These old-fashioned stretching exercises have been used by generations of athletes - and for all those generations they have been a bad idea. If your trainer inflicts these on you, it may just be from lack of awareness.
Goal is to stretch your neck; actual effect is to put harmful stresses on your neck vertebrae. Especially not for those of us who spend the day hunched over a comp.
Double leg-lift, straight legs
Strains the back muscles and doesn't even work out the muscles it was supposed to benefit -- the abdominals. Again, there really are simpler ways to go after that gut minus the strain this puts on the lower back.
Supposed to stretch out hamstring muscles on backs of legs, instead strains lower back. There are simpler stretches for the hamstring that do not put any load on the spine.
Sitting on the floor, bend one knee backward, extend other knee and lean forward; exercise puts dangerous stress on knee and hip joints,especially if you force bent knee downward. Looks cool and may make you feel like you are aping top athletes but you can be sure that they no longer push their joints into contortions similar to this particular one.