The Mariners are the only team to attempt this mostly weight-less approach. By using exercises that focus more on actual body movements used in the game rather than the usual emphasis on weightlifting, the Mariners are hoping to become more athletic and less prone to injuries.
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Pretty gutsy approach. I wonder how many players that have been lifting their whole lives will find this very inconvenient. This might become a much bigger story if it indeed works. Or if it has a bad clubhouse effect. It could go either way.