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May 18, 2022
Ab training has been a confusing and conflicting topic for many fitness fanatics for years. Some never train them for fear of a blocky waist, some train them daily to try and get them as cut as possible, and some train them for two weeks at the end of a leg workout only to forget about them for the next three months. Regardless of where you currently fall on this ab training continuum, it’s important to know how best to train them. By developing that knowledge, you can make informed decisions and remove any doubt about how to maximize your ab workouts. This article will cover the 9 best dumbbell ab exercises to build a defined midsection based on the functions and anatomy of the abdominal musculature, and give you tools of how to incorporate them into your training.
The muscles making up the midsection that can be seen from the front are known as the anterolateral abdominal wall. This is made up of 5 muscles, ranging from deep-lying to superficial. The deep-lying musculature, like the transverse abdominis and pyramidalis, have functional roles, holding organs in place, increasing intra-abdominal pressure, and preventing hernias.
In this article, we will focus on the anterior core muscles that concentrically and eccentrically contract during ab exercises: the internal obliques, external obliques and rectus abdominis. The external obliques and rectus abdominis just so happen to be the muscles giving the mid-section a defined, well-developed and aesthetic look.
The internal obliques are the middle later of the lateral abdominal wall, sitting superficially to the transverse abdominis and beneath the external obliques. It is a broad and thin muscular sheet, with fibers that run diagonally up the abdomen.
Origins and insertions:
The internal obliques have multiple origins and insertion sites. The anterior fibers originate from the iliopectineal arch, found on the lower section on the outside of the pelvis. The fibers angle downwards towards the midline on the front of the body, linking up with the transverse abdominis before inserting into the pubic crest and pecten pubis at the front of the pelvis. The lateral fibers come from the top of the iliac crest, the uppermost part of the pelvic structure. These fibers run towards the front of the body, forming the rectus sheath, and inserting into the linea alba running down the center of the abdomen. The fibers angle horizontally and slightly upwards from the origin to the insertion points. Finally, the posterior fibers originate from the posterior iliac crest and thoracolumbar fascia. Their fibers angle diagonally up the torso and attach to the lower three ribs.
In short, the internal obliques originate from various parts of the pelvis, attaching closer to the midline of the abdomen. The fibers angle slightly down - in the case of the anterior fibers - or upwards in the case of the lateral and posterior fibers.
Like most muscles, the function of the internal obliques is determined by their origins, insertions, and fiber direction. When they are contracted bilaterally, at the same time, the trunk is flexed. If you contract one at a time, the trunk flexes laterally and rotates ipsilaterally (i.e. towards the same side). Crunching your torse to the left means the internal obliques on the left-hand side are contracting.
These are the largest and most superficial muscle of the lateral abdomen. Sitting on top of the internal obliques and transverse abdominis, the external obliques give you a defined and chiseled look to your midsection, framing your abs.
Origins and insertions:
The external obliques originate from the outside surfaces of ribs 5-12. The attachments get gradually wider on the rib cage as you go from rib 5-12, starting just outside nipple width at rib 5 and ending around the back of the torso at rib 12. The fibers run diagonally from the origin to its insertions - the linea alba, pubic tubercle, and anterior iliac crest. As mentioned before, the linea alba runs down the middle of the abdomen, while the pubic tubercle and anterior iliac crest are located around the pelvis. In essence, the muscle runs diagonally down from the ribs to various points closer to the midline, perpendicular to the internal obliques.
Although the fibers run across not alongside the internal obliques, the external obliques carry out essentially the same functions. Their unilateral contraction causes lateral trunk flexion and rotation towards the side contraction, while bilateral contraction causes trunk flexion.
This is the muscle that spring to mind when anyone mentioned ab training. The rectus abdominis is responsible for the often sought after 6 pack abs, sitting as the most superficial anterior abdominal muscle. The segments that make up the 6 - or even 8 blocks in some cases - are caused by tendinous intersections. Unfortunately, no amount of ab training will change how many of these sections you have, whether it's 4 pack abs vs. 6 pack vs. 8 pack, but well-developed muscles can make these intersections deeper, creating more visible and deep-set abs.
