Stick to stable exercises with lots of ROM, that are limited by the target muscle group and that you can load properly. Good hamstring exercises include Seated Leg Curls, RDLs and GMs. Rather than using the wrong exercises, many people are performing the right exercises improperly. The most common offender is poorly performed hip hinges.

A not-so-brief note on biomechanics

Before delving into exercise selection, I thought I would address something not many people think about. Why do RDLs do a better job of targeting the hamstrings, than, say, a conventional deadlift? Why are squats a bad hamstring exercise?

Understanding why this is will (hopefully) stop seeing conventional/sumo deadlifts and squats as great hamstring exercises. The reason is that the hamstrings (well, 3 out of 4 heads, at any rate) are biarticular muscles. This means that they attach both at the knees but also at the hips.

The hamstrings’ functions are to extend the hip (like a hip thrust or RDL) and to flex the knee (like a leg curl). This means that when your knees are being extended, your hamstrings lengthen, and vice versa. This also means that when your hips are being flexed, your hamstrings lengthen, and vice versa.

Here’s why squats and deadlifts aren’t the best hamstring builder: we know that training a muscle group at long lengths is useful for growth. We also know that for a muscle group to grow & contribute as much as it can to a movement, it should shorten quite a bit. For squats and deadlifts, because you are simultaneously extending the hips and the knees, the hamstrings are shortening at the hips while being stretched at the knees. Because of this same reason, you also never get a great hamstring stretch from these exercises. The result? Deadlifts and (especially) squats aren’t a great hamstring exercise.

This is where RDLs and Good Mornings come in – provided they are properly performed, which they rarely are. By locking the knee in place just shy of full extension (i.e. not letting it move) while you let your hips flex and extend, you achieve two things:

1. You get a great hamstring stretch. Because knee extension lengthens the hamstring, and you’re near full knee extension, your hamstrings are lengthened at the knee. Then, when you flex the hips (i.e. go down in a RDL or GM), you further stretch the hamstrings at the hips. By the time you get to the bottom of a RDL or GM, you’ve stretched the hamstrings about as much as they physically can.. and, since we know that training at long lengths is good for growth, this is a good thing.

2. Your hamstrings can actually shorten and do a lot of work. Because the hamstrings are no longer being lengthened at the knee, they can actually shorten and effectively contract under tension to a greater extent than they would during normal deadlifts or squats.

Taken together, these two points mean that RDLs and GMs are MUCH better options for hamstring growth than normal deadlifts or squats.

Seated Leg Curls

If all I was concerned with was growing the hamstrings*, the seated leg curl might be the single best exercise. There’s been an emerging line of research that shows training a muscle group through its longer lengths (i.e. through more stretched positions) seems to induce more growth. As such, seated leg curls have been suggested to be better for hamstring growth than lying leg curls.

Additionally, you need to consider that the hamstrings has 4 heads. Three of them (the biceps femoris’ long head, the semi-tendinosus and the semi-membranosus) contribute to hip extension (like a RDL), while all 4 heads (the 3 I mentioned + the short head of the biceps femoris) contribute to knee flexion (like a leg curl).

What does this mean? When performing RDLs or Good Mornings, you’re not training the entirety of the hamstrings. Leg Curls, on the other hand, train all 4 heads. So, if I had to pick ONE exercise for just hamstrings, I’d pick seated leg curls.

*Importantly, while seated leg curls probably do a better job of stimulating the hamstrings, it’s certainly possible that lying leg curls would reduce the contribution of the hamstrings, relying moreso on other knee flexors (like the gastrocnemius) that don’t attach at the hip and whose length isn’t impacted by hip position. Because of this, for good overall physique development (i.e. not just hamstring/bicep/tricep/calf size, but all muscle groups who do similar functions without being biarticular/attaching at another joint), you’re likely best off including both exercises that maximise the stretch on a single muscle group (i.e. hamstrings in the seated leg curl) and exercises where the stretch on that muscle group isn’t the emphasis, potentially allowing other agonist muscle groups to get stimulated more.

RDL Variations

There’s a lot of RDL variations. Provided you can perform them with a good SFR (Stimulus to Fatigue Ratio), the exact variation doesn’t matter too much. That being said, here’s a few things I’ve encountered in trying some of them.

Barbell RDLs: These are a solid option. If I had to nitpick, the fact that you either have to walk the weight out of the rack or do a first rep without a stretch reflex lowers the exercise’s SFR slightly.

