Sore Muscles After Running: What Causes DOMS and How to Recover

You went for a run after some time off, ramped up the intensity or simply tried a new route with more hills. The next day, going down stairs feels like a serious ordeal. Muscle soreness has arrived.

Although virtually every runner has experienced it, there is a lot of confusion about what muscle soreness actually is, what causes it and what truly works to relieve it. In this guide we explain everything you need to know to understand your post-run soreness and manage it intelligently.

What muscle soreness actually is

Muscle soreness after exercise is scientifically known as DOMS (Delayed Onset Muscle Soreness). It is a natural inflammatory response that occurs when your muscles suffer micro-damage to their fibers as a result of an effort they are not accustomed to.

The lactic acid myth has been circulating for decades, but science debunked it long ago. Lactic acid is cleared from your muscles in less than an hour after you stop exercising, while DOMS appears hours or even days later. There are no lactate crystals stuck in your muscles.

What actually happens is a three-phase process:

1. Mechanical damage: eccentric contractions (when the muscle lengthens while generating force, such as running downhill) cause micro-tears in the muscle fibers and in the connective tissue surrounding them
2. Inflammatory response: the body sends inflammatory cells to the damaged area to clean up injured tissue, which produces swelling, tenderness and pain
3. Repair and adaptation: the fibers rebuild stronger than before, which explains why the same workout produces less soreness the second time around

Why it happens after running

Not every run produces muscle soreness. Understanding what triggers it will help you prevent it or at least anticipate when you know it is coming.

The main triggers for runners

• Downhills and hills: running downhill is the number-one trigger for muscle soreness in runners. Your quads work eccentrically (braking your body against gravity), which generates more micro-damage than running on flat ground or uphill
• Volume or intensity spikes: jumping from 20 to 35 km per week overnight, or doing your first speed interval session, subjects your muscles to an unfamiliar effort
• Coming back after a break: if you have been 2-3 weeks without running, your muscles lose part of their adaptation and the first session back virtually guarantees soreness
• New surface: switching from pavement to trail, or to beach sand, recruits different muscle fibers and stabilizers that are not trained
• Different shoes: breaking in shoes with a very different drop or cushioning changes your biomechanics and can produce soreness in unexpected areas

How long muscle soreness lasts

DOMS follows a fairly predictable timeline, although the intensity varies depending on the person and the stimulus:

• 6-12 hours after: you start to feel stiffness and slight tenderness when you move the affected muscles
• 24-48 hours: the pain reaches its peak. Moving is hard, stairs become the enemy and even sitting down can hurt
• 48-72 hours: the pain starts to subside gradually. You can move more normally although you still feel discomfort when pressing on the muscle or making wide movements
• 5-7 days: full resolution in most cases. The muscles are repaired and, thanks to the repeated-bout effect, they will be more resistant to the same stimulus next time

5 ways to relieve muscle soreness

There is no magic cure that eliminates DOMS instantly, but there are evidence-backed strategies that speed up recovery and reduce pain significantly.

1. Low-intensity active movement

It sounds counterintuitive, but moving is the best thing you can do when you have sore muscles. A 20-30 minute walk, an easy session on the stationary bike or a gentle swim increases blood flow to the damaged muscles without adding more mechanical stress. This accelerates the removal of waste products and the delivery of nutrients for repair.

2. Foam rolling (self-myofascial release)

A foam roller is one of the most effective tools for reducing the intensity of muscle soreness. Several studies have shown that 10-15 minutes of foam rolling after training significantly reduces muscle pain over the following 24-72 hours. Apply moderate pressure on the affected muscles for 60-90 seconds per muscle group.

3. Strategic nutrition

What you eat after training directly influences how fast your muscles repair. Make sure you consume enough protein (20-30 g) within 2 hours of your workout to supply the amino acids needed for repair. Foods rich in antioxidants (berries, tart cherry, turmeric) also help modulate the inflammatory response without blocking it completely.

4. Gentle stretching and mobility

Gentle static stretches (without forcing or seeking pain) help maintain range of motion and reduce the feeling of stiffness. Hold each stretch for 20-30 seconds without bouncing. Do not stretch aggressively when you have intense soreness, as adding mechanical tension to already damaged muscles can delay recovery.

5. Temperature contrast therapy

Alternating between cold water (10-15 °C for 1-2 minutes) and warm water (38-40 °C for 3-4 minutes) creates a vascular pumping effect that improves local circulation. Repeat 3-4 cycles, always ending with cold. Cold water immersion alone is also effective, especially in the first 24 hours, for reducing excessive inflammation.

Can I run with sore muscles?

The short answer: it depends on the intensity. Mild to moderate soreness is not a reason to skip your workout, but it is a reason to modify it.

When you can run

• Mild soreness (1-3 out of 10): you feel stiffness at the start but it fades within the first 10-15 minutes of the run. You can train normally, even doing long easy runs at a comfortable pace
• Moderate soreness (4-5 out of 10): you feel pain when you move but it does not limit function. Do a short, easy jog (30-40 minutes) at a recovery pace. Avoid intervals, hills or fast tempos

When it is better not to run

• Intense soreness (6+ out of 10): the pain alters your running form, makes you limp or changes your mechanics. Running with altered biomechanics is a recipe for compensatory injuries. Opt for active rest: walking, swimming or stationary cycling
• Asymmetric pain: if the soreness is much worse on one side than the other, there may be more going on than simple DOMS

When to worry

Muscle soreness is normal and does not require medical attention. But there are situations where what looks like DOMS could be something more serious. Watch for these warning signs:

• Excessive duration: if the pain does not improve at all after 7 days, it could be an actual muscle injury (partial tear, strain) rather than simple soreness
• Highly localized pain: DOMS is felt across the entire muscle. A sharp, pinpoint pain in one specific spot suggests a specific tissue injury
• Visible swelling: some inflammation is normal with soreness, but marked, visible swelling, especially in one leg only, needs professional assessment
• Dark urine (tea or cola colored): this may indicate rhabdomyolysis, a serious condition where muscle fibers break down massively and release myoglobin into the bloodstream. It requires urgent medical attention
• Pain that gets worse instead of better: DOMS peaks at 48 hours and then improves. If the pain keeps escalating after the third day, something else is going on
• Significant loss of strength: being unable to support your own weight, inability to flex or extend your leg, or marked weakness beyond normal discomfort

Frequently asked questions

Carlos Ruiz Founder

Over 8,000 km run and plenty of sore muscles along the way. If there is one thing I have learned, it is that soreness is part of the process, but it does not have to ruin your training week.

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