UB-BICEPS-X


BICEPS – EXERCISES


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TRAINING


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BICEPS BRACHII – REVIEW
– Including Moment Arm Data


Biceps – Beardsley
The elbow flexors are a small elbow flexor muscle group comprising four individual muscles: biceps brachii long head, biceps brachii short head, brachialis, and brachioradialis


#1. Internal moment arm lengths – elbow angle


– The elbow flexors have different origins and insertions and therefore different leverages
– The leverages change over the course of the joint angle range of motion (ROM).
Exercises that involve peak forces near to full elbow extension (like preacher curls) will require the greatest contributions from the biceps brachii muscles.
Exercises that involve peak forces in full elbow flexion (like EZ bar curls against elastic resistance) will involve greater contribution from the brachioradialis.


#2. Internal moment arm lengths – wrist position


– Wrist position also affects the leverages of the biceps brachii long head and short head.
– When the wrist is supinated, the biceps brachii muscles have longer elbow flexion internal moment arm lengths
– When the wrist is pronated, the biceps brachii muscles have shorter elbow flexion internal moment arm lengths.
– This means that the biceps brachii will be more involved during supinated grip curls, while the brachioradialis will be more involved in pronated grip curls.


#3. Internal moment arm lengths – shoulder angle


– Shoulder angle also affects the leverages of the elbow flexors.
– The biceps brachii are not good shoulder flexors and probably have minimal leverage once the shoulder is elevated above 45 degrees.
– This means that exercises involving shoulder flexion are unlikely to be effective for training the biceps brachii.


#4. Sarcomere lengths


– Historically, it has often been assumed that strength training with a long maximum muscle length at the end of each rep (often in conjunction with a larger range of motion) will always produce greater hypertrophy.
– Yet, the elbow flexors often fail to display this tendency. Researchers have often attempted to “explain away” these results by suggesting that the particular exercises or study designs were not appropriate for determining the effects of strength training with long or short maximum muscle lengths.
– Nevertheless, there is an alternative physiological explanation. The amount of passive tension that a muscle fiber can produce during a stretch depends on the length that titin reaches during the stretch. Titin length during a stretch is determined by the number of sarcomeres in series in the muscle fiber. When a muscle fiber has a lot of sarcomeres in series, each sarcomere (and hence each titin molecule) does not stretch very far. Conversely, when a muscle fiber has few sarcomeres in series, each sarcomere (and therefore each titin molecule) stretches a long way. Titin typically only starts to produce passive force during a passive muscle stretch when the sarcomere reaches a point called the “descending limb” of the length-tension relationship. Researchers have shown that the sarcomeres of the biceps brachii tend not to reach this point during a normal strength training exercise.


#5. Recovery capacity


– The elbow flexors recover much more slowly than most of the other muscles in the body, although they are not typically a muscle group that often experiences a great deal of delayed onset muscle soreness (DOMS)
– This is a good example of why using DOMS to infer recovery status is not particularly helpful. Yet, this suggests that for the elbow flexors, the optimal training frequency for a given amount of workout volume will be much lower than for workouts that target other muscle groups.
– The elbow flexors likely recover slower than most other muscles partly due to the extremely high proportion of fast twitch muscle fibers that they contain. Fast twitch muscle fibers are more easily damaged after exercise because they have far fewer mitochondria. Therefore, they experience greater damage from the calpains (proteases) that are released in response to the influx of calcium ions during exercise.
– Additionally, the extremely high voluntary activation capacity of the elbow flexor muscle group means that more of the fast twitch fibers that are present inside the muscle can actually be activated (and therefore damaged by calcium ion influx) during maximal efforts. Together, the high very voluntary activation level and the fast twitch fiber proportion cause the muscle group to be one of the most easily-damaged muscle groups in the whole body.

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EMG STUDIES


BICEPS BRACHII
– Multiple Exercises

Biceps Brachii – Best Exercises – ACE – 2014 – Young, Porcari – Wisconsin-Lacrosse – PDF File .
Procedure
– 8 women and 8 men between the ages of 18 and 24; All subjects had some form of weightlifting experience
Results for the Biceps Brachii
1. Concentration Curl: 98%
2. Cable Curl: 80%
3. Chinup – Semi-Supinated Grip: 80%
4. Barbell Curl: 77%
5. EZ curl Wide: 74%
6. EZ curl Narrow: 71%
7. Incline Curl: 70%
8. Preacher Curl: 69%


BICEPS BRACHII, BRACHIORADIALIS
– EZ Curl, DB Curl, BB Curl

Differences in electromyographic activity of biceps brachii and brachioradialis while performing three variants of curl – Marcolin – 2018
Procedure
1×10 @65% 1-RM for each variant of curl
Results
Biceps Brachii: EZ Curl 75% . Barbell Curl 72% . DB Curl 70%
Brachioradialis: EZ Curl 45% . Barbell Curl 40% . DB Curl 35%


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