what is point of cross body hammer curl , aren't they same as hammer curl work same muscle, is their any benefit except tat they can carry more weight ?
Elbow Flexor Activation
To keep this part simple..
- Palms face up (full supination) you'll emphasize the biceps.
- Palms face down (pronation) you'll emphasize the brachialis
- The brachioradialis, which is targeted with a neural grip, attaches too close to your forearm for there to be any major difference. This position would have the greater effect the on the biceps…
A little applied anatomy. The biceps -- a two-headed muscle, comprised of the short head (which sits on the inner portion of the upper arm) and the long head (which sits on the outer portion of the upper arm). The long head of the muscle crosses the shoulder while the short head originates from the front of the scapula.
Why does this matter?
Well, during performance of exercises where the upper arm is held behind the body, the long head is placed in a greater position of stretch compared to the short head and therefore is able to generate maximal force. Conversely, during performance of movements
When the upper arm is held out in front of the body, the long head is slackened to a greater degree (this phenomenon called active insufficiency) and therefore force production is compromised.
Research shows that aspects of the biceps are “partitioned”, with both the long and short heads comprised of individual compartments, innervated by branches of the primary nerves.
- The lateral portion of the muscle are recruited for elbow flexion.
- Fibers in the medial aspect are recruited for supination
- Centrally located fibers are recruited for non-linear combinations of flexion and supination.
Furthermore, the short head appears to be more active in the latter part of an arm curl (i.e. greater elbow flexion) while the long head is more active in the early phase.
Sources: http://journals.lww.com/jbjsjournal/Abstract/1957/39050/Integrated_Actions_and_Functions_of_the_Chief.11.aspx http://journals.lww.com/corr/Abstract/1997/03000/Biceps_Activity_During_Shoulder_Motion__An.17.aspx https://www.ncbi.nlm.nih.gov/pubmed/7570586 https://www.ncbi.nlm.nih.gov/pubmed/7570586
Note: Some of these journals require membership to access.
It's a fallacy to think that bad form results in no muscle development in ALL cases. I'm not saying put on 3 plates on your squat and quarter rep it or try curling 135 lbs by thrusting your pelvic in and jerk the bar into your chest but you should no you have to lift heavy (or progressively so) to further scar muscle tissue and hypertrophy.
That being said, people who've been doing it a while probably know the drill on doing it with perfect form but probably start off their workout with something like a cross body curl with heavy weight to get some cheat curls, and stimulate lots of different fibers. When you cross curl vs regular hammer curl you're hitting different parts of your body (try it out, it's harder in some cases because it's like a standing concentration curl).
Experiment on yourself to see how it feels. Try combining cheat curling and strict form curls. Try both hammer and cross body.