Side, elbow and basic planks: great exercises to improve posture and activate your core muscles.
If you run, or just want to feel better and improve your posture, planks are an excellent exercise you can do to achieve this. Do these prior to a run, improve your upper body stamina for longer runs or just help your core work better.
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Please also check out http://www.lifehack.org/292578/7-things-that-will-happen-when-you-start-doing-planks-every-day. This is where we found this exercise. Also visit http://darebee.com/ for some great exercises as well