Hamstring Strains: Causes and Prevention

By 4Football Staff · October 16, 2026 · 10 min read

Why sprinting football players pull hamstrings, how the grades of strain differ, why re-injury is so common, and which strengthening habits lower the risk.

A wide receiver streaks down the sideline, the ball is in the air and, in the middle of a full-speed stride, he pulls up. He grabs the back of his thigh, slows to a hobble and drops to the turf. There was no contact and no defender within five yards. The hamstring simply could not handle what the sprint asked of it.

Few injuries are as closely tied to speed. Football rewards explosive running, and the muscle group at the back of the thigh is one of the engines of that running. It is also one of the most commonly strained muscle groups in sports that involve sprinting, and one of the most likely to be hurt a second time.

This article explains what the hamstrings do, how and why they get strained, how clinicians describe the severity, what recovery generally involves and why re-injury is such a problem. It also covers the prevention habits that research supports. It is general education, not a diagnosis. Any muscle injury that causes more than mild discomfort should be looked at by an athletic trainer or physician.

What the hamstrings are

"The hamstring" is really three muscles that run along the back of the thigh from the lower part of the pelvis to the bones of the lower leg. The three are the biceps femoris, on the outer side, and the semitendinosus and semimembranosus on the inner side. Their names are less important than what they do.

• They bend the knee, pulling the heel toward the buttocks.
• They extend the hip, pulling the thigh backward, which is a major part of the push of every running step.
• They work as a brake, slowing the lower leg as it swings forward during running so that the knee does not snap straight.

That last job is the one most closely tied to injury. In the final moment of each stride, as the leg swings forward and the foot prepares to hit the ground, the hamstrings are lengthening while they are also contracting hard. This type of contraction, where a muscle produces force while being stretched, is called an eccentric contraction. It is a normal part of running, but it puts great stress on the muscle at the moment it is stretched most.

How hamstring strains happen

A strain is an injury to a muscle or the tendon that attaches it, ranging from overstretched fibers to a tear. (A sprain, by contrast, involves a ligament. Our article on ankle sprains covers that distinction.) Hamstring strains in football fall into a few common patterns.

Sprinting injuries

The classic hamstring injury occurs during high-speed running, especially near top speed or while accelerating hard. It usually happens in the late swing phase of the stride, when the muscle is being asked to brake the leg. Receivers, running backs, defensive backs, returners and kick coverage players are the players most exposed, because they reach top speed often.

Stretching injuries

A second pattern occurs when the leg is pushed into extreme stretch with the hip bent and the knee straight, such as when a player slips, does a split, or reaches to make a tackle. These injuries often affect a different part of the muscle and tendon and may involve a longer recovery.

Kicking and slow-speed injuries

Kickers and punters can strain a hamstring as the kicking leg swings through. Linemen can strain it while driving or pulling. The risk depends on the movement, not only on the speed.

Why some players are more at risk

Researchers have studied hamstring injuries for years, and the strongest finding is simple: a previous hamstring strain is the best predictor of another one. Other risk factors have varying levels of support.

• Previous injury. A muscle that has been injured before may have scar tissue, lingering weakness or altered running mechanics.
• Age. Risk generally goes up as athletes get older.
• Fatigue. Many strains occur late in games or practices, when muscles are tired and coordination slips.
• Strength imbalance. Weak hamstrings relative to the quadriceps, or weakness between the two legs, may raise risk.
• Hip and core control. If the pelvis and trunk do not stay stable while running, the hamstrings can be loaded awkwardly.
• Sudden jumps in workload. A player who returns from a break and sprints at full speed without building up is more vulnerable. This is common at the start of preseason.
• Insufficient high-speed running. Counterintuitively, players who do not practice sprinting can be at higher risk when they sprint in games.
• Flexibility. The role of flexibility is debated. Stretching alone has not been shown to prevent hamstring strains reliably, though the question is still being studied.

Several of those factors, such as fatigue and workload, are things a coaching staff can manage. That is why prevention programs target them.

Grading severity

Clinicians commonly describe muscle strains in three grades. The exact definitions vary a bit between sources, but the idea is as follows.

Imaging, often an MRI, can show where the injury is and how severe it is, and the location matters. An injury near the middle of the muscle often recovers faster than one close to the attachment at the pelvis. Only a clinician can assess this; a player should not try to grade the injury from how it feels.

Some severe injuries, particularly complete tears of the tendon at the pelvis, may involve surgery. Most hamstring strains do not.

What to do right away

When a player pulls up with a hamstring injury, the immediate steps are straightforward.

1. Stop playing. Continuing to run on a strained hamstring can turn a mild injury into a severe one.
2. Get an evaluation. The athletic trainer or a physician should check the muscle. Our article on the role of the athletic trainer explains how that sideline assessment works.
3. Control symptoms. Clinicians commonly use measures such as relative rest, compression and ice for comfort in the first days, but the specifics should come from the person treating the injury.
4. Avoid aggressive stretching. Pulling hard on a freshly injured hamstring can irritate it.
5. Seek care for severe signs. A large bruise, severe pain, a visible gap or dent in the muscle, or inability to walk calls for prompt medical attention.

How recovery works

Recovery from a hamstring strain depends on the grade, the location and the athlete. There is no single schedule, and clinicians are cautious about quoting dates. A mild strain may allow a return in a matter of days to a couple of weeks, while a severe one can take months. The sequence of rehabilitation, though, follows a pattern.