Origins and insertions:
Originating from the pubic symphysis and crest at the pelvis, the rectus abdominis runs vertically up the abdomen inserting xiphoid processes and costal cartilages of ribs 5-7.
The primary function of the rectus abdominis is trunk flexion. However, it also acts to prevent lordosis and anterior pelvic tilt. While the rectus abdominis is one muscle, it has multiple sections - often referred to as the lower and upper parts of the abs. The upper abs are more active during trunk flexion, and the lower abs work more on controlling the pelvis. However, they don’t work independently, so both will be stimulated during either action just to varying degrees.
Like any other muscle, the rectus abdominis and internal and external obliques grow best when standard principles of hypertrophy are applied to training. You should pick exercises that:
Exercises like planks and carries have their place in resistance training. These can be excellent overall exercises; however, they fail to meet these criteria, making them an inefficient way to directly develop deep cut abs. Moreover, if you’re training program contains heavy compounds like squats and deadlifts, the muscles of your midsection are heavily stressed isometrically anyway. This is especially the case if you incorporate unilateral standing exercises. The exercises below are focussed on maximizing hypertrophy, so isometrics won't be included.
With the above parameters in mind, below are the best ab exercises with dumbbells.
To keep things nice and neat, we are categorizing these weighted ab exercises by:
Despite them being two different muscles, the internal and external obliques work in synergy to produce trunk flexion, lateral trunk flexion and trunk rotation. The exercises below will target both the internal and external obliques simultaneously.
Unless specifically targeted, it’s rare for trainees to perform trunk lateral flexion in the gym. Side bends force you to stretch the obliques underload, a great driver of muscle hypertrophy. This stretch is relatively uncommon, with the obliques generally used to stabilize the trunk, in exercises like lunges, without a full range of motion. Lateral flexion is also a part of daily life, used when picking up the shopping, so strengthening these muscles in various ranges can only benefit your functional mobility.
This exercise will train the obliques on the opposite side of the dumbbell. It can help you develop a better connection with the exercise if you use the non-dumbbell holding hand to try and feel your obliques on the working side.
One thing to be aware of is this exercise does not fully shorten the obliques. If you want to take them through a full range, pair this with an exercise like decline Russian twists (below) or even a cable side bend focusing on shortening the muscle.
Russian twists, named because of their use as a conditioning tool in the Russian army, are commonplace in gyms globally. Their original version is performed by having your legs hover in the air and the upper and lower body in a V-shape, twisting to touch a weight down on each side. However, their form is hard to standardize and quickly becomes a hip-flexor test and neglects the goal of the movement, rotation. Adding a decline bench to secure your legs lets you focus on the obliques with added stability. These also allow you to train the obliques through a full range. As you twist to the right, shortening the right-hand side, the left obliques get a fuller stretch and going the other way does the same for the other side. One final benefit is that these train the rectus abdominis isometrically, especially the lower section, to hold the decline position. This means they can be a one-stop shop for an ab session if you’re short on time or just want to add a bit of volume to the whole midsection.
Unlike regular side planks, this variation lengthens and shortens the obliques through lateral flexion. They are also very easily accessible - not requiring heavyweight, which side-bends can, or a decline bench. This makes them an excellent option for a busy gym or home training.
You should aim to keep your head, body, legs and feet in one straight line. If you find the range of motion too short, you can elevate your feet on a bumper plate.
The lower abs can be hard to train and connect with for many, feeling the movements in their lower back or hip flexors. The dumbbell exercises below should provide you with stability and tips to make the most of your lower ab without falling into common traps.
One of the most common - and commonly butchered - ab exercises is the hanging leg raises. Done correctly, these force you to lift your legs by tilting your pelvis and crunching your abs. If you’re strong enough to perform these properly, they can be a great addition to your lower ab training.
This exercise often turns into swinging, momentum, and hip flexors. If you can’t perform this with straight legs, you can shorten the range of motion and make it easier by keeping your knees bent.
