An exercise machine to strengthen abdominal muscles may include a first unit and a second unit. The first unit may be adjustably coupled to the second unit. Each of the first unit and the second unit may include a track, an end bridge adjustably coupled to the track towards a first end of the track, a handle disposed proximate an outer surface of the track and towards a second end of the track, a platform slidably coupled to the track and configured to slide along at least a portion of a length of the track between the end bridge and the handle, and a tensioning element. A first end of the tensioning element may be coupled to the end bridge and a second end of the tensioning element may be coupled to the platform. The platform may include a knee adapter configured to accommodate a knee of a user.