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Core exercises. Your abs are the bowstring to your back, if you have weak abs, you'll feel it in your back first. Wearing a heavy bag puts added stress on you back, which engages you abs, but we ...
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Core exercises. Your abs are the bowstring to your back, if you have weak abs, you'll feel it in your back first. Wearing a heavy bag puts added stress on you back, which engages you abs, but we ...