I highly recommend this fascinating interview with David Epstein on his new book, The Sports Gene: Inside the Science of Extraordinary Athletic Performance. This immediately propelled the book to the top of my "must read" list.
You can hear him interviewed here:
David Epstein and The Sports Gene
It's well worth listening to. It's approximately 45 minutes long.
What is it about? The effects of genetics on training.
Practice is critical, but what if some people are more genetically predisposed to benefiting from that practice? In other words, if person A and B do the same amount of practice, but A is genetically disposed to benefit more from X hours of practice. If they both do X hours of practice, A will be better. B may simply not be able to catch up (think of sports stars who think about and practice their sport from extreme youth, from morning to night.)
Extending that to training, it can help explain why some routines make people and yet break some other people. Why some folks gain strength easily and others have such a hard time adding it - perhaps they'd be reversed if the goal was weight loss, or endurance training.
This goes a long way to explaining why there are so many ways to get stronger, yet they all don't work on all people. And why if they do work on everyone, not everyone can keep on that same program as long, or benefit as much as others. Some people start to back squat and add weight workout after workout for weeks, and top out at a high strength. Others add weight just as quickly but stall out sooner and just don't end up as strong. It's common to say it's hard work vs. not enough hard work, but given equal amounts of hard work, genetics is starting to tell us it's just that one person might be more predisposed to benefit from that modality.
This is pretty exciting stuff - if training can start to be tailored to both your goals and your genetic predisposition, it can end in better results for the work you put in. We do this now on an ad hoc basis - we try different training modalities, we look at your body type and try to extrapolate from other people's results giving those modalities and body type, etc. You see it as "Skinny Guy" routines and "Mass Gain for Hardgainers" and "High volume programs" for "mesomorphs" and so on. It's a question of trying to find out by hit-or-miss which training will benefit you the most, and which is spinning your wheels.
You still need to put the work in - as David Epstein says, it was never a question of practice helping, the question is, exactly how much of a result is practice? You need to put in the effort. But it seems like genetics helps you determine how much you get out of every unit of effort you put in.
Review: Why Michael Couldn't Hit (maybe great genetics, but not enough practice)