Injury types

Hamstring Injuries: Grades, Typical Absences and Why They Come Back

Published 2026-10-26 · Daily IL team

This article is general information, not medical advice. For any individual player’s return date, follow the club’s official announcements.

It is one of the most familiar sights in sport: a player at full sprint suddenly pulls up and grabs the back of the thigh. More often than not, the next injury report mentions the hamstring. It happens to wingers chasing a through ball, to baseball runners digging for first base and to receivers running a deep route, which is why “hamstring” is one of the words you will see most often on any injury list.

What the hamstrings are

“Hamstring” is a collective name for three muscles at the back of the thigh: the biceps femoris, the semitendinosus and the semimembranosus. They start at the bottom of the pelvis, cross the back of the knee and attach to the lower leg, so they both bend the knee and extend the hip.

During sprinting they act as the brakes. As the lower leg swings forward before the foot lands, the hamstrings have to produce force while they are being stretched. That moment of high load is widely thought to be when most sprint-related strains happen. High-speed running injuries most often involve the biceps femoris on the outside of the thigh. Injuries from slow, extreme stretching — think of a high kick or a dancer’s split — more often affect the semimembranosus near its upper tendon, and research suggests these stretch-type injuries tend to take longer to recover from.

Grade 1, 2 and 3: what changes

Doctors usually describe muscle strains on a three-grade scale. Many teams and imaging specialists now use more detailed MRI-based systems, such as the British Athletics Muscle Injury Classification, but the basic three grades are enough to make sense of most news reports.

Grade	What is damaged	Typical time out (rough range)
Grade 1	Fibres overstretched, very little tearing	A few days to about 2 weeks
Grade 2	Partial tear of the muscle	Several weeks, sometimes 1–2 months
Grade 3	Complete tear of muscle or tendon	Months; 6+ months after some surgeries

Treat these ranges as a guide, not a schedule. Within the same grade, injuries closer to the pelvis, or ones that extend into the tendon running inside the muscle, tend to take longer.

The most severe grade 3 injuries are tendon avulsions, where the tendon pulls away from the bone. These are often repaired surgically. According to the American Academy of Orthopaedic Surgeons, rehabilitation after repair of the upper (pelvis-end) tendon usually lasts at least six months, while athletes who have the lower (knee-end) tendon repaired typically need about three months before returning to sport.

How long professionals actually miss

The best long-running data comes from European football. The UEFA Elite Club Injury Study followed top men’s clubs for 21 seasons and found that the median absence for a hamstring injury was about 13 days. Injuries with visible structural damage had a median of 17 days, while “functional” injuries without structural damage on imaging had a median of around 6 days.

So the most common professional picture is roughly two weeks — but a median means half of all cases last longer. A clinical review of return-to-sport research lists several early warning signs that an injury is likely to keep a player out for more than 40 days: a high initial pain score, pain during everyday activities lasting more than three days, a popping sound at the moment of injury, and visible bruising.

The same UEFA study found that hamstring injuries grew from 12% of all injuries in 2001/02 to 24% in 2021/22. From 2014/15 onward, the injury rate rose a little each year in both matches and training, and the rate in matches was around ten times higher than in training.

Why hamstrings keep coming back

Few injuries have a reputation for recurrence like this one. In the UEFA data, about 18% of hamstring injuries were re-injuries, and roughly seven in ten of those happened within two months of the player’s return. Other reviews put the recurrence rate as high as one in three and identify the first two weeks after returning as the riskiest window.

Commonly cited reasons include:

Returning before full recovery. Pain can settle before strength and flexibility on the injured side are fully back.
Scar tissue. Healing tissue may not behave exactly like the original muscle.
Previous injury itself. Athletes with a prior hamstring strain have been found to have more than twice the risk of a new one.
Fatigue and imbalance. Tired muscles late in a game and strength differences between the front and back of the thigh are both listed as risk factors.

How a player rehabs matters too. One comparison cited in a clinical review found that athletes whose programme progressively added agility and trunk-stabilisation work re-injured far less often — both two weeks and one year after returning — than those who did stretching and isolated strengthening alone. That is part of why modern clubs clear players only after they pass a series of sprinting, cutting and strength benchmarks, not just once the pain is gone.

Because a recurrence usually costs more time than the first injury, teams often hold a player out a game or two longer than fans expect, or limit minutes in the first matches back.

Which sports and positions see it most

Hamstring strains cluster in sports built around acceleration and top speed:

Football (soccer): wingers, full-backs and forwards who make repeated sprints.
American football: wide receivers, running backs and defensive backs.
Baseball: batters running out ground balls, base stealers and outfielders chasing fly balls.
Rugby and sprint athletics: classic high-risk sports.
Dance and kicking sports: more of the slower, stretch-type injuries.

Research also points to higher risk with older age and during preseason, when players are still building fitness, and higher rates in competition than in practice.

On Daily IL

When Daily IL builds a game’s injury report, each entry records the body part and the injury type — for example “left hamstring strain” — together with the status the team has announced: OUT, DOUBTFUL, QUESTIONABLE, PROBABLE, IL (injured list), SUSPENDED or RETURNED. You can read what each status means in our status guide.

With hamstrings in particular, a player marked RETURNED may still have his minutes managed for a while, because the weeks right after a comeback are when recurrences are most common.

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