Much the same as the hanging leg raises, this exercise focuses on the lower abs by controlling the pelvic tilt, working to prevent lordosis and bring the ribs and pelvis towards each other. Using the roman chair supports the lower back, giving you a surface to push into, adding stability. This makes the exercise easier to control and allows you to focus on contracting the abs without worrying about swinging backwards and forwards.
Like the hanging leg raises these can be made easier by bending your knees to reduce the length of the moment arm.
The final lower ab movement is similar to the above but easier to perform. This makes them a solid option for a second ab exercise when you might already be fatigued or if you’re struggling to perform lower ab exercises efficiently. A second benefit is the bench means there is a definitive start and stop point, making them easy to track, standardize and ultimately progress.
The upper abs are generally associated with the trunk flexion and crunching motion people perform. This is typically what people think of when someone mentions ab training to them. The exercises below are variations to help you get the most out of upper ab training, improving on some common exercises.
Despite this being in the upper ab section, this exercise attacks the whole rectus abdominis. This makes them another great movement to get the most bang-for-your-buck with your ab training. Additionally, they’re simple to progress and track, with a clear start and endpoint. Finally, unless you’re flailing around, these provide stability and let you really focus on the abs.
Swiss balls have gotten a lot of attention. Some herald their added instability as a great way to increase exercise difficulty and core activation, while others dismiss them as a way of decreasing weight used and deflecting attention from target muscles. In this case, the swiss ball is used because of its shape and malleability and not instability. By crunching on the ball and not the floor, you allow your lower back to arch and ribs and pelvis to separate, increasing the stretch on the abs. As previously mentioned, stretching under load is a great way to elicit hypertrophy, making this a very viable option.
Much like the swiss ball, Bosu-balls have come under fire for some of the weird and whacky exercises people perform on them. Despite their perceived benefits and downfalls, they make a great addition to ab training. The ball side acts like a swiss ball, allowing you to stretch the abs further than you could on the floor. One additional benefit of the Bosu-ball is the flat back. This lets you set up in one spot without fear of the ball rolling away or changing position on your back. This variation mixes the stability and range of motion of regular and swiss ball crunches, making them an excellent weapon in the arsenal.
These are performed almost identically to the swiss ball crunch.
Just like any other muscle, abs need to be trained with adequate volume and frequency, and with considered exercise selection and progressive overload.
The midsection has been separated to help understand the functions and which dumbbell exercises target each area best. However, the obliques and upper and lower abs have huge crossover, and it’s almost impossible to train one part without another. For example, you might perform a hanging leg raise for the lower abs, but co-contraction of the obliques also causes trunk flexion, and the upper and lower abs can’t be isolated from one another. This means you don’t have to perform an exercise targeting each section of every session. You could train abs twice per week - one session using an oblique and lower ab exercise and the other using an upper and lower ab exercise - and get adequate volume everywhere. This is emphasized by their contribution to compound movements.
If you aim for 4-6 sets per week per section, spread across 2-3 sessions, you would likely be getting adequate volume, and you can always add more if it’s required. Finally, because of the difficulty isolating the abs, with the lower back and hip flexors keen to spoil the fun, lower rep ranges (4-8) are often impractical. Aiming for 10-15 reps on your first set can help prevent the reps from falling too far in subsequent sets.
Repeat for 2-3 rounds. Rest as needed between exercises and rounds.
You could switch between these two workouts for a month or so then switch things up once it becomes easy. You should also aim to progressive overload by adding reps (to the high end of the rep scheme) and then adding weight by using a heavier dumbbell.
Well-developed abs can make the midsection look defined with deeper cuts. However, this is dependent on your body fat levels. Regardless of your abs development, if your body fat levels are too high, your abs won’t show. So, train your abs hard with and without weighted ab exercises, but remember you’ll need to work on your diet to ensure they can be shown off. As the old saying goes, “Abs are developed in the gym and revealed in the kitchen.”
Author: Tom MacCormick (BSc in Sports Science and Coaching, MSc in Strength and Conditioning)
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