I got this note from an old buddy of mine recently...his salutation refers to the original Irish spelling of "Heffernan," which was, apparently. O'heFearrNain, arbitrary capitalization and all:

O heyyyyyyyyyyyyfairnain!  Brother it has been far too long. I wanted to ask you about training: If I stick to a decent weight in my work out on machines, if I work on the number of reps in a set and do two sets, is that good for my muscles? And what effect does it have?  I want to tone, not build. I'm too huge already.

The question boils down to what rep scheme is optimal for eliciting tone, but not size?

It's one of those questions that for a long time everyone had a pat answer to, but these days I'm not sure the answer is pat at all.

In the CSCS manual, which I don't have in front of me but memorized all 800 pages of last year, the breakdown is pretty much what we all learned in Muscle and Fitness:  4-6 reps give you strength, 8-12 reps gives you size, and 15-20 reps gives you endurance. 

These days you might see a discussion of fiber types thrown into the mix, to lend an air of erudition to the proceedings:  type-I muscle fibers are slow-twitch, responsible for endurance activity, and have low potential for hypertrophy; type-II fibers are fast-twitch, responsible for strength-and-power activity, and grow like crazy. 

The "size principle," to get even more science-y on you, states that any activity which stimulates the fast-twitchers will also stimulate the slow-twitchers, though the reverse is not true.  The slow twitchers are pretty much always in on the action, but the big guys don't join the fight unitl they're absolutely needed.

So the party line is to leave the light-weight stuff alone if you're going for size and concentrate on low-to-medium high reps.

But hold the phone!  Just in the last few weeks, a couple of the more smartypants trainers out there have gone and recommended high reps for muscle growth:  Chad Waterbury, king of 10 x 3, touted doing 100 reps of pushups and 50 reps of pullups daily (over multiple sets, granted) to pack on torso size!  I myself have had good luck shaking things up with a single set of reps in the 25-30 range.  It's hard as hell, granted (I'm talking about 25 difficult reps, mind you:  like 25 chin-ups or 25 dips), but it works.

Back in the day, folks believed that working with super-heavy weights affected primarily neural changes:  that is, improvements in the nervous system's efficiency rather than muscle growth. Lately, though, some innovative types have challenged that notion as well, and gone with super-heavy weights in the 3-5 range for a high number of sets--once thought the domain of people seeking strength, but not size, to pack on the contractile tissue.  Guess what?  That seems to work too.  

And then there's the traditional hypertrophy rep range of 8-12, the old standby that everyone falls back on once in awhile.  And there's a reason for that:  it works. 

The things that seem common across these three training protocols are:

1)  Working hard--if not to failure, exactly, then close to it and

2)  Time under tension:  two hard sets of 20 keep the muscles under tension for about 2-3 minutes total--about the same as eight sets of three or three sets of twelve, assuming that you slow down your rep speed when working heavy like a normal human.

I don't know if those are the magic keys to muscle growth, but they may be as close as we have right now. 

So if you're trying to avoid muscle growth, and still get a workout, I'd play with factor #2: time under tension,  either by doing fewer sets of heavy weight (3 x 3, for example), or more reps with a lighter weight (2 x 30, say).  This is not to say that either of those rep schemes won't produce muscle growth as well--they might.  But I'd say they're less likely to produce growth than the methods above.

Fact is that people grow on all kinds of weird programs:  high rep, low rep, medium rep.  It makes sense, if you think about it:  if someone is, say 80% slow-twitch fibers, he may indeed get bigger stimulating those fibers, which might only grow 15%, than he would targeting the paltry 20% of his muscle mass comprised of fast-twitch fibers, even if they grow a whopping 50%.

The final question:  is there such a thing as "tone"?  Lou Schuler discussed this in one of his New Rules books.  Tonus, in trainer speak, is a real thing:  it refers to the amount of tension that a given muscle habitually holds.  It may look good, especially in photographs--a tense muscle jiggles less than a relaxed one and is therefore less likely to be mistaken for fat--but having a lot of extra tension hanging around your muscles isn't really all that great.  It can screw up your motor patterns, give you headaches, back pain, and muscle spasms, and overall, make you look like a total tool.

If you don't believe me, check yourself out in the mirror sometime and shrug your shoulders up around your ears; then ask yourself if you'd honestly be willing to buy a car from a guy who looked like that.  Then just shrug them a little, so the tension is less apparent, and ask yourself the same question.  Finally, relax your shoulders fully and see how your trustworthiness automatically goes up a few notches.  That's what extra muscle tone--also known as tightness, rigidity, and all-around uptight-ness--gets you. 

The place to be is to have muscles that can spring into action when you need them, but are loosey-goosey and relaxed otherwise, not getting in the way of fluid movement.  Think NBA stars when they get on the court:  those guys are anything but rigid. 

I think what people mean when they use the "t-word" is some combination of leanness and slight muscle growth--meaning that the difference in size and "tone" may really be a difference in degree rather than kind.

*numbers completely made up