Lean Muscle Mass

Fitness has become fairly important to me, and I'm going to make an attempt to tackle a variety of questions I've had. The first is about lean muscle mass.


'Lean muscle mass' is a term commonly used to advertise workout programs, exercise equipment, and fitness supplements. If you just break it down by words, it's easy to tell why this marketing term works so well. To the layman, 'Lean muscle mass' simply refers to a physique with minimal body fat and toned muscular structure.


For a while now, I've been going to the gym to develop lean muscle mass, and I realized I have no idea what I'm trying to accomplish. The term 'lean muscle mass' seems to mean that there are muscle fibers that differentiate themselves from fat or bulk muscle fibers. This isn't true. There are different types of muscle fibers, but they only way they differ is the rate at which they fire. Slow twitch (Type I) muscle fibers are prevalent in endurance athletes. The use oxygen more efficiently and generate ATP to be used over an extended period. Consequently, fast twitch (Type II) muscle fibers fire more rapidly and use the same amount of energy only at a higher rate.

What people really want when they say they want 'lean muscle mass' is muscular hypertrophy. The higher your muscle density the more definition you have. The popular misconception is that this is done by performing excercises with low weights and high repetitions. Most people think that they don't want to bulk up and become oversized like body builders. But the truth is that body builders are ripped. They have a ridiculous amount of muscular hypertrophy. They also have a ridiculous amount of muscle mass. It takes an incredible amount of work to become that size, and the average person won't get there.

If you want to have a fit physique, there are two things you have to do: lose fat and gain muscle. Gaining muscle is actually important to losing fat as the more muscle you have, the more energy those muscles will expend. For fat loss, what you really need is a calorie deficit. Intake less than you expend, and you'll naturally have to use the energy stored in the fat you have. There are a large number of ways to accomplish both of these.

So why do some people perform sets of high reps and some of low reps. This has more to do with what type of muscle fibers you have. The ratio of Type I to Type II muscle fibers is largely hereditary. High reps with a lower weight will utilize your slow twitch fibers more effectively, and low reps will utilize your fast twitch. It's possible to alter the amount of one type of twitch fiber in comparison to the other, but that's not really the goal of the average gym-goer. For fitness, you should really be training for strength and endurance rather than the shape your muscles are.

Unfortunately, I'm hardly an expert. Please give me your opinoins.

Note: Many women naturally want to avoid the size that accompanies increasing muscle strength. This is probably where the idea of low weight high reps comes from. What they are really doing is inhibiting the potential of their muscle growth. They will get desired results, but of course, they won't obtain the same strength.


Muscle fibers:
http://sportsmedicine.about.com/od/anatomyandphysiology/a/MuscleFiberType.htm
http://www.faqs.org/sports-science/Mo-Pl/Muscle-Fibers-Fast-and-Slow-Twitch.html

Hypertrophy:
http://strengthtraining.suite101.com/article.cfm/weight_loss_weight_training
http://en.wikipedia.org/wiki/Muscle_hypertrophy

Others:
http://www.shawnlebrunfitness.com/building-lean-muscle-mass.html