The hamstring group has three muscles, not four. This gets miscounted constantly because the biceps femoris has two heads, so people list four names and call it four muscles. The three are biceps femoris, with a long head and a short head, semitendinosus and semimembranosus.
That detail matters for training, because the short head of the biceps femoris is the one exception in the group. Every other hamstring crosses both the hip and the knee, originating on the ischial tuberosity of the pelvis and attaching below the knee. The short head starts on the femur itself, so it only acts on the knee. Everything else in the group extends the hip and flexes the knee, which is why hamstring training that only involves one of those two joints leaves work on the table.
the exercise with actual outcome data
Almost no single exercise has been tested for injury prevention with the rigor applied to the Nordic hamstring curl. Multiple systematic reviews and meta-analyses of team sport athletes have found that programs including it cut hamstring injury incidence by roughly 51 percent compared with programs that do not. A 2024 review in the sports science literature reported the same figure, up to 51 percent.
The mechanism is eccentric loading at long muscle length. You kneel, have a partner hold your ankles or wedge them under something solid, and lower your torso toward the floor as slowly as you can while keeping hips extended. The hamstrings lengthen under high tension, which is precisely the condition in which they tear during sprinting.
The honest caveat: those injury reduction numbers come from athletic populations, mostly soccer players, who sprint at maximum speed regularly. If you do not sprint, your baseline hamstring injury risk is much lower and the absolute benefit shrinks accordingly. The strength gains still transfer.
Nordics are also hard. Most people cannot control the first half of the descent, let alone the bottom. Start with a band looped around your chest and anchored overhead to take load off, or do the eccentric portion only from a shallower angle. Two sets of five, twice a week, is a reasonable starting dose and it will make you sore for several days the first time.
where the standing leg curl fits, which is barely
The standing leg curl, where you balance on one leg and curl the other heel toward your glutes, gets prescribed as a hamstring exercise. It is mostly a balance drill.
Body weight alone provides almost no resistance to knee flexion in that position, because you are lifting a lower leg against gravity through a short lever. The load is trivial for anyone who trains at all. Standing on a Bosu ball makes the balance harder without making the hamstring work harder, which is the opposite of progressive overload.
If you want the movement pattern with real load, use a cable with an ankle strap or a machine. If you want balance training, do single-leg work that loads something: single-leg Romanian deadlifts, split squats, step-downs. The Bosu ball progression takes a low-value exercise and makes it a lower-value exercise more slowly.
the two functions, split into exercises
| Exercise | Primary function trained | Notes |
|---|---|---|
| Romanian deadlift | Hip extension, long length | Highest loadable option, best glute involvement |
| Nordic curl | Knee flexion, eccentric | Only exercise with injury-prevention outcome data |
| Single-leg RDL | Hip extension plus stability | Exposes side-to-side differences |
| Hip thrust | Hip extension, short length | Glute-dominant, hamstrings secondary |
| Lying or seated leg curl | Knee flexion, loaded | Seated version trains longer muscle length |
| Standing leg curl, body weight | Balance | Minimal hamstring stimulus |
A reasonable week covers both joints: one hip-extension exercise loaded heavy, one knee-flexion exercise, and one single-leg variation. Three exercises total. Everything beyond that is preference.
the glute question
An article title about the backside usually means glutes, and the hamstrings are the supporting cast there. The gluteus maximus is the primary hip extensor and it responds to loaded hip extension: squats, hip thrusts, Romanian deadlifts, step-ups, and sprinting.
The claim I would push back on is that the hip thrust is the superior glute exercise because EMG readings are high. EMG measures electrical activation during a movement, which correlates with muscle growth imperfectly at best. A 2020 comparison of squats and hip thrusts found different patterns of gluteal hypertrophy across regions of the muscle rather than one exercise winning outright. Doing both is a better bet than optimizing between them based on a surface electrode reading.
the progression nobody respects
Hamstrings respond to load, and most people never load them. Body weight glute bridges on a mat for three sets of fifteen is a warm-up, not a stimulus, and doing it for a year produces a year of warm-ups.
If you can do fifteen reps of something without effort, it is not building anything. Add weight, add a single-leg variation, or slow the eccentric to four seconds. The Romanian deadlift in particular should climb: a woman who trains consistently for a year should be pulling a loaded barbell, not holding 10-pound dumbbells.
the tightness misunderstanding
People who feel tight hamstrings usually stretch them. That sometimes helps and sometimes makes things worse, because the sensation of tightness is not always short muscle. A posteriorly tilted pelvis from sitting puts the hamstrings under passive tension all day, and they feel tight while already being lengthened. Stretching a muscle that is already long does not address the position causing it.
The test: lie on your back and raise one straight leg. If you get to roughly 80 degrees, your hamstring length is fine and tightness is a neural or positional issue rather than a flexibility deficit. Loading through a full range, as in a controlled Romanian deadlift, tends to improve that sensation more reliably than static stretching does.
If you have a history of hamstring tears or ongoing pain at the ischial tuberosity, get it assessed rather than training through it. High hamstring tendinopathy in particular responds to specific loading and gets worse with the aggressive stretching most people default to.