The jack knife complex is the combination of the jack knife, rotating jack knife and single-leg jack knife.
 
Perform the prescribed number of each variation and immediately move on to the next. For example, 2 jack knives, 2 rotating jack knives, and 2 single-leg jack knives, then repeat that series for the total number of reps in the set.
 
Between each rep, return to an extended body position without allowing the heels to touch the floor, keeping the abs crunched to maintain a hollow position and continuous tension.
 
Purpose
The jack knife complex is an easy but effective way to address multiple aspects of ab work and trunk control into a single exercise with no equipment.
 
Programming
The jack knife complex should be performed for sets of 10-30+, with anything from 2-16+ reps of each variation in each series.
 
Variations
The jack knife complex can be done with a pause at the top and/or bottom.