Imaginary chair

This is a very intense workout for the quadriceps muscles, and it can be very painful to hold this position for extended periods.

Wall sits are used as a primary strengthening exercise in many sports requiring strong quadriceps including fencing, ice hockey, sailing (mostly small boat racing), skiing and track and field.

[citation needed] Wall sitting primarily builds isometric strength and endurance in glutes, calves, quadriceps, hamstrings, and adductor muscles.

A study in the British Journal of Sports Medicine of 270 trials found that isometric exercises which involve engaging muscles without movement, such as wall sits and planks, were more effective than other types of exercise for reducing blood pressure.

Four repetitions of a two-minute wall sit followed by two minutes' rest, three times per week, was recommended to reduce blood pressure.