Football Injuries: Concussion, Knees, Ankles, Heat and the Heart

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Third quarter on a Friday night. The running back takes a hard hit at the sideline and gets up a beat too slowly, shaking his head. The athletic trainer is already jogging over. Football injuries come with a collision sport, from youth leagues and high school to college, the NFL and adult flag and tackle leagues. Knowing what to look for, and when to pull a player out, matters more than any piece of gear.

Below: the injuries football players get most, how to spot them, how to lower the risk and when to see a professional. It’s general information, not medical advice.

How often football players get hurt

In a national study of US high school football, athletic trainers recorded 4.08 injuries per 1,000 athlete-exposures (one practice or game per player). Player-to-player contact caused 64% of them, most often while being tackled (24.4%) or tackling (21.8%). In college, football has more catastrophic injuries than any other sport, according to recommendations endorsed by 13 medical organizations. That’s a reason to take prevention and emergency plans seriously.

Concussion: recognize and remove

Of 20 high school sports in a five-year study, football had the highest concussion rate: 10.4 per 10,000 athlete-exposures. The CDC’s HEADS UP program asks everyone on the sideline to watch for a player who looks confused or stunned, reacts slowly, is suddenly clumsy or has sudden memory problems, and to listen for headache, dizziness or balance problems, nausea, sensitivity to light or noise, or feeling slowed down.

• Remove the player from play right away after a hit to the head or body if you see any signs. Don’t try to judge how serious it is yourself.
• Keep them out for the rest of that day and until a healthcare provider clears them. Signs can appear hours later.
• Return in steps: getting back to full contact goes stage by stage under a provider’s care and usually takes a week or more.
• Call 911 for danger signs: a seizure, passing out or extreme drowsiness, a headache that keeps getting worse, vomiting that won’t stop, slurred speech, weakness or numbness, growing confusion, or one pupil larger than the other.

Lowering the risk. Practice is where contact is easiest to control, so the National Federation of State High School Associations (NFHS) recommends full contact (“thud” and “live action”) in no more than 2–3 practices a week, ideally no more than 30 minutes a day and 60–90 minutes a week. A well-fitted helmet may lower concussion risk but can’t eliminate it, the NFHS adds. The American Academy of Pediatrics asks for zero tolerance for illegal head-first hits, proper tackling technique, athletic trainers on sidelines and more flag football options for kids. In the NFL, players in sessions where the soft Guardian Cap helmet shell was required had nearly 50% fewer concussions than the pre-mandate average, and 2024 had the fewest preseason concussions since tracking began in 2015.

CTE: what we know and what we don’t

Chronic traumatic encephalopathy (CTE) is a brain disease that, the CDC says, can only be diagnosed after death. Research suggests it’s caused in part by repeated head injuries, including concussions and the smaller hits that cause no symptoms.

The research on football is striking. In a 2017 study of 202 brains donated by families of former players, CTE was found in 177, including 110 of 111 former NFL players, 48 of 53 college players and 3 of 14 high school players. A 2020 study of 266 donated brains found the odds of CTE roughly doubled with every 2.6 years of football played. The researchers stress these were donated brains, a “convenience sample” that leans toward players whose families saw problems, so they don’t show how common CTE is among all players. The CDC adds that nobody knows how many hits raise the risk, and that most people with past head injuries don’t develop CTE.

What you can act on: fewer total hits to the head (contact limits, technique, flag football for young kids if your family chooses) and taking every concussion seriously. Changes in memory, mood or behavior in a former player deserve a doctor’s visit; many of these symptoms can be treated. In crisis, call or text 988.

Knee injuries: ACL and MCL

The MCL (medial collateral ligament, on the inner side of the knee) is often hurt by a blow to the outside of the knee, for example from the side in a pile or block. AAOS says MCL tears make up as much as 43–52% of all knee injuries and names football among the sports where they are more common. The ACL usually tears without contact, when a player plants and cuts, pivots or lands awkwardly. The NFL reported that ACL tears dropped 25% in the 2025 regular season, tying a seven-season low, mostly through fewer non-contact tears.

Some linemen wear hinged knee braces. A look-back study of NFL offensive linemen (2014–2020) found brace wearers had fewer major knee injuries, though it can’t prove the braces caused it. Ask your athletic trainer first. A soft knee sleeve adds warmth and compression but isn’t a ligament brace. See a professional for a “pop,” quick swelling, a knee that gives way or locks, or pain putting weight on it.

Ankle sprains and the high ankle sprain

The usual ankle sprain happens when the foot rolls inward. A high ankle sprain is different: it injures the syndesmosis, the ligaments that hold the two lower-leg bones (tibia and fibula) together just above the ankle. AAOS says a high ankle sprain can usually be treated without surgery but may take longer to heal than a normal sprain; when it comes with a fracture, surgery is needed. Pain above the ankle or a sprain that isn’t improving needs a check.

