Unfortunate that 7th graders play one sport all year (i.e. Hawks) They will burn out and get overuse injuries. Multisport is proven to lead to success in sports and life.( lacrosse dad orthopaedic surgeon)
You are thinking of pitchers in baseball and tennis players which put excessive stress on one particular movement. You really think soccer, football, and basketball work entirely different muscles and joints than lacrosse? Hawks and other top level clubs due minor lacrosse activities and a few practices in the off season to keep muscle memory there but not much more.
