6 to 8 reps or 8 to 12 reps or 10 to 15 reps does it matter

Ok, I've read a number of posts from this forum and I have seen some things that make me question what I am doing.

I currently do Cardio (60 minutes) and Weight Lifting (30 minutes) every day except weekends.  I focus on 1 or 2 muscle groups per weight lifting day so that I can rest for 1 to 2 days inbetween.

My goal is to tone my muscles not look like Mr. Universe.  I want definition not bulk (i actually like being able to bend my arms and legs).

I have been taught that to get bulk you use max weight 6 to 8 reps for 2 sets.  For tone I have been taught 10 to 15 reps for 3 sets.

I am doing 8 to 12 reps for 3 sets because I want a little of both right now until I reach where I want to be shape wise.

Is what I am doing correct?  Should I be doing 6-8 reps and 2 sets even if I just want to get definition?  Please explain your opinion with as much facts as possible.

 I think it's the progressive overload part as well - when you lift and teach your body to get more efficient at recruiting your muscle fibres, your body will be able to use fewer of these to move any given weight. If you stopped adding weight to the exercise you'd still keep on getting stronger, so eventually you'd pass right through the various rep zones. Once you hit the point where you're essentially doing cardio (>20-25 reps) you're not challenging your muscles all that much as far as maximal strength goes, and your body won't "need" to keep all that energetically expensive muscle around.

 I mean, your muscles are always in a state of protein turnover and if you look at the biochemistry of what's going on with it can get intensely detailed, but yeah, training using external resistance and progressive overload means that you're using your existing muscle mass more efficiently - if you were in a calorie surplus while training your body would supercompensate and add muscle mass, but in a deficit it simply doesn't have the energy it takes to synthesise new muscle protein available. Well, more or less - people like Jasontarin and Duke makes you kinda wonder about some of the details; the picture can't be as clear-cut as all that.

 But yes, my detail-oriented exercise nerd fascination for for minutia aside, you're absolutely correct - lift the heaviest weight you can manage for at most 8-12 reps.

i just want to add my perspective, which is that if you focus on increasing strength and do low reps, then after a few weeks you can do 8-12 of an increased weight.  this means you're doing more work, burning more calories.  and at that point you'll be engaging even more hypertrophy, ostensibly preserving even more muscle than you would at 8-12 reps of a lower weight.

we all know we should switch things up every X number of weeks or so.  i'm just saying how i see it.  however, i will say that i would recommend doing 8-12 first (focus on improving your diet w/o the distraction of pushing your myofibrillar muscle fibers to the max); then moving on to something that will build strength (low reps); then perhaps returning to 8-12 or doing 5-8 or whatever strikes your fancy. 

Original Post by spirochete:

:( but I'm a mesomorph my thighs gain 3 inches with each squat

don't be jealous...of my genetics. ;) 

i appreciate the teasing (especially because i used the mesomorph word today in a post on the weight loss forum), but my muscle actually does pop out pretty quickly after starting a fitness routine time and time again. and if you want to think i'm exaggerating, thats okay too.  or if you think its just the fat popping out, you could be right.