Muscle strain: course and gradual return to activity

A strain injury occurs during forceful muscle work, most often in sport. It is most common at the front or back of the thigh and in the calf [3]. The injury causes bleeding in the muscle and an inflammatory reaction around the site of injury [3].

In a strain at the back of the thigh, the hamstring, muscle fibres most often tear where the muscle passes into the tendon. Explosive sports such as sprinting and football are most exposed. Poor training base, poor warm-up, fatigue and previous hamstring injury increase the risk [1]. Much of what is described below concerns the hamstring, since the sources describe the course best for this injury.

In a strain at the back of the thigh the pain comes suddenly, and you usually have to stop the activity. The strength in the thigh is reduced because of the pain [1]. A dent in the muscle may be felt, and a collection of blood may cause a lump [1].

An ordinary strain is often diagnosed from how the injury occurred and a clinical examination [1]. MRI can be used to distinguish a complete tendon rupture from an avulsion injury, where the tendon attachment at the pelvis tears loose [1].

Avulsion injury is often overlooked early, and the suspicion often arises only when treatment does not lead to progress [1].

NHI recommends stopping the activity that caused the injury and using rest, cold for at least 20 minutes without freezing the skin, compression with a bandage and elevation of the injured area [3]. For an injury at the back of the thigh the same is described: rest, cooling, a compression bandage and elevation [2].

The muscle should be offloaded for the first three days, and massage, stretching and heat should be avoided during this period [3]. With larger bleeding one should wait about five days before starting active exercises, while with smaller bleeding one can start earlier [2]. The sources also mention short-term use of anti-inflammatory medication in larger injuries, after consulting a doctor [2][3].

After the first days NHI describes gradually stretching and loading lightly, without triggering the pain. Eccentric and isometric exercises are mentioned as beneficial, and in larger injuries guidance from a professional can be useful [3].

For a strain at the back of the thigh NHI describes rehabilitation in three stages [2]. The sources give no fixed time frames for each stage. Instead you move on when specific criteria are met.

• Early stage: gentle movement exercises. You move on when you can walk normally without pain, jog slowly without pain and perform pain-free hamstring contractions with the knee bent 90 degrees.
• Build-up: gradual increase in intensity and range of motion, with eccentric strength exercises and stretching. You move on when full strength has been regained without pain and you can jog forwards and backwards at half speed without pain.
• Return to sport: eccentric strength exercises and sport-specific exercises, without limitations in mobility.

Cycling is mentioned as a good start, because it increases circulation in the area. Training intensity should be increased gradually, since returning to sport too quickly carries a risk of recurrence [2].

The prognosis is usually good, particularly with correct first aid and patient rehabilitation. With a simple injury at the back of the thigh one can at best be back in training after a few weeks [1][2]. The injury nevertheless often leads to longer absence from explosive sports such as sprinting [2]. The sources give no time frames for other muscle groups.

In serious injuries with severe pain you should see a doctor, and you should also contact a doctor before starting anti-inflammatory medication [3].

A feeling that something is tearing, severe pain, difficulty walking and pain when sitting, with a marked bruise at the top of the thigh within a few days, can indicate an avulsion injury. It requires prompt assessment, and delayed treatment gives a poorer prognosis [1].

A physiotherapist can examine where the injury is, explain what is a reasonable load and plan rehabilitation in steps with you. If it is unclear how extensive the injury is, diagnostic ultrasound can be used as a supplement. If you are a runner, you can also read about running injuries.

What is the difference between a muscle strain and a muscle injury from a blow?

A muscle strain occurs during forceful muscle work, while a muscle injury from a blow is caused by direct impact on the muscle. Both cause bleeding and an inflammatory reaction, and the treatment is the same [3].

How long should I offload a muscle strain?

NHI writes that the muscle should be offloaded for the first three days, without massage, stretching or heat. After that the load is increased gradually without triggering the pain [3].

When can I train again after a muscle strain?

It depends on the injury. The sources describe moving on in rehabilitation when specific criteria are met, not on a fixed date. With a simple strain at the back of the thigh one can at best be back in training after a few weeks [1][2].

Why do some people have a recurrence?

NHI writes that returning to sport too early carries a high risk of recurrence, and that training intensity should be increased gradually [1][2].

The article on follow-up after a fracture describes a different course with gradual rehabilitation. You can find more articles in the overview of articles.

This article was written by Dr.Dropin Fysikalske and is based on the sources listed below. It gives general information and does not replace an examination by a healthcare professional.

The websites were accessed and read on 22 October 2026.

1. Strekkskade på baksiden av låret (hamstringskade) (Hamstring strain). NHI.no, based on Legehåndboka. Last updated 26 January 2022. Link

2. Strekkskade på baksiden av låret, behandling (Hamstring strain, treatment). NHI.no. Last updated 26 January 2022. Link

3. Muskel- og strekkskader (Muscle and strain injuries). NHI.no. Last updated 31 March 2022. Link