1. Settle the injury. The first phase is about reducing pain and swelling and protecting the muscle while it begins to heal.
2. Restore gentle motion and basic strength. Movement starts within a pain-free range. The athlete begins simple strengthening exercises that do not cause pain.
3. Build strength, especially eccentric strength. Exercises that load the muscle as it lengthens are central, because that is what it needs to do while sprinting.
4. Progress to running. Jogging is followed by faster running, with careful attention to how the leg feels. The athlete reintroduces high-speed running in steps.
5. Add football movement. Cutting, acceleration, deceleration and position-specific drills come in last.
6. Pass return-to-play criteria. Many clinicians use strength comparisons between the legs, running tests and a pain-free examination before clearing a player, rather than relying on dates alone.

The most common mistake is stopping rehabilitation when the pain stops. Pain-free does not mean strong, and a muscle that feels fine at a jog may not be ready for a full-speed sprint. This is a major reason hamstring strains recur.

The problem of re-injury

Hamstring strains have a reputation for coming back. An athlete returns, performs well for a few games and then re-injures the same muscle, often in the first weeks after returning. Several things contribute.

• Incomplete healing and weakness. The muscle looks fine but has not regained its full eccentric strength.
• Altered movement. Athletes may unconsciously change their running mechanics to protect the injury, which can overload other tissues.
• Rushed return. Pressure to play, whether from a coach, a team situation or the player himself, can cut the process short.
• Skipped prevention. Once back on the field, the player stops the strengthening work that helped the recovery.

The lesson for teams is that hamstring management does not end with the return to play. It continues with ongoing strength work and careful workload management. On the professional level, you will often see players listed as limited in practice on the injuries page while a team brings them back gradually.

Prevention: what the evidence supports

The best news in the hamstring literature is that targeted training works. Some of the strongest evidence in sports injury prevention concerns hamstring strength programs.

Eccentric strengthening

Exercises that train the hamstrings while they lengthen have the most support. The best-known example is the Nordic hamstring exercise, in which an athlete kneels with the ankles anchored and slowly lowers the body forward, resisting the fall with the hamstrings. Reviews that pooled results from many studies have found that programs including this exercise were associated with substantially fewer hamstring injuries. It is demanding, and it should be introduced gradually, with the volume built over weeks. Other exercises, such as supported single-leg bridges and Romanian deadlifts, also load the muscle.

Regular exposure to sprinting

Hamstrings are best prepared for sprinting by sprinting. Programs that include progressive high-speed running, building up over time, prepare the muscle for the demands of games. Our article on speed training and sprint mechanics covers how to build that exposure.

Hip, glute and core work

A stable pelvis and strong glutes share the work of running with the hamstrings. Exercises such as bridges, step-ups and core stabilization are part of a balanced program.

Warm-up

A proper warm-up raises muscle temperature and gradually increases the speed of movement. A sensible warm-up builds from jogging and dynamic movement to short accelerations before full-speed running. Our article on injury prevention, warm-ups and prehab outlines one approach.

Workload management

Coaches can reduce risk by increasing sprinting and conditioning gradually after layoffs, avoiding the largest spikes in volume, and watching players who show signs of fatigue. The first week of preseason is a time to be careful.

Flexibility and mobility

Maintaining a good range of motion is part of general health, but a stretching-only plan is not a reliable hamstring prevention strategy on its own.

A hypothetical return to sprinting

To see why the progression matters, imagine a defensive back who strained a hamstring and has been cleared by his medical staff to start running again. This is an illustration, not a prescription, and a real plan would come from the athlete's own clinicians.

In the first running sessions he jogs and does gentle accelerations at well under full effort, stopping if the muscle tightens. A few sessions later, he adds longer strides at about three-quarters effort. Only after those feel normal, and after strength tests look good, does he try short sprints at close to full speed, and the staff watches his stride for any sign of favoring the leg. Cutting and backpedaling drills come after that, and the final step is practicing against receivers at game speed.

Every stage has a pass-or-wait rule: if the leg is sore afterward or the stride looks uneven, he repeats the stage instead of advancing. That patience feels slow to an athlete who wants to play, but it is far shorter than missing another month with a second injury. The same logic applies to a high school player who is eager to return for a rivalry game.

Common mistakes

• Playing through "tightness." A tight hamstring that worsens with running is a warning sign, not a toughness test.
• Skipping the warm-up. Cold, sudden sprints are a classic setup.
• Doing only the quick exercises. Eccentric strength takes weeks to build and must be maintained.
• Returning at the first day of no pain. Strength and sprint readiness lag behind comfort.
• Ignoring the rest of the chain. Hip and core weakness can overload the hamstrings.
• Self-diagnosing. A sharp pain in the back of the thigh can also come from other issues, including the lower back or nerves, so get it checked.

For fantasy managers and fans

Hamstring injuries are a staple of the weekly injury report, and they are famous for lingering. A player listed with a hamstring issue may play through it at reduced speed, miss a week or return and re-injure it. Fantasy managers can use the fantasy resources and the injuries page to see how a player's status changes during the week, and should be cautious about expecting full-speed output from a receiver or running back who just came back from a hamstring problem. The same applies to a player's profile as you look into a particular athlete. It is a general caution, not a prediction about any individual.

The short version

• The hamstrings are three muscles at the back of the thigh that bend the knee, extend the hip and brake the swinging leg during running.
• Most strains happen during high-speed running or extreme stretching, and a previous hamstring injury is the strongest known risk factor.
• Strains are graded from mild to severe by a clinician, and recovery ranges from days to months depending on the grade and the location.
• Rehabilitation has to rebuild eccentric strength and gradually restore sprinting, not only remove pain.
• Re-injury is common, often because of rushed returns or stopping the strength work.
• Eccentric strengthening such as the Nordic hamstring exercise, regular progressive sprinting, hip and core work, a good warm-up and careful workload management lower the risk.