I understand that rows and flys are two different exercises so this question isn't how to do them, but why would someone do one over the other? Is there better muscle activation with one? better pump? or just person preference?
They work different muscles?
Rows are generally back lifts, flies hit your chest.
Well there are different types of flies, I'm talking about something like dumbbell rows vs back flys
you mean rear delt flyes?
I suppose if that's the only kind you can do to work your back, maybe the question should be rear delt rows vs flies
Even so, the answer is the same... they hit different muscles [within the back].
Someone would pick rows over flys because rows are a better exercise. They will make you stronger and bigger than flys.
Why do you want to know the answer? Trying to figure out what you should do in your own workout? Bet with a friend? Just because you're curious?
With flys your arms will usually fatigue before your back will. Thus, you can lift heavier weights for longer with rows, and build more muscle in the back. However, flys emphasize the rear delts more than rows do.
I just want to know for the sake of knowing, thank you for your answer
They would to rows to build their back and they would to flys to build their rear delts. I do both. They are not mutually exclusive.
Mostly this. Rows are a compound movement, flys are essentially an isolation movement. Rows are primarily a lat exercise, and secondarily a bicep exercise. They also promote growth in the mid back. The flys are very specifically oriented towards working the rhomboids and rear delts, and potentially the lower traps a bit, depending on how they're performed.
The rows can be performed with super-heavy weights, so greater overall muscle stimulation is achieved. If you like both exercises, super-setting can make sense with these exercises. I don't incorporate the rear delt flys much at all, as I prefer barbell high pulls and cable face pulls w/ a rope. These exercises can be more easily overloaded, the leverages are more favorable for stress throughout the movement.
In a fly, the weight becomes exponentially harder to move as a rep is being performed, and momentum is usually used to complete difficult reps. You don't have that problem with face pulls, and you can hold the contraction (generally a good technique for back work).
Hope this helps!
This is kinda like asking about the bench press vs front raises, sorta. They are, obviously, two different exercises that address/train different muscle groups.
To tack onto all the good input so far, bent flyes are generally used to make the rear delts the main movers, but the entire upper back can come more into play if the weight is bumped up and/or some body english is used. Rows are one of the most basic movements to target the majority of the back (lats, upper back, mid back, some low back depending on form).
And just to confuse things a little more, there's always an elbows-out row, which uses the rowing motion (and the added strength of increased arm movement) but places more of an emphasis on the upper back, kinda like a "bent over dumbbell face pull".
(If I'm using these, I'd actually shoot to keep the elbows higher/even more in line with the shoulder rather than angled back towards the hips.)
I think OP is talking about rear delt flyes v. rear delt rows. Rear delt rows do NOT hit the entire back, and if performed correctly hammer the hell out of just the rear delts. http://www.youtube.com/watch?v=Wqu7NqHJxEs
That was a distracting video. I know it was supposed to be demonstrating something, but I couldn't keep my eyes off of that waist.
You may be right, but OP did specifically say dumbbell rows in his 2nd post, not rear delt rows.
EDIT: just saw where you got this, in his 3rd post he changed it to rear delt rows. I have no idea what OP is looking for, lol.