April 1, 2009

    Quick, where is your core?

    Meeting a potential athlete, one of the first things we ask them is what they are specifically trying to improve. In other words, what’s their goal? Most of the time athletes want to get faster or stronger, more resistant to injury, but one we hear a lot is that they want a stronger “core.” This highlights one of the great marketing campaigns in the fitness world, the idea of “core training”. From golfers to grandmas, everyone this day is getting a stronger “core”. Every piece of fitness equipment sold on info-mercial promises that it will improve your “core strength”. So what is this “core training”, and why don’t we do it?

    Let’s start off by making a distinction; “core” is a marketing term used to make the muscles of your abdomen, or trunk sound better. “Abdomen training” just doesn’t sound that cool and won’t sell enough stability balls. The back and abdominal muscles responsible for flexing and extending, as well as rotating your trunk make up your “core”. They are active almost all day, whether you are sitting or standing, walking, or playing a sport. High speed, or explosive movements found in most sports do place a grater strain on all the muscles and connective tissues of your body, including those of your trunk. The goal of resistance training is to improve the strength and working capacity of your muscles and connective tissues, to improve sport performance and increase resistance to injury. So how can you improve the strength of your trunk muscles to adapt to the stress of explosive movement, and improve specific sport performance?

    These days, it is popular to use certain implements to change traditional resistance exercises to better emphasize the use of trunk stability muscles. We’ve all see people at the gym doing exercises on or with large rubber inflated balls (“swiss balls”), Bosu balls (yoga ball cut in half) and thick soft foam pads. The idea here is that the unstable surface further challenges your ability to balance, and therefore recruits and stimulates your trunk muscles to a greater extent. Research out of the School of Human Movement Studies at Charles University in Australia specifically compared muscular activity during a traditional squat exercise while standing on stable floor, a foam mat and a Bosu ball. The researchers found that not only did the stable floor produce the greatest muscular stimulus, but unstable surfaces (foam pad and Bosu ball) negatively affected movement mechanics to the point of becoming dangerous for lower extremity (legs) joints and connective tissues.

    So what about doing exercises that specifically target “core” muscles? Research from the Neuromuscular Laboratory at Appalachian State University compared the activity of trunk muscles while doing two traditional barbell resistance exercises (squat and dead lift), and three popular “core” specific stability ball exercises. The traditional barbell exercises produced greater muscular stimulus than the stability ball movements. Researchers went on to say that the stability ball exercises did not produce enough muscular stimulus to increase strength or hypertrophy (growth) in healthy subjects. Further research out of The Department of Biokinesiology and Physical Therapy at The University of Southern California tested the activity of four key trunk muscles during two popular spine stabilization exercises (Dead Bug and Quadruped). Again, researchers found that the muscular recruitment during the exercises was not great enough to provide a strengthening effect in healthy subjects.

    What athletes need to take away is that all training is “core” training, trunk muscles are active during every sporting movement. As the intensity of the movement increases (i.e. when you jump higher or swing harder), the stress on your trunk muscles becomes greater. But the best part is that these trunk muscles will adapt to the increased stress. So, if you use barbell squats to improve the strength of your leg muscles, you’ll also be improving your trunk strength just by supporting the weight on the bar. As your legs get stronger and you are able to lift more weight, your trunk muscles adapt proportionately to the increased load on your back (or chest). Stability balls and foam pads are great for use in a physical therapy setting, helping injured or elderly people train their impaired balance and coordination. But, if your trainer is using these implements to improve your strength and sporting performance, chances are they aren’t trained in the field of sport science, and probably don’t know how to properly teach you how to squat.

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