Why Do Muscles Get Sore After Exercise? Understanding DOMS and Recovery

It’s a common experience: you finish a challenging workout feeling great, but the next day, your muscles ache. This post-exercise soreness, often referred to as DOMS (delayed onset muscle soreness), is a normal response to certain types of physical activity and is generally temporary.
 
Let’s explore what DOMS is, why it happens, and what to expect during recovery.

The science behind post-exercise soreness

DOMS refers to the muscle tenderness and stiffness that typically appears 12 to 24 hours after exercise, peaking around 24 to 72 hours.
 
It usually happens when your muscles experience unfamiliar stress, such as a new workout routine, higher intensity exercise, or eccentric movements (where the muscle lengthens under tension, like during downhill running or lowering weights).
 
These activities can cause tiny changes in the muscle fibres, which then triggers the body’s natural repair process.

How DOMS is different from an injury

DOMS is usually felt as a dull, aching soreness in the muscles you’ve worked, and it tends to ease within a few days as your muscles recover and adapt.
 
In contrast, an injury often presents as sharp or sudden pain, swelling, or pain that worsens rather than improves.
 
If discomfort persists beyond a few days, or if you experience significant swelling, bruising, or joint pain, it may be worth checking in with a healthcare professional.

Microtears and muscle repair

When you exercise, particularly during strength or resistance training, your muscle fibres undergo microscopic tears. This process is completely natural and part of how muscles adapt and grow stronger.
 
The repair process that follows involves the body rebuilding these fibres, which can lead to temporary soreness as your muscles adjust to the new level of demand.

The role of exercise type and intensity

The kind of exercise you do plays a major role in whether you experience DOMS. Eccentric exercises, such as squats, lunges, or running downhill, are well known for causing greater post-exercise soreness compared to concentric movements (where the muscle shortens, like during lifting).
 
Higher intensity sessions or sudden increases in training volume can also contribute to more noticeable soreness.

Other factors that can increase soreness

Your level of conditioning, hydration, and even recovery habits can influence how sore you feel after a workout. For example, starting a completely new exercise program or skipping adequate cool-down stretches may lead to more discomfort.
 
Individual factors, such as age and fitness level, can also play a role in how your muscles respond to physical stress.

Typical recovery timeline for DOMS

For most people, DOMS starts within the first day after exercise, peaks at about two to three days, and then gradually subsides over the following days.
 
While the duration varies depending on the workout’s intensity and your overall fitness, soreness from DOMS usually resolves within a week without requiring specific treatment.

When soreness may be a sign of something else

If muscle soreness lasts longer than a week, gets progressively worse, or is accompanied by swelling, severe weakness, or dark urine, it may indicate something beyond normal DOMS. In these cases, it’s best to seek guidance from a healthcare professional for an accurate assessment.

Active recovery strategies (stretching, gentle movement, massage)

Low-intensity activities like walking, cycling, or light yoga can help maintain blood flow to sore muscles, which supports the delivery of oxygen and nutrients.
 
Gentle stretching after exercise may also help improve flexibility and reduce stiffness. Some people also find light massage or foam rolling helpful for easing muscle tightness and promoting relaxation.

Nutrition and hydration for recovery

Eating a balanced diet after exercise supports the body’s natural recovery processes. Meals that include a mix of carbohydrates, protein, and healthy fats provide the building blocks muscles need for repair and energy replenishment.
 
Staying well hydrated is equally important, as fluids support normal muscle function and overall wellbeing.

Nutrients that support muscle function (e.g., magnesium, protein)

Certain nutrients play key roles in maintaining healthy muscle function. Protein provides the amino acids necessary for muscle repair, while minerals like magnesium contribute to normal muscle contraction and relaxation.
 
Including a variety of nutrient-rich foods in your daily diet helps ensure your muscles get the support they need.

When light exercise can help

If soreness is mild and you feel capable, light or low-impact activity can sometimes help ease stiffness. Gentle exercise like swimming, stretching, or an easy walk keeps blood circulating and may support the recovery process without adding significant strain on sore muscles.

When to rest instead

If the soreness is intense, affects your range of motion, or comes with sharp pain, it may be better to give your muscles time to recover.
 
Resting allows your body to complete the natural repair process and helps reduce the risk of injury. Listening to your body is key. If in doubt, take a break or opt for a lighter workout.

Warming up and cooling down

Starting your workout with a proper warm-up and ending with a cool-down routine can help prepare your muscles for activity and support recovery afterward. A few minutes of dynamic stretches before exercise and gentle movements afterward can make a noticeable difference over time.

Gradual progression in training

Jumping into an intense workout too quickly is one of the main reasons people experience DOMS. Gradually increasing the intensity, duration, and frequency of your training gives your muscles time to adapt and helps reduce the likelihood of excessive soreness.

Supporting your body with nutrition and rest

Adequate nutrition, hydration, and quality sleep are essential parts of recovery. Giving your body the fuel and rest it needs helps maintain energy levels and supports muscle repair between workouts. Consistency in these habits can lead to better performance and comfort over time.