This is a response to the query: “Why do leg muscles tighten up after sitting for a while?”
There are several causes: (1) The type, style, shape, of the chair; Is it because you were driving for some 40 minutes in a small car with a newfangled driver’s bucket seat? (2) Obesity; (3) Posture; (4) Room temperature.
There are also several aspects of tightening muscles: (5) Do the lower leg muscles tighten up? (6) Do the outer thigh muscles tighten up? (7) Do the hamstrings tighten up?
(1) A common cause of leg muscles tightening up after sitting for a while is when in the seated position, the knees are higher than the butt. A low driver’s bucket seat, a sunken sofa chair, especially the giant leather ones, are the direct causes.
(2), (3) Excessive top-heavy body shape and body weight, and pregnancy will cause the leg muscles to tighten up while standing for a longer time. While seated, the upper body, the torso with a larger belly, have their center of gravity in line with the butt cleavage. When sitting in a giant soft sofa, the butt sinks into the chair and the kees become higher than the butt. And since the back of the sofa is usually quite far back, one will automatically lean backwards. The head and the neck are against the back of the big sofa. Your bent neck and your thighs and lower legs have to essentially sustain your upper body weight, i.e., the torso and the belly, and the center of gravity is skewed towards the back of the sunken butt to align with the bent neck. In this posture, the leg muscles tighten up, and so will your precious neck muscles.
(4) Room temperature that is too cold, wind blowing at the legs, etc. will tighten up the leg muscles.
(5), (6), (7) Many very different causes will bring on leg muscle tightness depending on which part of the leg muscles tighten up.
Take note of the type of chair you are sitting in that brings on leg muscle tightness, the location of where you sit, etc. and then take note of which part of the leg muscles tighten up.