How to Do the Jefferson Curl to Strengthen Your Back and Stretch Your Hamstrings

The Jefferson curl is an exercise that mobilizes the spine, strengthens the muscles of the lower back and core and provides a stretch for the hamstrings. If you have a healthy back, this movement can help you increase the strength and resiliency of your spine.

Most common strength-training exercises recruit the lower-back muscles in a supporting (aka stabilizing) role. For example, when you do a push-up, you want your lower back and core muscles to help lock your torso into place.

It's less common to directly train your lower-back muscles or take your spine through its full available ranges of flexion. Because the Jefferson curl exercise does exactly this, it may be the perfect move to help you strengthen your lower back and improve its mobility.

• ​What is a Jefferson curl?​ The Jefferson curl is a spinal articulation exercise. This means you intentionally bend over through your spine, flexing your lumbar spine as much as possible before standing up again.
• ​Who invented the Jefferson curl?​ If you're wondering about Jefferson curl history, the move is named for Charles Jefferson, a famous circus strongman performer known for lifting impressive amounts of weight off the floor in a variety of ways. Other exercises, including the Jefferson deadlift, were also named after him.
• ​What muscles do Jefferson curls work?​ Jefferson curls primarily target the muscles of the low back including the erector spinae, spinal extensors and internal obliques. They also provide a loaded stretch for your hamstrings.
• ​Does the Jefferson curl build muscle?​ Any strength-training exercise has the potential to build muscle. However, because the Jefferson curl stretch typically uses light weights and fewer sets and reps, you shouldn't expect this exercise to pack on muscle. It primarily functions as a strength and mobility exercise, not a hypertrophy (muscle building) exercise.
• ​Who can do the Jefferson curl?​ If you have no history of back pain and you've already spent some time building strength in your core, glutes and hamstrings, you can begin to add the standing Jefferson curl to your training. Folks with pre-existing back pain — especially flexion-intolerant back pain where your back hurts when you bend over — or anyone who experiences tingling or numbness in their legs should skip this one for now.

If you've been lifting weights for any amount of time, you've probably heard that rounding your back is bad and should be avoided at all costs. But is this really supported by evidence?

In a March 2021 article in ​Strength and Conditioning​, researchers compared numerous studies that examined the relationship between back injuries and different types of training. When looking at studies that measured lumbar spine flexion (rounding of the back) during lifting tasks, researchers found little evidence to support the idea that rounding your spine when lifting something boosts your risk of injury.

Earlier August 2011 research published in ​Strength and Conditioning​ observed that the claim that dynamic flexion exercises injure your spine (if your spine is healthy) remains "highly speculative." This is due to the fact that most studies surrounding this topic have been done on animals, not humans.

Most of these studies reached their conclusions by observing spinal injuries occurred after taking animal spines through several thousand consecutive flexion cycles. However, this might not be relevant for humans because no human ever performs that many reps in a row during a workout.

The time you take to rest and recover between sets and between workouts may also help your spine become stronger and less prone to injuries, according to the March 2021 article.

If you have a healthy back, research suggests including a small amount of spinal-flexion training in your workout probably won't lead to injuries. It may actually make you more resilient and less likely to get hurt in the future.

With that said, some folks should stay away from flexion exercises like the Jefferson curl. If you already have a hurt back or know bending over exacerbates pain, you should probably avoid flexion for now, according to the August 2011 study.

Genetic factors also play a big role in the likelihood that you'll develop back problems, according to the March 2021 article. If someone in your immediate family has back pain or has had a back injury, you may want to be more cautious about including movements like the Jefferson curl in your own workouts.

Your core and lower back primarily play stabilizing roles when you move, helping to resist unwanted movement and transferring the force between your powerful hips and upper body. However, this area of the body is capable of extending (arching) and flexing (rounding). By targeting these movements, you can improve overall core and low-back strength.

Most core and lower-back exercises don't take your muscles through a complete range of motion. The Jefferson curl is different because it takes your spine through its full range of flexion. Doing this exercise can help make your core training more well-rounded.

Many people who complain of tight hamstrings actually have overly lengthened hamstrings due to anterior pelvic tilt (when the front part of your pelvis is rotated downward). For others, however, that tight feeling really does come from the hamstrings. Combining stretching exercises with core strengthening and focusing on proper lifting form can help.

One of the best ways to stretch your hamstrings is by adding load to the Jefferson curl. Weights help gently pull your body into a deeper stretch than you could achieve on your own. With the Jefferson curl, you can combine the force of gravity with the external force of the weight you're holding to provide a great hamstring stretch.

