Isometric neck extension against strap (Cervical extension strengthening isometric, with band, sitting; 02)

Sit or stand up straight with a strap looped around the back of your head.
Hold the ends of the band firmly in front of you ensuring there is tension in the strap.
Press the back of your head into the strap as though trying to look up.
Resist the movement with the strap with both hands.
Ensure you keep your head in the neutral position.
Hold this position.
Relax, and repeat.