It’s often the little things that separate the best from the rest, and if you’re an undersized hardgainer, you can’t afford to neglect anything. In this article, we address five muscles you probably haven’t been working directly and explain why and how you should.

BRACHIALIS 

This muscle runs underneath the biceps and is visible on the outside of each upper arm. It works with the biceps as a flexor of the elbow joint, but, unlike the biceps, does not have a role in supinating the forearm — as occurs in the outward rotation during supinating dumbbell curls.

WHY BOTHER? The brachialis adds width to your arms, and when the bi’s are flexed, a well-developed brach bulges out as an impressive knot on the outside between the biceps and triceps, supplying greater density, depth and details. We probably don’t have to sell you on growing a crucial “gun part,” but since you’re already hitting brachialis when you work bi’s, do you need to do more? Yes, because in palms-up or supinating curls, the biceps are doing the brunt of the work. To maximize brachialis development, do one type of curl that focuses on this muscle in each biceps session.

TRAINING To target the brachialis, curl a weight with either a palms-down grip or a thumbs-up grip. For the former, do barbell reverse curls with a medium grip, either standing or on a preacher bench. For the latter, do hammer curls with two dumbbells, simultaneously or alternating. Three or four sets of 10 to 12 reps should sting the brach, and because both of these exercises work the forearms (especially the brachioradialis) more than palms-up curls, you may want to do them at the end of your biceps routine and just before wrist curls and reverse wrist curls. (You are doing reverse wrist curls, right? Keep reading.)

SERRATUS ANTERIOR 

The serratus anterior lies atop the outer sides of the highest eight ribs and connects to the upper, inner area of the scapula. The fingerlike ridges are visible just below the outer edges of the pectorals. The main function of the serratus anterior is to pull the scapula forward, as at the top of a bench press, if you let your shoulders come off the bench to raise the barbell higher than is customary. This muscle also works to stabilize the scapula and assists in rotating it upward.

WHY BOTHER? Visually, the serratus anterior muscles set off the pecs and abs and tie the front to the back. At lean bodyweights, development of this part gives a physique that “finished” look. OK, that’s snazzy and all, but as with brachialis, you may assume you’re already stimulating the serratus anterior — in this case, via pullovers and pulldowns. In fact, those exercises don’t do much more for the serratus anterior than give the part a good stretch, because, contrary to accepted belief, the motion of pulling your arms from overhead toward your waist is not a direct function of the serratus anterior.

TRAINING  Hold your arms straight out in front of you. Now, reach even farther, feeling your scapulas rounding. This is the primary function of your serratus anterior muscles. To duplicate this, do some chest presses with the same exaggerated range of motion. Don’t do this on your maximum sets, but instead incorporate it into your warm-up sets and, as you grow stronger, the lighter sets of a pyramid. You can also do pushups with the same scapula-rounding contractions and barbell front raises while maintaining this posture.

STERNOCLEIDOMASTOID

These two muscles run from just below and behind the ears (connecting to the base of the skull) to the top of the breastbone and collarbone at the base of the throat. Along with smaller neck muscles, the sternocleidomastoids act to tilt the head to the sides and, along with smaller neck muscles, allow the head to rotate and tilt forward.

WHY BOTHER?  If you don’t require neck strength for wrestling or football, you may not need to train these muscles. Some bodybuilders find that their necks expand from isometric strain during exercises like deadlifts and shrugs (not to mention the girth added by trapezius growth). Others, such as pros Chris Cormier and Hide Yamagishi, have done heavy neck training to muscle-up this area. How big you want a specific bodypart to be is your choice, but remember that your neck is usually the most visible indicator of strength — and it’s on display even when you’re fully clothed. Don’t be a pencilneck. A lot of hardgainers reading this could benefit from the sort of “headstand” that can never be compared to a writing utensil.

TRAINING  Some well-equipped gyms have neck machines, but if you don’t have access to one, lie face-up on a bench with your head off the end, put a folded towel on your face and hold a weight plate to the towel. Then let your head drop down as far as possible and lift it back up as far as possible. Repeat this while lying on your right and left sides and while lying face-down; the latter works the muscles at the rear of your neck. Do two or three giant sets of this four-direction rotation, “necking” in each direction for 12 to 20 reps.

TIBIALIS ANTERIOR 

The tibialis anterior is situated on the lateral side of the tibia (shinbone) and spans the length of the bone from the foot to the knee. The primary function of this muscle is dorsiflexion (pulling the foot upward toward the ankle), and it also works to stabilize the ankle and balance the leg.

WHY BOTHER?  There are two reasons to train the tibialis anterior. The first is injury prevention. If you participate in sports that involve running, you’re probably aware of shin splints, a common issue often thought to be caused by a strength imbalance between the gastrocnemius and tibialis anterior. As a bodybuilder who regularly trains the back of your lower legs, the much weaker front of your lower legs may be especially vulnerable to problems anytime you run. The other reason to work the tibialis anterior is visual. It’s a small muscle, but it can impart depth in the lower legs when viewed from the front — especially when you’re at a lean bodyweight and standing on a competition stage.

TRAINING  Most gyms don’t have a tibialis machine, but you can duplicate the motion by sitting on a leg curl machine facing the ankle pads. Hook your toes under the pads and lift your toes toward your shins. Very little weight will be necessary to work these small muscles. Do three or four sets of 10 to 15 reps in each calf workout.

WRIST EXTENSOR 

The extensor muscles, which lie on the top of each forearm, have various functions in manipulating the complex mechanics of the hands, but their primary job is moving the top of the hands backward toward the wrists.

WHY BOTHER?  Forearms are frequently neglected, and even many bodybuilders who throw in a few sets for them do only wrist curls, which work the wrist flexors but not the extensors. Like the tibialis, wrist extensors are relatively weak, but that’s no excuse for bypassing them. With training, their new strength will assist your grip in other lifts. Maybe the best reason for working extensors is that, after your neck, your forearms are typically your most visible muscles, fully exposed whenever you wear short sleeves.

TRAINING  Target wrist extensors with reverse wrist curls, whether with a barbell, dumbbell(s) or a bar attached to a cable. Move your hands through a full range of motion on each rep, from down as far as possible to back as far as possible, for four sets of 12 to 20 reps.

SMALL PARTS, BIG IMPACT 

Like parts of a train undercarriage, all five of the preceding small muscles serve crucial roles in moving you about. What’s more, from just below your head to just above your toes, they’re each highly visible and, taken together, they can have a major impact on whether your physique is viewed as something like a boxcar or its flip side: a complex, carefully constructed creation. – FLEX