Among the many biceps brachii building exercises available to the average exerciser, there are few as effective as the standard bicep curl - a movement that involves the exerciser supinating their grip and drawing a weight upwards towards their humerus bone, thereby deeply activating the biceps muscle group.
However, the standard biceps curl is often split into two main variants; that being the biceps curl performed with a single or pair of dumbbells, or the biceps curl performed with a loaded straight barbell respectively.
Though these two variants of the bicep curl appear functionally the same, a few key distinctions between them may result in somewhat different outcomes for the exerciser, be it a different form of training stimulus, risk of injury, or even set and repetition scheme programming.
The barbell and dumbbell curl are two open kinetic chain isolation exercises that make use of free weight implements in order to induce a moderate level of resistance to the biceps brachii and several of its surrounding muscles, both in a dynamic and static capacity.
In the case of the dumbbell curl, the exerciser may perform the movement in a unilateral or bilateral fashion depending on their preferences and availability of equipment, while the barbell curl is strictly a bilateral exercise that recruits both sides of the body’s musculature due to the length of the standard barbell.
For the most part - yes, both the dumbbell and barbell variants of the standard bicep curl work the biceps brachii as the primary mover muscle group, with secondary or stabilizer muscle groups such as the brachioradialis and brachialis also being activated to near parallel intensities between the two exercise variants.
This is not to say that the two variants activate said muscle groups to the same extent or intensity as the other, however, and several key differences native to the lifting modalities involved in each exercise variant can result in different forms of training stimulus, or even different results under the right conditions.
From an external point of view, the dumbbell and barbell curl appear to have quite similar form cues and mechanics; however, this is not entirely true, as the length and shape of the barbell used in the barbell curl make its own exercise form more cumbersome and distinct from that of the dumbbell curl.
This is due to the position that the barbell curl places the wrists in throughout the middle of the repetition, forcing them to bend in an unnatural and potentially injurious angle unless the exerciser alters their elbow positioning.
As such, unlike in the dumbbell curl where the exerciser may maximize biceps brachii muscle group recruitment by keeping their elbows tucked to their sides, the exerciser will instead have to raise their elbows forward in order to retain a safe wrist positioning during a repetition of the barbell curl.
In addition to this, the fact that the dumbbell curl utilizes two separate sources of resistance instead of the single length of the barbell also equates to a more natural elbow to shoulder angle being adopted, allowing the exerciser to perform the exercise in a manner more in line with their own unique biomechanics.
Throughout the repetition, the dumbbells will allow the exerciser to rotate their wrists - something otherwise dangerous or difficult with the usage of the barbell curl, as it locks the exerciser’s hands in place, reducing the total range of motion of the exercise and by extension the intensity at which the biceps brachii are recruited in.
Though the muscle group activation (namely the biceps brachii) is the same between the dumbbell and barbell curl, certain differences in their individual mechanics and form can equate to distinctions between the sort of training stimulus provided and the intensity of said stimulus therein.
As more specific muscle group activation and higher repetition volume per set equates to an improvement in total muscular hypertrophy, it is no surprise that the slower and more focused dumbbell curl induces greater mass growth in the biceps brachii than its barbell based counterpart.
As the mechanics and form of a traditional biceps curl is more conducive to biceps brachii muscle fiber recruitment as a reduced loading of secondary muscle groups is induced, muscular hypertrophic response will only be further reinforced.
This is not to say that the higher level of resistance that the barbell curl allows is not also effective at inducing hypertrophy - simply that the aforementioned characteristics of the dumbbell curl work far better and more efficiently at inducing muscular hypertrophy.
Just as the dumbbell curl is more efficient at inducing muscular hypertrophy in an exerciser, the barbell curl is an excellent exercise for making the exerciser and their central nervous system accustomed to supramaximal loads or heavier levels of resistance that are otherwise not feasible with dumbbells alone.
Though this may present certain flaws such as safety issues and a risk of wrist, elbow or shoulder impingements - performing a heavy barbell curl set with proper form should reduce these issues to a certain extent.
All in all, the biceps curl is generally not seen as a strength based movement, and is otherwise usually performed for the purposes of acting as a light auxiliary exercise or as a mass builder for the biceps; both of which do not require significant amounts of weight be used.
For general improvements in the exerciser’s athleticism, it is the barbell curl that once again is capable of improving both the explosiveness, power, strength and bodily coordination of the exerciser - not only by requiring that the exerciser act in a unilateral fashion, but also by inducing strength adaptations throughout their entire body.
One drawback presented by the barbell curl that the dumbbell curl otherwise does not have is that of significant injury risk, either by overuse of the various joints involved in the standard barbell curl or by causing impingements and tears as the wrists, elbows or biceps are placed in an unfavorable position.
This is caused by the manner in which the barbell curl locks in the wrists, preventing rotation during the mid-point of the repetition and forcing the elbows to raise away from their tucked-in position against the exerciser’s sides, placing a larger amount of pressure and shear force on the elbows, wrists and biceps brachii themselves.
In addition to this, any muscular imbalances already present in the exerciser’s body relating to the biceps will only be further worsened by the barbell curl, which will allow the weaker side of the body to be overtaken by the stronger half due to the bilateral nature of the exercise - something that is otherwise easily rectified through the use of dumbbell curls.
Though progressive overload is entirely possible with both the dumbbell and barbell curl, the fact that the majority of dumbbell brands are of a fixed nature and do not otherwise allow for small scale adjustments reduce the capacity to which they may aid in progressive overloading.
This is not so much the case in the barbell curl, wherein the exerciser may microload additional weight as small as 1.25 kilograms or 2.5 pounds that allow for incremental improvements to be made on a daily or weekly basis, over time forcing an adaptation in the biceps brachii that is otherwise known as progressive overload.
While other forms of achieving progressive overload are entirely possible (especially with the dumbbell curl), the usage of weight as an incremental progression is generally the most fool-proof and concrete method of doing so, making the barbell curl better for tracking progress or progressing in a training program.
In the majority of cases; no, the barbell curl and the dumbbell curl do not need to be combined within the same workout.
This is due to the fact that the barbell and dumbbell curl are similar enough in training stimulus and muscular activation pattern to preclude the use of the other, with the barbell or dumbbell curl being sufficient enough an exercise that further training with identical exercises will not be required.
The rare few cases where this may actually be applicable mostly revolve around sports and athleticism-related training modalities, or individuals wishing to achieve a very specific training stimulus.
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2. Marcolin G, Panizzolo FA, Petrone N, Moro T, Grigoletto D, Piccolo D, Paoli A. Differences in electromyographic activity of biceps brachii and brachioradialis while performing three variants of curl. PeerJ. 2018 Jul 13;6:e5165. doi: 10.7717/peerj.5165. PMID: 30013836; PMCID: PMC6047503.