Federal airport security screeners have one of the highest injury rates in the nation — mostly because of strains, sprains and spasms from struggling with luggage at poorly designed checkpoints, according to a USA Today review of federal labor and homeland security records.

Injured workers at the Transportation Security Administration (TSA), more than two-thirds of whom are screeners, missed nearly a quarter-million days of work last year. The lost job time has contributed to a staffing shortage that has strained checkpoint security and lengthened lines at airports.