Muscle soreness

Muscle soreness is pain that is felt in the muscles. Overloading the muscles results in muscle soreness. This means that a (too) heavy training session causes muscle soreness. As a result of muscle soreness, muscle strength is temporarily reduced and muscle tension is temporarily increased.

In general, muscle soreness is the result of strenuous effort. Muscle soreness can occur quite soon after exertion, but it can also set in later. It is often worst on the second day. After a few days, the muscle soreness disappears again.

Different types of muscle soreness

There are two different types of muscle soreness: acute muscle soreness and delayed muscle soreness.

Acute muscle soreness
Acute muscle soreness is felt during and immediately after a training session or heavy labour. A few minutes to a few hours after exertion, the pain has disappeared. This pain is caused by the accumulation of lactic acid. Lactic acid is a waste product produced during exertion. When the exertion is too high, the body cannot remove this waste product quickly enough.

Delayed muscle soreness
Delayed muscle soreness is the most familiar type of muscle soreness. It is also sometimes called DOMS (delayed onset muscle soreness). This muscle soreness is felt one or two days after exertion.

To properly understand delayed muscle soreness, a brief explanation of different muscle contractions is needed.

• Isometric contraction.
  The muscle generates force without movement. For example, sitting against a wall. The muscle remains the same length.
• Concentric contraction.
  The muscle generates force with movement. The muscle shortens during the contraction. For example, bending the elbow (with a small weight in the hand). The biceps muscle shortens, becoming thicker and more visible.
• Eccentric contraction.
  The muscle lengthens while producing force. So during the effort the muscle is stretched. For example, the controlled return movement from a bent elbow. Movements going downwards are usually eccentric movements, such as walking downstairs, going down a slope, and the downward phase of a squat or push-up.

Delayed muscle soreness is mainly a result of eccentric contractions. Tiny muscle damage occurs here.

Due to the damage, processes arise in the muscle cells that cause pain and swelling. The subsequent inflammatory response is the start of recovery.

Training with muscle soreness

Because of the muscle damage, (sporting) performance is reduced during a period of muscle soreness. It is therefore not possible to train fully with muscle soreness. In addition, it does not feel pleasant; the muscles are painful and stiff.

If you reduce the training load, it is possible to train. As a rule of thumb, reduce the load by about 10% to 20%. This is easy to apply for strength training: simply use 10% to 20% less weight. For other activities or sports, this is more difficult.

Research has shown that training with muscle soreness does not cause additional muscle damage, provided the load is reduced. Training therefore does not delay the recovery process.

It is not advisable to keep training with muscle soreness all the time. A muscle needs time to recover fully.

Treatment of muscle soreness

Muscle soreness is an overuse of the muscles. It is therefore important to take enough time for the muscles to recover. Moving with muscle soreness is allowed, but the advice is not to train the affected muscles too hard while they are still painful.

Muscle soreness can be treated with massage, active recovery (gentle movement), contrast baths (warm/cold), and compression clothing (tight clothing). Normally, muscle soreness disappears after a few days.

It is often assumed that stretching muscles before or after training can prevent muscle soreness. This has not been scientifically proven. A good training build-up, a cool-down, drinking enough water, and replenishing minerals and proteins promotes recovery. In this, a cool-down means moving the muscles gently (such as walking, cycling, or swimming).

Preventing muscle soreness

There is no clear approach to prevent muscle soreness. Regular exercise reduces muscle soreness, although well-trained people can also develop muscle soreness after a training session that requires maximal effort.

Muscle soreness and flu

Muscle soreness can also be the result of conditions that affect the whole body. Flu is a well-known example. Do not exercise intensively if you have a fever.