Bracing has real evidence in football. In a trial of 2,081 players at 50 high schools, those who wore lace-up ankle braces had less than half the rate of acute ankle injuries of players without them (0.48 vs 1.12 per 1,000 exposures). The braces didn’t reduce knee injuries or make injuries less severe. See our ankle brace guide.

Shoulder injuries, burners and stingers

• Shoulder separation (AC joint): usually from a fall or hit directly onto the point of the shoulder, which damages the ligaments where the collarbone meets the shoulder blade. Most people recover without surgery, AAOS says.
• Dislocation: the ball of the upper arm comes out of the socket. Get medical care; don’t put it back yourself.
• Burners and stingers: a stretched or pinched nerve in the neck and shoulder sends a burning or electric shock down one arm, often with numbness or weakness. AAOS says tackling or blocking in football is the activity that causes them most. No return until symptoms are fully gone, and never with weakness or neck pain. Symptoms in both arms or repeat stingers need a full exam.

Hamstring strains

Hamstrings usually go during sprinting, when the muscle is stretched and loaded at the same time. In an NFL review of 2008–2020, 2,101 hamstring injuries hit 1,354 players, and a third of them got hurt again. The best-studied prevention is the Nordic hamstring exercise: a 2019 analysis of 15 studies and 8,459 athletes found programs that include it cut hamstring injuries by up to 51%. Start it in the off-season (see football training) and build up slowly.

Heat illness: the preventable emergency

Exertional heat stroke is the leading cause of preventable death in high school sports, says the NFHS, and football carries most of the risk. In a CDC study of high school athletes, football players had heat illness at 10 times the rate of eight other sports; 70.7% of cases happened in football and 66.3% in August. The NFHS reports that football heat stroke deaths have happened during conditioning, not games, mostly in the first days of a new season, and 97% have involved linemen, whose bigger bodies make more heat and shed it slowly.

Prevention is a gradual start in the heat (see preseason heat acclimatization), water breaks, lighter gear and practices when it’s hot and humid, and watching every player. Clumsiness, stumbling, collapse, confusion or acting strangely mean stop, call 911 and start cooling on site: the NFHS says an ice-water tub is the preferred method, and the rule is “cool first, transport later.”

The heart: sudden cardiac arrest

On January 2, 2023, Buffalo Bills safety Damar Hamlin collapsed after a tackle on Monday Night Football. Medical staff gave CPR and used an AED (automated external defibrillator) on the field; he survived and returned to play. He has said the cause was commotio cordis, a rare event where a blow to the chest stops the heart. The American Heart Association (AHA) calls sudden cardiac arrest the leading cause of death in student athletes and says immediate CPR can double or triple the chance of survival.

The NFL-founded Smart Heart Sports Coalition asks every school for three things: a written emergency action plan that is rehearsed every year, an AED within 1–3 minutes of every field, and CPR and AED training for coaches. If a player collapses and isn’t responding normally, call 911, start hands-only CPR (push hard and fast in the center of the chest) and get the AED.

When to see a doctor, physical therapist or athletic trainer

Every player should have a pre-season physical. After that, don’t play through pain. AAOS says a player with a joint injury should have no pain, no swelling, full motion and normal strength before returning, and a player with a concussion should be cleared by a doctor. A sports medicine physician manages most sports injuries without surgery, a physical therapist guides rehab, and an athletic trainer, a licensed health care professional, is often first on the field. Start there.

Protective gear worth having

Pop Warner’s required gear, as listed by AAOS, includes a mouth guard; the Shock Doctor Gel Max Power Carbon is a gel guard that molds to your teeth and works strapped or strapless. For ankles, the McDavid 195 is a lace-up brace with figure-8 straps, the style tested in that high school trial. The stiffer Zamst A2-DX is made for high ankle sprains, the maker says. For hot days, Thorne Advanced Electrolytes is our NSF Certified for Sport pick from the electrolyte guide.

Keep going: the football hub, game day, recovery after games, recovery tools, and our soccer section for another cleated sport.

Football injury FAQs

When can a player go back after a concussion?

Not the same day, and only after a healthcare provider clears them. The return goes in steps and usually takes a week or more.

Does playing football cause CTE?

Research links CTE to repeated head impacts, and more years of football were tied to higher odds in brain-bank studies. But CTE can only be diagnosed after death, studies so far used donated brains, and the CDC says most people with past head injuries don’t develop it. Fewer hits to the head is the sensible goal.

How long does a high ankle sprain take to heal?

Usually longer than a regular ankle sprain, depending on severity. A doctor may order X-rays or an MRI to rule out a fracture.

Should football players wear ankle braces?

Many can benefit: a high school trial found lace-up braces cut acute ankle injuries by more than half. They didn’t prevent knee injuries. Ask your athletic trainer.

What are the signs of heat stroke at football practice?

Clumsiness, stumbling, collapse, confusion or unusual behavior during hard work in the heat. Stop activity, call 911 and cool the player right away, ideally in an ice-water tub, before transport.