Perhaps the biggest benefit of the Jefferson curl is it can make you more resilient by exposing your body to positions you aren't typically in. Many injuries happen because life sometimes throws your body into unpredictable positions. When external forces — such as slipping on ice or picking up a heavy object at a weird angle — overwhelm your internal resources to manage them, you can get hurt.

Physical training can safely expose you to new and different positions. Ideally, your workouts have you moving in multiple planes of motion, using different body positions (supine, half kneeling, standing, etc.) and training all the major movement patterns of the body (squat, lunge, hinge, push, pull, carry, etc.). You try something new, then you take time to rest, adapt and build back stronger. In this way, your ability to handle greater loads and feel strong in many situations increases over time.

Although the old adage says you should "lift with your legs, not your back," it's totally unrealistic to expect that you'll never round your spine. Most of us round our spines every single day to pick up small items from the floor, tie our shoes or get out of bed.

Spinal flexion shows up during lifting exercises (such as squats and kettlebell swings) even when people are specifically coached to avoid it, according to the March 2021 article. Fearing spinal flexion and avoiding it at all costs actually makes you more fragile and can increase your expectation of pain.

So, instead of being afraid to bend over, prepare and train for it. Begin with body-weight flexion movements, then gradually progress up to loaded Jefferson curls. When your body is more familiar with spinal flexion, you may be less likely to get hurt in that position in the future.

If you're just getting started with spinal-flexion training, you should take your time easing into the movement before adding extra load or range of motion.

You can turn the Jefferson curl into a body-weight, floor-based movement that's perfect for a warm-up or cooldown. This is also a great option for people wanting to do the Jefferson curl at home who may not have a box or step to stand on.

When you can do this body-weight version without struggling to touch the floor, you can consider moving up to the box so you can get a fuller range of motion. You can always continue to practice without weights on the box if you don't yet feel ready to add more load or don't have a box available.

If you want to increase the difficulty of this exercise, it's better to do so by changing your body position as opposed to increasing the amount of weight used. Performing the Jefferson curl on a slanted or angled box increases the stretch on your hamstrings, making the exercise more challenging.

You should never experience any pain while performing this exercise. If you do feel pain, take a step back and reduce or remove the weight. If you still feel pain after making these changes, the Jefferson curl is probably not a good fit for you, and you should remove it from your workouts.

Perform the Jefferson curl slowly so you can focus on moving at each segment of your spine. Going slowly increases your ability to control your body and get the most out of the exercise. When you go too fast, you lose a lot of the potential benefits of strengthening and mobilizing your spine.

The hip hinge is the movement pattern behind familiar exercises like deadlifts and kettlebell swings. It requires you to slightly bend your knees while reaching your hips as far back behind you as you can. During a hip hinge, your spine primarily stays neutral, which means it doesn't move very much in either direction.

Jefferson curls should look very different than hip hinges. Instead of trying to keep your back relatively neutral, you should round it as much as possible. And instead of reaching your hips back behind you, keep your hip position relatively stable as you bend over.

Some people bend their knees too much when performing the Jefferson curl to compensate for tight hamstrings. But when you bend your knees, you lose some of the benefits of this exercise. Keep your knees as straight as possible to get the best hamstring stretch.

Jefferson curl weight should be fairly light. The risks of going heavy outweigh the benefits of the exercise, so don't worry about adding lots of load from week to week. It's best to be conservative and focus on moving with good control in as full of a range of motion as you can handle. To gauge this, you should have about 3 to 5 reps left in the tank at the end of each set.

Most of us come to the gym either right after waking up or after a long day of sitting in front of a computer. In both of these scenarios, your spine has been locked in one position for an extended period of time. So, how often should you Jefferson curl? It's a good idea to gently mobilize your spine before you engage in an intense exercise session. Begin with the cat-cow stretch on the floor, then progress to the Jefferson curl.

Powerlifters like to use Jefferson curls at the end of a leg day filled with heavy squats and deadlifts. Lifting heavy barbells compresses the spine. When you perform the Jefferson curl, you help to alleviate some of this pressure and kickstart the recovery process. Try pairing Jefferson curls with dead hangs for a full-body stretch that feels fantastic after lots of heavy lifting.

You don't need a lot of volume to get the benefits of Jefferson curls. Begin with just 2 to 3 sets of 5 to 10 reps. As you get stronger, you can add another set or a few more reps as needed. Just keep in mind that for the Jefferson curl, less is often more.