What's the difference between you and someone who is really freaking strong? What's the difference between the average 5'8" 185lb American male, and the guy in this picture? The guy in this picture is Jim Leonhard. Jim is a free safety for the New York Jets. He's a full 4 inches shorter and 30 pounds lighter than the average free safety, and is tasked with stopping guys who might have 8 inches and 80 lbs on him. Think about that for a second. This "average-sized" guy gets paid $2 million dollars a year to run across a field and tackle other professional athletes who are carrying 70% more mass than him at the same speed in the opposite direction. You don't have to be Newton to realize that Jim Leonhard is a freaking strong dude. But how?
Lean Mass
Let's get this out of the way right now, you are fatter than Jim. Even if you weigh 185lbs, Jim conservatively has no more than 14% body fat where as the average American man has 25% body fat. So Jim has 159lbs of "lean mass" where as you might have only 139lbs. That extra 14% of muscle that Jim has put on with years of a Wisconsin farm-boy diet and exercise allows him to pack a hell of a lot more punch than you. But it doesn't tell the whole story. Jim's probably put in a decade of training to do something better than you, me, or anyone we know. Jim can recruit.
Strength is a Skill
Just for a little recap, your body is a sack of meat with some interior scaffolding. Your brain turns that sack of meat into a moving tool by getting muscles to fire in a coordinated effort to direct energy from the ground, through your skeleton, and into whatever you want to pick up, move, carry, or throw. When you train a movement, your brain gets better at coordinating that effort. And it does this in 3 important ways:
- More Stability: When you hold a weight over your head, you will feel your entire body fighting to stay underneath it and keep the whole sack of meat + weight upright. But as you do this more, your brain learns to coordinate all those muscles better so that you are more stable. This means force can be directed from the ground, through your bones, and into the weight more efficiently, which means you can lift more weight more easily. In a classic example, it's the difference between firing a canon from a fort or from a canoe.
- More Gas: As you place more stress on your muscles and start trying to recruit more of them into movements, your brain learns that it's ok to put more 'umph' into those movements. Some of this is actual structural change as more neural connections between your brain and muscles are created ("somatic motor neurons") and more fibers are grown in the existing muscle ("myofibrillar hypertrophy"), but most of this new 'umph' (up to 80% in the first 6 weeks of training) is just your brain turning up the volume to the existing connections and firing different types of muscle fibers in a better order to produce more force.
- Less Brakes: Every muscle that pulls on a bone in your body has a muscle that pulls on the same bone in the opposite direction. This is what creates the stability you need to keep your meat sack moving around, but it also means that our movements have a built in braking system. The stronger you get, the more comfortable your brain is with letting the brakes off a little. Then a little more, etc. Some powerlifters and sprinters are so strong that they have trained their brains into letting off nearly all the brakes and risk getting injured by actually pulling their muscles off their bones.
So to sum up, Jim can recruit more muscle fibers, more quickly, more efficiently, with more 'umph,' less in the way, and all from a more stable base of support. In short, he's a strong little SOB with 236 tackles in 2010.
Why You Care
This is good news for everyone, including those people that just wanna drop some fat and look better by the pool. The stronger you get, the more muscle you can recruit into every movement. The more muscle you can recruit, the more calories you burn just doing stuff. Stronger people have more of a buffer to work with. They can indulge a little more in the calories department from time to time because it's easier for them to burn it off without really trying. Weaker people have to work with such razor-thin margins on their calories that it makes healthy habits seem impossibly strict. So the stronger you get, the more cupcakes you can "accidentally" eat, and the better your quality of life your will be. It all comes down to better recruiting what you got and training the skill of strength.