Dubois B., Esculier J.F., Soft-tissue injuries simply need PEACE and LOVE, British Journal of Sports Medicine, 2020.
• Herbert R.D., de Noronha M., Kamper S.J., Stretching to prevent or reduce muscle soreness after exercise, Cochrane Database of Systematic Reviews, 2011.