Trap Bar RDLs: These are also a solid option. The same minor criticism applies as for BB RDLs. A few slight advantages the trap bar has is that it may be safer and that it can be used for extra forearm stimulus (since it is easier to hold on to RDL-weight without straps than it is for straight bar RDLs). Finally, one minor issue that can lower its SFR is the instability component – if you grip the weight slightly off-center, the bar can roll forwards/backwards, throwing off technique and lowering SFR.

DB RDLs: These are also a solid option. The same minor criticism applies as for BB RDLs. Another minor/major issue (depending on your size) is how awkward the lift can get with heavier/bigger dumbbells and bigger thighs. The dumbbells will rub against the front/side of your thighs, making the exercise awkward, potentially lowering its SFR.

Smith Machine RDLs: These are a solid option. Unlike all the other options, you don’t need to walk the weight out or do an awkward first rep. However, one limitation this does suffer from is that it becomes quite hard to re-rack the weight after a set when the weight gets heavy. You could leave the weight on the floor, but that would re-introduce the issue of the first rep being rough, lowering SFR.

Good Morning Variations

GM Variations fill a similar niche to RDL variations. They train hip extension without knee movement, making them a great hamstring exercise. They are less stimulative of forearm/upper trap growth - not that RDLs are the best exercise for forearm/upper trap growth either – but are also less fatiguing. One way of viewing GMs is as a slightly less compound hip extension exercise than RDLs.

I think GMs are a good substitute and/or addition to RDLs. For one, they likely stimulate your muscles in a slightly different way, which makes them useful for exercise variation. Secondly, in my experience (as well as some of my clients’), they can be done more successfully for higher rep ranges. Don’t get me wrong – I’m not suggesting you do sets of 30 on GMs. However, while I’ve rarely had much success programming RDLs for much more than 12 reps, I’ve had success with doing GMs in the 10-20 rep range. Finally, one minor (but noteworthy, should you struggle with this) consideration is that the bar being on your back can give certain muscle groups a bit more of a break. For example, if the long head of your triceps is constantly sore and/or injured from lots of back, triceps and compound front delt and chest work, GMs can be a good substitute for RDLs.

Suboptimal exercises

Poorly performed “hip hinges”

RDLs are rather commonly butchered. An emphasis on load over technique has led many people to cut their ROM, let their knees flex during the eccentric and round their back in the pursuit of “touching new weights” and “growing new tissue”. All 3 of these mistakes reduce the stimulus gained and/or increase the fatigue generated from doing the exercise. Cutting your ROM likely leads to worse growth, letting your knees flex effectively does the same thing (remember: flexing the knees shortens the hamstrings, which means they go through less ROM) while also allowing you to use more load and fatiguing your quads and rounding your back may lead to an increase in injury risk for no additional hamstring stimulus.

Nordic Curls

Now, before the Strength & Conditioning staff from sport organizations all around the world send me death threats, let me explain my stance. Nordic Curls are a fine exercise for injury prevention. They require next to no equipment (provided you have a training partner), are specific to most sports (you rarely end up in deep knee flexion, so training those joint angles isn’t as beneficial as training the more shallow ones) and heavily load the hamstrings eccentrically (which, if my memory isn’t failing me, is favourable over concentric work for injury prevention).

But… for growth? They’re not great. First off, being strong enough to do them for more than 5 reps (BOTH the eccentric and the concentric) is very rare. We know sets of less than 5 reps probably aren’t as good at growing muscle than sets of 5-30 reps, so that’s an issue for most people. Secondly, the Nordic curl is fundamentally partial ROM for knee flexion; the most ROM you can get under tension is 90 degrees. A properly performed lying leg curl, for instance, is usually around 120 degrees or more of knee flexion. Finally, while this is a minor gripe (RDLs and GMs somewhat suffer from this same limitation, to be fully transparent), the resistance curve of the Nordic leg curl is probably suboptimal. The exercise is virtually unloaded at the start of a rep and gets super difficult at the bottom. This probably diminishes its “effective” (i.e. under tension) ROM all the more.

 

That wraps up the hamstrings. More muscle group exercise selection articles on the way!

Reminder: if you’d like to see what effective hamstring programming looks like, check out the Hamstring Specialisation Template. For the first week, it will be 33% off!