TempoLife › Features › Muscle and body-part reference › hamstrings
Hamstrings
Three muscles spanning hip and knee that extend the hip, bend the knee, and are the most commonly strained muscle group in sprinting sport.
Latin name: Musculi ischiocrurales. In plain English, the three muscles at the back of the thigh. It is filed here under thigh.
Reference information, not a diagnosis. Where a symptom is described below, it is there so you can describe your own more precisely to a clinician — not so you can name what you have.
Where it is
All three hamstrings but one head arise from the sitting bone, the ischial tuberosity, and run down the back of the thigh to cross the knee — biceps femoris to the outside, semitendinosus and semimembranosus to the inside. Because they cross both the hip and the knee, their length depends on the position of both joints at once, which is why a straight-leg raise feels so different from a knee extension while seated.
The short head of biceps femoris is the exception: it arises from the femur, crosses only the knee, and has a different nerve supply from the rest of the group. That difference in innervation is occasionally significant in nerve injuries.
| Feature | Detail |
|---|---|
| Muscles | Biceps femoris (long and short heads), semitendinosus and semimembranosus |
| Origin | Ischial tuberosity for all except the short head of biceps femoris, which arises from the linea aspera and lateral supracondylar line of the femur |
| Insertion | Biceps femoris to the head of the fibula; semitendinosus to the pes anserinus on the medial tibia; semimembranosus to the posterior aspect of the medial tibial condyle |
| Nerve | Tibial division of the sciatic nerve (L5-S2); the short head of biceps femoris by the common fibular division |
| Main actions | Extension of the hip and flexion of the knee; rotation of the flexed knee |
What it does
They extend the hip and flex the knee, but in running they rarely do either in isolation. Their hardest work happens in late swing phase, when the leg is reaching forward: the hamstrings contract while lengthening to slow the shin down before the foot lands. That eccentric braking action, at long muscle length and high speed, is where sprint-related strains occur, and biceps femoris long head is the usual site.
This is also why eccentric training has become the standard preventive approach. Programmes built around the Nordic hamstring curl, which loads the muscles eccentrically at long length, have been shown in team-sport trials to reduce hamstring injury rates. It is one of the better-supported injury prevention findings in sports medicine.
Exercises that load it
| Exercise | Category | Muscles the exercise library lists |
|---|---|---|
| Deadlift | Strength | Hamstrings, glutes, back, grip |
| Kettlebell swing | Conditioning | Glutes, hamstrings, back, core |
| Glute bridge | Strength | Glutes, hamstrings, core |
| Tempo running (12 km/h) | Cardio | Legs, heart, lungs |
| Rowing machine | Cardio | Legs, back, arms, heart |
Hip-hinge movements — deadlifts, Romanian deadlifts, good mornings, swings — load them as hip extensors under stretch. Leg curls and Nordic curls load the knee flexion role, the second with a strong eccentric emphasis. Sprinting loads them harder than any gym exercise, which is why returning to sprinting after a strain needs to be built up deliberately rather than tested all at once.
How it is lengthened
A standing or seated forward reach with the knee straight, or a supine strap stretch with the hip flexed and the knee gradually straightening, are the standard ways. Keep the pelvis tipping forward rather than rounding the lower back — otherwise you are stretching the back, not the hamstrings. Nerve tension can mimic hamstring tightness, so a stretch that produces tingling or a sharp line down the leg should be eased off and mentioned to a clinician.
When it goes wrong
| Problem | What it typically feels like | Usual setting |
|---|---|---|
| Acute hamstring strain | A sudden grab at the back of the thigh during sprinting, with pain on stretch and on contraction | Maximal-speed running; most often the long head of biceps femoris near the musculotendinous junction |
| Proximal hamstring tendinopathy | A deep ache right at the sitting bone, worse with sitting, and with stretching or uphill running | Gradual overload in runners; slow to settle and often mistreated with aggressive stretching |
| Referred nerve pain | A line of pain or tingling down the back of the thigh that does not behave like a muscle injury | Lumbar nerve root or deep gluteal nerve irritation rather than a muscle problem |
A sudden pop at the sitting bone with severe bruising and difficulty walking can be a tendon avulsion and needs prompt assessment. Back-of-thigh pain with numbness, weakness or pain past the knee is more likely nerve-related and should be examined.
Nothing on this page is a treatment plan. If a problem is limiting what you do, is not improving, or is getting worse, the right next step is an assessment by a doctor or a physiotherapist who can examine you.
Sources: descriptive anatomy from Gray's Anatomy of the Human Body, 20th US edition (1918), which is in the public domain; Latin names follow Terminologia Anatomica, published by the Federative International Programme for Anatomical Terminology. Nerve root levels are the conventional ranges taught from those sources and vary between individuals and between textbooks. Exercise cross-links use the TempoLife exercise library. Checked 2026-09-06.
Frequently asked questions
Why are hamstring injuries so common in football?
Because sprinting loads these muscles eccentrically at long length and high speed, which is the most demanding thing you can ask of a muscle. Sports with repeated maximal sprints see the most of them.
Do Nordic curls prevent hamstring injuries?
Programmes including eccentric hamstring exercises such as the Nordic curl have reduced hamstring injury rates in trials in team sport. Compliance is the hard part — the exercise is demanding and produces significant soreness at first.
Is tight hamstrings the reason I cannot touch my toes?
Sometimes, but not always. Toe-touch range depends on hamstring length, hip mobility, lower back flexion, and nerve sensitivity. Plenty of people with strong flexible hamstrings still cannot reach the floor.
Nearby in this reference
Quadriceps femoris
The four muscles at the front of the thigh
Deltoid
The cap of the shoulder
Rotator cuff
The four small muscles that hold the shoulder in its socket
Trapezius
The big diamond across the upper back and neck
Rhomboids
The straps that pull the shoulder blades together
Serratus anterior
The finger-like muscle on the ribs that pins the shoulder blade down
All 34 body parts · Exercise library · Body map
Training is easier to judge when it is written down
TempoLife logs workouts, steps and sleep together, so a week of training and a week of recovery can be read side by side.