On 4/23/24, 2 employees were loading a gasoline generator into the bed of a pick up truck. They then traveled to their jobsite. Once at the job site, an EE stated that EE thought EE pulled a muscle in EE's back while lifting the generator. EE was taken to the clinic & released. On 5/7/24 EE returned to the clinic with back pain from the generator lift. EE was issued restrictions.