By: Emily Fonnesbeck
As you probably know, gravity is the force that pulls you towards the earth. At a rate of 32.2 ft/s², gravity can be your friend and sometimes your enemy. Tripping on your four-inch heels as you maneuver the stairs? Enemy. Working out? Friend! Confused? Ok, let me explain.
When you work out, and especially when you lift weights, opposing forces help you get the job done. Learning a simple concept can maximize your work out and allow gravity to help you in the best possible way.
Concentric vs. Eccentric Motion
A concentric motion is a motion that closes the joint angle. For example, in a bicep curl, the concentric motion is the one that brings your forearm closer to your body, thus closing that 90 to 180 degree angle. The girl on the right (B) has just finished her concentric movement, bringing the bar close to her.
Conversely, the girl on the left (A) has just finished her eccentric motion, or the motion that makes the joint angle larger. Easy enough, right? Concentric in, eccentric away. Now that you understand the concentric and eccentric motions, you can do something with that little golden nugget of knowledge I have just planted in your brain.
Since we have an illustration, we will use the bicep curl for an example. When the average person does a bicep curl, they tend to curl up (concentrically) fast and hard, and then let gravity take the weight down quickly in the eccentric motion. This is easy to do, and a common mistake, but yes, it is a mistake. This is why: you build more muscle in the eccentric motion than in the concentric motion! Let me rephrase. In the bicep curl, you build more muscle and burn more fat when you concentrate on the “down” portion of the exercise.
This concept applies to all weight training exercises, and can really make a difference in your training. So, next time you lift weights, really concentrate on what you are doing. Make sure that both the concentric and eccentric motions are slow and controlled, especially on the eccentric. Don’t let gravity pull that weight down! If you have to do a fast motion, make it the motion on the way up, and make the motion on the way down the one that counts.
As always, be careful not to hurt yourself or burn yourself out. A strength training regimen is the like the Prince Charming of your Cinderella weight-loss plan, so make those hours in the gym count!