The better you understand your muscles and what they are capable of, the more you can do with them, whether it’s acing a tennis serve, running a race or just turning heads on the beach! Let’s start with the basics. There are over 650 muscles in the human body made up of three types: the cardiac muscle found in your heart, the smooth muscle that lines organs such as your stomach and esophagus, and skeletal muscle, which attaches to your bones via tendons. Skeletal muscles are the ones we are discussing in this article and they make up 30 to 40 percent of your body mass and are largely voluntary, meaning that you make them move.

Grow What You’ve Got

The number of muscle fibers you have was determined by the time you are in middle school. While you can’t increase the number of muscle fibers you have after puberty, you can control how big the fibers get which will determine how tight and strong you look.

Hurts So Good

When you cut your finger, your body heals, but if often overcompensates by leaving a scab. Something similar happens with muscles. Hoisting a barbell can cause microscopic tears in the muscle fibers. As a result, waves of white blood cells rush in to patch things up. While they’re at it, they release chemicals that set off pain receptors. The process peaks in about 36 hours post workout. This is referred to as delayed-onset muscle soreness, or DOMS. Try to resist the urge to take an over-the-counter pain medication to relieve the discomfort. This may blunt your body’s ability to rebuild muscle, meaning you get stronger more slowly. Kneading or massaging the muscle using slow, deep circles will provide relief. Soaking in a tub with epsom salts will also feel good.

Slow vs. Fast Twitch

All muscle fibers are not created equal. Slow-twitch fibers are perfect for endurance but don’t pack a whole lot of power. Fast-twitch fibers do the opposite. They offer bursts of rapid fire energy, but only for a short amount of time. Your genes control how much of one type or the other you have. If you’re looking to increase your endurance for a marathon, hone your slow-twitch muscles by lifting 2 to 3 sets with lighter weights, eking out 12 to 15 reps. If you want to improve your 5k final kick, try cranking out 2 to 3 sets of 6 to 8 reps at a heavier weight.

Our Muscles are Smart

When you fire a powerful punch in kickboxing class, your brain sends a signal down a nerve cell, telling certain muscle fibers in your arms, back, core and legs to contract. After a series of microscopic reactions, you deliver the knockout blow! As you practice, your brain and muscles learn to communicate more efficiently and you become more coordinated.

Visualize This

In 2007, researchers found that when healthy men and women spent 4 weeks visualizing themselves lifting weights, their actual strength went up 4 percent without ever lifting a single dumbbell. By comparison, a group that actually did strength train gained 5 percent and a control group that did nothing lost 0.2 percent. Bottom line? Thinking about exercises may help bolster the pathways between your brain and your muscles.

To Bulk Up or Not to Bulk Up

Weight lifting will not turn you into a raging superhero. It’s just not in your blood. Testosterone helps men gain bulk. When they lift weights the hormone causes their muscle fibers to grow. Since women have 20 to 30 percent less testosterone than men, women will gain strength without the bulk.

Men vs. Women – Who’s Stronger?

When researchers compared the muscle strength of men and women, they found that men were about 50 percent stronger than women. But when they factored in body weight and muscle weight, they discovered that, on a muscle to muscle basis, women are just as strong as men.

Where You’re Most Likely to Grow

It’s the width of your shoulders. Generally there isn’t a lot of fat around a person’s deltoids, so muscle growth there is more defined under your skin.

And finally…Why Do They Hurt After a Workout?

Recently researchers at the University of California, Berkeley, discovered the reason your muscles burn after a workout. Lactic acid. The acid is a main source of fuel for your muscles. When you push yourself, your muscles convert glucose from food into lactic acid which is moved via proteins to the mitochondria, your muscles’ energy factories. The more you work out, the more efficiently your body uses lactate as fuel…which means you can go longer and harder. Feel the burn…LOVE the burn!