Main muscles worked
lower back, quadratus lumborum, multifidii, buttocks, hamstrings (the latter two muscle groups are especially heavily worked in back extensions that use conventional apparatus)
The multifidus muscle group is deep to the erector spinae, from the sacrum to the neck, and extends and rotates the vertebral column.
Capsule description
flex and extend your torso while keeping your legs fixed
The basic or conventional back extension, often called a hyperextension, has your legs fixed and your torso moves into line with them. In the reverse back extension, your torso is fixed and your legs move into line with it. The reverse back extension is a valuable exercise but it doesn’t provide the spinal flexion and extension of the conventional back extension, and the special apparatus required isn’t commonly available. Therefore, the reverse back extension isn’t included in this book.
Done correctly, back extensions involve safe flexion (or rounding) of the spine, and extension (or straightening) of the spine, whereas deadlifts, done correctly, primarily involve static contraction of the spinal erectors. For safety, deadlifts should never be performed with a rounded back.
The back extension strengthens the lower back in a way that deadlifts may not, because of the spinal extension of the former. The back extension may even strengthen some muscles of the lower back that deadlifts can’t. Back extensions aren’t, however, a substitute for deadlifts unless you’re unable to do any form of deadlift safely. When compared, deadlifts are whole-body exercises, whereas back extensions affect limited musculature.
For most trainees, back extensions and deadlifts are complementary, and correct use of both will produce the best overall results.
The top photograph shows a partially extended neck. In this exercise, maintain a neutral neck—neither extended, nor flexed.
A purpose-built apparatus is available in many gyms for the basic back extension.
Rest your upper thighs on the support pad, and your heels or calves against the rearmost support. With your hands on the floor, find the position so that the front edge of the support pad doesn’t hurt your groin. You may need additional padding over that edge. If the apparatus has adjustable components, fine-tune them for thigh and groin comfort.
Keep your knees slightly bent, to avoid exaggerated stress on them.
With your head and torso hanging vertically, cross your forearms on your chest. Raise your torso in a slow, smooth, controlled, symmetrical fashion until your torso is parallel with the floor, or just above parallel. Hold the top position for two seconds.
As you return to the starting position, gradually round (flex) your spine. Pause for a second at the bottom, then slowly and smoothly start the next rep. Rounding the spine on the descent, and then extending or straightening it on the ascent, are required for the best effect.
This exercise is commonly done with the hands behind the head, or with a plate held behind the head. Both place unnecessary strain on the neck and cervical vertebrae. Keep your forearms crossed on your chest, and hold a plate or dumbbell to your chest when extra resistance is needed.
Inhale at the bottom position or during the descent, and exhale during the ascent; or, just breathe freely—don’t hold your breath. You may need multiple breaths per rep.
Apparatus improvisation
If you don’t have access to a purpose-built apparatus for the back extension, or a machine, try an old-fashioned way. Elevate a horizontal bench on crates or boxes. Place your thighs on the bench, face down, and put your hands on the floor. Find the precise position on the bench that’s comfortable. Have an assistant hold you down, at your calves. You may need a folded towel under your knees, and over the edge of the bench, for padding. Then perform the basic back extension.
Alternatively, position a bench or board over the pins in a power rack, set at the appropriate height to permit a full range of motion at the bottom of the exercise. The bench or board must be secured in position so that it can’t slide off the pins during use. Furthermore, jam the rear of the bench or board between a pair of pins, so that it can’t come out of position during a set. Use a belt to strap your legs to the bench.
In both cases, experiment to find the position to be held or strapped to the bench that’s comfortable for your knees. Avoid compression of your kneecaps.
This is an alternative to the basic back extension. Exercise the same control, flexion, and extension as in the basic back extension, and the same method of holding resistance. To bring your torso into line with your legs in the 45-degree back extension, your back has to come up to above parallel with the floor.
Generally, the 45-degree back extension provides greater muscular loading at the bottom of the movement, while the basic version provides greater loading at the top.
Using the set-ups for the basic and 45-degree back extensions, spinal extension alone is possible if technique is modified as illustrated on the right. This yields a shortened overall range of motion relative to traditional back extensions, but focuses the work on the spinal musculature. In traditional back extensions there’s back and hip extension. For back or spinal extension alone, keep your lower vertebrae fixed throughout, and move only your middle and upper vertebrae. Practice is required before this technique can be mastered.
Back extension machines are also called lower-back or lumbar-extension machines. Different brands have different designs, and the effectiveness for the lumbar musculature varies. The MedX lumbar-extension machine is probably the premier one. Because of their design and use, some back extension machines provide little or no meaningful exercise for the lumbar musculature.
To be maximally effective for working the lumbar musculature, a back extension machine must fully restrain the body in four locations: feet, knees, thighs, and pelvis. The feet are restrained by a foot board. The knees are restrained by a belt or bar. The thighs are restrained by a belt strapped tightly over the upper thighs. The pelvis is restrained by a pad that’s positioned against the rear of the hips. (Some machines may have head rests, too.)
If any of these four restraints are absent, or not correctly employed, you’ll increase the involvement of your hamstrings and muscles of your hips, but reduce the involvement of your lumbar-extension muscles. For best effect on your lumbar musculature, there must be no movement of your legs, thighs, or pelvis. The muscles of your legs, thighs, and hips contract, but the restraints prevent these muscles contributing substantial force to the movement.
It’s also essential that you don’t involve your hands. Cross your hands on your chest. Furthermore, it’s critical that you use a controlled rep speed, and a safe range of motion.
Follow the manufacturer’s set-up guidelines, and fine-tune to suit you.
In the starting position, flex (round) your back moderately. Then as you extend your back, gradually straighten and then slightly arch your back. Don’t exaggerate the arch. Move smoothly at all times, including the turnaround points of each rep.
Take at least three seconds for the positive phase of the rep; pause for a second at the extended, fully contracted position, with your scapulae fully retracted; and then take at least a further three seconds for the negative phase, while gradually rounding your back. Pause for a second in the starting position, then smoothly move into the next rep.
Use as full a range of motion as is safe for you. At first, don’t try the maximum degree of (forward) flexion or (rearward) extension.
Start with minimal resistance, and very low intensity of effort. Only after you know the maximum safe range of motion for you—after perhaps a couple of weeks use—should you start to increase resistance and effort levels gradually. You may find that your flexibility increases during the first few weeks of use, and permits a greater safe range of motion. But even when you’ve fully adapted to the machine back extension, don’t work it until muscular exhaustion because that may cause injury. Train each work set hard, but not until your limit.
Be especially careful if you have had any back injuries.
Don’t try to maintain a flat back in the back extension. It’s important that the spine flexes and extends, that is, rounds and arches moderately. Without this flexion and extension, the lumbar musculature won’t be fully stimulated.
Progression in back extensions
The 45-degree back extension may be a good introduction to back extensions if you don’t have sufficient strength to perform the basic version for the required reps, and don’t have access to a back extension machine. (A back extension machine can be used with little or no resistance, but the basic and 45-degree back extensions have the minimum resistance of the weight of your torso.) Graduate to the basic back extension after two to three months on the 45-degree version. If the 45-degree back extension is currently too difficult, use the back extension while on the floor, without equipment. Once you can perform 20 controlled, smooth floor back extensions with your arms extended, elbows straight, and a pause at the top of each rep, progress to another form of the back extension. Try the 45degree back extension, or, if the set-up for that exercise isn’t available, try the basic back extension.
If you have access to the basic and 45-degree back extensions, do a single work set of each rather than two sets of only one of them. Alternatively, use the machine back extension.