Maybe if your a body builder this 2% would be important(if i were to agree with that statement), but for someone who wants to get stronger in the lift, barbell is where its at. We can all agree you can bench more with a barbell vs dumbell.
Why would it matter if youre a bodybuilder or not?
The thread title is "difficulty ISOLATING muscle groups."
This extre weight load we are lifting helps with the release of growth hormone. Barbell lifts generally release more gh vs dumbells lifts. This extra gh released is far more beneficial than trying to stimulate that extra 2% pec muscle.
Ummm, NO.... The evidence overwhelmingly indicates that workout-induced hormone spikes have no effect on muscle growth and strength gains. Don’t waste your time chasing GH spikes during and after your workouts.
Not saying abandon dumbells, as they have their place. But instead add them after your barbell work. Variety is key.
Focus on important training variables such as volume, rep ranges that induce hypertophy (8-12 reps), getting the proper nutrition and rest.
SOURCES:
Buresh R, et al. The effect of resistive exercise rest interval on hormonal response, strength, and hypertrophy with training. Journal of Strength & Conditioning Research, 2009 Jan; 23 (1):62-71.
Goto K, et al. Muscular adaptations to combinations of high and low intensity resistance exercises.Journal of Strength & Conditioning Research, 2004; 18: 730-737.
Yarasheski KE, et al. Effect of growth hormone and resistance exercise on muscle growth in young men. Am J Physiol Endocrinol Metab, 1992; 262: E261–E267.