Update:
An important example… the biceps require an underhand grip to fully activate. This not only improves the moment arm, but more importantly, it limits neural inhibition that prevents supination when curling. Furthermore, actively supinating throughout the motion will further emphasize the biceps, while likely including additional motor units that are located medially within this two-headed muscle.
Summary:
Overhand, underhand, and neutral grips affect the lengths of active muscles on many bodybuilding exercises. This occurs through different means, though often unnoticed by internally or externally rotating the shoulder. Therefore, the grip will affect the emphases and lengths for the involved muscles.
Many trainees choose whatever grip comes naturally for an exercise, or whichever makes the movement feel easiest. Perhaps they believe that grip only matters somewhat for pulling exercises and muscles.
Once you understand the anatomy though, and pay attention to how the muscles stretch and contract, it becomes clear that changing grip is more complex.
The choice of grip matters especially because your grip partially determines the degree of internal or external rotation at the shoulder, among other changes. These shift the lengths for various muscles on a variety of exercises. Long muscle lengths are important toward achieving maximum muscle growth.
Possible Grips
- Overhand (pronated) grip
This grip encourages internal rotation of the shoulder.
- Underhand (supinated) grip
This grip encourages external rotation of the shoulder.
- Neutral (hammer) grip
A neutral grip is a bit more complicated.
A neutral grip with a medium position, so the elbows line up with the wrists, attains a position between internal and external rotation.
A neutral grip with the elbows outside the wrists, usually with the hands placed closely, leads to internal rotation.
A neutral grip with the elbows inside the wrists, usually with the hands placed apart, leads to external rotation.
Proper Grip Applications
- Pectoralis Major (Sternal & Clavicular)
A better way to isolate upper pecs is using dumbbells for the incline press holding a neutral grip. This permits lower stretching and really targets the pecs.
– Frank Zane
On a dumbbell flat bench press, regardless of incline, a neutral or slightly underhand grip with the hands far apart will externally rotate the shoulder.
Since the chest assists to internally rotate the shoulder, we know that external rotation will impart an additional stretch at the bottom of the movement, boosting muscle growth.
This also explains why many bodybuilders convert from barbells and dumbbells on pressing movements, so as to attain that extra stretch at the bottom.
- Latissimus Dorsi & Teres Major
I guarantee you that you will feel a more powerful contraction of the lats with the narrow underhand grip.
– Dorian Yates
On a cable row performed with a rounded back, use a neutral or slightly underhand grip while pulling, similar to a bench press. This really stretches the lats, which also assist with internal rotation.
One way to achieve this is to use two single-arm attachments instead of a straight bar.
An underhand pull-up or pull-down also allows an extra stretch for the teres major. This occurs because the lats are shortened when the lower back is arched, allowing maximum shoulder extension to really stretch and work this muscle.
- Brachioradialis
The brachioradialis stretches the most with a pronated or overhand grip on any pulling or curl exercise.
- Brachialis
The brachialis generates lots of active tension on pulling exercises, since the biceps don’t change their length and therefore don’t contribute much, yet without much of a stretch.
Both underhand and overhand grips allow for less elbow extension, since the brachioradialis is preferentially stretched. Therefore, applying a preacher curl bench to slightly hyperextend the elbow, with a neutral hammer grip, would best stretch and work the brachialis.
Focusing on the brachialis can be helpful toward adding girth on the arms, much like how developing the soleus adds to calf size through seated heel raises.
The brachialis actually has a similar volume as both heads of the biceps combined, so don’t underestimate stretching this muscle for additional growth!
- Posterior Deltoid, Infraspinatus, & Teres Minor
On rear lateral raises, an internally rotated grip, with the hand overhand or pronated, will stretch the posterior deltoid, infraspinatus, and teres minor better. This is because these muscles all contribute toward external rotation of the shoulder.
- Lateral & Medial Heads of the Triceps
While this is unlikely to make much a great difference, an underhand grip may slightly favor the medial head of the triceps.
While many dismiss this as broscience, some of the scientific literature supports this notion.
Overhand, Underhand, & Neutral Grips in Bodybuilding
Bodybuilders have traditionally advocated a full range of motion. When analyzing the biomechanics alone, this may seem foolish, placing the muscle along a weak active portion of length-tension relationship curve. It also can increase joint stress due to the extreme positions.
It creates more passive tension, due to a deeper stretch. This increases overall mechanical tension that drives growth. This leads to a unique form of growth from sarcomeres in-series.
The increased range of motion and stretch seems to facilitate the pump. This pump correlates with increased metabolic stress, especially when applied with the principle of constant tension. Consider how much more you feel it on an incline curl versus a regular one. This seems another factor for muscle growth.
The increased range of motion allows enough time to muster power. This recruits the fast-twitch muscle fibers most responsible for growth. Heavy weight and going to failure within a reasonable rep range then maximizes tension for these fibers by slowing the movement down.
A full range of motion may even allow different regions within a muscle to be targeted. This may occur due to the length-tension portion of the curve for muscle fibers changing throughout the range of motion, even if medium and long lengths are still optimal for overall active and passive tensions respectively.
Nonetheless, upon a closer look, a full range of motion contributes toward several vital goals in bodybuilding.
Ultimately then, the extra stretch possible is valuable over using more weight for partial reps.
The extra stretch achieved especially through internal or external shoulder rotation can be manipulated by overhand, underhand, and neutral grips. Consider using the proper grips per exercise to further drive muscle growth.