Thursday, July 14, 2011

SuppVersity EMG Series - Biceps Brachii: The Very Best Exercises for Sleeve Bursting Biceps

Posted by Nurul Hidayah at 9:13 PM
Image 1: The biceps brachii attaches
directly to the shoulder joint
(Användare:Chriz @ Wikipedia)
As its name already implies, the bi-ceps (lat. for "two-heads") brachii is made up of two muscle strands, both of which attach to different parts of the shoulder joint:
  • the caput longum (long head), which attaches to the tuberculum supraglenoidale scapulae and facilitates internal rotation and abduction of the arm, and
  • the caput breve (short head), which attaches to the processus coacoideus and facilitates anteversion and adduction of the arm
Their individual kinetic functions aside, both heads of the biceps brachii work synergistically during basic curl movements and more complex movements such as the supination of your palm. In that, the individual position of the hands determines, which of the two heads of the biceps carry the main load of the movement.
ChestBicepsBackCoreLegsTricepsShoulders
Navigate the SuppVersity EMG Series - Click on the desired body part to see the optimal exercises.
Due to the biceps anatomy, a supinated grip (palms of the hands face up) is required for optimal force development. As the degree of pronation (palms facing down) increases and the biceps tendon winds more and more around the radius, the potential for maximal force development decreases and m. brachialis and m. brachioradialis take over (cf. image 2). Keep that in mind, when you look at the following data on the most "effective" biceps exercises and whenever you design a training routine and make sure to train biceps and brachialis from a variety of angles to facilitate optimal progress in terms of strength and size.  

The most effective exercises* for the biceps brachii are
Image 2: Anatomy of the biceps brachii
(1-long head, 2-short head),
brachioradialis
(3) and brachialis (4).
* if not indicated otherwise, all exercises are to be performed with a supinated (palms facing up) grip
  • Dumbbell concentration curls, seated, supramaximal weight, negative eccentric*
  • Dumbbell Concentration Curls, seated
  • Scott curl, straight bar
  • Cable curl, using a straight-bar attachment
  • Straight bar curls, standing, wide (> shoulder width) grip
  • Dumbbell preacher curl, unilateral, on a 60° incline
** performing a negative eccentric means that you rise the dumbbell (+20-30% heavier than you would normally use) with the help of your free hand (apply just as much force as is necessary) and then lower the weight as slowly as possible using just the trained arm.
Figure 1: Degree of muscle activation (as measure via EMG) in comparison to reference exercise barbell curl (data adapted from Boeckh-Behrens & Buskies. 2000)
If you have a closer look at the data in figure 1, you will notice that the differences between the classic biceps exercises is relatively small. With proper loading (i.e. weight) and form the overall activation of the two heads of the biceps (caput longum and caput breve) differs by only 10%, ranging from the dumbbell preacher curl on an 60° incline to the dumbbell concentration curl seated sideways on a bench, with the back of your upper arm supported by your thighs. In those cases the intensity technique, here, so called negatives, can make a significant difference. The 20%-30% load-increase for the negative vs. the normal concentration curl improves its already superior muscle activation by a whopping +40%!
Note: You can employ negative eccentrics on other biceps exercises, as well. In fact, many pro bodybuilder "cheat" (i.e. they use momentum) on the concentric phase (way up) of regular barbell and dumbbell curls and to then try and resist gravity on the way down, as long as possible. Boeckh-Behrens & Buskies did not specifically test the effect of this practice, but it stands to reason that it would bring about similar effects as the controlled variety that was tested in the study.
Supinated, Hammer, Rotating or Pronated grip - What works best for big biceps? From the introductory remarks on the physiology of the biceps brachii and its synergists the m. brachialis and the m. brachioradialis it should be obvious that varying grip angle and widths can have a major impact on the degree each of these muscles is involved in a given exercise. The activation pattern for the biceps brachii during the concentration curl, for example largely depends on the grip you employ.
Figure 2: Degree of muscle activation (as measure via EMG) during concentration curls in percantage of concentration durls performed with a supinated grip (data adapted from Boeckh-Behrens & Buskies. 2000)
With the exception of the pronated grip*** the overall activation remains high (cf. figure 2), when switching from a supinated to a hammer (90°, thumbs up) or a rotating (neutral / hammer position at the beginning of the movement, supinated grip at the top). The high activation of the biceps brachii by "Hammer curls" (dumbbell curls with a hammer grip) is somewhat surprising, in fact the mean EMG value was even 3pts higher (766pts vs. 763pts) compared to the supinated version of the concentration curl. This is particularly interesting, as it goes against "broscience", which tells you that the hammer grip would specifically target the m. brachialis. *** although Boeckh-Behrens & Buskies did not measure the activation pattern of the m. brachioradialis, it stands to reason that it will carry the main load of pronated concentration curls.  

Grip width - does it really make a difference?

Despite the fact that a shoulder wide grip probably comes most naturally to most trainees, many trainers, pro bodybuilders and figure competitors suggest to train with varying grip widths for "aesthetic" reasons. And in fact, even the initial crash course on biceps anatomy should suffice to understand that grip width, just as grip angle, will influence the activation patterns of the individual heads of the biceps brachii (wide grip for long head, narrow grip for short head), m. brachialis (narrow grip) and the m. brachioradialis. The overall activation patter of the sum of caput longum and cuput breve, i.e. the two heads of the biceps brachii, on the other hand remains pretty stable (cf. figure 3).
Figure 3: Change in muscle activation (as measure via EMG) during barbell curls (straight bar) in percentage of curls done with a shoulder-wide grip (data adapted from Boeckh-Behrens & Buskies. 2000)
While the extra-wide grip (shoulder width +20cm) does not change the activation pattern significantly (and will probably hurt your wrists), executing the barbell curl with a straight bar, using a narrow grip (hands 10cm apart) significantly reduces the activation of the biceps brachii and increases the load on the m. brachialis. In summary, all of the classic curl movements activate the biceps brachii to a similar degree. Against that background, proper form and loading (selecting a weight that trains the muscle, not your ego) become increasingly important.
Don't be that guy who does ballistic curling movements using ridiculously high weights that may build huge traps (due to the jerking at the beginning of each curl), but leave his bi's underdeveloped. Rather take advantage of the variety of effective biceps exercises and hit your biceps from different angles and with different grip widths, in order to provide fresh growth stimuli every time you hit the gym.
Incorporate negatives, whenever you feel you are hitting a plateau; do not use negatives every workout, because negative eccentrics cause significant damage to the muscle tissue, which - if done too frequently - can eventually lead to atrophy instead of hypertrophy.

Image 3: The concentration curl has been
a staple in bodybuilding since the days
of Arnold Schwarzenegger
- rightly, as the EMG data indicates.
An EMG-optimized routine

There is of course a myriad of ways of combining the individual exercises, my personal recommendation for overall biceps development (based on EMG measures) would yet be as follows
  1. Barbell curls - straight bar, supinated shoulder wide grip; explosive concentric, controlled excentric movements, high loads, 6-8 reps
  2. Scott curls - campered bar, supinated narraw grip; full stretch at the bottom; medium load, 8-10 reps
  3. Dumbbell concentration curls - switch between supinated and hammer grip; medium load or supramaximal load (use sparingly) 10 reps (use other arm for assistance, if needed)
You may notice that I do not make volume (i.e. set) recommendations. This is due to the fact that I found that everyone has to find what works best for him / her in terms of optimal volume, training frequency and body part splits. This may also change over time / according to lifestyle factors / nutrition and supplementation.

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