We carry water bottles, music players, phones and activity trackers. And although we use them to make our runs easier, hereís the bad news: They could be slowing us down.
To understand why an MP3 player or a water bottle might hinder your progress, a brief lesson in biomechanics is in order.
Your upper body plays a critical role when you run. (Thatís why the bad guys never get far when they escape from police custody in handcuffs.) Both the arms and the torso come into play, helping the legs lift the body and working together to create a smooth stride.
Good running form starts in the hands. They should be relaxed and comfortable. If youíre holding something, youíll create tension and imbalance in your upper body.
No matter the object ó a water bottle, an iPod, a set of keys ó holding something alters your form and makes you exert more energy. And the more effort you expend, the faster youíll tire.
To see how this happens, pretend to grip a bottle and move your arms as you would while running. Even without the bottle, your forearm muscles contract.
Or try running with your fists clenched. That tension in your hands creeps to your forearms, then your upper arms. This makes shoulder rotation more difficult, which inhibits your leg drive.
To become more relaxed, hold a saltine cracker between your thumb and forefinger, and try not to break it while running.
Itís easy to see how even an empty water bottle or an iPod could have a detrimental effect on your gait.
On a physiological level, when you run, your blood gets redistributed to the areas of your body that need it.
As your hand and forearm muscles contract, blood flow to those places increases. But as you power up that hill, your blood has better places to be ó like your legs. To the casual runner, this diverted blood flow means a less enjoyable run (or a more painful one).
The bigger problem, however, is that these objects make your form asymmetrical. Jonathan Cane, co-author of ďThe Complete Idiotís Guide to Weight Training,Ē said he can always spot people holding something. ďThese people have what I call ĎiPod arms.í One arm moves less than the other.Ē
When one arm has less motion than the other, one stride will be shorter than the other, hence the asymmetry.
Form imbalance is not only inefficient, it could lead to injury. When your arms are unbalanced everything about your form is unbalanced.
You might end up putting more stress than usual on a muscle group. Or you might stress one side more than the other. This might not seem like a big deal, but multiply that one stride by the thousands you take during a run, and it adds up.
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